Driveshaft or wheel bearing?

[-Joe]

A loud moaning noise can be heard coming from the drivers footwell when the car is in motion. The noise sounds louder from inside the car. It is loudest at about 40mph+ and gets louder still whilst turning left.

In an attempt to cure the problem I recently replaced the whole right hand driveshaft assembly with a 2nd hand assembly. I noticed that the replacement had if anything slightly more wear than the assembly I took off. Both driveshaft assemblys seemed to have less wear in them than in other driveshafts I had replaced before on other cars. The center bearing seemed in good order.

After re-assembling the car I noticed the noise remains.. The noise can be heard even when rolling down hill in neutral, it's not the engine or gearbox.

I have tested for wear in the wheel bearings and can sense none with the wheel rocking test. I have run the car with the right hand side jacked up so that I can run the right hand front wheel at 40mph with the car stopped. The noise is loud inside the car yet quiet near the spinning road wheel.

I jacked up the left hand side and did the same test. No noise at all on the left hand side.

Using a stethoscope I can hear the noise on the right hand hub and subframe but cannot identify it's source.

So... Are both driveshafts new and old at fault, or could it be wheel bearing noise, but broadcasted from inboard. Could both center driveshaft hanging bearings be at fault even though they feel ok when off the car?

[Mike Noc]

Joe you can't discount the gearbox even if you still get the noise when in neutral.

Simon.h had a similar noise and this what he found:

'The only way I found out 100% it was the gearbox, was to jack the front of the car off the ground and safety sit it on blocks of timber under the chassis so the engine could be taken up through the gears. With the car in 5th gear and doing 50 mph with both wheels spinning (with my son at the wheel and me laying under the car) I got him to drop it into neutral and turn engine off so wheels spin from 50 mph to 0 mph without any noise from engine.
And the noise the gear was unbelievable!'
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[FrenchMike]

I agree "A loud moaning noise " is typical of a bearing noise ;
inside the box.:shrug:

[Simon.h]

Joe you can't discount the gearbox even if you still get the noise when in neutral.

Simon.h had a similar noise and this what he found:

'The only way I found out 100% it was the gearbox, was to jack the front of the car off the ground and safety sit it on blocks of timber under the chassis so the engine could be taken up through the gears. With the car in 5th gear and doing 50 mph with both wheels spinning (with my son at the wheel and me laying under the car) I got him to drop it into neutral and turn engine off so wheels spin from 50 mph to 0 mph without any noise from engine.
And the noise the gear was unbelievable!'
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Cheers Mike, that saved me writing it again.

And my fault was a bearing on the final drive inside the gearbox which looks like was down to someone in the past putting the wrong oil in the gearbox.

[-Joe]

I will lift up the car on stands and get right under it and listen closely to the gearbox.

When I did my tests I lifted up one side at a time and didn't get right under the car!

It was only noisy when the drivers side wheel was turning, which made me disregard the gearbox as the cause, would a broken diff bearing not effect both sides?

[pnstuch]

i had a similair noise on my connie v6 auto...i changed the driveshaft, hub bearinngs etc. yet the noise was still there..a couple of mechanic friends drove the car around and both said it sounded like the driveshaft...
then one mechanic friend who used to work for the main Rover dealer told me that the 75 had a fault with the rear tracking and to check the rear tyres...i know it sounds like the noise was coming from the footwell, but after checking the rear tryes i found one of them had worn funny on the inner side....difficult to see without jacking the car and spinning the wheel and feeling the tyre....
changed the trye and hey presto.....the car was back to normal....:}:}

just a suggestion.....

[Mike Noc]

When one of my rear wheel bearings got noisy I couldn't tell where the drone was coming from - even to narrow it down to the front or rear of the car.

Couldn't feel any play or roughness when turning the wheels by hand either.

After swapping the wheels around to rule them out I changed the rear wheel bearings anyway. It was only with the OSR bearing off the car that it felt slightly rough when turned.

[-Joe]

Replaced the drive shaft, that didn't fix the problem. I replaced the hub and that did. So it was the wheel bearing in the end.

The strange thing is that the noise didn't seem to come from the hub. The noise seemed louder inside the car, or under it, as if it were coming from somewhere in the region of the drive shaft center bearing.

I conclude that the noise was something vibrating in resonance to the in audible vibration originating in the wheel bearing.