C2Differential Fluid Change

[Alan Drake]

Have my 64 differential out. Would be be wise to remove the cover (303),let fluid drain and refill with std gear oil and GM posi additive?
Would make cleaning the cover simplier.
Fluid was last done in 1975, but only a few 1,000 since then some at 1/4 at a time.

[Duke W.]

Re: C2Differential Fluid Change

As long as the axle is on the bench, an oil change would be a good idea.

Check and clean out any sludge at the bottom of the carrier. This is common on Positraction axles. and the sludge is probably clutch wear debris, especially if the axle has a lot of miles from the original build or last overhaul.

Once the cover is open you can do some basic checks like ring and pinion backlash and tooth contact pattern. Also check side yoke end play and if excessive, remove and check side yokes for excessive end wear. I co-authored a Corvette Restorer article on axle overhaul a couple of years ago that you might want to read to refresh your memory on axle issues.

It might be easier to refill the axle after it's reinstalled on the vehicle to avoid any spillage.

Use the GM axle oil or a commercial SAE 80W-90 GL-5 gear oil along with s 4-oz. bottle of limited slip additive.

Short fill the axle a few ounces. If you get chatter, add 2 more ounces of additive and test. Once sufficient additive is present to prevent chatter, top off the axle. Maximum level should be to the bottom of the fill plug WHEN THE OIL IS HOT - slightly below when cold. Minumum hot level is a quarter-inch below the fill plug. Axle capacity is 3.7 pints.

It's best to use the minimum amount of additive required to prevent chatter. Excess additive reduces clutch preload torque.

Duke

[Alan Drake]

Re: Thanks Duke and articles are . . .

Looked at the two articles, for reference to other members;
Winter 2005 Rear Axle Side York End Play
Spring 2005 Corvette Rear Axles