Edmunds Mustang vs Camaro vs Challenger

[GoCougs]

I still see camber change in double wish bone suspension - I didn't think that any were equal arm length - just too much lateral slide.

[ChrisV]

Double-wishbone and multilink IRS don't experience any camber change when the suspension is compressed (either in hard cornering or hard acceleration).  They also don't experience any camber change when one wheel hits a bump and the other doesn't, unlike a live axle.

Um what? You compress the rear of an IRS car under hard accelleration and you will definitely see negative camber the same as if you lower it There is a curve that the wheels follow under compression, both front and rear. as you compress front OR rear, you get camber change, otherwise when you lowered a car you would NOT need to align it for camber, and you'd never see this:















Sorry, but as you compress the IRS or IFS, as the tire follows the arc of the A arm or control arm, the camber changes.

[GoCougs]

Um what? You compress the rear of an IRS car under hard accelleration and you will definitely see negative camber the same as if you lower it There is a curve that the wheels follow under compression, both front and rear. as you compress front OR rear, you get camber change, otherwise when you lowered a car you would NOT need to align it for camber, and you'd never see this.

I think MX793 was correct when it comes to no camber change in equal-length component suspensions, but I always thought that any wishbone/multi-link suspension used unequal-lengths with the top components being shorter, to keep tabs on track change during compression (the trade off being camber change).

[ChrisV]

Actualy, what happens is that those setups are designed to make sure camber doesn't change when being compressed in cornering, when the body of the car is leaning, and thus the tire stays vertical to the ground, even though the camber as compared to the car's chassis has changed... But on bumps, the camber certainly does change. And especially under accelleration when you get squat in the rear.

[S204STi]

No, an unequal length setup tends to create camber gain with compression.  But since the car is leaning on that corner it has the effect of keeping the tire flat relative to the road (but if you look at it in relation to the chassis there is a gain in camber).

This is based on a setup similar to a Mustang II, where the upper control arm is not only shorter but the upper ball joint is located higher than the pivot points on the chassis.  On many GM UEL control arm setups the ball joint is actually lower than the pivot points at the chassis, meaning that the tire suffers camber loss during compression.

Basically a double wishbone suspension can be setup for all sorts of angle control.  I've seen some where the rear tire not only gains camber but also sees a toe adjustment (some Nissan rear suspension, etc.) during compression by mounting the upper arm at a slight angle compared to the lower arm.

Imagine this:

   -----o

-------o

If they both move an equal amount upward, because the upper arm has a smaller arc it will pull the knuckle inward, causing camber gain.

[Raza]

That car looks broken. 

[ChrisV]

No, an unequal length setup tends to create camber gain with compression.  But since the car is leaning on that corner it has the effect of keeping the tire flat relative to the road (but if you look at it in relation to the chassis there is a gain in camber).

Exactly what I had just said.

[S204STi]

Exactly what I had just said.

I first read your post which said that it keeps the tire level, but I missed the one above it which stated what I needlessly elaborated on.  My bad.