Ovalized trailing arm mounting holes - Chevy Impala SS Forum
 
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post #1 of 10 (permalink) Old 06-19-2018, 06:23 AM Thread Starter
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Ovalized trailing arm mounting holes

Hi guys,
At least one of the bolt holes on the frame that the trailing arms mount to is ovalized. This causes a clunk upon hard acceleration.
Specifically, it's the inboard hole on the passenger side upper arm bracket.
If anyone on here has ever repaired these, could you please give me some tips?
What thickness washers did you weld to the frame?
How did you ensure washers were correctly positioned before welding?
For the nut side of the upper arms, does the body have to be lifted to allow access?
Thanks

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post #2 of 10 (permalink) Old 06-19-2018, 07:40 AM
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On my last FWB I fixed with about 3x4" 1/8" plate and weldbond. It was winter did not hold so I roughed up surfaces again and reglued, and then drilled in 2 heavy sheet metal screws. So screws held better than glue. Held for 14 years. Still is by all accounts of new owner.



On my '88 Monte I just dremeled contact grooves in a very heavy washer and the frame and epoxied. It's holding after 16 years.


The welded approach likely lots faster, but welder costs money . And did not know how to get car to a shop to do it without the arms connected.


To center I noticed equal mushrooming both ends so just centered in the slot. For washer gauge just find some "very thick". lol

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Last edited by 96 Black; 06-19-2018 at 11:13 AM.
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post #3 of 10 (permalink) Old 06-19-2018, 08:34 AM
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Push bolt through the hole and washer to center the washer and tighten with the nut.
This will hold it while you weld around the washer.
Don't use epoxy or JB weld.

Nab
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post #4 of 10 (permalink) Old 08-26-2018, 10:38 AM Thread Starter
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Does the body need to be lifted to allow access for welding though?
Thanks

Remember, when not sure what to do, hit the throttle.
It may not end well, but at least it'll end the suspense.
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post #5 of 10 (permalink) Old 08-26-2018, 11:30 AM
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Any shop can do this repair easily/quickly.
Look for a local welding outfit they'll probably be the cheapest option.
A good muffler/exhaust only shop may be an option as well.
A frame shop would also be an option, but would likely charge more.

Depending on how bad the hole is? May consider the frame shop option so they get the rear axle aligned properly.
If the hole is really bad could wind up with a big thrust angle in the back if welded without being"correct".

Last edited by babywag; 08-26-2018 at 11:46 AM.
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post #6 of 10 (permalink) Old 08-28-2018, 09:48 AM Thread Starter
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I'm probably going to have the rear axle out of the car in the near future to change the ring & pinion.
While it's out, I might as well repair the mounts on the frame. I just need to know if I'll need to lift the body to allow access for welding.

Remember, when not sure what to do, hit the throttle.
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post #7 of 10 (permalink) Old 08-28-2018, 08:07 PM
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It will be tight if it is on the nut side. You really need a lift to get to it. You may even have to drop the exhaust pipe on that side. To get it in the correct position, you can measure the other side and make them match. You can get some 1/8 inch thick fender washers that should be strong enough. If it is moving, it is probably elongated on both sides of the bracket, so measuring it is probably the best way to get it positioned correctly.

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post #8 of 10 (permalink) Old 08-29-2018, 06:12 AM Thread Starter
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Quote:
Originally Posted by Fred Kiehl View Post
It will be tight if it is on the nut side. You really need a lift to get to it. You may even have to drop the exhaust pipe on that side. To get it in the correct position, you can measure the other side and make them match. You can get some 1/8 inch thick fender washers that should be strong enough. If it is moving, it is probably elongated on both sides of the bracket, so measuring it is probably the best way to get it positioned correctly.
Thanks Fred, this is good to know before I start tackling this job

Remember, when not sure what to do, hit the throttle.
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post #9 of 10 (permalink) Old 08-29-2018, 06:33 AM
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Here are a couple more tidbits: When assembling, do not tighten the bolt unless you have the car sitting on the suspension, or you will damage the bushing. I am putting new bushings on my wagon, and there is not much space to work. The bolts are extremely tight, and you can only get about an eighth of a turn with a ratchet. The nut is on the outside, and has no space for a ratchet, so I put a vicegrips on the nut, and needed an extension on an 18" breaker bar to get the bolts loose. They are torqued to 125 lb. ft.

1991 OCC 461 (.030 over 454) BBC, 3.23 posi, flash to pass, drop spindles & springs, Impala rims, Hydroboost, Recaros, MOMO/wood SW w/QR, custom wood shift knob, Pioneer DEH P77DH
1992 OCC now with 5.7 tbi, DEH P77DH
For a parts list, check https://www.impalassforum.com/vBulle...ion-parts.html
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post #10 of 10 (permalink) Old 09-11-2018, 07:43 AM Thread Starter
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So I pulled the axle last night.
A year ago, I installed adjustable length upper trailing arms.
At that time I was also going to install the Dick Miller trailing arm mount braces for the SEDAN (he told me they'd fit). When I realized they didn't fit, I took the car to a shop & asked them to modify/lengthen the braces to fit & install them for me.
Well, last night I come to see that the braces WEREN'T EVEN BOLTED DOWN at their upper ends.
I also saw that the jam nut on the adjustable length trailing arms was tightened to the WRONG SIDE of the threaded rod. I suspect that this is the cause of the clunking.



Anyway, the arm mounting holes aren't ovalized that severely (see photos, 14mm bolt held in place for reference), not sure if they need attention, I figure that when the bolt is torqued, the mount pinches the bushing forcefully enough that it won't move. Thoughts?

The shop was Speedy in Bedford, Nova Scotia, in case anyone local considers taking their car there.
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Remember, when not sure what to do, hit the throttle.
It may not end well, but at least it'll end the suspense.

Last edited by Big Jack; 09-11-2018 at 05:40 PM.
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