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Topic: Rear Differential Leak

in Forum: C3 Driveline Components


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Rear Differential Leak (1/8)
 7/4/09 10:33am
77 Red Corvette
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Joined: 3/23/2008
Posts: 81

Last year we replaced the yolk seals on the rear differential of our 1977 Vette. We basically rebuild the whole rear end including putting on the better heavier designed cover. We have put since then over 3,000 miles on the car. We have noticed some very slight drips on the driveway after driving him. I had a local mechanic look at it. He said that I shouldn't  worry about it and that they all leak just a little. I read in the service manual that after 6,000 miles you should top off the diff fluid. That to me reads as if it they all indeed do leak a little.
 
I don't want to have to replace the seals again if this is just the design problem.
 
Thanx,
Anni and her Demon Evil Smile
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Rear Differential Leak (2/8)
 7/4/09 11:08am
Adams' AppleLifetime Member
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


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Where is it leaking, tho? You can expect to see some slight seepage from the diff over time, but if it's dripping on the ground where its parked, that might be a bit much.
Cast iron is  slightly porous, meaning it can/will seep liquids thru it, but not normally enough to drip. It's possible the diff has too much lube in it. If it does, then when it gets hot while driving, the lube expands, and it can spit out thru the vent, and run all the way down to the ground.
I'd suggest finding out where the leak actually is, but my feeling is, if it's enough to hit the floor, it's too much. Also, just because the seals have been replaced doesn't mean they won't leak...they might, and then they might not.


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Rear Differential Leak (3/8)
 7/4/09 11:17am
77 Red Corvette
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It is leaking from the yolks. And like I said it's just a couple of liitle drips after driving and then it stops.
 
So your saying that there should not be any leaks.
 
Thanx,
Anni
Rear Differential Leak (4/8)
 7/4/09 11:29am
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Duncanville, TX - USA

Vette(s):
#1-1974 L-48 4spd Cp Med Red Metallic/Black deluxe int w/AC/tilt/tele./p/w-p/b/ Am-Fm/map light National/Regional/Chapter NCRS "Top Flight" #2-1985 Bright Red/Carmine Cp.L-98/auto Member: NCRS, NCRS Texas, Corvette Legends of Texas


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The actual seals themselves shouldn't leak at all. You may sometimes get leakage around the outside of the seals, where they press into the housing, but a leak from the rubber area/sealing surface isn't normal, imho.
If the leak/seep is not enough to drop the lube level down, then you'll just have to clean the drips up, that's all. Just be sure to keep a check on the level, and see how it is.


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Rear Differential Leak (5/8)
 7/4/09 11:42am
anips
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sonoma, CA - USA

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72 LT-1 AC coupe,69 l-36 coupe


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the yolk might have a groove wore into it kinda like the one you get on a vibration dampner, you can  put a speedy sleeve on the yolk and replace the seal without pulling the 3rd. member, when you replace the seal put a smear of RTV around the OD of the seal before you drive it in, that way it won't leak between the housing and seal.
Rear Differential Leak (6/8)
 7/4/09 3:50pm
KDADDY79
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Dutchess County, NY - USA

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White '79 Corvette. It's a driver.


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Could the bolts that hold on the cover need to be re-tightened/torqued.?
I was just thinking that after a few thousand miles of driving/vibration they may need some attention.
Just thought I'd throw this idea out there.
Kevin
Rear Differential Leak (7/8)
 7/4/09 10:24pm
BKVETTE
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Calhoun City, MS - USA

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1977 Black T-Top


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I  had my side yokes replaced  about a year ago and the mechanic showed me where the yokes had  actually  worn into the housing  and  he said  if I didn't  get  another  housing  it could possibly  leak  a little.  Because the seal might not seal off real good.Just wondering if your housing could be worn  a little and didn't seal off good. Just a thought.
Rear Differential Leak (8/8)
 7/5/09 10:06am
77 Red Corvette
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Thank you to everyone who responded to this posting. Even though I'm not looking forward to having to do this job yet again I just can't stand leaks. You have given me some good suggestions.

 
I will probably continue to enjoy driving the car this summer and then in the fall perhaps see about tackling this problem. At least the couple of drips that do leak are very small and stop shortly after he is parked. Just hate leaks ... LOL
 
Have a great day!
Anni and her Demon!
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