Rear Diff, Gasket?

**kool-aide** · 06-22-2008, 02:34 PM

Because I'm bitter right now I'd like to say RTV sucks.

Ok, so I changed the oil in the read diff this weekend. I used RTV on the diff and on the cover with the gasket in between. If it makes a diff its that reddish orange color RTV.

The directions said run a 7/16 to 1/4 inch bead for best results and around bolt holes. Finger tight the bolts, let it sit for an hour, then 1/4 turn.

Well I doubt I used a 1/4 inch bead, hard to say, but I didn't use much of the stuff. I waited about an hour and then torqued the bolts per specs. So I didn't exactly follow the directions on the tube.

While I was torquing own the bolts you could hear the RTV squish and pop like it had little air bubbles in it. A little came out around the bolts. Maybe thats because the bead gets real close to the edge?

Any way, I noticed the gasket starting moving and by then it was too late, it ripped about the bolt holes. I wasn't happy.

After a few around town trips today I checked the rear. Is it normal for the gasket to be wet from the gear oil? Its not dripping, and no spots in the driveway. But is that RTV and gasket combo going to hold up? I can take pics if it helps, not sure how good they will look.

thanks

kool-aide

**kool-aide** · 06-22-2008, 02:54 PM

you can see photos here

http://www.cardomain.com/ride/2954870

The nasty goo stuff on the rear end and torque arm were there before the fluid change. It's tough taking photos upside down, but man I love stock ride height. I can still get my butt under the car, if i suck it in lol....

**thearborbarber** · 06-22-2008, 04:06 PM

I usually use RTV Black. For the rear diff. I've had best luck with just the felpro gasket by its self.

**kool-aide** · 06-22-2008, 04:36 PM

thanks

The oil isn't old and a gasket is only 4 bucks. I may redo it this weekend.

Does any one know if GM used RTV at the factory or just a regular paper gasket?

**thearborbarber** · 06-22-2008, 05:44 PM

When I did my 99 last year it looked like it had never been done before and there wasn't any RTV, just an old gasket that was a pain to scrape off.

**LS2Tuner** · 06-22-2008, 06:31 PM

We NEVER use gaskets on stock steel covers. Just a good old tube of Ultra Black. Spread a bead out with your finger allow it to sit up for 20 min. and bolt her up. Never had a leak yet in 15 years. We usually only use gasket's on the big aluminum girdle style covers due to movement.

**Orcus79** · 06-22-2008, 11:31 PM

ditto with the above, use the black stuff, in my books, it's really the only stuff to use. I don't think that the red stuff is suitable for use with oil anyways.

**kool-aide** · 06-23-2008, 01:34 PM

ok, i have never used RTV, so the parts guy picked it out. What is the diff in colors?

So you actually spread the bead out, huh, i didn't think that was good. That would probably eliminate the air popping sound.

Well it still looks like crap in my pin, but doesn't seem to leak. I don't want to buy new oil, but I'm worried about trying to reuse the current oil knowing it has to have the additive in it. If i loose too much I guess I can add oil and then additive again, ugh.

I may just leave it alone, not sure.

thanks

I'd like to hear more about the RTV colors and how you guys apply it, both sides, one side, how much, etc.

**kool-aide** · 06-23-2008, 01:39 PM

are you guys talking about this stuff?

http://www.permatex.com/products/Aut...sket_Maker.htm

I don't know much about RTV so I don't know what brands are out there. I know mine is permatex red.

**LS2Tuner** · 06-23-2008, 02:56 PM

Originally Posted by kool-aide

are you guys talking about this stuff?

http://www.permatex.com/products/Aut...sket_Maker.htm

I don't know much about RTV so I don't know what brands are out there. I know mine is permatex red.

Yes thats it!

First clean the cover and the housing off with some brake clean.

Second.
Take the tip they supply you with and cut it off 3 sizes back. Place a bead ON THE COVER in the middle. Then take your finger and spread the bead with your finger. It shouldn't be thicker than 1/8". Then allow it to set up 20 min. as long as it's 75* longer if cooler out. Then just bolt up.

**kool-aide** · 06-23-2008, 04:07 PM

Originally Posted by LS2Tuner

Yes thats it!

First clean the cover and the housing off with some brake clean.

Second.
Take the tip they supply you with and cut it off 3 sizes back. Place a bead ON THE COVER in the middle. Then take your finger and spread the bead with your finger. It shouldn't be thicker than 1/8". Then allow it to set up 20 min. as long as it's 75* longer if cooler out. Then just bolt up.

what about around the bolt holes?

3 sizes back, man I only cut it to the first ridge line. And look how much came squishing out.

**LS2Tuner** · 06-23-2008, 04:14 PM

Originally Posted by kool-aide

what about around the bolt holes?

3 sizes back, man I only cut it to the first ridge line. And look how much came squishing out.

The bolts holes will be fine. Remember your quickly moving this bead around the middle of the cover. I usually pause for a second in between the holes. Your going to end up with excess on your finger after spreading it. It doesn't take much just a thin coat.

And on your color ? I have NEVER used red. We usually use Ultra Black,Ultra Gray,and Ultra Cooper for everything we need.

**kool-aide** · 06-24-2008, 01:56 PM

Originally Posted by LS2Tuner

The bolts holes will be fine. Remember your quickly moving this bead around the middle of the cover. I usually pause for a second in between the holes. Your going to end up with excess on your finger after spreading it. It doesn't take much just a thin coat.

And on your color ? I have NEVER used red. We usually use Ultra Black,Ultra Gray,and Ultra Cooper for everything we need.

i'm still unsure about the bolt holes. Are you saying you don't go around them? Do you go over them? That doesn't seem right.

Yeah I went down the middle, as best I could, of the diff and cover. It seemed logical to do that. I didn't go very fast, mostly because the stuff comes out slow. That may be because I didn't use a very big hole. When it came to the bolt holes I made a circle around them pushing the RTV together to make sure it was as good as a complete run as possible.

I will remember the colors next time.

**kool-aide** · 06-24-2008, 01:57 PM

Originally Posted by thearborbarber

When I did my 99 last year it looked like it had never been done before and there wasn't any RTV, just an old gasket that was a pain to scrape off.

mine too. about 90% or more was stuck to the diff. I spent probably 30 min scraping. It didn't look like it had RTV on it, but I thought it was worth asking.

**LS2Tuner** · 06-24-2008, 02:05 PM

Originally Posted by kool-aide

i'm still unsure about the bolt holes. Are you saying you don't go around them? Do you go over them? That doesn't seem right.

Yeah I went down the middle, as best I could, of the diff and cover. It seemed logical to do that. I didn't go very fast, mostly because the stuff comes out slow. That may be because I didn't use a very big hole. When it came to the bolt holes I made a circle around them pushing the RTV together to make sure it was as good as a complete run as possible.

I will remember the colors next time.

You are spreading the bead out with your finger across the whole surface area. So you can go on side or the other or just pause for a second like I do. Once you have spread this out with your finger the cover has a solid THIN layer of silicon.

**kool-aide** · 06-24-2008, 02:13 PM

I think I get the picture. To me it always seemed as if the idea was to "make" a gasket with this stuff, e.g. no breaks, gaps, or missing spots. So as you're spreading you pick a side of the bolt hole and keep going in one continuous smear.

Do you find it easier to put it on the diff or the cover? Of course I would say the cover since it is not under the car, but hen again I have no clue, lol...

The one thing i didn't do was clean the surface with anything more than scraping and a shop towel. I did notice it was really tough to keep the very bottom dry. Even after it looked like all the old oil was out, it always seem to have a thin line of oil sliding down the very dead center bottom.

**LS2Tuner** · 06-24-2008, 02:22 PM

Yes you are smearing it out across just like a gasket ON the cover.

But first off cover and housing need to be cleaned of ALL old silicon and oil. (brake clean and a razor blade)

I use the side of my finger to spread it out so some silicon gets on both sides of the bolt hole.

**kool-aide** · 06-24-2008, 02:26 PM

well, i guess i know what i will be doing this weekend, lol...

thanks

**LS2Tuner** · 06-24-2008, 02:32 PM

No problem glad to help.

Don't be scared of the brake clean. Just spray the shit out of the housing and wipe clean with a rag. What ever you do if you get some over spray of the brake clean on a painted surface that you don't want it on. . . . . . . .DON'T TOUCH IT JUST LET IT EVAPERATE! ! ! I learned that the hard way 12-13 years ago.