Morris Minor Owners Club

I was recently given a rear axle from an MG Midget of unknown history. The axle was complete with a 3.9:1 differential which, although very dirty, looked to be in decent shape. I decided to give it a try and installed the diff on my car. Having been out for a short drive today, I found that above about 45 mph the rear end starts to make a whining noise. If I lift off the accelerator, the whining stops immediately but as soon as I give it some gas again the whining starts back up. Below 45 mph, it seems to be okay.

Obviously, something's not quite right inside the diff but what? A bearing in need of replacement? Gear wear? Having never had one of these apart, I'm not sure quite what I'm up against. Does it sound like something that the average guy could handle or is it a specialist job?

If you look in the Workshop Manual it has a section on rebuilding the final drive. Very probably just needs the pinion adjusting - unless the gears have been badly worn running low on oil/with dirty oil. You could check if the 'big nut' on the pinion shaft is tight. If you don't have a Manual - Google is your friend for a free download....