Warm Differential
Thread Starter
Racer
Joined: Oct 2007
Posts: 284
Likes: 6
From: Palm PA
Warm Differential
Most of my driving is short distances but once a year I drive to the Ocean City MD Corvette Show from PA. 3.5 hours of highway driving. Pulling off of the PA turnpike the rear made a clunking noise while turning and the same noise turning into the driveway and parking in the garage. I know from previous posts the limited slip clutches are the source. When I removed the luggage from the rear compartment the carpet over the diff was warm. Is this normal? I have 3.70 gears and 3,250 rpm on the tack at 70MPH. I checked the fluid tonight and it is 1/2" low. Should I just top off with some positraction additive from GM?
68 Vetteman
68 Vetteman
Pro
Joined: May 2013
Posts: 672
Likes: 31
From: Rapid City South Dakota
When was the last time the diff lube was changed? I would think the heat is from the exhaust system. As for the 3.70's. it's no big deal, lots of guys run lower diff gears with overdrive transmissions, which reduces the engine speed but the diff gears are still spinning like crazy..
Drifting
Joined: Jan 2011
Posts: 1,853
Likes: 81
From: Hamilton Virginia
70 mph with 3:70 gears, it will get pretty warm. The clunking sound mainly when your turning even the slightest will be the clutches. Best way to handle that is to suck out all the old fluid and put in new fluid with posi additive. As previously posted, the warmth on the carpet can be from the exhaust if yours is still in the stock position.
Thread Starter
Racer
Joined: Oct 2007
Posts: 284
Likes: 6
From: Palm PA
It's not leaking any fluid and I have sidepipes. I've never changed the fluid since I bought it 10 years ago but will drain the old fluid and refill it. I just never noticed the warm carpeting on my other trips. Thanks
68 Vetteman
68 Vetteman
Pro
Joined: May 2013
Posts: 672
Likes: 31
From: Rapid City South Dakota
Yes I would start with changing the diff fluid, no telling what kind of condition it is in....
Burning Brakes
Joined: Jul 2006
Posts: 1,047
Likes: 12
From: SoCal
Not necessarily. My '73 made that type of noise while turning (right turns, IIRC) and the cause was the tranny mount was shot.
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