Diff hum in AE86

**robert1** · 23-09-2007, 01:27 PM

I've just replaced all the bearings in the Scorpion diff in my Sprinter and it hums. Do I have any options other than throw the lot away and get a Hilux LSD?
Robert

**EVOSTi** · 23-09-2007, 06:38 PM

what made you think it was a bearing? maybe its the pinion/crown wheel allignment.

**oldcorollas** · 23-09-2007, 06:59 PM

bearings not replaced tru to the housing?

**robert1** · 23-09-2007, 09:29 PM

To evosti, It was an old diff that had not been apart before and it made increasingly bad noises in reverse on over-run with a lot of backlash.
To oldcorollas, bearings fitted correctly, I've been a fitter for 45 years.
Thanks for your interest fellas
Robert

**Hen** · 24-09-2007, 08:03 PM

I tend to agree with Evo's suggestion. Have the crown/pinion meshing/backlash setup properly (if you can't do it yourself). This or even badly worn gears will cause a shocking whine. And if it goes away at the balance point between accelerating and engine braking then I'd definitely point the finger at the gears.

Hen

**oldcorollas** · 24-09-2007, 08:15 PM

Originally Posted by robert1

To evosti, It was an old diff that had not been apart before and it made increasingly bad noises in reverse on over-run with a lot of backlash.
To oldcorollas, bearings fitted correctly, I've been a fitter for 45 years.
Thanks for your interest fellas
Robert

so.. it may have been worn a bit with shitty adjustment.. now it has been put back together correctly with correct backlash... perhaps it just needs time to wear the teeth in again... or they are already gone.

is the hum from bearings or teeth? is the housing bent? axles bent? did the hum only start after changing bearings? if so, what else changed...

**robert1** · 24-09-2007, 08:34 PM

Hen and others,
the hum does go away when the foot comes off the pedal (on overrun) the old diff made noise since I bought it at Pick and Payless 6 years ago, I just got around to doing something about it so the gears are probably worn a bit by now. I will pull it out again and check the mesh pattern with blue which I should have done in the first place but it went together easily and the backlash seemed ok.
Do any of you fellas know what the preload is on the crownwheel bearings. It has the threaded adjusters to preload the bearings. I left them where they were but if I need to adjust the mesh then they will need to be moved. I guess if I move each side by the same amount then the preload should stay the same.
Robert

**EVOSTi** · 24-09-2007, 08:37 PM

i dont know what the setting is but i always mark where it was, then turn it maybe as much as 1/4 tighter when i put it back together depending how long its been since it was last appart.