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8-3/4 gasket

I tried an expensive reusable rubber gasket with no RTV, OEM paper gasket with RTV and still had leaks. My leak was via the studs where they come through the flange; they are knurled and press fit into the flange.

I took Doctor Diff's advice and used Permatex Gear Oil RTV with no leaks:

41869461_081413_sm.jpg
 
Makes you wonder why dr diff sells the gaskets.
I'm about to install the pig and axles now that i have the 3.55s and axle bearings installed. I thought maybe the gasket was needed for general spacing. I thought some metal to metal surfaces might mate better with a gasket rather than just sealant.
 
themechanic said:
I tried an expensive reusable rubber gasket with no RTV, OEM paper gasket with RTV and still had leaks. My leak was via the studs where they come through the flange; they are knurled and press fit into the flange.

I took Doctor Diff's advice and used Permatex Gear Oil RTV with no leaks:

View attachment 409309
Click to expand...
I've never seen that product. Still learning all these years later.
 
I also think it may have had something to do with installing the third member with the housing out of the car. I applied the RTV on the housing with the flange facing up then dropped the pumpkin down on top. That way I got an even distribution of pressure on the RTV around the flange.

Dr Diff also suggested using Ford 9 inch rear copper washers to seal the bolt holes. That worked but made it a major PITA to remove the pumpkin when I learned my housing was bent.
 
I just cleaned the housing and 3rd member mating surfaces real good, then used Permatex ultra oil resistant RTV on there. That has worked great on 2 rear ends with no leaks for several years.
 
I just used a paper gasket, so far my leak is too slow for me to care about. Maybe one drip a week or so. Whenever I need to remove it I'll be using that gear gasket goo. As far as leaks go anyway the rear end is the least of my problems. Transmission leaks way more.
 
I use the gasket and coat both sides with Indian head shellac..Never had one leak
 
I used black rtv on mine don't leak a drop indian head is a real mother to get off if you have to get in there again
 
Gray rtv is best for rears no gaskets ,I assy dump truck rears with gray and car rears its a pain to pull it apart later though
 
When I switched mine I used the paper gasket with a thin film of black RTV on each side of the paper, no leaks.
 
Just my old overkill self lol, main reason was I didn't want the fight of getting the old style gasket sealer off if I ever had to change it out again, the rtv you can pretty much rub off the cast with your finger and it helps seal around the studs, the paper...... I just wanted in there to seal , mine had a old paper one to start with when I tore it down.
 
Bb70charger500 said:
Gray rtv is best for rears no gaskets ,I assy dump truck rears with gray and car rears its a pain to pull it apart later though
Click to expand...

Ultra Grey is all I use, anywhere on the motor or rear end. That is all my engine builder on my poly used. It is fantastic on metal to metal. Never had one leak.
 
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