Rear end groan
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Intermediate
Joined: Mar 2007
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Rear end groan
My 71 convertible groans when I turn left or right while moving. No noise when turning front wheels while still. diff fluid seems full and clean (Limited slip 80-90 gear oil) Any ideas. thanks!
Melting Slicks
Joined: Dec 2009
Posts: 3,229
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From: Thunder Bay
There is a special posi additive required for Corvette limited slip differentials. Get some. Add it. Do some figure eights in the nearest parking lot. Chances are that will take care of it.
Heel & Toe
Joined: Feb 2017
Posts: 17
Likes: 2
From: OH
I can give my experience with the diff. I was at a light and turned right and within about 150 feet there a sound like a metal hammer hitting the underside of the car. After investigation - it did end up being the diff oil so I changed it and added 8oz of TransX (suggested by my local Corvette restorer - the clutch plates in the diff were rubbing). It was pretty easy to take care once I figured that out. The only sound I have left in the rear now is a groan when you push the rear end sideways (parked) - I was told it is probably the rear leaf spring liners so that is on my list this year to look at.
Last edited by mike1969; Mar 13, 2017 at 01:24 PM.
Le Mans Master
Joined: Jun 2006
Posts: 6,399
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From: Tampa Florida
Thread Starter
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Joined: Mar 2007
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Thanks for the suggestions. Is the pictured 85W-145 limited slip gear oil? I'm wondering if I ought to be adding the additive to gear oil that is labeled limited slip.
Also I'm wondering if 80W-90 is a better weight for my conditions? I'm in California's Central Valley, so it's rarely much below freezing (and I won't be driving my vette then!), but does get over 100 degrees F during the summer when I might be driving.
Also I'm wondering if 80W-90 is a better weight for my conditions? I'm in California's Central Valley, so it's rarely much below freezing (and I won't be driving my vette then!), but does get over 100 degrees F during the summer when I might be driving.
Last edited by Sophocles; Mar 17, 2017 at 05:35 PM.
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Le Mans Master
Joined: Jun 2006
Posts: 6,399
Likes: 1,226
From: Tampa Florida
Thanks for the suggestions. Is the pictured 85W-145 limited slip gear oil? I'm wondering if I ought to be adding the additive to gear oil that is labeled limited slip.
Also I'm wondering if 80W-90 is a better weight for my conditions? I'm in California's Central Valley, so it's rarely much below freezing (and I won't be driving my vette then!), but does get over 100 degrees F during the summer when I might be driving.
Also I'm wondering if 80W-90 is a better weight for my conditions? I'm in California's Central Valley, so it's rarely much below freezing (and I won't be driving my vette then!), but does get over 100 degrees F during the summer when I might be driving.
https://www.corvetteforum.com/forums...diagnosis.html
I used the GM fluid and additive previously in this photo, but found the Lucas 85/140 along with 2 bottles of GM additive to work better.
Last edited by 71 Green 454; Mar 17, 2017 at 08:04 PM.
Thread Starter
Intermediate
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Instructor
Joined: Dec 2016
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From: Wollongong Great Southern Land