Excess Rear Wheel Camber ????

[David T]

Most people who have done this use just an adjustable lower link. Seems to work just fine. This will affect Thrust Angle (aka rear toe) so you really should get a 4 wheel alignment and make sure you have the right amount (and correct type) of shims in the TAB's.

[nkemp]

OK ... it has been a while (ADD/ADHD slows progress :-). I installed the DMCH suspension (rear only so far ... can't wait for the front fun) and have been playing with different adjustments. I'd swear my car is unique ... but that is not likely the case.

First off ... the camber is neutral when hanging ( weight on jack, not the wheels.)

I adjusted the AVO shocks as follows
- 5" of thread exposed (7.5" from center of lower mounting bolt to top of white bushing/washer/spacer/disk)
- My rim to SS fender (measuring vertically) is 6 1/2" passenger and 6 1/4" driver
- Using a square on the pavement, the difference in distance to the square from the top of the rim to the bottom is 1 3/8" (passenger) and about 1" difference on the driver side.
- This could partially be from how I measured but I don't think it is much.
- The top rubber cushion is in place.
- The bushings seem tight (not sloppy)
- The tire insides are worn from years of driving this way. But I don't want to get new tires until this is fixed. I don't see how wear would affect the wheel camber
- This is the 2nd set of lower control arms but they are the same length as the originals as I recall.

Today I lowered the shocks:
- 4 3/8" thread exposed
- Wheel rim to SS fender is 5 3/8" (I don't use the floor to frame height since that includes to many other variables) 5 3/9 seems a bit low.
- The wheel camber difference top to bottom is an inch and maybe an 1/8th (Again I used a square but this time it was on the cement floor so it is a pretty good number)
- And the wheels/tires still look like $#!+ from the rear view

I'm tempted to put in the original suspension just to see where this all started ... but swapping out suspension is not all that much fun.

So for those out there with the DMCH suspension, what is yours adjusted to? Measure (please!) either the thread exposed below the cup ut the top of the white disk to the center of the lower mounting bolt.

[David T]

First of all you cannot properly measure camber with a square and trying to measure it with the wheel off the ground means nothing. Camber is measured at ride height meaning you must put the weight of the car on the suspension. You can get it close with the square but you really should take the car to an alignment shop to get it right.

[nkemp]

First of all you cannot properly measure camber with a square and trying to measure it with the wheel off the ground means nothing. Camber is measured at ride height meaning you must put the weight of the car on the suspension. You can get it close with the square but you really should take the car to an alignment shop to get it right.

It was measured with the car on the ground. The measurements are meant as rough measurements not as an alignment. I'm trying to get it better by adjusting ride height.

[David T]

The camber will only be correct at the spec'ed ride height. It is non adjustable unless you get the adjustable lower links. If it is not correct at the specified ride height, something is bent or broken. It must be equal and correct on both sides.

[DMCMW Dave]

It was measured with the car on the ground. The measurements are meant as rough measurements not as an alignment. I'm trying to get it better by adjusting ride height.

A square is good enough to see how far out it is. We've installed lots of the lowering kits and I don't ever recall seeing one with that much camber unless the car is really slammed. Typically I've seen that issue on cars with cut springs. It's also pretty unusual to see bad bushings in the rear control arms, typically only on very high mile (Hi Oliver) cars.

Couple more thoughts - I just went out and measured my own car (Houston pre-AVO setup with Houston/Eibach springs). I have adjustable lower arms on my car and it was set up at an alignment shop. I see 3/8" neg camber at the upper part of the tire using a rafter square. That's not even accounting for the bulge at the bottom of the tire, so in reality it's equal to or less than 1/4". Not the same shocks but the springs really set the ride height, so for the record, sitting on the ground, I get 5-13/16" from the center of the lower shock bolt to the top of the adjusting rings/bottom of the factory spring collar.

I've heard rumors, completely unsubstantiated by me, that some early frames can be way out of the "final" tolerance specs. Seems that may be what you are dealing with.

BTW both upper and lower adjustable control arms do seem to be available. For adjustment, the bottom ones are certainly easier to swing a wrench on. I believe the reason for adjustable uppers is that they are more invisible. Be sure the design you buy has threads on both parts of the adjuster (one end is left hand thread). I've seen a few out there where you have to disconnect one end of the control arm and rotate it to make the adjustment. That makes for a really annoying (i.e. expensive) time at the alignment shop.

Also IMO tire wear is caused more by excessive toe-in than camber. Look at many modern IRS cars (BMW in my experience) that have suspension setup for crisper handling. They look cambered in, and do tend to eat up rear tires, but the tire wear actually seems very even when they are worn out.

[nkemp]

Dave, thanks for the reply. To the point of early cars and potentially a "way out of the "final" tolerance specs" problem, I wanted to eliminate this option/problem instead of chasing it ... if you know what I mean.

I use a rafter square as well. I set the bottom so that the bottom of the wheel to the square distance is some easy number such as 3". Then I measure the top of the wheel. It makes the math easier. Also, I drive the car a mile or so to set in the springs. It makes a big difference. I'm not sure how the alignment shops get it right if they are unweighting the springs to make the ride height adjustment.

Also, I have also been measuring from the top of the wheel to the fender point straight up from it. To me this eliminates variability in tire characteristics, pressure, flat spots, wear and the like. Some like to set to the frame over the floor height but that has the previously mentioned variations. The trouble is that there is no factory spec for wheel to fender ... unless you had a factory spec car and created the measurement from that.

The benefit of using the upper adjustable control arm, as far as I can tell, it that it moves the wheel perpendicular to the frame/car (the bushing tube is perpendicular to the arm). The bottom control arms have an angle (bushing tube to the arm has an angle to it other than 90). Shortening the lower arm causes some (albeit minor) toe in adjustment. But as you mentioned, there is not a lot of room up near upper control arm to work in.

It is a really nice day, so I'll slide under the car and set it to your spec to see what happens. ... and the wife wonders why I have grit on my pillow so often

[Rich]

See inserted comments in bold italics with data about our D's rear suspension. It is set up very much like Dave's is:

Couple more thoughts - I just went out and measured my own car (Houston pre-AVO setup with Houston/Eibach springs) Same on ours. I have adjustable lower arms on my car and it was set up at an alignment shop. Same equipment and alignment process on ours I see 3/8" neg camber at the upper part of the tire using a rafter square Same on ours. That's not even accounting for the bulge at the bottom of the tire, so in reality it's equal to or less than 1/4". Not the same shocks but the springs really set the ride height, so for the record, sitting on the ground, I get 5-13/16" Ours measures 6.0in. in this dimension from the center of the lower shock bolt to the top of the adjusting rings/bottom of the factory spring collar.

These readings are same on both L and R sides.
For reference ours is set to the specified-for-alignment 5.5in rear ride height measured at center of rear x-member.
Tire wear has been fine.

[DMCMW Dave]

[COLOR=#000000]Also, I have also been measuring from the top of the wheel to the fender point straight up from it. To me this eliminates variability in tire characteristics, pressure, flat spots, wear and the like. Some like to set to the frame over the floor height but that has the previously mentioned variations. The trouble is that there is no factory spec for wheel to fender ... unless you had a factory spec car and created the measurement from that.

The benefit of using the upper adjustable control arm, as far as I can tell, it that it moves the wheel perpendicular to the frame/car (the bushing tube is perpendicular to the arm). The bottom control arms have an angle (bushing tube to the arm has an angle to it other than 90). Shortening the lower arm causes some (albeit minor) toe in adjustment. But as you mentioned, there is not a lot of room up near upper control arm to work in.

Problem with using the fender as a reference is that they are not only different from car to car, they are different from side to side on the same car! The fiberglass body is notoriously un-uniform, and keep in mind that the build process for the car was generally to install the doors, get them working and sealing, then install all the remaining stainless and align them to the doors!

I can't count the number of times I've heard from people complaining that the measurement from ground to fender lip is different from side to side, sometimes as much as an inch. With the car being level! If you want to drive yourself nuts go make this measurement. Some cars may be symmetrical, but most are not. This ought to generate some interesting discussion as well.

Your measurement method (to the wheel rim rather than the tire) is a lot more accurate than what I was casually doing. You can do a little trigonometry and figure out what the real angle is. There is a spec in the Tech manual, giving neg 1/4 degree to neg 3/4 degree non-adjustable. Front is zero to neg 1/2 degree, also non-adjustable. There is nothing all that magical about an alignment shop, measurements are measurements if you are careful. You are probably MORE accurate than the typical chain-store alignment guy.

[nkemp]

I just lowered the spring cup to Dave's 5 13/16":
- Driver side 1 1/4" difference top to bottom of the wheel
- Passenger side 1 1/2" difference to to bottom of wheel
- Crossmember is about 4 1/4"off the ground

Tires: 245/60 33PSI

Without doing the geometry ... I know it is a lot out of spec