Differential

cauchoiskev · Post by **cauchoiskev** » Fri Oct 23, 2009 9:46 pm

I think my diff is a bit noisy (swishing noise, a bit like warped brake discs, but it's not the brakes).

The noise comes from the centre-left side, the driveshafts seem fine. Clutch in, noise stops. It's not very loud, but I've got rid of every other creak, whistle and squeak from this car, so now I can hear it.

Question : has anybody ever changed the roller bearings of a BX diff ? Also, are any petrol BL diffs the same as the diesel BE ones ?

DavidRutherford · Post by **DavidRutherford** » Fri Oct 23, 2009 10:15 pm

cauchoiskev wrote:The noise comes from the centre-left side, the driveshafts seem fine. Clutch in, noise stops. It's not very loud, but I've got rid of every other creak, whistle and squeak from this car, so now I can hear it.

In which case it's not the diff, as diff bearing noises will continue regardless of the clutch position. My first thought would be input shaft bearings, as I've heard the swooshy noise of a tired bearing from here many times before on a BE gearbox. Does it make this noise in relation to engine speed or road speed?

Try dumping the gear oil and filling it up with 15w-40 engine oil (which is roughly the same viscosity as 75w-80w gear oil, and is what was specified for early BE gearboxes). That has been known to shut up many a tired BE gearbox. It also makes for a slightly nicer gearchange, and at about £3 for a gearboxfull (two litres) can be changed on a regular basis without incurring much cost.

cauchoiskev · Post by **cauchoiskev** » Sat Oct 24, 2009 9:11 am

It's a road-speed related noise, David, so I counted out the gearbox itself.

My thinking on the diff bearings was that they were being noisy when under load, i.e. with the clutch out. I can also stop the noise when going downhill by balancing the accelerator so that the car is in effect just coasting.

DavidRutherford · Post by **DavidRutherford** » Sat Oct 24, 2009 12:22 pm

In my experience, bearings don't generally change their noise level in relation to load, it's much more related to speed. However, gear tooth whine would very much change in relation to load, so I suspect that it could indeed be the diff, but more likely the crownwheel and pinion rather than the bearings.

Does it make noise on the over-run as well (IE when everything is loaded up the other way around)?

cauchoiskev · Post by **cauchoiskev** » Sat Oct 24, 2009 6:11 pm

Yes, it does indeed whine exactly the same on over-run. So it looks like I may be on the look-out for a low-milage diff then (this one has done 320000km). Do you know if any petrol box diffs are interchangeable with the diesels ?

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