Diff whine saga

[Rajvosa]

Hi guys need some advice
recently swapped my 4.1 diff with a friend for his stock one. We stripped the front diff bolt during instal so diff was clunky.

gave it to a mechanic to sort out, and he installed an M16 bolt. Needed to drill through the AKG diff bush to fit the bolt.

when I got the car back it developed this whine when off gas pedal and in little higher speeds, 60/70kms /hr onwards. He thought maybe the big washer that he used with the bolt was the cause. Tried different bolt and noise is still there.

Rest of bushes are stock in drivetrain other than front diff bush.

[fattycharged]

I'd assume the stock differential was whining before you installed it and/or it's now just more audible due to that AKG

[maupineda]

People assume gear swap is straight forward, but more often than not the pinion depth is not adjusted. Your issue is very likely wrong gear mesh.

[sapote]

when I got the car back it developed this whine when off gas pedal and in little higher speeds, 60/70kms /hr onwards. He thought maybe the big washer that he used with the bolt was the cause. Tried different bolt and noise is still there.

.

It's not clear which car has the whine -- yours/stock diff or the friend/4.1

[Rajvosa]

It's not clear which car has the whine -- yours/stock diff or the friend/4.1

the stock diff I got off him.

[Rajvosa]

People assume gear swap is straight forward, but more often than not the pinion depth is not adjusted. Your issue is very likely wrong gear mesh.

We did straight swap. I installed a stock diff into my car.

[Slideways]

If anything, the 4.10 should make more noise than that stock diff. Did you ride in the car with the stock diff before the swap?

[Rajvosa]

If anything, the 4.10 should make more noise than that stock diff. Did you ride in the car with the stock diff before the swap?

No I didn’t. But I had it in my car briefly until clunk started and then gave to mechanic to sort the diff bush bolt. I didn’t notice the whine back then

[Slideways]

Can he check that everything is mounted and torqued properly? After that, either he can try a modified stock front diff bushing or the diff has to come apart for bearings/internal parts.

[old///MFanatic]

No I didn’t. But I had it in my car briefly until clunk started and then gave to mechanic to sort the diff bush bolt. I didn’t notice the whine back then

So did you remove it or someone else? And after you removed it you didn’t drop/impact the diff on input flange hard by chance (when lifting/moving it)?
I’d check the torque on the bolts and would also suspect a larger washer used might hit metal. But you already checked that. Next variable is the aftermarket front diff bushing.

[EthanolTurbo]

If you're using a poly bushing it will cause a shitload of whine.

[duracellttu]

If you're using a poly bushing it will cause a shitload of whine.

+1…I don't care what people say about different combinations of poly and stock bushings in different locations. Any poly or solid diff bushings will give you a noticeable amount of whine. Go back to stock in the front and it will solve a majority, if not all of your problem.

If you have poly or solid subframe bushings, then that will also be a contributing factor.

[bigjae46]

If you're using a poly bushing it will cause a shitload of whine.

This.

All diffs whine. The question is can you hear it?

[Speed Monkey]

So you say you have a lot of whine?
Here is the perfect accompaniment to go with you whine…