Rebuilt Differential Help

[walterL]

Hi Guys. I just rebuilt my GU4/G80 read differential on my 2011 Tahoe. 1st couple of days all was fine, super quiet, no rattling, clunking, grinding, all was perfect. Had to run some errands last night and when I went to turn into a driveway there was like a loud pop/clunk came from the rear area. When I went to back out and turned sharp to back out of the space it did it again. Then I had to take a narrow hard curve path to drive around the building to leave and the whole time I have the wheels turned it did it a couple more times. When I got back out on to the road and got straightened up, all drove quiet and great again. It does fine in soft curves, going straight, or backing straight, but if I have a hard curve or have to turn sharp like to get in a parking spot, or to turn in a driveway, loud pops and clunks. What could it be? I really need help in a big way with this, PLEASE!

 

[Foggy]

Add a bottle of limited slip to it
Did you break it in ??? Needs to be driven slowly
in a wide figure 8 pattern several times. Then let it cool.
Then take it on a 15 drive and then let it cool.
Then change the gear oil in it (add limited slip additive if your
synthetic gear lube doesn't show it has it)

 

[walterL]

Add a bottle of limited slip to it
Did you break it in ??? Needs to be driven slowly
in a wide figure 8 pattern several times. Then let it cool.
Then take it on a 15 drive and then let it cool.
Then change the gear oil in it (add limited slip additive if your
synthetic gear lube doesn't show it has it)

This was my 1st diff. to rebuild. I have only driven slow(45mph) with it, but did not do fig. 8's. I did use Valvoline synthetic oil for limited slip. Thanks for the help and I will try the figure 8'sand see what happens. Since I did use the limited slip oil, should I still change it again? Again, thanks for the help, you don't know just how much I appreciate it.

 

[B-train]

It almost sounds like too much preload to me. It's been a LONG time since I had one apart, but there are specific procedures to follow for preload, tooth engagement, etc. I'm not a professional on rear ends, but my guess is the limited slip portion is too tight and doesn't want to float in a neutral state like it should.

If you have an area that is slippery (snow, wet grass) try doing the same maneuvers and see how it reacts. It will probably be quiet because the tire can slip as needed without being locked to pavement.

 

[walterL]

It almost sounds like too much preload to me. It's been a LONG time since I had one apart, but there are specific procedures to follow for preload, tooth engagement, etc. I'm not a professional on rear ends, but my guess is the limited slip portion is too tight and doesn't want to float in a neutral state like it should.

If you have an area that is slippery (snow, wet grass) try doing the same maneuvers and see how it reacts. It will probably be quiet because the tire can slip as needed without being locked to pavement.

I had a preload between 20-25 in/lbs. I will give this a shot as well. I have to get this going right so all the advice I can get is welcome. Thank you.

 

[B-train]

I think maybe what I should have also added is that the shim stack-up for the carrier can also have an effect on operation. I'm hoping it's just some sticky clutches that need a little break-in.

 

[j91z28d1]

what brand diff did you go with? or did you rebuild stock?

what fluid to use is a slippery slope lol.

 

[Foggy]

This was my 1st diff. to rebuild. I have only driven slow(45mph) with it, but did not do fig. 8's. I did use Valvoline synthetic oil for limited slip. Thanks for the help and I will try the figure 8'sand see what happens. Since I did use the limited slip oil, should I still change it again? Again, thanks for the help, you don't know just how much I appreciate it.

Yes. Change it after the break in procedure. Some diffs like having the extra
limited slip additive in addition to being a GL-5 Spec.. Make sure your valvoline
is a GL-5. I have both on the shelf. Don't assume because it's synthetic that it's
GL5 and has enough limited slip additive for your particular set up

 

[j91z28d1]

Assuming you have the oem g80 diff. I can only tell you what I experienced with mine and what I've read. but it makes sense to me.

first the g80 in our truck with the weights and stuff is not in any way a limited slip. is a cluch based locker. it is not meant to slip when locked. it seems to kill clutches very quickly if it doesn't lock.

when I got my truck I did the fluids just because I doubt they had ever been done. had no rear end issues at the time. so I picked up fluid at the local auto parts store, I don't even remember which, probably Valvoline since that's what most carry that's good. it listed the limited slip on the bottle. didn't think anything about it.

few days later my wife calls says she was parking and the rear end felt like it was locking up like the race cars we used to be around with a spool. she was around at the track back with me and friends forever ago. so she is familiar with us trying to push cars to the lanes with a a spool, (locked diff) I told her I'd check it out when she got home. so I took it around, and in a parking lot doing tight turns the diff would chatter like it was trying to lock. it shouldn't be doing that unless one tire is spinning faster be a decent amount.

so after some Googling, it seems like it doesn't happen to everyone but some get chatter when putting limited slip fluid in it since it's a locker I guess. I was skeptical but went back to the store and looked thru all the fluid. not a single one lists without limited slip. so I gave up, ran up to the dealer parts department just before they closed. looked up what they have for my vin. it's pricey like everything there. you'll have like 50$ in fluid. but came home, dumped it and added the new stuff. went out to the same parking lot, after a few figure 8s it was smooth. hasn't made a sound since and seems to be correct.

I learned to use the gm stuff from the corvette world. they have a true limited slip and they have like 7 tsb's about diff chatter, cluncks and worn clutches. there's been 7 revisions to the fluid and it has its own part number and the correct amount and type of additive already mixed it. there's 50 page threads on it on their boards, so when I did that car I went straight to gm and got fluid. wasn't going to deal with that hassle haha.


just my experience. your experience, especially with a fresh rebuild might be different. I believe most people have no issues with auto parts store fluid. I wouldn't have never known if I didn't spend a night digging up old threads.