There are multiple manufacturers of independent suspensions, and I have been looking at them closely. I ended up purchasing a TCI set up from Pete and Jakes. I selected this unit because it had several more desirable features and was actually less costly than some of its competitors. I know they have been around a long time and even market complete chassis set ups. In looking at the suspensions, I noticed that on many/most of them, the upper A arm is not parallel to the ground......yet some are parallel to the ground. Is this just a difference in adjustments or designs? I would like to know how this positioning affects driveability and what the pros and cons are. Here are some pictures to illustrate what I'm saying. Heidts Here is the Pete and Jakes Display set up Another Heidts notice that the top arm is angled more than the one in the first picture.
The length and angle of the arms in relation to each other dictate what the tyre (tire) does when the suspension moves, particularly under compression. To best se it in action you need to visualise (or draw it up) what each arm does when the suspension rises or falls. You want the top arm to move in a tighter circle or shorter arc than the bottom to promote the top of the wheel to move inwards more than the bottom. By moving the top of the wheel inwards, promoting negative camber, you improve cornering. Do so searching in Goggle and you will find enough reading material to last the rest of you life. Suspension geometry is fascinating and actually quite complex.
Lower control arms that are level or at an upward angle(bj higher than pivot), tend to have bad roll centers and will not handle well. Also note that the P&Js frame is unloaded , put a body and drivetrain in it the control arms will probably be similarly angled as the completed cars. It puts the roll center in the ground, making for a teeter totter of a ride. Some pure race cars do have near horizontal lower control arms however these cars are so low and have low mass as well as low center of gravity, that it won't affect them as badly as a street vehicle. F1 cars have some extreme funk when it comes to geometry but they operate in a different world. Ideally if you want a lowered ride, the inner pivot points would be moved up, leaving the BJ at the desired height while maintaining a decent roll center. On the 32 it can get away with a bit, engine is behind axle centerline, car is relatively small and light~2500lbs. All in all I don't think there will be any difference looking at the angles.
Spindle height and control arm mounting height can be different per how these are designed. Taller spindles or lowering the upper arm mounting position was used to improve handling on older cars. The upper arm angling upward towards the spindle
Both upper and lower pointing downward is ideal. If the upper only is lower it can shorten the instant centre which raises the roll centre. But the benefit of this is ^^^ is camber gain which is more desirable. Low roll centre increases bodyroll [overturning moment] but this can be controlled with roll stiffness. Understand all these "quirks" are only a problem at the limit of tyre adhesion. If lateral acceleration loads [weight transfer] exceed the vertical weight of the vehicle you can get "jacking" on a corner. This ^^^^ is very similar to Anti-Squat / Squat at the CG on a drag car [which most people confuse for overturning moment] The rules aren't "set in concrete" They raised the lower inner pivot on F1 cars to gat the same camber gain [this method was needed for the High Nose Venturi Aerodynamics] this was in 2001 But these cars also have massive down force that would exceed any "jacking" and very limited suspension movement. Generally all these changes are engineering "integrity" [ the taller spindle will spread /dissipate the loads through a wider area.] It is all about force over resistance [with leverage in between] The force is applied at the CGH, and the resistance is applied at the tyre contact patch Modern race cars [open wheelers] are trending towards raising the lower A-Arm for Aero purposes, but this creates an increased cantilever effect between the tyre contact patch and upper A-Arm [but carbon fibre and Titanium is now the normal materials] The old Shelby drop was used purely for camber gain, If a car had zero bodyroll no camber gain is needed at all Back then the cars were quite softly sprung. They needed to be [because they were all understeering pigs]
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