diff help!

Post Thu Jan 31, 2013 11:19 pm

Noticed a whine for a while now, a say a whine, its more of a hiss from beneath the rear seats that gets louder the faster i go.

Is it a common problem from the diff and is it advisable not to use it?

Post Thu Jan 31, 2013 11:21 pm

Are you sure it's not the fuel pump?

Diffs can whine on for years - try a thicker grade of oil in it to quieten it down a bit.

Post Thu Jan 31, 2013 11:33 pm

Maybe. The noise cant be heard below 25mph its strange. put a thicker grade in and hope for the best! Thanks

Post Thu Jan 31, 2013 11:39 pm

could be your prop or prop bearing?

Post Thu Jan 31, 2013 11:39 pm

what about rear wheel bearings??

Post Fri Feb 01, 2013 6:52 am

I think I finally diagnosed what this is a few years ago. Mostly heard on convertibles for some reasson but I know exactly the sound you're hearing and it's not bearing rumble or C&P hum.

The issue is at the input flange. The flange is bolted up to a cup washer which wraps around the nose of the pig iron casing. The casing swells with rust and the inner face of the return lip of the cup, rubs against the swollen outer casing. If you take the diff out and turn the input flange, you'll hear it chaffing.

Ideally it wants the input flange removing with the cup washer and the nose of the casing filing clean. I reckon then your noise will be gone.

Post Fri Feb 01, 2013 9:28 am

B7 wrote: Ideally it wants the input flange removing with the cup washer and the nose of the casing filing clean. I reckon then your noise will be gone.

DON'T remove the input flange retaining nut, unless you know exactly what you're doing! To refit this nut "by the book" requires the diff. in pieces and special measuring equipment.

Post Fri Feb 01, 2013 9:31 am

Brianmoooore wrote:
B7 wrote: Ideally it wants the input flange removing with the cup washer and the nose of the casing filing clean. I reckon then your noise will be gone.
DON'T remove the input flange retaining nut, unless you know exactly what you're doing! To refit this nut "by the book" requires the diff. in pieces and special measuring equipment.

Correct, i should have said this. It's preloaded.

Post Sat Feb 02, 2013 6:04 pm

not just a squirt of WD then no? lol

Post Sun Feb 03, 2013 11:25 am

The zizzing noise is worn pinion bearings. When they get bad, you get the whine that changes note power pn/power off as the pinion to crownwheel mesh changes slightly. EP140 makes it a lot quieter. I just changed the diff in my Compact because it whined like a bastard over 60 and had a lot of backlash (driveline shunt) when changing gear. On the floor though it seemed perfect: nice and clean/dry, full of oil and the pinion turns smoothly. Small case diffs are nowhere near as tough as the 188 big case.