ZZtop2

Just finished an alignment at a shop with a nice computerized rack and need some input.

Car: 1972 Coupe
Wheels/tires: 17x8" front with 245/45/17, 18x9" rear with 275/40/18
Suspension: Stock front with 3/4" sway bar Bilstein HD shocks, 360# composite rear spring with no sway bar, 8" bolts and Bilstein Sport shocks. Car sits level left to right

Alignment:
Front Left: -0.6deg camber, 0.05deg toe IN, caster?
Front Right: -0.6deg camber, 0.05deg toe IN, caster?

Rear Left: -0.5deg camber, 0.45deg toe IN
Rear Right: -0.4deg camber, 0.30deg toe IN

Looks like the rear toe is excessive (0.75deg total toe IN but not sure what that converts to in inches). I did not have shims to adjust, but can buy shims and go back to the shop if needed.

Car drives nice and straight.

The shop could not measure caster, shocking given the nice alignment rack, and I think that is where my problem might be.

Problem: Steering wheel is centered and nice and tight from 12 o'clock to 1 o'clock and beyond when turning right. Steering is sloppy/loose from 12 o'clock to 11 o'clock when turning left, then nice and tight beyond that.

I measured the tie rods and they are equal length, measuring 15.25" from grease nipple to grease nipple. Rag joint is in good shape and steering lash has several threads showing above jam nut so I do not believe it has been messed with and I have not touched it. That brings us to the shims in the upper control arm and the unknown caster.

Front Left upper control arm shims: 1/2" thick front bolt, 7/16" thick rear bolt
Front Right upper control arm shims: 1/4" thick front bolt, 9/16" thick rear bolt

I believe this means I have much more positive caster on the passenger side than the driver side. Could this be causing the loose wheel when turning left and how should I go about fixing the problem? It would be great if I can fix this without re-aligning the front, but if I have to, so be it.

Thanks in advance.

gcusmano74

Shop cannot measure caster? Strange.
The car will lead to the side of the least positive caster. If it tracks straight and true on a straight and level highway, it has pretty close to equal caster left and right.
I am not an expert, but it looks like maybe not enough front toe, and perhaps a bit much rear toe.
The steering box is designed to be tightest when the wheel is straight ahead. It tends to get a bit looser as the wheel is turned farther away from center.
IMHO, a 360# rear spring is a bit much for a stock front spring. The stock rear spring was probably a 170# rate, so you have more than doubled it. Maybe find yourself a 1" Addco front bar to balance it out.
Sorting this stuff out is an interesting challenge.
Have fun.

wombvette

Cant measure Caster? WTF

LoneStarV

Find a new shop that knows what they're doing. Call Vansteel and order these. Stainless steel i think. Spend a few bucks with a forum supporting vendor then pick their brain on what alignment you should be using. They have a great reputation for customer service and will be more than happy to help you.

http://www.vansteel.com/index.cfm?fu...up=102&ID=1601

ZZtop2

Guys, thanks for the comments so far. To be clear, I am not worried about sorting out the cars driving dynamics/balance at this point. I will get there, although it is not bad from what little I have driven it so far.

What I want to get fixed right now is the loose/sloppy wheel when turnign left, between 11 and 12 o'clock only. When turning right, 12 o'clock to 1 o'clock and beyond, the steering is perfect (responsive and tight).

The alignment specs are in the proper range based on all I have read from Guldstrand, VB&P, etc. with the exception of the unknown caster and the rear toe that may be excessive. I am wondering if the caster might be what is causing my steering play between 11 and 12 o'clock of if I should be looking elsewhere...

*edit* Perhaps a better way to describe the steering: When driving down a straight road, I can wiggle the steering wheel between 11 and 12 o'clock and the car has no response, just continues straight. Beyond 11 o'clock, the cars starts turning left. If I move the wheel just a hair to the right from 12 o'clock the car starts turning right. There is a dead spot/play between 11 and 12 o'clock. Normally this play would be centered, say between 11:30 and 12:30 on the wheel.

redvetracr

I believe a quarter of a degree (0.25*) is 1/8 of an inch, looking at my specs I see rear toe at 0.15 LH and 0.13 RH for a total of .028* or about 1/8 total rear toe in.

ZZtop2

Red, that's about what I am seeing too from looking around on the internet. From what I have read on the forums I believe I move shims from the outside of the rear trailing arms to the inside to move the toe out. Can anyone confirm?

redvetracr

that sounds correct, just hope you have some thin ones to move and some thick ones to pound back in.

77C34SPD

my before and after specs..

ZZtop2

77C34spd, not sure what you were trying to show me with your alignment? You are running positive camber up front and a LOT of toe in. I am running a more aggressive/responsive setup than that and happy with it except for the dead spot in the steering and the rear toe, which I will get fixed.

iokepakai

Do you have power steering? If so your control valve maybe suspect.There is a slight play ,delay with the stock system.I changed mine out to a Borgeson box,no control valve and hoses under the car.Steering is quick and tight.Installed a u joint instead of the rag joint.Did the swap in 09 no leaks since,performs flawless.Borgeson box bolts up looks factory.

redvetracr

those specs wouldn`t make me happy...

cagotzmann

Create 2 skid plates with flooring tiles. 2 Tiles each which grease between the tiles. Place under both wheels. Test with the car running and without the engine running. This will tell you if any of the power assist units is causing the problem. Also turn the wheel without any power assist you should be able to see where the lack of movement is. Also caster will not cause this problem. Low positive caster affects high speed straight line stability. Cross caster large variance will cause the car to push to the higher positive caster side. +2.75 positive caster is desired for most driving styles.

ZZtop2

Thanks for the trouble shooting idea.

It sounds like the consensus is the dead spot is in the steering, not in the alignment, so I will start looking there.

I will have the caster checked at another shop I use to make sure it is acceptable (atleast 2+ on each side).

gcusmano74

RR tire now shows negative toe. Does that mean toe out? Chevrolet specs do not allow toe out.

ZZtop2

You have very slight toe out in the RR, but you are basically set at zero toe in the rear which is ok. a little toe in is preferred. You should consider aligning the front to something similar to mine.

redvetracr

I believe on hard braking the rear wheels tend to toe out slightly so you don`t want zero toe and for sure don`t want toe out.