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HOW-TO: Drain and Fill Your Rear Axle


misterp

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the autotrak fluid is very nice and by design works very well in transfercases and probably automatic transmissions. i plan to test it someday on an 65E. as for making the awd work better using it, maybe with lower fluid temperatures, but the viscous coupler shouldn't be sharing fluid with the rest of the transfer case. the viscous coupler is a sealed unit.

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I know I jumped in kinda late on this, but I have a question. It seems like trying to save the gasket is a waste to me. I have always taken the cover off and used brake parts cleaner to try and get out as much debris as possible. I'm just wondering if it is neccesary to douche out the rear end. This may also be a dumb question but is the rear axle 9.5 or 8.5? Thanks

 

Dave

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I know I jumped in kinda late on this, but I have a question. It seems like trying to save the gasket is a waste to me. I have always taken the cover off and used brake parts cleaner to try and get out as much debris as possible. I'm just wondering if it is neccesary to douche out the rear end. This may also be a dumb question but is the rear axle 9.5 or 8.5? Thanks

 

Dave

The G80 rear axle is also know as the GM 8.6. And I am not one to argue cleanliness, but have had no problems just changing fluids at appropriate intervals in my other vehicles.

 

Mr. P.

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Ok so you've decide to pull the rear diff cover and clean it out. If you want a new gasket you'll need Felpro pn# RDS55028 . At Advance our computer only lists a 9.5 ring gear. So I went back a couple of years and looked one up for a 98 Silverado with a 8.5 inch ring gear. MisterP informed me that it is really a 8.6 but the 8.5 gasket works great. BTW the gasket costs like $3.49 . Later

 

Dave

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I've already noticed a difference on launches, the rear-end feels a bit more squirley than before, I don't know if that is good or bad.  I can now definitely feel the power shifting from side to side off the line and the truck did not do this before, the rear used to stay planted rock solid.  Any thoughts on what's going on in there???

 

Mr. P.

 

Is your rear-end still acting up (that sounds kind of weird), or is everything back to normal? I was planning on doing the fluid change soon, good posts!

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the G80 applies to well more than the 8.6 rear. that is gm's code for limited slip/locking differentials. the 8.5 rear in the mid 90's was increased to the 8.625 ring gear size. it wasn't until the later years that the difference was pointed out to the public.

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Is your rear-end still acting up (that sounds kind of weird), or is everything back to normal?  I was planning on doing the fluid change soon, good posts!

Sorry to take so long to reply; no everything was fine within 48-hrs. I can definitely feel what everyone is complaining about now, that there is definitely no positraction above 20mph.

 

Mr. P.

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  • 3 weeks later...
So the front takes two quarts of 75-90 Mobil 1 Gear lube, and the capacity of the rear is what? Also, what is the capacity of the transfer case... how much is the Autotrack II fluid per qt.?

Thanks!

 

2 Quarts of the Auto-Trak II, about $6.50 a quart in my neck of the woods. Oh yeah, and that little super gadget from Wal-Mart (the pour spout Mr. P indicates in his how to, if you don't have a gear pump.) That thing is about $3 and screws onto all the different fluids.

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  • 3 weeks later...

Very good tech, P. I like your gasket saving technique. A little info on the additive, the formula was changed sometime in the mid to late 90s. Both Ford and GM used the same stuff (nasty smelling whale oil/sperm, whatever :puke: ). That may be the reason for the change, to work better with the newer rears.

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  • 3 months later...
  • 2 months later...
so does 04 and 05 have the drain plugs and not 03's?
Well ?

This was discussed a few posts earlier in this thread. Some differential housings in these trucks were produced with the drain plug, some were not; you are going to have to inspect your own vehicle and determine what the factory gave you to work with.

 

Mr. P. :)

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