Nightmare rear differentail

[JGarrett]

So here's the scoop. I have a 2010 2ss 6-speed. I had a shop install the GM 3.91 gear set. That shop did not put fluid in the diff. It made it almost 12K miles before it even made a sound. The second shop that worked on it did something wrong and after 5k miles the discs locked up full spool. Now here we are a year later, 5-7k miles and same deal, the discs have locked up. Three diffs in 3 years from 2 shops. There are no real engine mods to speak of and I do not abuse this car. It is my shop demo car, (I own custom audio shop) I drive 2 miles to the shop and back on business days, and the rest of the time it sits in the garage. I am torn between getting a stock diff from a salvage just to be done with it before spending $1500 to fix this again and worry about it in a years time. I had a recommendation to send it to RPM Transmissions in Indiana. Any input is appreciated.

[frankwjr]

peeps sell complete 3.91 diff's on here all the time...you should post the name of the shop that didn't put the fluid in....jeez...to bad yer not closer....did my own 3.91 upgrade in the garage...dang things r easy to work on....good luck OP...

[Vec]

almost twelve thousand miles with no fluid in the diff?

right...


I find that hard to believe.

[JGarrett]

[QUOTE=Vec;10044320]almost twelve thousand miles with no fluid in the diff?

right...


I find that hard to believe.[/QUOTE

I originally had the gears done in March 2015. The first build made it to the end of Oct. and I was commuting 60 miles one way 6 days a week. The math actually puts that closer to 17K. I daily this car. It has 140K on it, all mine. Here is a picture of the gears. I still have them. Nevermind the spider webs.

[Vec]

to clarify:

i cant believe they made it that long.

[frankwjr]

knife edge! holy mackerel amazing!

btw - 3.91 diff just avail!.http://www.camaro5.com/forums/showthread.php?t=518564

[pancherj]

You could shave with those! The real disturbing thing is that the point extends all the way too the root of the tooth. The mesh was way too deep! That’s why it is killing headsets. There is probably something in the case machined incorrectly.

[sixty9fordkiller]

from what i have learned, working on the differentials for 5th gens, the back lash is critical. Yours looks like the backlash may not have been within spec when the gears were installed.

just for your knowledge, listen to what the cat in this video is talking about. I think hes from eastern europe (not sure of the accent) so you'll have to listen closely to understand what hes saying but the guy know what he is doing/saying

you have to go by trial and error to get the correct backlash. there is absolutely no way around this step unless you get ultra lucky and the correct backlash is the initial trial but its is still a "trial and error" nonetheless. its happens. but you still have to check

part 1



part 2

[JGarrett]

A ford product would not have lasted a week! This is a testament to Chevy here. I agree with you guys that it wasn't setup right but 2 shops and 3 builds I would think somebody could have happened to accidentally get it right. I failed to mention, the second it failed, the axels had welded themselves to the spider gears or something. I have the diff almost out of the car and I think that has happened again as they are definitely stuck. I have been told these are fluid picky but then any camaro that gets a diff service at jiffy lube would have problems right? By the way both shops told me to kick rocks and neither of them care to stand behind their work. I would love to pick up that 1LE diff but will it fit without major mods? That guy in the videos makes it look easy but I am not sure I am comfortable getting into on my own. That is about the only thing vehicle related I have never done.

[frankwjr]

the diff's swap...no problem...only have to pull right axle..or just have a shop swap it...make sure they use LS SYNTHETIC lube...

[GRNFLSH]

Wow! I’ve never seen gears like that.

I haven’t set gear lash or preload, but I have helped a buddy swap C5 diffs which isn’t difficult. It did take some grunting to pop the axels loose. If your axels are stuck, I wonder if they may have a lip cut into the spines from running w/o fluid.

If you decide to have the gears replaced, I’ve heard good things about Bohannan Four Wheel Drive in Bentonville, they have a good reputation for diff work.

Good luck!

[Smirnoff]

Take it back to 1st shop (just validate they added the gear lube)!!!

[JGarrett]

So, I bought the 1LE diff and axels from Punisher_ATX. Thanks frankwjr. I have yet to remove the differential, the axels are indeed stuck but I will get it even if I have to cut them out. Once that happens I will open it up and post pics.

[frankwjr]

good luck brother, take your time and feel free to reach out with any q's...doin the work yourself will let you gain some appreciation for IMHO how well these cars are put together...plus hopefully save you some $$$...

ask Punisher or do you know if he had the axle seals replaced? very cheap items and an easy job while the diff is out...newer lubes can leak out of older seals...your prob OK but hey...

you got basic tools? definitely need tq wrench and some loctite when putting it all back together..

not sure how the axles are stuck..a little pry bar or large screw driver slipped between the axle and housing and give it a little "pop"...worst case just leave them in and drop it since your replacin it all anyway..

post pics and keep us update OP...peace out!