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Broken spring bolts

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Old Sep 15, 2010 | 09:52 PM
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Default Broken spring bolts

Two of the four bolts that hold the spring to the differential were snapped off before I acquired my '74. I have seen the ears towards the back broken off, but on my car the front two snapped off flush.

Has anyone ever seen this before? I am wondering if the previous owner broke them when installing the spring or if they broke while driving.

Thanks
Tom
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Old Sep 15, 2010 | 10:18 PM
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Could be he broke them off.. but more than likely a sign the rear spring was not installed properly.

The rear spring is to be installed snug when the car is elevated and only torqued down under the car weight! Failure to do this can result in broken ears and bolts.

Sometimes getting those bolts out can be a real PITA... Good luck.

Willcox
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Old Sep 15, 2010 | 10:32 PM
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Originally Posted by Willcox Corvette
Could be he broke them off.. but more than likely a sign the rear spring was not installed properly.

The rear spring is to be installed snug when the car is elevated and only torqued down under the car weight! Failure to do this can result in broken ears and bolts.

Sometimes getting those bolts out can be a real PITA... Good luck.

Willcox
I did NOT know that..! I don't have a lift so I'll have to really shimmy under there to do it when on the ground...!
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Old Sep 15, 2010 | 10:48 PM
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Originally Posted by MrJlr
I did NOT know that..! I don't have a lift so I'll have to really shimmy under there to do it when on the ground...!
It is easier to have the car on jack stands and a floor jack under each end of the spring to de-arch the spring
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Old Sep 15, 2010 | 10:49 PM
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i had one break on my 79, had to drill it and remove with an ez out, i replaced all 4 with grade 8 bolts, from napa, i used the method above to dearch the spring. two of the bolts,that are closest to the front need to have thicker washers because if too long a bolt is installed it will penetrate/crack into the rear cover, causing an oil leak.
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Old Sep 15, 2010 | 11:01 PM
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Originally Posted by MrJlr
I did NOT know that..! I don't have a lift so I'll have to really shimmy under there to do it when on the ground...!
Most don't know this so don't feel out in the blue. It is a common problem.

As long as you have the weight of the car on the spring when you torque it you'll be fine. The problem comes in to play when the rear spring is torqued before sprung...


Willcox
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Old Sep 15, 2010 | 11:04 PM
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Originally Posted by speedreed8
two of the bolts,that are closest to the front need to have thicker washers because if too long a bolt is installed it will penetrate/crack into the rear cover, causing an oil leak.
My luck will be that the bolts snapped when the bolts bottomed out. If this was the case, the bolt will be very difficult to remove with an easy out. I am going to remove the whole rear and swap it with a rebuilt one I have.
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Old Sep 15, 2010 | 11:07 PM
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Originally Posted by speedreed8
i had one break on my 79
Speedreed8,

How did the bolt break? Was it while installing the bolt or while driving?
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Old Sep 16, 2010 | 12:35 AM
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Originally Posted by Willcox Corvette
Most don't know this so don't feel out in the blue. It is a common problem.

As long as you have the weight of the car on the spring when you torque it you'll be fine. The problem comes in to play when the rear spring is torqued before sprung...


Willcox
How about I set the back wheels on wheel ramps....the weight will be on it and I'll be able to get under it ?


EDIT: I'm done cleaning and painting....I'm putting it back together this weekend !!!!! Woo-Hoo !

Last edited by MrJlr; Sep 16, 2010 at 12:36 AM. Reason: add
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Old Sep 16, 2010 | 12:54 AM
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Originally Posted by MrJlr
How about I set the back wheels on wheel ramps....the weight will be on it and I'll be able to get under it ?
Install the spring and snug up the 4 bolts under the differential.
Then install the spring to trailing arm bolts and lower your Vette on to the ramps and torque the 4 bolts under the differential.
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Old Sep 16, 2010 | 01:30 AM
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Originally Posted by petes74ttop
Install the spring and snug up the 4 bolts under the differential.
Then install the spring to trailing arm bolts and lower your Vette on to the ramps and torque the 4 bolts under the differential.
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Old Sep 16, 2010 | 01:39 AM
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Great tip and good to know cause I just droped my diff and crossmember a few hours ago.
Thanks for the information.
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Old Sep 16, 2010 | 02:47 AM
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tom, i dont know how it broke, i noticed it while getting a new exhaust system installed.
i believe the original bolts were grade 5, thats why i went ahead and replaced all of them.
probably just fatique. it was the original spring and bolts. but who knows what previous bubba owners have done.!
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Old Sep 16, 2010 | 06:21 AM
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Let me know if the cover gets messed up, we have the HD covers in stock.

Andrew
800-442-0335
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