My '96 has the bolt hole "mis-machined" problem - Chevy Impala SS Forum
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post #1 of 12 (permalink) Old 10-01-2003, 06:45 AM
pnkfld
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My '96 SS has the issue where the driver's side wheel is about 1/2" further towards the front of the car than the the passenger side. Apparently it was a GM issue with bolt alignment when machining these chassis (only a limited # of cars affected).

GM's fix is to elongate the holes to the correct position. I'm not drilling my chassis. Do I live with this or is there another fix? Would one adjustable upper solve the problem?

Thank You!
Kurt
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post #2 of 12 (permalink) Old 10-01-2003, 10:45 AM
RJI
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I remember reading about that a long time ago but forgot most of it. Which mounting point was made in the wrong position? If it was the upper I would think that an adjustable upper arm could help some. If it's the bottom, I don't think anyone makes an adjustable arm. The areas you will have to watch is the pinion angle and Torsion "twisting" to the axel housing. The Geometery is different when the pivot point is moved back and forth compared to extending the length of the arm.
post #3 of 12 (permalink) Old 10-01-2003, 10:55 AM
MAUSS
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There's a TSB out on this subject. I probably have a copy of it at home on my other computer. I'll look for it tonight and E-mail you a copy if you'd like. It seems to me that elongating the hole was the GM solution.
 
post #4 of 12 (permalink) Old 10-01-2003, 11:53 AM
pnkfld
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Elongating the hole _is_ GM's solution, but not one that I'm about to attempt. I'm looking for an alternate - something where I can, maybe, upgrade a component (i.e. control arm) and fix my problem at the same time . . .

Wishful thinking maybe.
post #5 of 12 (permalink) Old 10-01-2003, 09:00 PM
Navy Lifer
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Some suggestions:

1. Verify wheelbase side to side

2. Put car on an accurate 4-wheel alignment system (Hunter laser system would be good) and get a rear thrust angle reading--if it is out of specs, that is reason enough to chase this problem.

This should give you some indication of the degree of problem.

As far as the TSB, the problem was advertised as improper "piercing" of the front lower control arm pivot hole--supposedly on the left side only, as I recall. Since it is very difficult to access the area of the frame that would need to be "fixed", the solution that GM offered by the TSB was to elongate the hole in the lower control arm bracket on the rear axle to allow the axle to be repositioned to "match up" with the other side of the car--essentially "swinging" the entire axle rearward on the affected (left?) side. I also recall that the TSB makes no mention of checking thrust or pinion angle, but those would need to be checked & rechecked if this process is carried out. The bulletin also does not direct that a doubler or locating bushing/washer be added to hold the axle to LCA in its new position, but if it is done following the TSB, I would only do it in this way (by adding something to positively fix the mounting position).

The pinion angle question was addressed in part by upper control arms that were 5mm shorter or longer, available from GM--again, no mention of these in the TSB.

The interesting thing about this TSB was that it was supposedly issued to address customer complaints about the visual difference in wheel position (ie. cosmetics), not to correct any technical problem. I just wonder how much better the car might drive if it was properly squared-up?
post #6 of 12 (permalink) Old 10-01-2003, 09:59 PM
96DCMSS
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Red face

Wow, this is the first time I've heard of this.....it's kinda scary

Gives me something new to look at on my impy now.....hopefully mines ok

Good luck with the correction
post #7 of 12 (permalink) Old 10-02-2003, 04:25 AM
Jimbeau
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I'm thinking that this is possibly just a cosmetic issue? If your rear wheels were a half inch off, the car would be noticeably dog tracking to anyone following you. Seems like you would have been told that or noticed it yourself. Yes, no? - Jim
post #8 of 12 (permalink) Old 10-02-2003, 06:24 AM
Navy Lifer
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Did a little searching:

http://www.alldata.com/TSB/10/94102004.html
533403 MAY 95 Rear Wheel - Tire Position in Wheel Well Opening

Found as line item 198 in 1994 Alldata listing, 208 (Caprice) and 197 (Impala SS) in 1995 listing--this TSB is not listed for 1996, suggesting that GM considered the problem "fixed" by the time 96 production started--or, for some reason it was never re-issued or extended to apply to 96 model year, since it was written and issued in early 1995. This bulletin is not listed as applicable to earlier (pre-94) cars.

More here from Forum---including most of text of the TSB, but no illustrations.

https://www.impalassforum.com/cgi-bin...=000087#000000

https://www.impalassforum.com/cgi-bin...=000078#000001

https://www.impalassforum.com/cgi-bin...=000741#000000
post #9 of 12 (permalink) Old 10-02-2003, 09:51 AM
96 Black
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I found an upper hole on my son's Monte Carlo SS had been hogged out into a slot (probably from a lose bolt) causing a loud chattering squeak whenever stopping. My fix involved two spare body bushing washers (they're real thick and have the right i.d.). I sliced off the edge of one to fit the concave recess pocket in the frame with the correct alignment of the bolt. A grinder and epoxy was used on the other washer to hold it in location.

I remember hearing of the TSB but all due respect to GM's cheap fix, if you have to make a slot in a UCA hole then you may consider this fix for fear of the same squeak I had . . .

Good luck
post #10 of 12 (permalink) Old 10-09-2003, 05:03 AM
Larry Burd
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I had my car aligned twice.. and the thrust angle was always 0.10 which means something is skewed by a tenth.....

Now you got me wondering????
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