Rear End Fluid Change

Ms Kiss · 03-30-01, 07:37 AM

Has anyone ever installed a drain plug for the differential? Or, know of an easy way to change the fluid without tearing it all apart?

Barbie

**DDLS3** · 03-30-01, 12:13 PM

Barbie,

I don't of anyone who has installed a drain plug in a differential. Even if you do, you usually have to remove the cover to install. At least thats the way it works when installing a drain plug in a transmission pan. Removing the diff cover is no big deal. Usually the gasket is a thin application of blue silicone. Remove the bolts except one or two on top which you want to leave backed out at least a 1/2". Gently pry the cover loose, use care not to bend it by working around the circumference. Clean all the old silcone off both faces, wipe out any debris and sludge with a lint free rag. Apply a thin bead of silicone and re-install the cover. Don't over tighten the bolts or you will squeeze out the silicone. Good luck!!

Dale

**trrgod** · 03-30-01, 12:56 PM

This is how I changed my rear end fluid.
Open fill hole with proper allen wrence.
Use a suction device(my buddie's shop has one that hooks up to his air supply, I've heard that you can buy a hand pump type at auto supply stores). Make sure the tube is as far down into case as possible.
Suck out all fluid.
Fill with oil and posi fluid.
You're done.
Why Corvette decided not to put in a drain plug is hard to understand.

**vigman** · 03-30-01, 03:46 PM

I did the same thing as trrgod.... anything else is a hassel!
Mike

**Ken** · 03-30-01, 05:41 PM

I'll have to go to the garage later to find it, but I'm sure I saw an article not too long ago that described the installation of a drain plug in the third member of Corvettes.

Remind me if I don't get back to you in a reasonable amount of time.

Ken

Ms Kiss · 03-30-01, 08:07 PM

The responses are appreciated. But what about the metal shavings? I am sure prior owners dumped the clutch once or twice. I plan on keeping this car and figured instead of tearing the unit apart why can't I drill a hole, tap it, irrigate it, use a magnet pen for the shavings, one more flush and fill, and throw a plug in. And, do that anually. Always thought that was part of regular maintanance. Estimates I got from GM dealerships just for a fluid change, were obscene.
Recommendations are very welcomed.

Barbie

**Ken** · 03-30-01, 09:33 PM

Originally posted by Ms Kiss
...why can't I drill a hole, tap it, irrigate it, use a magnet pen for the shavings, one more flush and fill, and throw a plug in.

Barbie, I can't find the article and I went back thru a years worth of Corvette Fever and Vette Magazine! I do believe that is how it was done. Sorry I can't be of any more help, but I'm sure if ya took yer time and measured everything twice, there shouldn't be a problem with your idea.

I did find an unrelated article that I was looking for; "Project: Lazarus" - vigmans story sounded familiar.

Ken

84c4 · 03-31-01, 09:07 AM

Barbie,

Ken was looking for the November 1998 issue of Corvette Fever, page 36. There is an article on installing a drain plug.

Contact the Corvette Clinic in Sanford, FL at 407-323-7804. They sell the kit that includes a template for where to drill the hole, drill bit with stop on it so you don't drill to far and a tap.

When you drill the hole the oil will keep the filings from going into the diff. A magnet will only collect material from gear wear since the housing is aluminum. Use Mineral spirits to flush with, solvent evaporates to quick and leaves metal behind.

One more thing, take a short drive to warm up the oil, but let the exhaust cool down, the oil will still be warm.

Have fun

Dave

**Ken** · 03-31-01, 02:06 PM

Originally posted by 84c4
...November 1998???

Man, I must be getting old. I could have sworn that I read that just recently! At least within the past year.
Oh well, at least you finally got the real dope Barbie. See, I wasn't crazy after all.

Thanks Dave

Ken

**trrgod** · 03-31-01, 02:58 PM

84c4- Have you actually put the drain plug in using this kit? I also have reservations on getting all the shavings out of it.
Barbie-any compatent mechanic can drain and fill. This should not be very costly. Certainly no more than 1/2 hour labor. Be sure to get the posi stuff from the dealer to give to the mech. to put in also with the new oil. You should not have to change rear oil every year unless you put a lot of miles on the car. Whoever does it must have a pump to put in oil because there is no room to tilt the oil bottles high enough. You can buy one of the pumps cheap at almost any car parts place.

84c4 · 03-31-01, 04:26 PM

trrgod,

I have not done it to a Corvette, but I have done it to several other applications where aluminum housings are involved. You don't get metal shavings like you do with steel, the aluminum is soft and the drill flutes pull it out, plus the warm oil is flowing outward washing everything down your arm. I feel it is a better way than trying to suck it out. The stuff you need to get out of the rear end has settled to the bottom. It has to be washed out to do it right.

Just my 2cents

Dave

Ms Kiss · 03-31-01, 06:00 PM

Thanks guys!! I thought siphoning wouldn't get all the harmfull deposits, and I am surprised more people haven't persued this.
Is this something I should be overly concerned about? I'd rather maintain it then have to fix it. And as far as mechanics go, boy, that's a hole other story.

Barbie

**Jack** · 04-01-01, 03:58 AM

Barbie:
Judging from your 6-speed logo, I'm assuming your pride and joy may be a C4 or C5. If it's an '84-'96, Eckler's latest catalog # 131 p 152 has a differential drain plug kit # 37626 at $70...kit has long drill w/stop, tap and plug...and instructions. I've seen similar kits at other vette houses. I second the warmed oil and mineral spirits. I do not have personal experience tapping vette diffs. Unfortunately, us C3 folk are apparently stuck using the turkey-baster or oyster-shuck methods. Good luck & let us know how it unfolds.
Jack
'71 cpe

Ms Kiss · 04-01-01, 08:08 AM

Well low and behold, how right you are. I am going to try the kit. Just when you think you have bought everything possible from Ecklers, Mad, CC, Zip etc., there is always something else isn't there? No wonder I am on a first name basis with the UPS delivery guys.

Thanks again.

Barbie

BubbleHead · 04-04-01, 04:54 AM

Barbie,

The diff plug is not a bad way to do things, BUT it's better to pull the cover and do a quick check on your gears and bearings. I do this on my Jeeps constantly. Both of them see rivers and deep mud pits. My case is probably a worst case scenario, but I always feel better to be able to check the wear pattern on the ring gear, along with the over all condition of my diffs.

Just something to think about.

Tim