Rear axle whine

[Jim Haines]

My 1971 MGB Automatic was restored 22 years ago, but has always had a slight whine from the rear end. This becomes apparent under load when I approach 30 mph, but will go as soon as I lift off the throttle. At the same time I had always been aware of rear end clunking, which is there when the car goes from Neutral into Drive (i.e. engaging the transmission) and also under normal driving conditions.
4/5 years ago I had the thrust washers replaced and although I was optimistic that the problems would be cured this hasn't happened.
The problem is not major, but I have the 'itch' to try and solve it.
I cannot get a replacement differential of the correct ratio, and I don't know if the pinion is available (can you fit a 'standard pinion to all axle ratios or are they matched?).
Noting that the whine only occurs under load does anyone know - is this likely to be the diff or it's bearings?
I have dug around on the net but cannot seem to find a definitive response.
Can anybody help, please?

[Ian F]

Hi Jim,
I've not got any easy answer for you I'm afraid, but maybe some words of comfort! I've had a 1972 BGT for nearly 40 years and still on the same axle. Always had a bit of a noisy axle including clunks - which were lessened by replacing the cup shaped thrust washers (an easy job really) and a bit of a whine. I recently stripped out a wheel bearing trying to get to the bottom of a throb at 70mph on the motorway, but all looked well so I just put it back together.
All in all, the view I have formed is that these axles are pretty well everlasting and you just have to get used to them singing! If you really want to hear what's going on, take out the back seat, the carpet underneath and the metal cover over the battery boxes. Then go for a run (ideally in the dry) and have a listen to what's going on. You might be surprised at the noises emanating from the axle!
Just make sure you have good quality correct grade of oil to lubricate everything and continue driving it. If you aren't happy with doing that then there are a number of companies who will rebuild your axle for you - not sure it will sound much different though!!

IanF.

[Jim Haines]

I finally bit the bullet and had the axle completely rebuilt by a specialist. Painfully expensive, but such is the way of the world.....
Have to say that I am very pleased with the results - a bit like the "difference between chalk and cheese". The clonking and banging which happened when I put mine into gear (mine is an automatic gearbox) has gone, as has the whine (apparently caused by the case hardening wearing from the crown wheel).
The only down side is that I couldn't get the right ratio - correct ones for an automatic are as rare as hen's teeth, I am told, so I have a standard ratio for a manual gearbox again and the engine is still a 'bit busy'.
Looking forward now to some happy motoring..

[Ian F]

Jim,
just coming back to this topic - can you advise who rebuilt your axle please? There appears to be a bit of a shortage of these amongst the usual suppliers.

Ian F