Seff

Took my car to get aligned. The mechanic said I'd have a hard time getting her to run straight, since my rear axle's crooked, like the picture below. Am I looking at getting a new frame? Making out my rear lower control arms and finding out if they're different lengths?

oldcutlass

What are the measurements from center hub of axle to center of the front hub on each side?

Seff

Since I only had string, it's a rough measurement at the moment - but the difference between the two sides is roughly 60 mm.

oldcutlass

So about 2.36" Have you checked your rear control arm bushings, are the control arms bent? Are there a disproportionate amount of shims on the front?

Seff

Bushings are new (Moog) as of this summer, and the arms weren't bent at that time. I'll lift the car this weekend and measure arms bolt to bolt.

I fear it's my frame, since I know it's been in an accident.

allyolds68

Get it on a frame machine, measure it, and pull it.

Seff

We don't have many frame shops over here.

Seff

Measured the length of the lower control arms, they're the same length. So, I will measure diagonally between lift points to see if it's crooked.

oldcutlass

Look at both frame rails to see if there was previous damage. The rear has fixed mounting points.

Allan R

Isn't this the car you restored? IIRC you have another donor car with another frame? Check the control arm attach points on the other frame and compare. Where was your car hit?

Octania

over two inches?
I vote unmatched control arms.

4speed455

I sure there would be other symptoms also, but how about a bent axle?

Allan R

Chris, the CA's are the same length
A 2" difference side to side should also show up as dog tracking if the frame is bent.

Seff

This frame was hit on the left frame horn. The other frame was hit hard in the rear. If I'm getting a replacement frame, it'll be a convertible frame.

I don't know if it doglegs, but I'm lifting the car again soon to find out what the devil's going on.

Allan R

This is a collision repair chart for 1970 Chevelle, which is the same for Cutlass. The reference lines will be identical. Basic frame information is also in the CSM on page 2-1

Seff

Measured the frame today. The K measurement differed about 12 mm, and the wheel hub to wheel hub distance ended up being 10 mm apart, side to side. I dunno what the alignment guy had been drinking.

Allan R

Your measurements sound like they're close enough to spec. Try taking it to a different shop for alighment and see what they say. 10 and 12mm is very small amounts especially with the sloppier tolerances allowed at the factory when these cars were initially built.

Seff

Yeah, I'm not that worried now. It's a 42 year old car with at least 200.000 miles and at least one crash under its belt.

brddg

Dog tracking is the common term used to describe a diamond frame condition. The wheelbase would not be different unless you had more than one problem. This second set of measurements sounds more believeable and will drive just fine. If you did have a two plus inch difference in wheelbase from side to side the suspension would be the parts most likely to be bent. Imagine how hard of a t-bone it would take to shorten one side of a car by that much!

Seff

Yeah, my friend and I stood under the car, and literally couldn't see anywhere where it might actually BE bent that much.

oldcutlass

What happened on this measurement? 10mm is a lot better.


I'd go to another alignment shop.

Seff

I did it with string and tape in the parking lot. The only reason I believed it was that the alignment guy said so.

oldcutlass

Anyway sounds to me the alignment guy didn't want to mess with it. They aren't as easy as a newer car and takes some skill. A good alignment guy is very rare now a days. You might ask some fellow car enthusiasts in your area who they use. I've also found that shops that deal with trucks have a better understanding also.

Seff

Yeah, I'm not messing with random shops anymore. They're too accustomed to newer cars.

Allan R

Interestingly enough, I was told that since I took my rear axle out and refurbed it, the best thing I could do is a modern 4 wheel alignment.

Seff

I assume this was someone who didn't know better?

I used a lift at the base, and one of the mechanics heard my predicament and asked where the adjustments on the rear control arms were supposed to be made. He then too one look and shook his head.

oldcutlass

I don't mind when they hook the machine up for and check 4 wheel alignment, as most require the sensors hung from all 4 wheels now a days anyway. However I will only pay for a 2 wheel.

Allan R

Actually he's very well versed on the topic and is a credible mechanic. He commented that since I'd done BOTH the front and rear suspensions, it wouldn't be a bad idea to see how close they were to being right on. Of course we know there's no adjust-ability on the rear, but it gives a reference line to the front. The cost of 4 wheel alignment is the same as 2 wheel, and if a good shop does the job I feel much better.

Seff

Makes sense.