whining diff

[eastona]

OK, it went like this....fantastic drive home, first hairpin negotiated well, second hairpin looming. Hard on the brakes, down to third, on the accelerator for the apex, then massive trampy bouncing across the road .

What a plonker. It's 39 years old. there was what seemed like a screechy noise, couldn't determine where it was from (could have been engine or transmission) then just normal noises. Until I hit 50 - 60, where I have a HUGE diff whine. It's OK, but 50 miles a day is a bit wearing

I presume the diff needs shimming, and that violent unloading / loading caused by the wheel losing grip repeatedly must have dislodged/screwed up some of the old shims.

Question is, how long do these things last in this condition? I need it every (week)day and could do without the time and expense of dropping the diff out.

I presume it's not difficult, just fiddly to do (I read my 1970 workshop manual which has comprehensive instructions) and where do I buy shims from?

I love this car, and it's extremely capable, I just need to remember it's not a hot hatch

should I drop the diff oil first to look for evidence of mashed and mangled shims coming out with the oil?

Andrew
(off to look up prices for dial guages and shims)

[MoggyTech]

Are you sure the whine is from the diff and not the propshaft UJ's? It's almost impossible to break a diff on a Moggy. Anyway, if it is the diff, it's an hour job to swap it out. Drop proshaft at the rear, drain diff oil, remove rear wheels and brake drums, slide halfshafts out a few inches.
Remove old diff, fit new gasket and new diff.

In any case, before doing anything, check and grease the propshaft UJ's
There should be no play in any direction, but you need to hold each side of the shaft with the UJ in the middle under test. 10mm or less freeplay when rotating the propshaft to check diff endfloat.

Rebuilding a diff requires a load of patience. Dial guages can be had for £20 these days, and Crownwheel and Pinion bits are available, not sure about planet gears and shims though.

[bmcecosse]

It's not going to be 'shims' - but it could well be that something has broken inside the diff - maybe even a half-shaft - so you should investigate asap. And yes - a half-shaft can break and the broken part wedges inside the diff leaving drive to one rear wheel only. Happened to me - at least the car gets you home like that! To check -jack up one rear wheel at a time and see if they are both connected to the prop shaft - or is one free-wheeling. And UJ joints don't whine - they may rattle and bang but no whining.

[MoggyTech]

UJ's may shriek if they are run dry

[eastona]

Blimey, 3 replies, doesn't anyone sleep here

I've broked a couple of half shafts before, (L-R and Midget) so I'll check the "drive to one wheel only" theory. (probably before driving to work!) It seems but if it's happened to you before, then it's always possible for it to happen again. (and I don't fancy being stuck in the middle of nowhere with "no wheel drive" )

I'll also check the UJs. Possible that I haven't greased them recently

Trying to avoid the cost of a recon diff, I may be resigned to rebuild myself, but I'll try UJs, halfshafts first.

Forgot to say, it whines when accelerating/cruising, but not on the overrun
Andrew
resolving to treat Maggie gently from now on.

[bmcecosse]

Mine broke after heavy axle tramping - during an 'Autotest' Competition. Bang and strange noises - jack up and no drive to one wheel - drove it carefully home. On removing diff found broken section had fallen inwards so jamming the diff - which was what allowed me to get it home. It was 40 years ago - so can't say now if it 'whined' - but the circs of the breaking sound a bit like yours.

[eastona]

unfortunately they do sound alarmingly similar.

there again, a half shaft isn't too bad to change, I should just pull the diff to make sure I clean all the bits out.

Andrew

[eastona]

not the half shalfts. Jacked up each side in turn, handbrake off, in gear, neither side would budge (save for the usual diff backlash)

I'll try UJs tomorrow.

Andrew

[bmcecosse]

Oh well - it was worth a go. Maybe the cross pin in the diff has broken (very regular in powerful Minis which have essentially the same diff) - although that would normally lose all drive - and not be a source of whining.

[aupickup]

i have a 4.22 diff for sale £30.00 , looks good

[eastona]

Oh well - it was worth a go.

certainly was.

very regular in powerful Minis which have essentially the same diff

I like the "powerful" bit! It's a standard 1098. I see what you're saying though.

I'm going to grease the UJs (just to rule them out) and then drop the diff oil this weekend just to see if there is any metal in it.

When I've time (a rare commodity at the moment ) and money (even rarer!) I'll pull it and check. Thanks Aupickup, certainly easier to pull and replace with a good unit than having to repair before work the next day .

Andrew

[Peetee]

I would plump for a damaged wheel bearing.

[bmcecosse]

That's a possibility!

[IaininTenbury]

Are you sure the whine is from the diff and not the propshaft UJ's? It's almost impossible to break a diff on a Moggy.

I'm not proud, but I've proved that wrong on a couple of occaisions... The most recent in the van on the M56. The diff had been whining badly for a few weeks, but I'd ignored it. Then I felt a slight lurch, like someone tapping the brakes. I was doing about 50 at the time, and was just thinking 'that didn't feel nice, perhaps I ought to slow down' when the back axle locked up solid giving an interesting exercise in car control to park on on the hard shoulder...
The postmortem revealed that the bearing on the pinion shaft had broken up and all the rollers had gone round one side and jammed up. The sudden stopping had bent both halfshafts on the splines as the rear wheels tried to carry on rotating... The cause? Almost a complete lack of oil - I hadn't noticed the leak.

The other one was a few years ago in another van, competing in a Production Car Trial. Suddenly lost drive on one of the hills. Explained to the Clerk of the course that it most likely would be a halfshaft, but its ok because I had a spare, then after removing both, I went back to explain, "I thinks its the diff, but its OK because I've got one in the spares box for ballast" We did manage to return and complete the event. The cause? Just being brutal to an old high mileage Minor and the cross pin broke...

As for your problem, i'd guess if it sounds like diff whine it will be. Probably a bearing broken up a bit so the crown wheel and pinion are no longer in true mesh. I'd have said it'll run for ages like that before the M56 incident. Now I'd check it asap!

[Judge]

I well recall my eldest daughters Minor, "I thought they all made that noise". Oil was like mercury.