Two non-obvious things about front axle load
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- Опубликовано: 29 сен 2024
- #axleweights #GVM #GCM #payload
Did you know your 4x4 has a front axle load limit, and the effect of adding weight at the front of the car on the front and rear axles? And the effect of wheelbase? All explained here!
Post questions as comments!
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10:56 which is why towing 5th wheel camper is typically safer. . Less sway.
Yesssss!! Very interesting.
I learnt all about this trying to get 50/50 weight distribution in my car was wondering why when I removed something or relocated it it wasn't giving me the same reading on the scale
I had not thought about it but it is similar to a C of G calc for an aircraft - a really useful explanation as usual - thanks for producing all these videos , i find myself going back to them often as a reference
Thanks Mike, and yes it is similar now I think about it too! You know what happens if the CoG is behind the CoP...well if the CoG on a vehicle is such there is mimimal weight on the front axle, there is a problem!
Is there an ideal weight distribution fore/aft and why? Does this vary by application such as off/on road? My 4x4 truck is 6.5 tonnes GVM with approx. 2.7 on the front and 3.4 on the rear....
Excellent question. The perfect weight distribution varies from moment to moment. Ideally though, central.
Great explanation!! I have a question... How do you work out the increase in Towball Download if you install a longer tow hitch?? I have changed my tow hitch to give me a bit more clearance (approx 55mm) at the rear of my wagon (for convenience sake when hitching and unhitching).
Use the same principle, wheelbase and overhang
This really makes you stop and think how much adding a bull bar winch spotlights aerials to the very front of a car must affect handling on the limit
Even before the limit!
That was excellent, thank you.
Glad you enjoyed it!
Great video. As a pilot and having studied weight & balance, arms and C of G I found it very well explained. Hope all the weekend warriors understand it and other impiortant factors like unstrung weight..
yes, drew on my own flying training for that one...CoG so important in aircraft! Unsprung weight to follow....
How does it work with non-centered loads /diagonal?
Good question and essentially the same as the axle load is total axle load, not per wheel.
3:23 Adding weight to your vehicle’s front for towing may be a good idea 🤞🏼.
Love this practical example. Many people just add stuff to their vehicles and don’t think about the consequences. Thanks for helping to keep us all informed.
So if you are towing a heavy van adding a bullbar will often be beneficial to your weight distributions.
This is interesting Because the Holden Crewman had basically 2 types V6 and V8.
The V6 can carry more load than the V8 in the vehicle its self ,
But the V8 can tow more than the V6 and it's not because of the power.
(Approximately and the same specs for 2WD and AWD)
VZ V6 = 1150kg load and 2150kg tow (Alloytec)
VZ V8 = 850kg load and 2500kg tow (LS)
VY V6 = 1050kg load and 2500kg tow (Ecotec) ?
Before the comments go nuts on what the books say about this,
I have the VY V6 and it is plated from factory as such.
According to specs the 3800 is the least powerful of them yet can handle the most work.
Can you think why this is ??? (why did I think of Dora the explorer here) 🤣
I can make a guess! If the GVM is the same, the V8 would be heavier and therefore have less payload. Towing capacity is not to do with power it's more often limited by cooling to the engine or transmission, so presumably the V8 has better cooling than the V6.
@@L2SFBC That's a good point , as best I can see the V8 and the Ecotec are Cast Iron motors giving more weight to the steer as the tub extends back past the axle quite a bit before we find the tow-ball , so balance is better. If you load the V8 tub to 1 ton and step on it, sure the springs are strong enough (All Crewman have M86 axles) but because of the chassis design it will do just as the Torana does when fitted with a 350 small block, "The doors pop open" shhh no one wants to admit that bit 🤣.
Top video. It's about time someone addressed this. Good work.
Glad you liked it! Please share 👍
not sure if you're aware of this but the line you drew through jk wranglers front bars goes through foam in front of the chassis mounting points. the line actually ends up being the foremost part of the vehicle when you get rid of the plastic park bench off the front.
I wasn't thank you...it's the principle, and it is possible the line could be accurate, a winch may protude for example.
@@L2SFBC nah winch sits between the chassis rails on a properly designed bar. but yes the concept is simple one.
ok thanks
Hey Rob - does all-round self leveling air suspension on, say, a modern Land Rover, offset the multiplying effect in any way?
Yes but not significantly. What I describe is a reasonable model for the purposes of estimation, but if you want to get super accurate then you'll need to model the effect of suspension compression and extension front/rear, and tyre compression, and the effect of a changing CoG...beyond what I can do and not needed so the answer is "yes it does but not to any practical degree".
@@L2SFBC Absolutely true. Unfortunately too many people believe to solve the "issue" with stronger suspensions but, as you said, the truth is "yes it does but not to any practical degree".
Suspension modifications does affect driving dynamics to some degree, an automatic levelling system will firm up the front to compensate the added weight, but, the balance of the vehicle remains unchanged, regardless of stronger springs, or higher air pressure in the factory system. No matter what, you still have more weight in front, and that will change dynamics. These days, the dynamics and changes to those matter more than ever, given the vehicle stability systems etc, that are programmed and tuned to an expected dynamic. Changing it may produce unintentionally response in an emergency when the vehicle takes control to avoid loosing traction as an example.
@@brianjensen5200 everything counts under dynamic conditions, even the driver's mood.
@@nicknick7052 Yes and no. What I meant to say, is related to stability control systems. They're active when the driver no longer is in control.
Thank you for sharing
🙏🏆🤗🇺🇲
In your comparison. the two door Wrangler was an old JK. The 4 door is a JL. Your principals still apply of course.
Oops, that was wrong...but yes, principles still valid
Excellent video and explanation Robert. I had the same issues with a work truck where I had to be careful with how I loaded it or the front axle would be overloaded, and counterintuitively, when it was fully loaded, there was less front axle load then when it was partially loaded. I made up a spreadsheet where you entered the weight and distance from either axle (as well as from the centre line of the truck) and the axle loads were calculated and you could easily change position of the various loads and see how it effected the axle loads.
Well explained and demonstrated. I have just worked out my front mounted winch is +21% and rear mounted spare stuff is approx +37%. Not good for the polar centre of gravity making vehicle a handle a bit more like a dumbbell if too much weight added outside wheelbase in proportion to kerb weight.
I would have said the extra weight on the front is going to cause extra wear on the steering and rubber joints over time. Better off having cart springs on the back if you carry a load. Also if anyone knows. . . .😬 What is the difference between TRC and A-TRAC on the Toyota Hilux 2012-2016 1KD 3.0 litre (TRC) to the current 2016> Hilux (A-TRAC). Is it the same system when it comes to braked traction control, does the old system sill have braked traction control when in 4wd low range? I saw your vid with the BMW vs Hilux. Thank you I really like your videos. 🇬🇧
Super interesting and informative
A good reason to change spring rates after getting on the gear fitted to the car. With a winch and steel bull-bar, the front springs are often way under-sprung for the additional loads.
Indeed!
Spring rates doesn't change the weight.
@@nicknick7052 Elaborate further.
They can if they create rake. Same principles in video. Higher rake in rear transfers weight to front, when loaded, even the load more.@@nicknick7052
Hi Robert,
First: I really enjoy your vids. In contrast to other "experts" who might have been "building and testing off-road vehicles for over 40 years", your tech info is accurate and well founded.
I do have a question/suggestion to the info in this video: the effects of adding weight to one axle or reducing the load on another by shifting that weight in the vehicle can be relatively simply explained using levers. Would this not have made the explanations more simple to follow?
Possibly yes...but I chose models
Obviously the maximum load on a front axle would be at maximum braking affect as the vehicle weight / inertia transfers to the front axle and the front brakes do most of the work. Do manufacturers actually publish a maximum allowed weight for a front axle or do you just have to assume the allowed load for the vehicle / 2 ?
No, it's a static load published. You are correct re load transfer (not weight!) and that's transient and accounted for.
I've always been curious about weight distribution and why vehicle manufacturers design their vehicles as they do. This really helps to describe why they do what they do!
Excellent subject matter choice.
Very impressed. Great information. Thankyou.
Glad you enjoyed it! Please share!
Mmm very interesting 🤔😳👍🏻
I put a 9000lb warn hidden winch on my 13 grand Cherokee. Man did it make it handle different especially on gravel roads crazy squirrelly if you try to make corrections at 35mph+
Lots of reasons; CoG change, more grip on the front axle, less on the rear...
Excellent information there. Thankfully I have plenty of leeway with my model Hilux, as I have the petrol V6, which shares all hardware with the diesel bar the engine and transmission. The engine happens to weigh 75kg less than the diesel. Even with that advantage, I have kept everything light, a 40kg bar, a 23kg winch and the battery behind the headlight has been replaced with an 11kg lithium.
Very wise choices there, all adds up!
Great coverage of a very important topic. People really need to know this stuff. The front axle or pivot point has the steering and (usually) IFS mechanicals so that’s a whole lot more moving parts than the rear that are stressed by that front axle load, especially while turning and/or braking.
There’s a reason why the front loading range is low and exceeding it seriously compromises safety in emergency manoeuvring. Stiffer springs in a “GVM upgrade” does not change your calculations to any meaningful extent so dealing with higher loading would require completely re-engineering the front end and upgrading many components.
I’m sceptical that many GVM upgrades really do this despite “engineering certification”.
Thanks, and agreed!
great video, thanks for posting. When towing our van with our Prado, I slide the unused rear seats forward to hopefully reduce rear axle load. Every bit helps.
Let's add weights in a way that they cancel each other :))
Exactly ! I use the same joke all the times. And some like the idea
I have a two door JL Wrangler. My instinct was that a steel bumper would do as you have said. Thank you for the demonstration. I decided to only install recovery points that weigh about 10K. No steel bumper and no winch.
Why not install a rear steel bumper to offset
@@trschurrthat’s what I did steel front and rear and even rear winch steel bumper it’s awesome
@@trschurr That is a good idea. I wonder how Robert wil see it?
Wrangler owners install larger tires in order to help offset the added weight due to the winch. This works because the spare tire mounts on the tailgate on the Wrangler. Another well thought out tutorial by Robert Pepper!
This is incredible! I never thought of this. Thank you sir. Will absolutely keep this in mind when dreaming of winches etc and what to install and where
Excellent video, One thing this video doesn't touch on is why you may want to have more weight up front: to balance the heavier loads in the rear and prevent light steering. Also help with low traction/up hill ascents. This is why I prefer to add some weight to the front such as air compressors/dual batteries etc. But not overdoing it of course. Overall, when fully loaded I like to have the load evenly distributed or slightly more on the front axle (which doesn't seem to happen for me practically speaking) for reasons mentioned.
Nice video, I've always felt for a work truck it's best to go for a long wheelbase and short overhangs. The long wheelbase also helps handling and safety at speed. I like the Triton but can't get over the rear overhang, of all the utes the Ranger has the longest wheelbase I think, but the Ineos ute will put the rest to shame in both wheelbase and overhang.
yes but not payload so it's kind of a moot point!
I have a two door Wrangler and you have access. Would you like to do a comparison off road some time?
I would, vs a 4 door!
@@L2SFBC Sorry a typo. I meant to say that you have access to a Jimmny. Would you like to compare the Jimny to a two door Wrangler?
I'd like to do 2 and 4 dr Wranglers to demonstrate wheelbase...
@@L2SFBC I can arrange that if you have a business email address