CUTLASS Thrust angle?

[RICKDIZZLE]

Friends, I have adjustable upper and lower trailing arms on my 1985 Cutty. I had the front end aligned last month and was dead on straight, steering wheel and all. In detailing the car for a show this weekend, I noticed that my rear end was about a half inch further right (to the passenger side) so I adjusted my uppers and got it measured back to dead center. Took the car out and sure enough when the car tracks straight, now the steering wheel is slightly turned to the right. I know this is due to the thrust angle of the rear end now being different then when the car was aligned. Im trying to understand the physics of why its straight but the wheel is now slightly right. Does it means that based on current front end alignment the axle is now to far forward on the drivers side?So should I....

A: Quit being OCD and not worry about it.
B: Get the front end realigned
C: Play with uppers and lowers to see of i can get it back straight.

Is there a way I can tell if the axle is straight? Measuring from tire to fender well the drivers side is a lil bit more forward...but I know that is not a good acurate measurement due to too many variables. Again I only adjusted the uppers...not the lowers at all.

Any help is appreciated!

 

[fleming442]

A string between jackstands, parallel to the frame, is the best way to measure because your body may not be square to the frame.
Now, if I understand correctly, you moved the entire rear toward the driver's side. That should not affect the front. It sounds like you rotated the housing somehow. The first thing to do would be correct the pinion angle, then get the front realigned.

 

[TURNA]

The rear being over to the pass side is very very common.

I have seen it on most GBody's

It is only noticable once you put larger tires on the car

 

[pontiacgp]

I would bring it back to the alignment shop and get them to redo it. Even though you got the front end aligned they did it in relation the the back wheels or at least they should have. Also check with the alignment shop that they did a full alignment. With the new cars alot of the alignment shops just set the toe. I had one place wnat to charge me an extra hour per side if they had to do the camber. I didn't even ask about the caster setting....

 

[RICKDIZZLE]

Thanks fellas! Yeah I only adjusted the upper adjustables so in theory it should have not messed with the thrust angle. I did just put brand new wheels and tires on both front and rear. Exact same size, offset and so on as my previous set. Maybe that somehow is messing w it. My set of wheels and tires I had on before only had 500 miles on them so like no wear. And these ones are brand new. So doubt that did anything.

If my steering wheel is to the right a tad while driving straight...if it were the rear end, that would mean drivers side is a tad further forward then the passanger correct?

 

[TURNA]

I would say if your steering wheel is off then just like pontiacgp said I would take it back to the shop that did the alignment