Marks69BB

How do I get all of the old fluid out of the diff. Then, should I clean it inside in any way or just add the new fluid? What fluid(s) should I use?

JSB69

I use a turkey baster and get as much out as I can. No other cleaning necessary unless you have reason to believe there's some loose metal in there. Refill with GM limited slip gear lube and one bottle of GM limited slip additive. Both are available at your local dealer. I've heard some members claim that there are other products besides GM's that work, but why bother when there's a sure thing.

fauxrs

an inexpensive pump can be had from any local parts store that will remove all the fluid from the diff. Refill with approved gear lube (use pump in the other direction) and posi additive - quantities I do not know off the top of my head.

Marks69BB

JSB/fauxrs - Thx for the replies. Looks like I'm off to the parts store again! :cheers:





[Modified by Marks69BB, 9:16 AM 2/4/2002]

dman535

Make sure your wear clothing that is disposable. That 80w90 coming out of the diff sticks to everything and it STINKS !

GaryS

I believe the pump is called a suction gun or pump. By pulling out on the handle you can create enough of a suction to pull even the 80W90 stuff. Shouldn't be more than $10 or so. It works well enough to get the oil out. You can help by driving your car for a few miles to get the diff. oil warm. If your car isn't road worthy or your roads aren't good (snow etc) then don't worry about it.
Gary

1LE

I used a a suction gun, looks like a grease gun, to do mine, got the Gun at
a local parts store for 11bucks. Worked very well. No mess at all. I did have a large pan under the rear to catch any mess.

Neo Fender

Everything already mentioned is good gouge (hand suction pump, the stink, etc.). Removing the spare tire carrier improved access on my '79.

Phlash

ditto the GM lube and limited slip additive. My posi had significant binding until I removed the old fluid and put in the good stuff. Car had been sitting about 4 years and needed some loosening up. :lol:

Phlash 72 BB Roadster

454Big

To get out ALL of the fluid you need to drop the diff and open the rear cover.

No big fun to do this, its a lot of work to do and the part is heavy!

As was said - usually not necessary except you know that there is metal in.
Some forum members drill in a drain hole, also there are aftermarket kits to do so.
I would recommend to drop the diff when drilling it. There can always come metal debris inside the system when drilling!

In a usual street driven Vette the diff doesn´t need to be dropped, just a regular check of the fluid level is recommended as well as replacing the fluid when it is time for !

Larry B.

Mark I made the mistake of cleaning the diff completely one time when I replaced the yokes. I put the correct fluid and additive in but got clutch chatter big time... I had to change fluid TWICE more to get it to settle down and hd no more problems. I would not use any type of solvent that my get inside. :jester

Frankenvette

Very seldom do I take my vette to the shop. Changing the diff fluid was one of those rare events. My local chevy dealer charged me about $50.00 to change the diff. This included 2 bottles of additive. Sure made this project painless.

Regards,

Jim