Castor camber settings, Troubleshooting Options

[Chad911sc]

Read many articles and watched a bunch of videos and thought I had it figured out. But my results are not matching from side to side.
I set the ride height where I wanted it, and then proceeded to check my camber. The passenger side with the strut pushed all the way in towards the gas tank and back as far as it would go towards the rear end, gives me a reading of almost a half of a degree of negative camber. That placement also gives me a reading of 3 degrees of castor.
The drivers side with the same placement of the strut tower gives me negative 3 degrees of camber and 3 degrees of castor.
I can’t figure out why the camber is not the same on both sides with the strut towers in the same position?? The castor is the same at 3 degrees on both sides, but even that as stated in many places should be at 6 degrees.
When I set my ride height, the drivers side had to be adjusted more down to set it evenly on both sides as far as tire to fender spacing. Is that the reason the readings are so off?
You can see in the pictures that the drivers side adjuster on the torsion bar is adjusted differently than the passenger side.
And yes I leveled the car before starting this entire process.
Thanks for any help you can provide!

[Superhawk996]

The method your using is not very accurate without anti-friction plates.

Camber of -0.5 degrees is plenty for street use. 3 degrees negative is excessive - adjust that side back toward zero. Spec is 0 +/- 20 minutes or 1/3 of a degree. If you were on the anti-friction plates you would probably pick up a bit more by releasing the sticktion that is in the interface between the tire and the board you’re parked on.

To accurately measure caster you need to be doing a steering sweep while on the anti-friction plates or a homemade facsimile of them.

The other thing you need to consider is whether the steering cross member that the rear of the LCA’s mount to is centered on the body. There is a minor amount of slop in the 4 mounting holes that can be moved side to side slightly. Won’t account for the whole cross camber difference fully but may be a tiny part of it.

Other possibilities extend all the way to a tweaked chassis but I would not jump to that conclusion until you get real numbers from a good alignment done on plates or a professional alignment by a shop that knows what they are doing (ie not a chain outlet)

Also one final comment - setting ride hight to fender lips really isn’t the proper way to set ride height due to body build variation. There is a procedure in the factory service manual. The drawback to the factory method is that it will set the front a bit higher than most want for the “look”. However, once you do that method, you can offset it to whatever your heart desires but it will still be more accurate side to side than using the fender lips.
http://p914-6info.net/PDFs/Group%204%20Front%20Axle.pdf

[SirAndy]

Maybe it's just the picture, but your caster looks off. It should be angled towards the back of the car, which is positive caster. I usually go for 6 degrees.
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PS: As motioned above, for street use, just a tick of negative camber is more than enough. I wouldn't run more than -0.5 in the front and maybe -1 in the back.
PPS: For AX and track use, all bets are off though.
PPPS: Some tires don't like negative camber. I once had a set of racing slicks that came with instructions to run them at 0 front and rear.

[Chad911sc]

I will check the crossmember today and see if I can shift it over a bit to the drivers side.
Yeah I don’t have the plates, never thought about the stiction of the tire. I did do the measurement the correct way though, turning it 20• out, then 20• in and take the measurement. I also drive it around and repeated the test and got the same results.
I know that I need 6 degrees of castor, but how do you obtain more castor when your strut top is pushed back as far as it will go and only getting 3 degrees?

[Superhawk996]

I know that I need 6 degrees of castor, but how do you obtain more castor when your strut top is pushed back as far as it will go and only getting 3 degrees?

You are not getting accurate caster measurements without some sort of an anti-friction slip plate. This is especially true for caster but also applies to camber to a lesser degree.

Without the slip plate, turning the wheel to measure caster just loads up rubber bushings and affects the measurement.

You need some sort of slip plane even if it’s a home brew. I’ve seen everything from greased cookie sheets, to sanded plywood, to a polished concrete floor with just wax paper under the tires. Another common solution is two pieces of laminate tile with grease between the two tiles.

I’m going to insert this video because it’s good and because it is an alignment of a 914 at home. See timestamp 7:18 for his plywood turn plate.


https://www.youtube.com/watch?v=ILPv_skgtzE?si=ec7smDKivwyGdhZU


PS - more important than having the full 6 degrees of caster is EQUAL caster side to side.