79corvette

I've just started driving my vette after it had been sitting in my garage for 11years. Once I have been driving the car for a little bit I hear this clunking from the differential at slow speeds and it causes the car to shake a little I think. Could that be because I need to change the fluid in it? Is it easy or should I just take it to the Chevy dealer to do?

71vettman

Sounds like the noise you are hearing is from the limited slip clutches "grabbing". When they sit they tend to get varnished and cause the clutches to grab and not engage smoothley. I would change the fluid and make sure it is the stuff for the limited slip rear ends. Then take it out in a parkinglot and drive in a figure eight at slow speeds untill the noise goes away. It might shound like the rear end is gona rip out of the car but the noise should eventually go away.
you might want to try diong the figure eights before you change the fluid as this may be enough to solve the problem.
Kevin


[Modified by 71vettman, 9:57 PM 3/3/2003]

WhyFly

My 80 had sat for about a year before I bought it and made the same kinds of sounds when I first started to drive it. I took it to the local Minute Lube and had the guys change the diff. fluid. Drove the car for about an hour after the change and also found a quiet parking lot and also drove it in reverse a bit. The noise disappeared. I waited about two weeks and took it back and had it changed once more and added some diff. treatment. That was two summers ago and the rear end has been quiet ever since.. Hope this helps..Good Luck :thumbs:

79corvette

Where do you guys get your differential fluid changed at? I quickly asked a place and they quoted me $59, is that about right(I'm 17, so trying to do things on a budget lol)?

page62

You can do it yourself. I did :D It's easiest if the spare tire is removed.

Go to a Chevy dealer and get two bottles of diff fluid and one bottle of posi additive (very important). Remove the diff plug (it's on the side). Suck out the old fluid by using something like a drill pump (cheap) and tubing. Take the tube and make sure it goes down toward the bottom. Then pump in the new fluid -- a drill pump can do both jobs for you. The unit is full when fluid starts running out the side.

59 bucks -- sheesh!

Touringpro

Everyone is giving you good advice. :) It's a pretty simple job if you remove the spare tire and use a vacuum pump to suck the old fluid out.

I did it a month or so ago and used a little less than 2 bottles of Mobil1 75W-90 synthetic gear oil (about $6/ea.) and a 4oz. bottle of 'Limited slip Axle Lubricant Additive' P/N 1052358 ($7 give or take from any Chevy or other GM dealer). :cheers: