Rear diff gasket... best goop to use?

obbop · August 4, 2004

Great tech articles!!!!! Very helpful. A BIG thanks to all who take the time and effort to share the info!!!!!

Read that it may be a good idea to coat the gasket with sealant. Any recommendations on the best type to use?

Feel free to offer other suggestions on the best goop etc. to use on the various maintenance areas.

TIA

asilverblazer · August 4, 2004

I didn't use any with no leaks to speak of.

AZ-Z71 · August 5, 2004

obbop,

What kind of vehicle/year? On the new body style I know that the rear diff cover has a built in rubber gasket. Accoding to the tech manual I have you don't need to add any sealant. I dont know about the older trucks if they used the older style gasket (Paper/felt) or not. If they did then I have heard of people using the sealant.

gnutruk · August 5, 2004

My 2002 1500 4x4 with G80 locking rear differential has a felt-paper gasket. I don't use any sealant, although I have read in earlier posts of people using RTF, or similiar product, with ok results.

If you do use any sort of "goop," make super-sure that none of it gets in the rear diff. gear lube. If any gets in there, it can radically affect the luberication qualities of the fluid.

Here's what I do:

After I drain, put on new gasket and replace the rear diff. cover, I torque the bolts down to 40 N-m (30 ft. lbs.) in a crosswise pattern (be sure to replace the brake cable guide in the top bolt that you would have removed when first taking the cover off).

Then I fill the diff. and go for a five or ten mile drive so the diff. comes up to normal operating temperature.

After I get back I allow the diff. to cool back down and then re-torque the cover bolts (and the drain and fill plugs) to 40 N-m (30 ft. lbs.) again, for they will have slightly expanded during the test run.

No leaks whatsoever, without having to use any sort of goop.

gnutruk

Ben · August 5, 2004

If you use synthetic fluid, then non-silicone RTV.

Trick is to put the non-silicone RTV on the diff housing flange. Wipe some fluid on the gasket.

Then bolt the cover on, but not fully tightened. Wait hour or more to allow the RTV to set. Then finish tightening to spec & fill.

You'll never have to buy another gasket again, unless you bugger it the next time take off the cover.

Next time, take off all of the cover bolts.

Wack the cover smack in the middle with rubber mallet.

The cover will "pop" off. Make sure to have catch pan underneath.

Wipe clean the gasket surface and mating surface of cover.

Clean everything and just bolt on the cover. No new gasket needed. Been doing this on the 1980 Silverado C10 for years. Ditto 1996 Sub.

etex211 · August 6, 2004

Glue the gasket to the cover (3M Weatherstrip Adhesive works great for this) and then put a coating of wheel bearing grease on the side of the gasket that mates to the housing. If you do this, you should be able to re-use the gasket time and time again. Just be sure to put another film of grease on with each application.

I use this method on the third member gasket on the 9" Ford rearend in my racecar and I can use the same gasket through 40 or 50 gear changes.

BurbanZ71 · March 26, 2007

Last night I drained out the gear goo in my 05 Burb, replaced the gasket with a new one from a local Chevy Dealer.

Everything looks good, although I was not able to get all the old gasket off both the cover & housing - should I be worried?

I have not done a road test yet - did run it for a few minutes while up on jack stands. Everything looks good, just concerned about the old gasket causing trouble.

When scraping the old gasket off how do you keep the junk from getting in the housing?

I have heard some people use brake cleaner to clean off the gears & old gasket - is this recommended?

azchevy · March 26, 2007

Do not use the factory gasket. Use The Right Stuff. Better than any gasket. I have used it on my diffs for 6 years with no problems

From their site:

The Right Stuff was formulated, in partnership with GM, Ford and DaimlerChrysler, to meet or exceed very rigorous performance standards for long-term sealability, durability and handling. The result was a material that is so reliable that it is used on their production lines

and specified in their service parts programs.

http://www.permatex.com/brand_right_stuff.htm

You can get it at auto zone.

Better than any gasket In my opinion and it is the only stuff I will ever use

rogerf · March 26, 2007

This idea (RTV + cut gasket) is not specific to servicing a differential. Have done this on over-the road buses for many years. As a general rule, I usually use a little RTV as a glue with cut paper gaskets especially joining two castings in high vibration situations (like on a diesel engine). Just make sure both surfaces are completely cleaned with solvent as you would with using RTV alone. On a sheetmetal differential cover, RTV by itself will seal just as well. Just make sure to not overtighten/distort the cover and let the RTV cure as long as possible before refilling.

ken1mod · March 26, 2007

gee,

I just use rtv and no gasket. no problems.

ken

demented · March 27, 2007

If you must use a sealant, General motors makes an excellent sealant called GMS(General Motors Sealant) available at any GM dealer. I've used it for years. It works great when you can't use a paper gasket.

BurbanZ71 · March 27, 2007

Everything looks good, although I was not able to get all the old gasket off both the cover & housing - should I be worried?

When scraping the old gasket off how do you keep the junk from getting in the housing?

I have heard some people use brake cleaner to clean off the gears & old gasket - is this recommended?

I did not mean to start a debate about the better method gasket vs. RTV or both. I was trying to ask three questions:

1) How to get the old gasket off.

2) What is the risk if all the old gasket is not removed?

3) How to prevent the old gasket from falling into the gears? Is a flush process recommended?

thanks!

ken1mod · March 27, 2007

Gentlemen,

Really, all differential covers are identical. Not rocket science. Rtv and no gaskets are common and really work great. Done it many times.

Ken

rogerf · March 27, 2007

I did not mean to start a debate about the better method gasket vs. RTV or both. I was trying to ask three questions:
1) How to get the old gasket off.

Scrape it with a sharpened putty knife, follow with fine sandpaper if necessary. On a small removable parts such as a diff cover a wire-wheel on a bench grinder makes short work of the job. Will sometimes use a fine wire wheeel in a drill to clean the housing.

2) What is the risk if all the old gasket is not removed?

This is what causes leaks as RTV won't stick to RTV. It's important to get it all.

3) How to prevent the old gasket from falling into the gears? Is a flush process recommended?

Cover the gears with a towel. Use solvent and wipe clean when done cleaning the gasket surface. In most cases it will be necessary to rinse the ring gear with solvent as it will drip oil onto the clean gasket surface (causing a leak) if you skip this step. Make sure you also clean any metal cuttings from the magnetic plate (if so equipped).

BurbanZ71 · March 28, 2007

2) What is the risk if all the old gasket is not removed?

This is what causes leaks as RTV won't stick to RTV. It's important to get it all.

This was the first change so the original factory paper gasket was still there. Parts are still there with a new gasket from the dealer - it seems to be OK but I have not driven more than a total of 50 miles in three short trips.

I am thinking it would be best to redo this with RTV only, a waste of some nice Mobil 1 gear oil, but still better than blowing out a perfectly good rear end.