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Body Mount Question

 
Old 02-10-2019, 09:58 PM
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Cavu2u
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Default Body Mount Question

About to replace the body mounts, as I've always heard a "rumbling" coming from the rear, seemingly just outside and down from the rear interior baggage area. I suppose the Differential Cross Member/Hanger bushings could also be making the noise, but want to replace the Body Bushings anyway.

Do those shims look "normal" for a 45 year-old Vette?

Right side shims appear in much better shape.
AAMOF, I'm surprised the rubber's condition looks as good as it does. Probably shows the difference of a car spending all it's life in a relatively dry climate and another that doesn't.



There's a little rust creepin' in there. I hope i caught it in time.

But my question again; Are shifting shims normal, like in the first photo?

Thanks.
Steve
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Old 02-11-2019, 12:04 AM
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cardo0
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Rear passenger body mount. Welded corner on caged nut.
Your rear body bushings look very good for their age. Mine were crumbling off. I think you will find those bushing look much better on the inside which is protected from the elements. Your bushings look so good I don't think I would replace them. And since I have mine out right now I want to replace mine with poly mounts on the #1 and #4 mount while keeping rubber on the #2 and #3 mounts. You said you want to replace your mounts. All of them or just the rear mounts? If the body is lifted high enough I would weld up the corners of the capture nuts cage while you can access them. I have a pix of one but not a very good pic.

As for the cross member bushings failing - forget it. They are very well protected and very difficult to remove. I replaced mine but needed a shop to get them out and they even complained. And what cam out had nothing wrong with them. It kinda defies our imagination of a nearly 50 year old part can survive but you will be disappointed if do remove them.

Those shims probably not shifting but were installed that way.
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Old 02-11-2019, 12:12 AM
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After stripping my 70' to the bone to rebuild it and judging by "how things were done on the line" I'd bet the shims pictured have been that way sine day one, no harm.
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Old 02-11-2019, 02:46 AM
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Those mounts look pretty darn good.
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Old 02-11-2019, 08:13 AM
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Originally Posted by croaker View Post
...Those mounts look pretty darn good...
Yep, and do not need to be replaced. The AIM shows the shims and how they were to be placed.
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Old 02-11-2019, 08:59 AM
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Originally Posted by cardo0 View Post
You said you want to replace your mounts. All of them or just the rear mounts?
All of them.

As for the cross member bushings failing - forget it. They are very well protected and very difficult to remove.
From some of the posts I've read, I've gotten that picture.
But what in hell is makin that noise? Sounds like a hollow rumble, associated with road vibration while driving. Annoying. Driving me nuts. Sure sounds like a dampener mount back there somewhere gone bad to me.

Those shims probably not shifting but were installed that way.
Seems odd the factory line work would be that sloppy, but perhaps they were, and in other steps of assembly too.
Thanks much.
Steve
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Old 02-11-2019, 09:05 AM
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Originally Posted by croaker View Post
Those mounts look pretty darn good.
70K miles and 45 years in a SoCal climate later, I do feel fortunate. But that noise!

Thanks.
Steve
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Old 02-11-2019, 09:15 AM
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Originally Posted by Easy Mike View Post
Yep, and do not need to be replaced.
It does seem foolish huh. But I'm just trying to eliminate that possibility of causing the rumbling noise.
What else could it be? Wish I could accurately record it and let you folks diagnose.

Thanks.
Steve
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Old 02-11-2019, 09:28 AM
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Originally Posted by Cavu2u View Post
It does seem foolish huh. But I'm just trying to eliminate that possibility of causing the rumbling noise.
What else could it be? Wish I could accurately record it and let you folks diagnose.

Thanks.
Steve
The front differential mount ?
https://warptown.com/project-corvett...t-replacement/

Differential mount
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Old 02-11-2019, 09:49 AM
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Originally Posted by caskiguy View Post
The front differential mount ?
https://warptown.com/project-corvett...t-replacement/

Differential mount
Thanks. Will take a closer look at it.
I've eliminated the spare tire/carrier unit and exhaust routing as a possible noise source.


Steve
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Old 02-11-2019, 10:01 AM
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Diff mount is possible. Does it clunk when you put it in reverse?

Could also be trailing arm bushings. These cars invent new ways to make noises every day.
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Old 02-11-2019, 10:34 AM
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Originally Posted by CA-Legal-Vette View Post
Diff mount is possible. Does it clunk when you put it in reverse?
Slightly. Noise seems to emanate from the rear left side.

Could also be trailing arm bushings.
I've not looked into this possibility. Thanks.

These cars invent new ways to make noises every day.
Indeed.
Steve
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Old 02-12-2019, 12:36 PM
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The differential has enough oil, right?

Wheel bearings can also make that kind of noise. Check for heating at each of your wheels.

Last edited by ignatz; 02-12-2019 at 01:15 PM.
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Old 02-12-2019, 06:53 PM
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I haven't checked the level lately, but I will now.
Thanks for the idea.

Steve
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