Out of all of the videos online explaining suspension systems, your videos are the best. You have a very good balance of keeping the information light, yet still detailed enough to explain complex design problems. Please keep making videos, I can't get enough!
Love your videos, but i did notice the rear spring shackle attachment moved on roll. And my other thought is, if you add two shocks when mounted outboard does that overcome the position. Interesting.... Make more videos...
6:40 this seems to be an arbitrary limitation. As a reasonably good structural engineer can design the frame-rail around the ideal shock location. There is nothing that prevents the frame rails from being farther outboard than this, with a significant bend, looping inward around the shock. Or even a narrowing of the rail section in this area, with a specialized shock mount designed to carry some of the frame loads across this frame rail weak point. Also, I think from how I understand this; the outboard shock can be angled to a more outboard mounting position at the axle, with the top canted inboard. If this angle was correct, the shock would provide maximum damping ratio at maximum body roll. While reducing damping ratio in the vertical by the sin of the angle. Although, this effect is probably small, perhaps 5%. It could be a meaningful improvement. Especially if the lower mounting point was located inside the wheel rim, very near the axle flange/hub. (Assuming this wont interfere with the brakes, which it probably will).
Justin, This is not an arbitrary limitation at all. The frame needs to be inboard of the inner tire sidewall throughout all of the tire's motions. This limits how far outboard the frame rails can go without increasing the track. Once the frame rail is placed as close to the tire as it will fit, then that sets the limit for how far outboard an inboard shock can go. You are also correct that you could narrow the frame rail in this area with some sort of specialized shock mount, but again, there are limits due to the motion of the shock under all the various axle motions. Also, don't forget that this section of the frame has to carry all the towing loads so it still needs to be very beefy. This is why you won't see OEM's scalping out the rails in this area. You are correct though that you can angle the shock to get a better motion ratio. Ideally you would want the shock perpendicular to the roll center, which on a leaf spring design is actually quite high, depending on where the springs are located (above or below the axle).
Having a constant motion ratio means you will get the maximum roll damping you can possibly get. I have never driven a vehicle that had too much roll damping so getting more is better. Having a lot of roll damping is a great way to make a car feel like it is stiffer in roll than it actually is (i.e. as if it had larger anti-roll bars) because the perception of roll is related more to the speed at which the vehicle rolls than to the actual roll angle. Adding lots of roll damping slows the roll rate down and makes the vehicle feel like it has higher roll stiffness.
Out of all of the videos online explaining suspension systems, your videos are the best. You have a very good balance of keeping the information light, yet still detailed enough to explain complex design problems. Please keep making videos, I can't get enough!
I have seen alot of Videos about suspension but these Videos are the best of all. Thank you.
Another well conceived and executed video. Please keep with it!
Very educational video! And wel made. I would only suggest adding some music, but be careful not to make it distracting or too loud.
Please do a video on natural frequencies of springs
5:44 "Here is a fictitious vehicle." Nice one. 😂
Love your videos, but i did notice the rear spring shackle attachment moved on roll. And my other thought is, if you add two shocks when mounted outboard does that overcome the position. Interesting.... Make more videos...
6:40 this seems to be an arbitrary limitation. As a reasonably good structural engineer can design the frame-rail around the ideal shock location. There is nothing that prevents the frame rails from being farther outboard than this, with a significant bend, looping inward around the shock. Or even a narrowing of the rail section in this area, with a specialized shock mount designed to carry some of the frame loads across this frame rail weak point.
Also, I think from how I understand this; the outboard shock can be angled to a more outboard mounting position at the axle, with the top canted inboard. If this angle was correct, the shock would provide maximum damping ratio at maximum body roll. While reducing damping ratio in the vertical by the sin of the angle. Although, this effect is probably small, perhaps 5%. It could be a meaningful improvement. Especially if the lower mounting point was located inside the wheel rim, very near the axle flange/hub. (Assuming this wont interfere with the brakes, which it probably will).
Justin, This is not an arbitrary limitation at all. The frame needs to be inboard of the inner tire sidewall throughout all of the tire's motions. This limits how far outboard the frame rails can go without increasing the track. Once the frame rail is placed as close to the tire as it will fit, then that sets the limit for how far outboard an inboard shock can go. You are also correct that you could narrow the frame rail in this area with some sort of specialized shock mount, but again, there are limits due to the motion of the shock under all the various axle motions. Also, don't forget that this section of the frame has to carry all the towing loads so it still needs to be very beefy. This is why you won't see OEM's scalping out the rails in this area.
You are correct though that you can angle the shock to get a better motion ratio. Ideally you would want the shock perpendicular to the roll center, which on a leaf spring design is actually quite high, depending on where the springs are located (above or below the axle).
By the way, why does having a consistent wheel-to-shock motion ratio between heave/pitch and roll make it easy to find the right setting for both?
Having a constant motion ratio means you will get the maximum roll damping you can possibly get. I have never driven a vehicle that had too much roll damping so getting more is better. Having a lot of roll damping is a great way to make a car feel like it is stiffer in roll than it actually is (i.e. as if it had larger anti-roll bars) because the perception of roll is related more to the speed at which the vehicle rolls than to the actual roll angle. Adding lots of roll damping slows the roll rate down and makes the vehicle feel like it has higher roll stiffness.
Well shoot, I ran out of videos!