50/50 weight distribution isn't actually ideal for a RWD car. "Perfect 50/50" was idealized for marketing purposes because its easy for a casual consumer to equate 50/50 with being "balanced" and "precise." It takes a lot more customer education to explain that a slight rear bias will actually handle better and that there isn't any particular perfect ratio because it depends on a lot of factors that most customers wont understand.
what you're saying doesn't go against the IRS because they actually are a bit heavier so they will slightly bias the weight towards the rear, not to mention they make handling better , seriously my 2004 golf mk5 has rear multi link IRS and its not even RWD, Ford was just saying :"handling?? naah"
Have you ever driven a close to 50/50 car? Like and RX8 or a BRZ? Or a Miata for that matter. All of them handle amazing. Granted that could be from something else other then the weight distribution, but all the sports cars that get close to that 50/50 handle incredibly
Definitely bro science, but wouldn’t a slight front-bias actually be best for a RWD car? I mean, basic physics say weight transfers to the rear when you drive, so a slight weight bias in the front actually leads to more-even grip on all 4 wheels? But the 50-50 makes sense because when you drive, you both accelerate AND brake, so 50-50 leads to less disturbance. And rear bias in a RWD car would get the most grip to the powering wheels, but would lead to the car wanting to fishtail under braking. Again; pseudo science, but it makes sense in the head.
@@stevensullivan603 oh yeah, when I was saying bro science, I was referring to what I was about to say. A lot of it seems to do more with slip angles. He has a good explanation, but most of that is when talking about constant speeds and consistent angles/turns.
You are a clever guy that knows his physics, but I disagree in one of your statements. "Solid axles are better than independent for track use"? That might be true if going in a straight line. In corners you need camber both for wear and mechanical performance. You also want as little unsprung weight as possible as there is no such thing as a perfect surface ;) I only know of 2 kinds of motorsports that prefer the solid axle. Drag Racing and Rally-Cross (The start is that important).
The start of a sprint race is very important. If you Are in front into the first corner you have a Big advantage as it is very difficult to make a pass in rally cross (this is why the joker lap was added). Some say Rally Cross is nothing more than a dragrace with a few corners added..
I am for the IRS. mainly for the real world driving. I like powerful street cars, so I build them where they are gonna spend most of their life on the street or road course. the solid axle is ok, but not fit for a TRUE driver's car. a IRS can be made to handle street duty and drag racing duty as well, so to me the IRS is a win - win. now if Ford really wants to make a dollar, they should make the new IRS swappable to all the older mustangs, then we all will have a choice of having an IRS or live axle.
I've owned a few cars and one of them was an 88 gt mustang with an 8.8 live rear. I have to say, you never have to worry about cv joints in the axles going bad, the wheel bearings last forever and they are very cheap to build and maintain. I am a big fan of the live axles, plus burnouts are easier!
Came across this today... A lot less gray. I remember watching this years ago, I still watch your stuff. You have a great channel! Just commented for the hell of it.
Irs is safer without a doubt especially in a high performance vehicle where you can bring the back end around a lot easier. Live axle has it's place though for drag racers or those who may feel nostalgic about it.
Makes sense, I wouldn't be surprised if that was exactly why. Not enough enthusiasts are going to make a fuss about it, ultimately it will sell much better at lower cost.
Good point. The 03-04 Cobras used CVD from the diff housing to the wheels. And true, I persoanlly have not seen any independent suspension units using U-joints. But I can't say all independent suspensions are always CVDs, there could be some smaller unknown makers who use U-joints.
Ford said that half of its Mustang fans live outside the US where going fast around corners is much more appreciated than drag racing in between traffic lights per say. The only problem with fast American cars has always been handling and i think its time to move forwards on that not backwards by installing live axle.
So I don't know about a set ratio that you can use, but what's more important is whether or not the components rotate. Wheels/rotors rotate, requiring extra power to rotate rather than just a stationary thing like a brake caliper. Rotational inertia plays a big role in acceleration, so lighter tires or wheels will make a big difference. I should have videos discussing rotational inertia eventually, it's an awesome topic.
Haha, I agree. Still confused why NASCAR has carbs (I think they just switched over though), pushrods, iron blocks, and 2 valves/cyl. But it's "tradition" and to some people that's important. I don't know...
Its not just a lower geared axel option. Its springs and dampers, new tires and rims, wheel bearings, toe links, rear shock mounts, newer fuel pump, strut braces, some visual effects, different exhaust system, and a few other things. All from the ZL1.
I apologize, I didn't realize it was a quote from Motor Trend. If you're going to use your Mustang for a daily driver/track car, I think independent is the way to go. However, if it is to be used for drag racing, it would be wise to keep the solid axle. This is why the Camaro COPO actually has a solid axle in the rear. But what I was saying in track cars cant apply the power drag cars can, because they're not going in a straight line, so the independent suspension can handle high enough torque.
Ford did this from 99-04. Plenty of guys swaping out entire suspensions. You can even for the IRS from a 99-04 onto a 79 Fox with no major modifications.
I just purchased a 2014 Shelby GT500 and have been doing research to decide what modifications I would do. I appreciate the young man in Engineering Explained for his post. You are outstanding! The best response so far to me has been from Mustang Guy. I know the Camaro ZL1 has an IRS and better handling on winding roads, but the Shelby with big HP and torque needs the live solid axle and will dust most rides from a stop light straight away where most challenges and my driving will take place.
The marketing argument stands firm for me because Mustang buyers are usually lovers of the brand. Promotion aspect receives a positive as you mentioned a buyer could be swayed by the fact that Ford is keeping up with the modern tech. However, the overall feedback of the current loyal client would be crucial to continuing with IRS or switching back to a live solid axle.
Because decreasing weight increases every aspect of a cars performance. It's one of the easiest ways to get an incredible performance gain. Saving weight is better than adding power in my opinion; less energy required to accelerate/decelerate, increases cornering ability and cornering potential with the use of downforce,
I understand your argument as it assumes either a multi-link, or double wishbone set up for the IRS. Another player for the role to consider is a trailing arm set up.They are extremely simple, to the point of easily utilizing torsion springs. No camber change, and they don't limit the CV geometry like either a Multi-link or a double wishbone do. They do have to be heavy to prevent lateral flex, but some creative use of an anti roll bar at the rear could reduce the need of material on the arms.
To add to what the video poster said they are ways to balance the weight with out adding more weight to the car. This can be done by moving the battery to the trunk and making the engine sit father back from the front axle ect.
"Being able to put down more power." That's a fairly uneducated comment. Using the right materials, or geometry, or drive shaft thicknesses, an IRS can handle any amount of torque you could reasonably put down on the road. Besides, the Shelby GT500 has enough problems as is putting the power down, and the weak link is not the drivetrain. It's because it's overpowered and the weight isn't distributed too well for a RWD car.
You hinted at it in the video but I don't think most people realize the Mustang had IRS in the SVT models of 1999 Cobra, 2000 Cobra R and 2003-2004 "Terminator" Cobra. That IRS setup I believe was borrowed from the 1989-1997 Thunderbird as I heard the rear control arms and CV shafts are interchangeable and that in turn may have even borrowed some from Jaguar before that! So that was an old design that goes back at least to the late 1980s but it still worked ok for the most part. No reason to think they couldn't do something better now. But that said you're right, solid rear axle can work very well on a smooth road course/track (I've heard old Mazda MX5 guys say the same) and it's very impressive how well the current Mustang can handle on a proper track with just a little bit of suspension modification. Considering the size and weight of the car it can handle very well. I could see Ford wanting to go either way, it's a tough decision. But you're right people will assume IRS is better. I see it all the time in Mustang videos people saying "how shitty it is because it still uses a sold rear axle" or at least, "how much better it would be with IRS" when it actuality may not really be. Damn, I don't know! I kinda want both! But having the option for both... could backfire. I'll just have to wait and see what Ford decides.
I read a while back in a Ford article that the reason they didn't put IRS in the new 2010-2011 is because it would cost Mustang owners an extra $3000 and a lot of lost rear seat room and trunk space. They said the extra $3000 was detrimental to them because it could decreases sales so they wanted it to be affordable and keep its record of being number 1 selling pony/muscle in the US.
That's interesting, didn't really think about it actually. What makes the difference? Seems to me that IRS could be just as effective, but I suppose there may be losses in constant velocity joints that don't occur with a more direct drive.
unsprung mass is supported directly by the wheels/tires. when there's a bump or weight shift (during maneuvering) unsprung mass is not controlled/dampened by the suspension system. unless you drive a gokart (usually dont have suspensions, meaning the whole car is unsprung mass) on smooth surface, you want to reduce unsprung mass as much as possible to improve handling characteristics.
Part 1 of 3: Before I begin, let me just say that I had no idea what IRS or Live Axle meant. In the light of your very comprehensive exposé, I think that Ford should definitely go for the IRS Here's why: 1. Research: Research is the thing that brings the world forward so it can only be positive to carry it out. and attempt to create something better... one way or another, they're gonna make it work. And there are also many positive by products of research - so it will definitely be beneficial
IRS ALL THE WAY! I drive a 94 Mustang GT and just recently traded my solid axle for an 03 Cobra IRS. And I love it! I autocross cross my car and hoon on the streets every single day and the car was just way to unpredictable. I felt as if the rear of my car would just float around and never have any grip despite my 315s I have out back. Now that I have an IRS I have way more control of the car. I have way more confidence, feel and can actually control the rear of the car with the throttle now.
I agree, it's an excellent car and for the money it's pretty much unmatched (from a statistical perspective). But could it improve it's real world driving ability with an IRS? That's what's to be determined.
one of the main disadvantages of Live Axle is controlling lateral movement of the unit, one of the greatest sources of instability, currently Ford uses a panhard bar set up on the Mustang, better that the multiple links used but not the best, I will like for them to keep the live axle but with a Watts link set up, they can beat the Crapmaro IRS easy with a refined live axle
I strongly agree man. The Mustang has always been built for the drag strips. Also to the uploader I find Live Axle much better for everyday driving (atleast for driving in Florida, Texas, and the South). Most of the roads are straight and it's easier to keep a live axle car straight. Plus I never have any problems on rough road in my third gen Camaro, or my dad's Ford Ranger. I have the most problems in my Mom's IRS Lexus!
Yeah I agree, tradition upheld in professional environments can really provide contrast showing-off new technology; first thing that comes to mind is how fast that electric car was(the one that has the documentary on who "killed" it).
An IRS doesn't magically make you corner at greater speeds. It does if the road is in poor condition, but if you're on a perfect flat track or something similar, you probably wouldn't notice a difference. The reason an IRS is a superior design is because it can handle situations that a live axle might cause you to kick the rear end out on, not because it increases the lateral g's your car can hold.
The only reason I feel for is putting an IRS in the mustang is for daily driving use and maybe for tracks (not drag strips). The IRS I think will yield a better daily driven ride over the Live rear. that being said I think it would be a cool idea if they made it an option to have either or. or make it so you can do a diret bolt over swap between the two so you can hit the strips on the weekend and swap it to IRS for the weekdays. a lot of work yes but i have seen people do crazier things lol
I agree, but F1's don't stay on a perfect track; many corners and apex's include rumble strips. I do agree also that an IRS allows for more manipulation of the wheels orientation. F1 has much higher cornering speeds than regular road cars, however, so enhancements are much more easily seen. If you want a Mustang to go around a smooth corner faster, swap out the tires, not the suspension. If you want the absolute best, then swap both, but tires are much cheaper and provide a greater difference.
It all boils down to wheel hop in this case. The greater mass exacerbates the bumpiness of the road, and means rather than the wheels rebounding a little and then gripping, the wheels hop for much longer and can't catch traction as readily.
At the track, rear wheels don't need to move individually. IRS minimizes contact patch as the suspension travels through its range of motion. The harder you push IRS, the more you're riding on the tire's edges or side walls. IRS contact patch narrows even further with ultra low profiles on huge 19" wheels. For spirited driving on public roads, IRS is better especially for the when you're on unfamiliar or bumpy roads, but the difference isn't much when you're comparing equally stiff suspensions.
One thing that you can also think about is which amount of mass is moving more/quicker? The Unsprung weight is going to be moving quite a bit more and faster therefore you would like to have that mass be as small as possible inorder to reduce your Kinetic Energy and impulse. (Ke=.5mv^2 and I=dP/dT)
I watched a you tube video of a 2004 svt cobra mustang with IRS beating a 2007 mustang cobra gt 500 by a tenth of a second. The o4 cobra had 390 bhp and the 07 gt500 had 450 bhp. This happened because of several reasons. 04 cobra has the IRS allowing more power to the wheels(dyno power) improved traction/wt. distribution, and ruduced weight by 200 pounds. This demonstrates that having the IRS, will allow the next generation mustang to accelerate faster than a live axle. Less wt. fun to drive!
Typically they are good on tracks. Maybe if you're takin a corner at really high speeds they wouldn't be fantastic... Also, as people really enjoy getting mods for their 'Stangs and doing work on them, the live axle might be a better fit for owners to fix things themselves
To answer your question. I think they should keep the live axle as long as they feel they can beat their main competition. And thats the Chevy Camaro. I'll give you two examples. The Ford Mustang Gt 5.0 posted slightly quicker lap times on some tracks vs. the Camaro SS with its IRS. And also a mustang GT 5.0 equaled a BMW m3 on a track. Only posting a lap time 1 tenth of a second slower. I say Ford is doing fine with solid rear axle.
Just found your videos. Awesome stuff! Actual educated discussions with real numbers and the real physics. Now then, the topic on my mind is rotational inertia and the measurable difference that unsprung mass reduction has on a vehicle. Certainly braking distance must be affected. Consider the company Tikore which sells titanium lug nuts just to reduce rotational inertia and thus reduce the forces which a brake system must absorb to stop a car. Assume traction and temperature is a constant.
Solid axles have a major benefit over IRS, the wheels are parallel to the road surface at all times even when the body is at full tilt! IRS has a tendency to change geometries with body roll. With that being said, body roll is just a visual representation of the G-force's on the car, if the suspension or wheels don't change their relative geometry to the road surface there will be no traction loss from body roll; making the design of the vehicle more important than the suspension type. It depends on the function of the vehicle and what you want to be doing as to what suspension is best at the time.
That's actually a disadvantage in a car that's going around a corner. You actually want to gain camber, something only short-long-arm suspensions can provide, for max grip as the tires sheer with a cornering load. Why do you think, even on solid axle mustangs, a track alignment calls for maximum font negative camber (which without cutting the strut towers is generally 3°)? Hell, why do you think F1 cars use independent suspension if a solid axle is better?
"if the suspension or wheels don't change their relative geometry to the road surface there will be no traction loss from body roll; making the design of the vehicle more important than the suspension type. It depends on the function of the vehicle and what you want to be doing as to what suspension is best at the time."
Gr1pEnemy Sure, if your tires are made of delrin. But they're not, they're made of rubber and they deform under a cornering load. This is why you need camber when cornering.
Funny thing is: a bloke named Klaus Arning--the guy who helped design the suspensions on the orignal Mustang, the GT-40, and others--ALREADY designed an IRS setup that would have been a bolt-in application for the Mustang--over 40 years ago! Arning's "T5" design was apparently patented, and supposedly designed to have inherent anti-dive and anti-squat characteristics. AFAIK, there's a guy named Duane Carling who's adapted this IRS for 5th-gen Mustangs as well...
the fact that the 50:50 ratio is almost maintained that is a more better suspension, but another thing about the IRS is that it allows more control for transfer of body weight like drifting or sharp corners
Ya im not sure how well that truck operates since I have never used one but im sure it works just as well as a leaf spring if you have a badass progessive coil spring.
It's interesting that you see more sophisticated (complicated and more expensive) suspension on European and Japanese cars, compared to standard cars in the US. I guess this is, ultimately, down to the roads - you can get away with a live axle with the straight and well maintained roads (not exclusively) in the US, whereas in Europe the roads are twisty and tend to be badly maintained (again not exclusively but particularly in the UK). Obviously cost and power handling ability are important too.
Also, production cars are built on "platforms" that are designed to work with certain range of components. I think that it would be rather difficult to design a platform that would allow easily installing an IRS and a LA. If I'm not mistaken, suspension type IS a factor that is taken into account when designing a platform. I guess a platform that would cater for both types of suspension could have drawbacks and compromise other things...
Real world driving isn't typically done at high speed so traction is less of an issue when compared to things like weight and gas mileage and stopping distance. I would be interested in hearing an argument for choosing an (LRA + Watts Link) as an upgrade versus the IRS as adding the Watts link would reduce performance differences while not adding as much cost, research and weight as an IRS.
It completely depends on whether they want the Mustang to turn into a more exclusive car or a little bit more common. With the continuation (and hopefully improvement) of the Live Axle, the Mustang would continue to be a car meant for serious driving that can rip it up on the tracks. With the switch to the IRS, Mustangs will only be slipping into a more regular car (although not quite). People will see it as a commuter or a family car. In my opinion, Ford should keep the Mustang more exclusive
IRS suspension is the way to go on a road sports car for the improved handling performance around the bends. Live axles are great for hot rods and off-roading. Its about time Ford made a change.
well, in my opinion i would say that the mustang is highly used for drag racing, street racing and burning outs purposes - to show the big block engine's power-, it comes from its heritage, yet putting the IRS surly would make the car flows better at the street and possibly more enjoyable, i would think if there would be a suspension that would be between those two or has both characteristics at least.
The live axle also takes a lot of space from the rear and with the new IRS ford can make the mustang have more space for the rear seats or a bigger fuel tank.
In my opinion I think Ford made a good choice going for IRS. You gotta remember that there's a lot of people buying these cars who aren't experienced drivers and will most likely never take the car to a track. I feel like good handling is very important on any car that's pushing a lot of power.
I think Ford should keep the live axle suspension. A Mustang is made to be wild. That's what makes it a Mustang. You must control and tame it with skill. But just in case the car is too wild for the driver and road conditions are poor, Mustang should develop a traction system that monitors and compensates for the unsprung mass of the live axle with the money they were going to spend on an irs.
Care to elaborate on why a 4 link would "get tons more better performance" than a 3 link? I'm no Mustang enthusiast, but from what I've read Ford specifically decided to go with 3 rather than 4 due to axle bind and the loss of traction in corners (oversteer).
could not agree more. I have a live axle mustang with light cf driveshaft and wheels, clutch etc.. its super efficient. about 10% vs. 25% from IRS. but I would trade it for an independent setup any day, putting power down is much better with the new Mustang IRS.
Why is anyone arguing? The new mustangs are killing the competition. The 5.0 runs with a 2011 M3(IRS) smashes the Camaro SS(IRS) and SRT8 392(IRS) and the boss is a straight up beast. I'm just excited to see what ford brings next. Love my 5.0!
I think it would be a good idea to make all 4 wheel drive vehicles with independent suspension all round especially expedition 4x4s and 4x4s that are used in remote areas where there is wild life. If a spring bok, deer, a rock or a pot hole suddenly appears in the middle of the road you can veer of the road on to the uneven surface and still be able to control the vehicle from maybe 50 mph down to 0. I am sure the insurance companies would reduce they quotes as well.
I believe it really depends what you want to do with the car....drag race on tracks...Live axle....street racing and daily IRS...Since I’m on street I prefer IRS...it handles the variables really well...verses Live which you can hit a bump and lose traction really bad...
hi! i'm restoring a 69 mustang and i was looking for modern suspension for it,your explanation was very helpful and simplistic so thanks you. as to "IRS" vs Solid axle, I think its more of a personal preference than anything else, personally i think Keep the solid axle, it dose its job well,high end cars use IRS but they also use electronically controlled AWD systems that help stabilize the vehicle at high speeds, neither is needed for a daily driver, BTW congrats on the job and good luck...
Fully functional without electronics, like the majority of suspensions. It's not an active suspension like you might find on BMW 6 series (or other car).
The main think for me is how the car's rear would shoot left or right severely over railroad tracks or large upsets on Michigan roads. I think the only thing I hated on the car was that when I had one.
Oh i forgot it all depends on what kind of driving you want to do it you want to drag race or drift you want the solid rear end due to it having dependent suspension now on circuit or sprint you want the independent suspension just due to the fact if you are turning at high speeds you don't want the rear coming out from underneath you (spinning out) so i think its just depends on what you do and like if you like fooling around and sliding go solid if you want to be precise than go independent
I think, like he said, Ford is doing it more for marketing than anything else; so that it is more competitive with European and Asian cars and being able to sell more these cars overseas. IRS does make the car handle better but it would only be noticeable if you actually take the to its limit which most people won't.
Mustang may have a solid axle option, installed at the dealer Just rumor at this point 2004 Cobra IRS was setup to be interchangeable, but it also made it less functional
Some of the live axle issues could be resolved with a watts linkage instead of a panhard rod, but I agree, it's about time for a good live axle system to be implemented. The benefits outweigh the disadvantages. Also with Ford's marketing division stressing bringing the mustang's image into the present and future starting with the 2013 refresh, a IRS is pratically guaranteed.
The double wishbone is clearly the better IRS, and while it does keep the tires parallel and planted to the pavement under hard straight-line braking and accelerating, as IRS cars roll in turns, it's a completely different story. How do live rear axles cause tire slippage? They have better bite from a better contact patch under hard braking/cornering/accelerating plus quick elevation changes or any combination thereof.
They should have a track package "plus" and "Pro" for factory v6 mustangs. They already have plenty of power and an IRS plus a factory power adder that will allow the owner to FURTHER tune the vehicle on boost would be SUPERB in a v6 mustang. I would love to have a 450hp mustang with beefie shocks, brakes, tires, and an IRS in the back. It'd be even better if they could get some of that corvette rear transaxle business going. The car would SHINE LIKE A DIAMOND!
ive always wanted a mustang i was planning on getting a 65 but the 2011's 5.0 convince to get a new one but from what learn the 2015 mustang it sounds great hopefully ill save a good 20 grand so i can buy one.
IRS sports cars have tight suspensions and don't negotiate bad road surfaces as well as you'd think. Better than LRA? Marginally if at all. Remember, a thick sway bar will communicate shock to the other 'independent' side. LRA has the clear advantage everywhere else including road courses. But then, the more technical a track is, the more LRA prevails. Push IRS too hard and fully compress/unload, and you're riding on the edge of those wide, low profile tires as opposed to full LRA contact patch.
And what about the in between option? De Dion axle: it's still a live axle, but the differential is attached to the car frame, so the unsprung mass is less than that of a traditional live axle.
one of the reasons why soo many people love the mustangs is because they have the best speed/performance to price ratio. 420hp for $30,000! i say keep the live axle for now because so far. mustangs still are the better track car in comparison to a camaro, which is the main competition. when other sport cars start to pass up the mustang. im sure ford will decide its time to invest in the irs.
IRS is better all around. I understand the nostalgic draw of a live axle but it's time for the mustang to become a little more modern. Besides we'll always have the older cars with the live axles to enjoy.
The biggest factor is going to be durability and power. A huge issue with the '13 shelby is durability in the rear end and driveshaft. The cost to design and make an IRS capable of handling even 500+HP for more than a couple thousand miles without issue would be pretty big and pump up the cost of the entire model line alot. It all depends on where Ford thinks the hearts of it's buyers are... If they target those who want street capability, the power is going to drop and prices are going up....
Let's see if the potential buyers would still go for the mustang considering it was more than good enough even with the live rear axle. A transition to IRS would mean it would be 10x better than it's current competition because it could still stand it's ground with an antiquated system? At least that's what i am assuming considering the ranting about the live rear axle. I switched from a Fiesta ST to a Mustang GT and didn't really have problems adapting and the roads over here are far from good.
50/50 weight distribution isn't actually ideal for a RWD car. "Perfect 50/50" was idealized for marketing purposes because its easy for a casual consumer to equate 50/50 with being "balanced" and "precise." It takes a lot more customer education to explain that a slight rear bias will actually handle better and that there isn't any particular perfect ratio because it depends on a lot of factors that most customers wont understand.
what you're saying doesn't go against the IRS because they actually are a bit heavier so they will slightly bias the weight towards the rear, not to mention they make handling better , seriously my 2004 golf mk5 has rear multi link IRS and its not even RWD, Ford was just saying :"handling?? naah"
Have you ever driven a close to 50/50 car? Like and RX8 or a BRZ? Or a Miata for that matter. All of them handle amazing. Granted that could be from something else other then the weight distribution, but all the sports cars that get close to that 50/50 handle incredibly
Definitely bro science, but wouldn’t a slight front-bias actually be best for a RWD car?
I mean, basic physics say weight transfers to the rear when you drive, so a slight weight bias in the front actually leads to more-even grip on all 4 wheels?
But the 50-50 makes sense because when you drive, you both accelerate AND brake, so 50-50 leads to less disturbance.
And rear bias in a RWD car would get the most grip to the powering wheels, but would lead to the car wanting to fishtail under braking.
Again; pseudo science, but it makes sense in the head.
@@Quesadila21 EE has another video on 50/50 weight distribution. You should check it out.
@@stevensullivan603 oh yeah, when I was saying bro science, I was referring to what I was about to say.
A lot of it seems to do more with slip angles.
He has a good explanation, but most of that is when talking about constant speeds and consistent angles/turns.
I don't like the IRS because it reminds me of taxes
True
lmfao!!!
Lmao!
Ya if there was no taxes I’d have a mystichrome AND a c6 z06
I am Canadian, tell me about taxes
You are a clever guy that knows his physics, but I disagree in one of your statements. "Solid axles are better than independent for track use"? That might be true if going in a straight line. In corners you need camber both for wear and mechanical performance. You also want as little unsprung weight as possible as there is no such thing as a perfect surface ;)
I only know of 2 kinds of motorsports that prefer the solid axle. Drag Racing and Rally-Cross (The start is that important).
why would you want a solid axle in rally cross?
im also confused about that
Also in Dakar. When you're race track is across countries and mostly in the middle of nowhere durability is king and ease of repair it's queen.
He meant a strait line bro here in America when people say track, they mean the drag strip
The start of a sprint race is very important. If you Are in front into the first corner you have a Big advantage as it is very difficult to make a pass in rally cross (this is why the joker lap was added). Some say Rally Cross is nothing more than a dragrace with a few corners added..
I am for the IRS. mainly for the real world driving. I like powerful street cars, so I build them where they are gonna spend most of their life on the street or road course. the solid axle is ok, but not fit for a TRUE driver's car. a IRS can be made to handle street duty and drag racing duty as well, so to me the IRS is a win - win. now if Ford really wants to make a dollar, they should make the new IRS swappable to all the older mustangs, then we all will have a choice of having an IRS or live axle.
PANTYEATR1 99-04 Cobra IRS fits 79-04 Mustang
I've owned a few cars and one of them was an 88 gt mustang with an 8.8 live rear. I have to say, you never have to worry about cv joints in the axles going bad, the wheel bearings last forever and they are very cheap to build and maintain. I am a big fan of the live axles, plus burnouts are easier!
Came across this today... A lot less gray. I remember watching this years ago, I still watch your stuff. You have a great channel! Just commented for the hell of it.
Rotational inertia is a phenomenal (and extraordinarily complicated, in my opinion) topic. I hope to get some basics on it eventually into my videos.
Irs is safer without a doubt especially in a high performance vehicle where you can bring the back end around a lot easier. Live axle has it's place though for drag racers or those who may feel nostalgic about it.
Thank you man, i was wondering what was the difference. Now i know..thx alot :)
IRS because less runover crowds
Makes sense, I wouldn't be surprised if that was exactly why. Not enough enthusiasts are going to make a fuss about it, ultimately it will sell much better at lower cost.
Good point. The 03-04 Cobras used CVD from the diff housing to the wheels.
And true, I persoanlly have not seen any independent suspension units using U-joints. But I can't say all independent suspensions are always CVDs, there could be some smaller unknown makers who use U-joints.
Ford said that half of its Mustang fans live outside the US where going fast around corners is much more appreciated than drag racing in between traffic lights per say. The only problem with fast American cars has always been handling and i think its time to move forwards on that not backwards by installing live axle.
Thank you for the kind words sir!
So I don't know about a set ratio that you can use, but what's more important is whether or not the components rotate. Wheels/rotors rotate, requiring extra power to rotate rather than just a stationary thing like a brake caliper. Rotational inertia plays a big role in acceleration, so lighter tires or wheels will make a big difference. I should have videos discussing rotational inertia eventually, it's an awesome topic.
It's all good. There just comes a point in discussion where it's best to discuss one on one rather than in a message thread. Thanks for understanding!
Haha, I agree. Still confused why NASCAR has carbs (I think they just switched over though), pushrods, iron blocks, and 2 valves/cyl. But it's "tradition" and to some people that's important. I don't know...
Its not just a lower geared axel option. Its springs and dampers, new tires and rims, wheel bearings, toe links, rear shock mounts, newer fuel pump, strut braces, some visual effects, different exhaust system, and a few other things.
All from the ZL1.
I apologize, I didn't realize it was a quote from Motor Trend. If you're going to use your Mustang for a daily driver/track car, I think independent is the way to go. However, if it is to be used for drag racing, it would be wise to keep the solid axle. This is why the Camaro COPO actually has a solid axle in the rear. But what I was saying in track cars cant apply the power drag cars can, because they're not going in a straight line, so the independent suspension can handle high enough torque.
Maybe give people the option of Live or IRS on the same year Mustang. That’ll really prove which is better.
Ford did this from 99-04. Plenty of guys swaping out entire suspensions. You can even for the IRS from a 99-04 onto a 79 Fox with no major modifications.
I just purchased a 2014 Shelby GT500 and have been doing research to decide what modifications I would do. I appreciate the young man in Engineering Explained for his post. You are outstanding! The best response so far to me has been from Mustang Guy. I know the Camaro ZL1 has an IRS and better handling on winding roads, but the Shelby with big HP and torque needs the live solid axle and will dust most rides from a stop light straight away where most challenges and my driving will take place.
The marketing argument stands firm for me because Mustang buyers are usually lovers of the brand. Promotion aspect receives a positive as you mentioned a buyer could be swayed by the fact that Ford is keeping up with the modern tech. However, the overall feedback of the current loyal client would be crucial to continuing with IRS or switching back to a live solid axle.
This is exactly what I was looking for.
Thanks for making this!
Because decreasing weight increases every aspect of a cars performance. It's one of the easiest ways to get an incredible performance gain. Saving weight is better than adding power in my opinion; less energy required to accelerate/decelerate, increases cornering ability and cornering potential with the use of downforce,
Glad you appreciate the videos, thanks for the input!
I understand your argument as it assumes either a multi-link, or double wishbone set up for the IRS. Another player for the role to consider is a trailing arm set up.They are extremely simple, to the point of easily utilizing torsion springs. No camber change, and they don't limit the CV geometry like either a Multi-link or a double wishbone do. They do have to be heavy to prevent lateral flex, but some creative use of an anti roll bar at the rear could reduce the need of material on the arms.
To add to what the video poster said they are ways to balance the weight with out adding more weight to the car. This can be done by moving the battery to the trunk and making the engine sit father back from the front axle ect.
"Being able to put down more power." That's a fairly uneducated comment. Using the right materials, or geometry, or drive shaft thicknesses, an IRS can handle any amount of torque you could reasonably put down on the road. Besides, the Shelby GT500 has enough problems as is putting the power down, and the weak link is not the drivetrain. It's because it's overpowered and the weight isn't distributed too well for a RWD car.
You hinted at it in the video but I don't think most people realize the Mustang had IRS in the SVT models of 1999 Cobra, 2000 Cobra R and 2003-2004 "Terminator" Cobra. That IRS setup I believe was borrowed from the 1989-1997 Thunderbird as I heard the rear control arms and CV shafts are interchangeable and that in turn may have even borrowed some from Jaguar before that! So that was an old design that goes back at least to the late 1980s but it still worked ok for the most part. No reason to think they couldn't do something better now. But that said you're right, solid rear axle can work very well on a smooth road course/track (I've heard old Mazda MX5 guys say the same) and it's very impressive how well the current Mustang can handle on a proper track with just a little bit of suspension modification. Considering the size and weight of the car it can handle very well. I could see Ford wanting to go either way, it's a tough decision. But you're right people will assume IRS is better. I see it all the time in Mustang videos people saying "how shitty it is because it still uses a sold rear axle" or at least, "how much better it would be with IRS" when it actuality may not really be. Damn, I don't know! I kinda want both! But having the option for both... could backfire. I'll just have to wait and see what Ford decides.
Different isn't always a bad thing. I think they're doing pretty well, and considering they never went under, different seems to be working for them.
Well, the tires and the drive axles, and control arms keep it in place. But the springs rest on top of it, supporting the weight above.
The IRS is heavier, but a lot of the mass that makes it up is still supported by springs/shocks, unlike the bulky solid axle.
I read a while back in a Ford article that the reason they didn't put IRS in the new 2010-2011 is because it would cost Mustang owners an extra $3000 and a lot of lost rear seat room and trunk space. They said the extra $3000 was detrimental to them because it could decreases sales so they wanted it to be affordable and keep its record of being number 1 selling pony/muscle in the US.
That's interesting, didn't really think about it actually. What makes the difference? Seems to me that IRS could be just as effective, but I suppose there may be losses in constant velocity joints that don't occur with a more direct drive.
What makes a solid axle poor for drifting?
I guess you mean “good” and I guess is predictability
unsprung mass is supported directly by the wheels/tires. when there's a bump or weight shift (during maneuvering) unsprung mass is not controlled/dampened by the suspension system. unless you drive a gokart (usually dont have suspensions, meaning the whole car is unsprung mass) on smooth surface, you want to reduce unsprung mass as much as possible to improve handling characteristics.
Somewhat, I'm a fan of efficiency, and hence in my opinion less weight is nearly always better.
sometimes i find myself watching video after video after video on ur channel. they are all so good! keep it up
Yes, the IRS is great for track days and road courses, but if the course is smooth enough the difference will likely be minimal.
Part 1 of 3:
Before I begin, let me just say that I had no idea what IRS or Live Axle meant.
In the light of your very comprehensive exposé, I think that Ford should definitely go for the IRS
Here's why:
1. Research: Research is the thing that brings the world forward so it can only be positive to carry it out. and attempt to create something better... one way or another, they're gonna make it work. And there are also many positive by products of research - so it will definitely be beneficial
IRS ALL THE WAY! I drive a 94 Mustang GT and just recently traded my solid axle for an 03 Cobra IRS. And I love it! I autocross cross my car and hoon on the streets every single day and the car was just way to unpredictable. I felt as if the rear of my car would just float around and never have any grip despite my 315s I have out back. Now that I have an IRS I have way more control of the car. I have way more confidence, feel and can actually control the rear of the car with the throttle now.
I agree, it's an excellent car and for the money it's pretty much unmatched (from a statistical perspective). But could it improve it's real world driving ability with an IRS? That's what's to be determined.
one of the main disadvantages of Live Axle is controlling lateral movement of the unit, one of the greatest sources of instability, currently Ford uses a panhard bar set up on the Mustang, better that the multiple links used but not the best, I will like for them to keep the live axle but with a Watts link set up, they can beat the Crapmaro IRS easy with a refined live axle
I strongly agree man. The Mustang has always been built for the drag strips.
Also to the uploader I find Live Axle much better for everyday driving (atleast for driving in Florida, Texas, and the South). Most of the roads are straight and it's easier to keep a live axle car straight. Plus I never have any problems on rough road in my third gen Camaro, or my dad's Ford Ranger. I have the most problems in my Mom's IRS Lexus!
Yeah I agree, tradition upheld in professional environments can really provide contrast showing-off new technology; first thing that comes to mind is how fast that electric car was(the one that has the documentary on who "killed" it).
An IRS doesn't magically make you corner at greater speeds. It does if the road is in poor condition, but if you're on a perfect flat track or something similar, you probably wouldn't notice a difference. The reason an IRS is a superior design is because it can handle situations that a live axle might cause you to kick the rear end out on, not because it increases the lateral g's your car can hold.
The only reason I feel for is putting an IRS in the mustang is for daily driving use and maybe for tracks (not drag strips). The IRS I think will yield a better daily driven ride over the Live rear. that being said I think it would be a cool idea if they made it an option to have either or. or make it so you can do a diret bolt over swap between the two so you can hit the strips on the weekend and swap it to IRS for the weekdays. a lot of work yes but i have seen people do crazier things lol
I agree, but F1's don't stay on a perfect track; many corners and apex's include rumble strips. I do agree also that an IRS allows for more manipulation of the wheels orientation. F1 has much higher cornering speeds than regular road cars, however, so enhancements are much more easily seen. If you want a Mustang to go around a smooth corner faster, swap out the tires, not the suspension. If you want the absolute best, then swap both, but tires are much cheaper and provide a greater difference.
It all boils down to wheel hop in this case. The greater mass exacerbates the bumpiness of the road, and means rather than the wheels rebounding a little and then gripping, the wheels hop for much longer and can't catch traction as readily.
At the track, rear wheels don't need to move individually. IRS minimizes contact patch as the suspension travels through its range of motion. The harder you push IRS, the more you're riding on the tire's edges or side walls. IRS contact patch narrows even further with ultra low profiles on huge 19" wheels.
For spirited driving on public roads, IRS is better especially for the when you're on unfamiliar or bumpy roads, but the difference isn't much when you're comparing equally stiff suspensions.
One thing that you can also think about is which amount of mass is moving more/quicker? The Unsprung weight is going to be moving quite a bit more and faster therefore you would like to have that mass be as small as possible inorder to reduce your Kinetic Energy and impulse. (Ke=.5mv^2 and I=dP/dT)
I watched a you tube video of a 2004 svt cobra mustang with IRS beating a 2007 mustang cobra gt 500 by a tenth of a second. The o4 cobra had 390 bhp and the 07 gt500 had 450 bhp. This happened because of several reasons. 04 cobra has the IRS allowing more power to the wheels(dyno power) improved traction/wt. distribution, and ruduced weight by 200 pounds. This demonstrates that having the IRS, will allow the next generation mustang to accelerate faster than a live axle. Less wt. fun to drive!
Typically they are good on tracks. Maybe if you're takin a corner at really high speeds they wouldn't be fantastic...
Also, as people really enjoy getting mods for their 'Stangs and doing work on them, the live axle might be a better fit for owners to fix things themselves
To answer your question. I think they should keep the live axle as long as they feel they can beat their main competition. And thats the Chevy Camaro. I'll give you two examples. The Ford Mustang Gt 5.0 posted slightly quicker lap times on some tracks vs. the Camaro SS with its IRS. And also a mustang GT 5.0 equaled a BMW m3 on a track. Only posting a lap time 1 tenth of a second slower. I say Ford is doing fine with solid rear axle.
Just found your videos. Awesome stuff! Actual educated discussions with real numbers and the real physics. Now then, the topic on my mind is rotational inertia and the measurable difference that unsprung mass reduction has on a vehicle. Certainly braking distance must be affected. Consider the company Tikore which sells titanium lug nuts just to reduce rotational inertia and thus reduce the forces which a brake system must absorb to stop a car. Assume traction and temperature is a constant.
Titanium lugs huh ? That's interesting
Solid axles have a major benefit over IRS, the wheels are parallel to the road surface at all times even when the body is at full tilt! IRS has a tendency to change geometries with body roll. With that being said, body roll is just a visual representation of the G-force's on the car, if the suspension or wheels don't change their relative geometry to the road surface there will be no traction loss from body roll; making the design of the vehicle more important than the suspension type.
It depends on the function of the vehicle and what you want to be doing as to what suspension is best at the time.
That's actually a disadvantage in a car that's going around a corner. You actually want to gain camber, something only short-long-arm suspensions can provide, for max grip as the tires sheer with a cornering load. Why do you think, even on solid axle mustangs, a track alignment calls for maximum font negative camber (which without cutting the strut towers is generally 3°)?
Hell, why do you think F1 cars use independent suspension if a solid axle is better?
"if the suspension or wheels don't change their relative geometry to the road surface there will be no traction loss from body roll; making the design of the vehicle more important than the suspension type.
It depends on the function of the vehicle and what you want to be doing as to what suspension is best at the time."
Gr1pEnemy Sure, if your tires are made of delrin. But they're not, they're made of rubber and they deform under a cornering load. This is why you need camber when cornering.
Funny thing is: a bloke named Klaus Arning--the guy who helped design the suspensions on the orignal Mustang, the GT-40, and others--ALREADY designed an IRS setup that would have been a bolt-in application for the Mustang--over 40 years ago!
Arning's "T5" design was apparently patented, and supposedly designed to have inherent anti-dive and anti-squat characteristics. AFAIK, there's a guy named Duane Carling who's adapted this IRS for 5th-gen Mustangs as well...
the fact that the 50:50 ratio is almost maintained that is a more better suspension, but another thing about the IRS is that it allows more control for transfer of body weight like drifting or sharp corners
Graduating in 14 days with a BSME.
Ya im not sure how well that truck operates since I have never used one but im sure it works just as well as a leaf spring if you have a badass progessive coil spring.
It's interesting that you see more sophisticated (complicated and more expensive) suspension on European and Japanese cars, compared to standard cars in the US. I guess this is, ultimately, down to the roads - you can get away with a live axle with the straight and well maintained roads (not exclusively) in the US, whereas in Europe the roads are twisty and tend to be badly maintained (again not exclusively but particularly in the UK). Obviously cost and power handling ability are important too.
Also, production cars are built on "platforms" that are designed to work with certain range of components. I think that it would be rather difficult to design a platform that would allow easily installing an IRS and a LA. If I'm not mistaken, suspension type IS a factor that is taken into account when designing a platform. I guess a platform that would cater for both types of suspension could have drawbacks and compromise other things...
by the way, yours was the first easy to find youtube video for suspensions. congrats.
Make the IRS standard, with a kit conversion to solid for drag/road racing purposes. That seems ideal to me
Real world driving isn't typically done at high speed so traction is less of an issue when compared to things like weight and gas mileage and stopping distance. I would be interested in hearing an argument for choosing an (LRA + Watts Link) as an upgrade versus the IRS as adding the Watts link would reduce performance differences while not adding as much cost, research and weight as an IRS.
It completely depends on whether they want the Mustang to turn into a more exclusive car or a little bit more common. With the continuation (and hopefully improvement) of the Live Axle, the Mustang would continue to be a car meant for serious driving that can rip it up on the tracks. With the switch to the IRS, Mustangs will only be slipping into a more regular car (although not quite). People will see it as a commuter or a family car. In my opinion, Ford should keep the Mustang more exclusive
IRS suspension is the way to go on a road sports car for the improved handling performance around the bends. Live axles are great for hot rods and off-roading. Its about time Ford made a change.
well, in my opinion i would say that the mustang is highly used for drag racing, street racing and burning outs purposes - to show the big block engine's power-, it comes from its heritage, yet putting the IRS surly would make the car flows better at the street and possibly more enjoyable, i would think if there would be a suspension that would be between those two or has both characteristics at least.
The live axle also takes a lot of space from the rear and with the new IRS ford can make the mustang have more space for the rear seats or a bigger fuel tank.
In my opinion I think Ford made a good choice going for IRS. You gotta remember that there's a lot of people buying these cars who aren't experienced drivers and will most likely never take the car to a track. I feel like good handling is very important on any car that's pushing a lot of power.
I think Ford should keep the live axle suspension. A Mustang is made to be wild. That's what makes it a Mustang. You must control and tame it with skill. But just in case the car is too wild for the driver and road conditions are poor, Mustang should develop a traction system that monitors and compensates for the unsprung mass of the live axle with the money they were going to spend on an irs.
I think eventually I could get around to it. I've got quite a list right now haha!
Care to elaborate on why a 4 link would "get tons more better performance" than a 3 link? I'm no Mustang enthusiast, but from what I've read Ford specifically decided to go with 3 rather than 4 due to axle bind and the loss of traction in corners (oversteer).
Live axle! Muscle are made to be strong and burning tires! (Yes, I'm an enthusiast)
love your vids...you rock. the way you do that super bent wrist pointing thing...I wish I could make it stop driving me nuts.
could not agree more. I have a live axle mustang with light cf driveshaft and wheels, clutch etc.. its super efficient. about 10% vs. 25% from IRS. but I would trade it for an independent setup any day, putting power down is much better with the new Mustang IRS.
Why is anyone arguing? The new mustangs are killing the competition. The 5.0 runs with a 2011 M3(IRS) smashes the Camaro SS(IRS) and SRT8 392(IRS) and the boss is a straight up beast. I'm just excited to see what ford brings next. Love my 5.0!
I think it would be a good idea to make all 4 wheel drive vehicles with independent suspension all round especially expedition 4x4s and 4x4s that are used in remote areas where there is wild life. If a spring bok, deer, a rock or a pot hole suddenly appears in the middle of the road you can veer of the road on to the uneven surface and still be able to control the vehicle from maybe 50 mph down to 0. I am sure the insurance companies would reduce they quotes as well.
I believe it really depends what you want to do with the car....drag race on tracks...Live axle....street racing and daily IRS...Since I’m on street I prefer IRS...it handles the variables really well...verses Live which you can hit a bump and lose traction really bad...
hi! i'm restoring a 69 mustang and i was looking for modern suspension for it,your explanation was very helpful and simplistic so thanks you. as to "IRS" vs Solid axle, I think its more of a personal preference than anything else, personally i think Keep the solid axle, it dose its job well,high end cars use IRS but they also use electronically controlled AWD systems that help stabilize the vehicle at high speeds, neither is needed for a daily driver, BTW congrats on the job and good luck...
Fully functional without electronics, like the majority of suspensions. It's not an active suspension like you might find on BMW 6 series (or other car).
The main think for me is how the car's rear would shoot left or right severely over railroad tracks or large upsets on Michigan roads. I think the only thing I hated on the car was that when I had one.
Muscle car is an American term for high-performance cars, usually but not limited to rear-wheel drive and fitted with a large and powerful V8 engine
Oh i forgot it all depends on what kind of driving you want to do it you want to drag race or drift you want the solid rear end due to it having dependent suspension now on circuit or sprint you want the independent suspension just due to the fact if you are turning at high speeds you don't want the rear coming out from underneath you (spinning out) so i think its just depends on what you do and like if you like fooling around and sliding go solid if you want to be precise than go independent
I think, like he said, Ford is doing it more for marketing than anything else; so that it is more competitive with European and Asian cars and being able to sell more these cars overseas. IRS does make the car handle better but it would only be noticeable if you actually take the to its limit which most people won't.
I've got a job lined up. No worries.
Glad to hear, thanks!
Mustang may have a solid axle option, installed at the dealer
Just rumor at this point
2004 Cobra IRS was setup to be interchangeable, but it also made it less functional
Some of the live axle issues could be resolved with a watts linkage instead of a panhard rod, but I agree, it's about time for a good live axle system to be implemented. The benefits outweigh the disadvantages. Also with Ford's marketing division stressing bringing the mustang's image into the present and future starting with the 2013 refresh, a IRS is pratically guaranteed.
The double wishbone is clearly the better IRS, and while it does keep the tires parallel and planted to the pavement under hard straight-line braking and accelerating, as IRS cars roll in turns, it's a completely different story.
How do live rear axles cause tire slippage? They have better bite from a better contact patch under hard braking/cornering/accelerating plus quick elevation changes or any combination thereof.
They should have a track package "plus" and "Pro" for factory v6 mustangs. They already have plenty of power and an IRS plus a factory power adder that will allow the owner to FURTHER tune the vehicle on boost would be SUPERB in a v6 mustang. I would love to have a 450hp mustang with beefie shocks, brakes, tires, and an IRS in the back. It'd be even better if they could get some of that corvette rear transaxle business going. The car would SHINE LIKE A DIAMOND!
ive always wanted a mustang i was planning on getting a 65 but the 2011's 5.0 convince to get a new one but from what learn the 2015 mustang it sounds great hopefully ill save a good 20 grand so i can buy one.
IRS sports cars have tight suspensions and don't negotiate bad road surfaces as well as you'd think. Better than LRA? Marginally if at all. Remember, a thick sway bar will communicate shock to the other 'independent' side. LRA has the clear advantage everywhere else including road courses. But then, the more technical a track is, the more LRA prevails. Push IRS too hard and fully compress/unload, and you're riding on the edge of those wide, low profile tires as opposed to full LRA contact patch.
And what about the in between option? De Dion axle: it's still a live axle, but the differential is attached to the car frame, so the unsprung mass is less than that of a traditional live axle.
one of the reasons why soo many people love the mustangs is because they have the best speed/performance to price ratio. 420hp for $30,000! i say keep the live axle for now because so far. mustangs still are the better track car in comparison to a camaro, which is the main competition. when other sport cars start to pass up the mustang. im sure ford will decide its time to invest in the irs.
IRS is better all around. I understand the nostalgic draw of a live axle but it's time for the mustang to become a little more modern. Besides we'll always have the older cars with the live axles to enjoy.
The biggest factor is going to be durability and power. A huge issue with the '13 shelby is durability in the rear end and driveshaft. The cost to design and make an IRS capable of handling even 500+HP for more than a couple thousand miles without issue would be pretty big and pump up the cost of the entire model line alot.
It all depends on where Ford thinks the hearts of it's buyers are... If they target those who want street capability, the power is going to drop and prices are going up....
i like mustang!! and i am looking foward owning a 2015 mustang with IRS mostly for GT and drifting
Thanks, I'm pretty excited!
Let's see if the potential buyers would still go for the mustang considering it was more than good enough even with the live rear axle. A transition to IRS would mean it would be 10x better than it's current competition because it could still stand it's ground with an antiquated system? At least that's what i am assuming considering the ranting about the live rear axle. I switched from a Fiesta ST to a Mustang GT and didn't really have problems adapting and the roads over here are far from good.