Transmission noise

[hornet964]

Hi
I'm not mechanical, so can you help me? On a 1970 minor, standard engine and transmission, all original at c.155,000 miles. I have a droning noise on the transmission. Pitch varies with road speed, is only present under load (so I think not wheel bearings). Doesn't vary with gear selected. Not there in neutral. I think that means it's the diff? The axle casing was changed quite recently, but with existing diff/drive shafts replaced (new rear wheel bearings). Any ideas?

If I need a recon diff, any recommendations for sourcing? And would a standard 1098 work with a 3.9 diff?

Thanks!

[philthehill]

I would suggest the diff is at fault.
The 3.9 mated to a 1098cc will work but you may find that the engine labours on the slightest hill.
The 4.22 standard diff is ideally suited to the 1098cc engine.
As regards sourcing a 4.22 diff 'e' bay would be a good start.

[myoldjalopy]

Is there enough oil in the diff? That would make it noisy. Having said that, some diffs are noisier than others. I drove a Minor with a whiny diff for years and just got used to it. It never failed.

[biomed32uk]

As the prior post my diff can be a little noisey, especially on the overrun around 40mph.

I am always sceptical of these things but I put some Forte Diff and Gear treatment in, on reccomendation.

It took about 400miles but it really has quietened it down substantially, not totally but I have really noticed the difference. So much so that I am not going to pull the diff out this winter now, it can stay like it is while I wait to be in the right place at the right time to acquire another one, not on my urgent list though now.

[hornet964]

Interesting, thanks for those comments. Yes, the oil check was my first thought as it had all been apart, but was fine. The issue only started after the change of axle, but as original diff and halfshafts went back in, hard to see what would have caused it. Maybe after all these years it just didn't like being disturbed! I'll try some additive before I swap the unit out, though with the current noise level I'm not sure how many miles I have left...

[biomed32uk]

Out of interest did the propshaft go back exactly where it came off ?, it may have become unbalanced now. If it was OK prior to being disturbed hard to belive the diff has worn. Something has changed, didn't damage a wheel bearing in the process ?.

Additives are no magic fix, if it really is worn out then it won't cure that.

[les]

There was an additive widely use years ago, it was called sawdust! Cowboys go back a long way.

[biomed32uk]

Banana skins as well apparently, might make EP90 smell better at the very least !. I certainly remember the old sawdust trick....

[martin418]

just a thought if the noise only started after the axle change it must be a problem with the replacement axle casing possibly it is slightly bent making one or both the half shafts run out loading the diff and making it whine