Rear Diff question

[STL_66 Chevy]

i am replacing the cover on my rear diff. and i have a couple questions...
1. some people say to use the gasket, some say use silicone! a couple said use both! what method should i use to beat the leaking dif battle?

2. i dont have a drain plug.... how do i know how much oil to put in? do i fill it until it comes out of the fill hole on the top passanger side of the dif housing?

thanks for any help you can give!

[raggedjim]

I've always used silicone on one side to hold it in position (usually the cover side because it is thin metal and the silicon will help seal any distorted areas)

Fill it until the oil starts to run out the fill hole.

Good luck, Rg

[joe231]

There is a product called "the right stuff" that is what I always used when I was working on cars for a living, no gasket. It is good stuff, bit spendy though. never had any comebacks.
ditto on the filling, fill it till it just starts to dribble out.

[STL_66 Chevy]

just to be clear, your recommending silicone only? no gasket?
thanks guys!

[raggedjim]

Sorry I wasn't clear... I do use the gasket but I use silicone on one side of it. My grandfather taught me that, but I can't say it's a better way than any other...

Rg

[STL_66 Chevy]

gotcha! thanks!

[83burban]

I've always used RTV Ultra Black on both sides of the gasket...never had a single leak on any gaskets installed

[STL_66 Chevy]

i though about using it it on both sides... but i thought i would give one side a shot and see how that works out... we will find out tomorrow! if so i will try both sides.... i some is good alot is better... i guess?

right now im fighting the leaks on my brake lines... it appears that the front brake line that came with my disc brake kit leaks from where the rubber line goes into the fitting... not cool! looks like i have to find a new one to replace it!

[shortbed70]

Don't use just silicone it will leak. I'm getting ready to do mine again with a gasket this time. I used silicone on dana 44+60's with good succes.

[greg64]

Here's two more cents...

I've used the Right Stuff in other spots and I'd agree that it works well. However.... since I have to remove the diff cover to drain the fluid (you guys actually change your fluid, right.... ), I don't want to have to fight with it. So, I put it together with a dry gasket.

Now, this is partially because if it actually does leak, it's not a huge deal to take it apart and try again. So, I'm not this optimistic with oil pans and intake manifolds because I REALLY don't want to have to take it apart again after it leaks.

What I really like the look of (but don't actually have) is the cast aluminum covers (less flex to begin with) that have a groove machined with an O-ring in it. Cover can be removed and replaced numerous times with no gasket and no goop.

[ChopperDr]

Lay the cover on something flat to see it it is true. Seems like I usually need to true them up. A file or sandpaper will get them flat. Be sure everything is super clean before reassembly. I use the tacky permatex gasket sealer. It keeps the gaskets in place, isnt messy, cleans up easy. Brush it on and its ready to go. Works for me.

Chop

[BlueJeep]

I build axles. I've done 100+ custom axles with new ring and pinions in the past few years so I find myself to be a credible source. Silicone ONLY is your best bet for a leak-proof seal. I have put them together both ways, and usually will only use the paper gasket in 4wd front axles where the diff cover is thicker. As was mentioned above, tin diff covers are very often not true on the sealing surface, so a paper gasket ISN'T going to work there. Many r&p master install kits now come with a tube of blue silicone instead of a gasket....for good reason.

The other thing I would mention seems like common sense, but many people skip it. Make sure both surfaces are clean. Roloc discs or twisted wire wheels on a grinder work great for this, followed by a rinsing with brake cleaner. Mine are always shiny bare metal when I put them together.

[83burban]

If your worried about having to change fluid, why not drill a hole, tap the hole and put a pipe plug in the bottom of the housing to facilitate draining for fluid changes? Seems like a simple upgrade to save the hassle of pulling the cover every time.

[Imperial Kustom]

Fel-Pro rubber coated steel core gasket. Hands down.

[STL_66 Chevy]

well i tried the method of gasket and silicone on the cover side and so far... NO LEAKS! its been several days but only time will tell. thanks for your help and if it does start to leak i will definitely try the other suggestions.