Caster / Camber

[pitts64]

Are the following statments true?

-Caster pulls to the negitive.

-Camber pulls to the Positive.

[pitts64]

I have my car handling very well now, but I get a slight drift (not pull) to the right. On some roads it's kind of nice, I don't have to correct. But I would like to tune it out.

[red67camaro]

Yes, caster will pull toward the side with less caster.

Camber will pull the way the wheel is leaning. If you have equal camber on both sides, the pull will cancel out. If you are running negative camber and have, say, -1/2 degree on the left side and -3/4 degree on the right, you will have a net pull to the left.

[pitts64]

Thanks 67...

[Twentyover]

Some alignments put some stagger in the camber to account for road crown

[Norm Peterson]

Or a little cross-caster.

[pitts64]

Right now I have no idea where my front end is as far as specs go I just know it handles and rides very well.
I added a 1/16" shim to the right rear bolt yesterday to tune out the drift to the right.

Does anybody know how much negative camber i added with a 1/16" shim? Is there a table?

When I get it perfect I was going to take it in to the alignment shop for a print out or is that a waste of time?

[tumper93]

1/2 degree.

[Norm Peterson]

Not enough information without factory UCA dimensions and knuckle height. But you also added a little positive caster which has its own effect on reducing right drift.

I'd at least DIY-measure the final settings. Maybe I'd get around to getting it checked professionally, but only at a place I'd trust (I've reliably heard that the "lifetime guarantee" shops don't always do their best work unless you happen to be buying something from them).


Norm

[Norm Peterson]

1/2 degree.

Depends on where the upper ball joint is relative to the front and rear shim stacks (since the front stack was left unchanged). If it's directly opposite the front stack, the amount of camber setting change would be negligible.

Wild-guessing at some UCA and knuckle dimensions, if the UBJ is directly opposite the rear stack, -0.5° camber setting change might be possible.

The caster setting change might be about +0.75° and is not particularly sensitive to UBJ fore/aft location.


Norm

[pitts64]

delete

[tumper93]

Depends on where the upper ball joint is relative to the front and rear shim stacks (since the front stack was left unchanged). If it's directly opposite the front stack, the amount of camber setting change would be negligible.

Wild-guessing at some UCA and knuckle dimensions, if the UBJ is directly opposite the rear stack, -0.5° camber setting change might be possible.

The caster setting change might be about +0.75° and is not particularly sensitive to UBJ fore/aft location.


Norm

You are right, but in most GM vehicles 1/8" shim equals 1°. This has been my experience over all these years and is what I use as a base to know how to adjust camber/caster. Sometimes it comes out a little more or a little less but is a good rule of thumb!

[pitts64]

Will adding negitive camber on a rear steer car toe it in?

It doesn't drift now that I added a 1/16" shim to add negitive camber at the side it was drifting to. But now my toe feels like its right in the middle no toe in or out with a very slight looseness while going straight. It also seems to have a more bump steer. I think I liked the slight drift better....

[red67camaro]

It depends on the relationship between the outer tie rod end and the lower ball joint. Vertical positioning as well as the length of the steering arm on the knuckle will both have an effect.

On a rear steer car, if the tie rod end is above the lower ball joint adding negative camber (moving the upper ball joint inward) will add toe in.

If the tie rod is below the lower ball joint the opposite will be true.

Increasing caster on a rear steer car will lower the outer tie rod end which will have an effect on bump steer.

If the tie rod is anywhere near the lower ball joint as far as vertical position, I would expect toe changes to be relatively small in response to minor caster/camber changes. It's always smart to check toe after any other adjustments.

[pitts64]

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[Rhino]

Something else that hasn't been mentioned... are you certain your rear axle is aligned properly to the car?

[pitts64]

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[Rick Dorion]

Part of the problem with street driven cars is that all roads aren't created equal. I regularly go from mild crown to pronounced crown to flat. So I have adjusted by caster to be the same on both sides.

[Norm Peterson]

Would I be correct in thinking that with solid upper control arm bushings, rubber lower control arm bushings and rear steer linkage, my car would add negative camber the faster it went with a slight toe in...

If you mean during cornering, no. Bushing compliance works toward positive camber on the outside wheel (and toward negative camber on the inside wheel). The opposite of what you'd normally prefer in both cases.

I don't think it would work that way even if you mean during straight-ahead travel with toe-in. That still results in lateral forces pushing the bottoms of the front tires inward (less negative camber). Maybe with static toe-out you'd get a little -camber gain, but if the bushings were soft enough to get much from this effect I'd be concerned that a shimmy might develop.

Compliance toe is a different issue.


Norm

[pitts64]

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