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Discussion Starter · #1 ·
Ok I got my old 3.55 open unit out and ready to put in the 3.80 posi unit. When I put the old unit in about 10k miles and 13 years ago I sealed the gasket to the housing. It looks to be in good shape, no cracks or peeling. My question is do I still need to replace the gasket or would it be ok to use the existing one. I did not have any leaks before. I'm also going to replace the cooper washers. Thanks for any help.
 

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I did the same..New copper washers. Leave the old gasket in place and run a small bead of good RTV silicone on the housing before you put the carrier in. No leaks.Most shops now only use the bead of silicone and no gasket.
 

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If your using Auburn Posi, make sure you use the additive fluid they supply with the unit. Also it is very important that first time out, you drive it for 25 miles, no more or no less, then let it cool down per thier instructions.
 

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Discussion Starter · #4 ·
It's not a auburn unit. It's a trak-loc w/ a 4 pinion set up I bought rebuilt. It came w/ the additive, it did say to make 3 tight left circle's then 3 tight right circle's. It didn't same anything about mileage. Is it a good idea to drive it several miles on the first run?
 

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It is a very good idea to limit your first outing to about 25 miles. Then let the rear cool completely before further usage. I like to let is sit overnight.

It seems that the bearings and the ring/pinion gears get quite hot when they first are learning to get along together. The preload will actually increase during this break-in, if you are using new bearings.
 
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