Diff and Transfer Case Torque Specs?

tnchevy · October 21, 2015

I have searched the web and can not find the torque specs I need. I've got 8k miles on my 2014 and plan on changing the fluid in both diffs and the transfer case at around 10k miles. I always changed the transmission fluid and filter every 30k miles on 2002 but didn't change the diff/transfer till I hit 100k miles on that truck. The downside to that was that my front diff started leaking after I changed it, I guess the dirty fluid had plugged the seals and the fresh was able to slip by. It leaked for 4 years like that and I just added 1/8 to 1/4 of a quart of diff fluid once every year. Also on my old truck the rear diff fluid was pretty darn clean with little to no metal fragments after 100k miles and the same with the transfer case but the front diff was a different story, it was black as coal and full of crap.

newdude · October 21, 2015

Are you looking for fastener specs (drain and fill plug)?

T-case fill and drain plug: 13 lb.ft. Fluid spec: Dexron VI, 1.6 quarts.

Frt. Diff drain and fill plug: 24 lb.ft. Fluid spec: Synthetic Gear Oil GM P/N 88900401 (GM Spec 9986115) 75w90, 1.51 quarts.

Rear diff fill plug: 24 lb.ft. Rear diff cover bolts: 20 lb.ft. Gasket can be reused if not damaged. Fluid spec: SAE 75W85 Synthetic Gear Oil GM P/N 19300457 or equivalent meeting GM Specification 9986375, 2.59 quarts.

Rear diff specs are for the 5.3 (I am assuming you do have a 5.3? If not let me know).

tnchevy · October 21, 2015

Thanks!!! That is exactly what I needed. The rear diff fluid is something new compared to my old truck, I don't recall seeing 75W85 synthetic before, may have to buy GM's which will probably cost an arm and a leg. I am also suprised to hear the gasket can be used again on the rear diff. My old 2002 had a drain plug for the rear diff fluid so I never took the cover off for it. I do have the 5.3.

newdude · October 22, 2015

Thanks!!! That is exactly what I needed. The rear diff fluid is something new compared to my old truck, I don't recall seeing 75W85 synthetic before, may have to buy GM's which will probably cost an arm and a leg. I am also suprised to hear the gasket can be used again on the rear diff. My old 2002 had a drain plug for the rear diff fluid so I never took the cover off for it. I do have the 5.3.

The GM 75w85 retails at $21.50/quart. Their 75w90 is $27.90/quart. Any nice dealers around you to work out a bundle discount?

tnchevy · October 22, 2015

I am surprised to hear the 75w85 is cheaper than the 75w90! I plan on putting 80w90 for the front, it is cheap and the owners manual does not call for the 75w90 synthetic for it. The 75w85 for the rear is not readily available for aftermarket (at least at oreillys) so I will probably just buy the GM brand for the rear diff. I had originally planned on changing out the diffs and transfer at 10k miles but I am starting to re-think that and may do them at 30k mile intervals with the transmission. I only drive 5 to 7 thousand miles a year so if nothing changes I am looking at 4 more years before changing them out. I am a little OCD when it comes to my own truck but my company trucks go 150k miles or more before we get new ones and we never touch the diffs, transfer, or transmission fluids unless a problem comes up which it rarely does.