I change my 3.23 gears on my limited slip differential to 3.90s everything was installed back to how it was oil was added at the end…however when i went to test drive it, it was whining and on reverse it would be popping…what could possibly be i need to fix it ASAP
I assume you added the appropriate oil and additive to the diff?
You changed the ring and pinion, right? Do you have all the proper tools, specifications, and procedures. A guy who’s built dozens of these can probably get it right on using nothing more than some spray on grease and his eyes and fingers. Anyone else will need an inch-pound torque wrench, a foot-pound torque wrench, a dial indicator, some other specialty tools and a few tries to get it right.
What was the pinion preload? Ring gear backlash?
Did you check the tooth contact pattern between the ring and pinion gears?
Tester
I agree with both @asemaster and @Tester here. I’m fairly adept at setting up a differential but there are so many necessary steps and techniques needed that it sends this task right out of the realm of a normal DIY job. It’s a long, involved process even for a pro and I’ve never seen it done properly on the first or even second try. It’s that complicated.
If you’re not aware of terms such as pinion pre-load, backlash, etc. then you will likely be redoing this; or having it done.
The cause might be narrowed down a bit more but it will require details on when the whining occurs; such as whining on acceleration, whining on deceleration, both, etc, etc.
I’m thinking of a local farmer here some years ago who told me he just slapped a 1700 dollar ring and pinion gear into his Case tractor. When I asked about the set-up on those gears he gave me a blank look and then stated “that crap ain’t necessary”.
Due to slow tractor speeds he got by with it for some years before it lunched itself. He now owns another plow puller… 
As said above, the pinion and ring gear are probably not meshing correctly. They have to be properly aligned, and they have to be separated by the precise amount specified by the manufacturer. It’s not that this is impossible to do. But it can be time consuming, esp the first time you do it. If you have a factory service manual, it’s all explained there. You may need to buy some shims too.
Did the ring gear carrier stay the same over that spread of ratios?
X2 George San Jose. The popping might be the gears not meshing correctly, which has killed the gearset.
@dannyboy1212 - how many differentials have you repaired in this way? If this is new to you, you probably want a pro to do this.
Make, Model, year…
Changing a ring and pinion is NOT for the first time DIY’er. I agree with ALL these posts, any one could cause you a problem that can destroy the new gears! At the very least they can make so much noise the people in the next lane to you will back off.
My first R&P change was successful but I had it in and out over 10 times on the bench before the contact pattern and backlash were correct. BTW, I ended up with the exact same pinion shim as the original gear set, took 4 tries to get there!
Sorry i reply late and yes is my first time …i need to learn some way or another…i found out the popping sound and the noise was because i did not change the pinion bearing to its proper size…however, now that i have everything set and on place everything works good. Foward reverse launch …just the detail of the whinning sound that still there…
A friend of mine said it could be the pinion depth.
Now my question is, can i leave the pinion shim from 323 gears on the 390 gears or do you all knoe if its a different one?
@dannyboy1212, chances are NONE of the original shims will properly line up the gears. Please review this video on properly setting up a differential. It requires precision tools, time, and patience. http://youtu.be/dAqAqODmcj4
wow. i clicked on this thread expecting someone needed gear oil.
i m slowly backing away, ready to turn and run.
you gearheads have fun…
my son would like this discussion, but its way over my head
Wes, if you only follow threads when you already know all about the subject, you don’t learn anything. It’s from following threads like this one that you learn.
While related to differentials, just not this particular one, I might add to the part about learning something.
I’ve set differentials up on foreign cars but not so much on domestics. A car dealer I used to do work for as an independent sent me a Ford F250 4 X 4 with a bad front differential.
I had to wrestle that thing a bit before learning about a tool I did not have. It’s called a “case stretcher” and is designed to spread that cast iron differential case a few thousandths of an inch.
Imagine forcing cast iron apart…
Managed to wade through the job without it but it wasn’t a ton of fun. The diff worked fine but I was sweating bullets until I knew for sure. The last thing I wanted to do was rip it all back apart.
OK, I learned something watching that. I learned I ain’t ever gonna do that.
Maybe this will help you…
Even if your rear end does not have a removable pumpkin, the basic building techniques are the same for any hypoid gear-set…
Hey guys i think i found out why it would be whinning on drive…i did not replace the crush sleeve i used the same one from my other pinion
@dannyboy1212, since you changed the gear set to a different gear ratio, the entire gear set has to be set up to assure long life and quiet operation. This means practically all the shims will need to be resized to line up the pinion gear and ring gear as the above videos show. Anything less and the gears will eat each other up in a short time.
The crush sleeve plays a critical role…It pre-loads the pinion bearings…They can only be used once…On a new sleeve, you carefully apply the listed torque to the pinion nut…This done as the last step in assembling a differential of this type…Before this, the contact pattern of the ring and pinion get set with shims…A special blue dye is used on the gears so you can observe the contact pattern…If it’s not right, it will howl like a Banshee…The carrier bearings can be adjusted left and right to obtain the correct gear clearance and pattern…It’s a skill that can take years to perfect…