Camber Gain: How Much Is Too Much?

[cdrod]

I'm very much a noob when it comes to modified suspensions and as such, I could really use some guidance from those more experienced than myself. I'm building a '72 Olds 442 convertible that will be street driven only, no autocross or racing. I'm just looking to correct the known GM A-body geometry issues and build a well-mannered, good handling car. My front suspension is comprised of factory drum spindles with +.9" upper & +.5" lower ball joints, SPC upper arms and stock lower arms.

I've assembled the parts and trying to dial in a good starting alignment before fully assembling the car. When I measure the camber gain through the full range of suspension travel I get 4-5 degrees of negative camber gain at full compression and only about 1 degree of positive camber change at full droop. I'm not sure I'm setting the ride height position correctly which could lead to higher camber gain numbers in compression. It would be helpful to know if there are any reference points that can be used to at least get the suspension close to an approximate ride height (for testing purposes).

Here are my questions:
1. When measuring the camber gain, should I assume ride height is half way between full bump & full droop?
2. Should the spring pockets in the lower arms be level with the ground at ride height?
3. How much suspension travel did the stock suspension have when in compression?
4. How much camber gain should I expect?
5. Are my measured results normal?
6. Is there such a thing as too much camber gain in bump?

Looking forward to your comments & suggestions!

Rodney

[stab6902]

Lots of good questions. All of your camber measurements should start at your desired ride height, which probably is not exactly in the middle of the suspension's available travel. If you don't have springs in the car, you can put the wheels and tires back on and hold the car up with jacks until it sits how you like it. Then measure the distance from the center of your wheels to the top of your wheel arch, and use that as your zero point for your camber measurements. The arms/spring pockets may or may not be level; it all depends on your desired stance. The next trick will be picking the right springs for your desired stance, but that's a different discussion.

I never measured how much compression travel an A body has stock. A good rule of thumb I heard is there should be a minimum of 3 inches compression travel and 2 inches droop. Of course more is better within reason.

I've read that a decent camber gain target for performance street cars is 0.7 degrees/inch. You should make a plot of camber gain vs travel to see the whole picture since it won't be linear.

Yes, there is a such thing as too much camber gain. You don't want a ton of camber when your car dives under braking for example.

This is a big topic that I don't have a ton of time to get into at the moment, but hopefully those comments are helpful.

[cornfedbill]

It is possible to add brake anti-dive by changing the upper control arm angle as viewed from the side. This will limit dive under braking and reduce unwanted camber gain when you only want to stop.

Camber gain on an autocross car would be more aggressive. For a street driven car, you would want something more subtle. It all depends upon your goals.

The spring rates you choose will have a dramatic effect on suspension movement under braking and cornering loads. Softer springs will generate more movement. If you run extremely stiff springs, your camber gain will be minimal by comparison.

[pitts64]

*******delete

[David Pozzi]

Lots of good questions. All of your camber measurements should start at your desired ride height, which probably is not exactly in the middle of the suspension's available travel. If you don't have springs in the car, you can put the wheels and tires back on and hold the car up with jacks until it sits how you like it. Then measure the distance from the center of your wheels to the top of your wheel arch, and use that as your zero point for your camber measurements. The arms/spring pockets may or may not be level; it all depends on your desired stance. The next trick will be picking the right springs for your desired stance, but that's a different discussion.

I never measured how much compression travel an A body has stock. A good rule of thumb I heard is there should be a minimum of 3 inches compression travel and 2 inches droop. Of course more is better within reason.

I've read that a decent camber gain target for performance street cars is 0.7 degrees/inch. You should make a plot of camber gain vs travel to see the whole picture since it won't be linear.

Yes, there is a such thing as too much camber gain. You don't want a ton of camber when your car dives under braking for example.

This is a big topic that I don't have a ton of time to get into at the moment, but hopefully those comments are helpful.

Great advice. .7 deg gain per inch of bump is what I've heard too. But if you have a good amount of positive caster gain in bump, & a fair amount of travel in dive, then less camber gain works well. The caster gain will give you more neg camber in the turns. Your starting ride height is critical when figuring this out. You need to insure your roll center is not going below ground and not moving close to the outside (loaded) tire.