Rear axle noise?

[Mineralman]

My Laser has a whining noise emanating from the back, even without the wife in the car….. strangely I didn’t notice it from the passenger seat ob the test drive when buying the car but it is quite pronounced. It starts at about 25 to 30 mph and gets a little louder with speed. I am assuming it is the diff and not a wheel bearing and how can you tell the difference? The diff plug has been “ mullered” at some point so my guess is it has run low on oil at some stage. When I purchased the car it had a lot of annoying faults and I have cured most of these, the diff noise being one of the last. The car has only done 65k miles. If it is the diff is there a good additive such as Molyslip I can use to quieten it a bit as I am not going to repair or replace the diff on a car that does less than 1000 miles per annum. Thanks in advance.

[nemo]

Wheel bearing noise will become more pronounced on bends or roundabouts when the weight of the car is thrown more onto the relevant bearing. (so if you go round a bend to the left and the hum increases, the right hand bearing is worn) Does the noise get worse when you go on/off the gas? It `sounds` like crown wheel/pinion wear (whine rather than hum?) eitherway it`s really important that you get the filler plug out and check the oil level! If you didn`t notice on test drive and it`s now getting louder, it could be deteriorating due to low oil- but you MAY still be able to save it.
(Apologies if you`ve checked oil: I assumed from your comments the plug had proved a problem?)

[Mineralman]

Hi, yes, I have checked the oil and put a small amount in but it wasn’t very low. The filler plug has signs of being an issue to remove but someone before me must have freed it off as it was not difficult to remove. I haven’t noticed the noise being worse on bends. It seems to be consistent with speed, noise level increases as speed does starting about 30mph. It is like a scraping sort of noise. Wondered wether to drain the diff, add new oil and an additive?

[nemo]

Scraping is odd.... are you absolutely sure there`s nothing getting too close to the whheels or propshaft? Usual cries of distress are hums or whines. If the axle`s full of oil there`s really not much else you can do... I wouldn`t bother with additives.

[Mineralman]

I would describe it as a scraping noise, metal on metal contact. I cannot see any contact on the prop or rear wheels with anything else. I did remove lowering blocks off the rear springs as they are 2.8 springs, the car was too low on the rear and the exhaust hit the rear anti roll bar. Much better since I took the blocks out.

[D366Y]

I recently had a similar issue and was whining louder and louder as you increased speed, changed the wheel bearings and voila problem solved

I would say that considering the relatively cheap cost of buying and replacing the rear bearings I'd say do it and see if it solves the problem - if it does then great, if not then at least you have ruled it out and also invested in the car anyway

Cheers
Danny

[Major_Tom]

A worn prop shaft centre bearing makes a whine. More of a drone, or a churning sort of noise.

[Mineralman]

Is there a way of checking the rear wheel bearings in situ, play in the wheels, vibration through the backplates if the wheels are spun or similar?

[nemo]

Obviously you may be able to feel roughness or play in the bearing. Trouble is you can`t `spin` the wheels like the front as they`re dragging the diff assembly too - which also makes its own noise.

[SCP440]

Wheel bearing noise normally increases with speed but diff noise usally changes when you lift off the throttle. It could be a bearing inside the diff. As has been said for what rear wheel bearing cost that has to be the cheapest option or find another good diff. Its not that big a job to replace.
Dont bother with any of the addatives, none of them will work on a worn diff or bearing what ever they claim.

[Major_Tom]

Wheel bearing noise normally increases with speed but diff noise usally changes when you lift off the throttle. It could be a bearing inside the diff. As has been said for what rear wheel bearing cost that has to be the cheapest option or find another good diff. Its not that big a job to replace.
Dont bother with any of the addatives, none of them will work on a worn diff or bearing what ever they claim.

The same symptoms occurred in mine. I changed the wheelbearings, no difference. Then I swapped the axle with a known goodun thinking it was the diff. It was the prop shaft centre bearing the whole time. Grinding, churning noise coming from the back.

For the hassle and cost involved changing wheelbearings and diffs, do the prop shaft centre one first. I wish I had.

[bobsright]

Scrapping noise? I might look inside the brake drums for something wedged that's rubbing against the drum. Look at driver's side first as you said it wasn't noticeable from the passenger seat. Just my thoughts.

[Mineralman]

Thanks all. Don’t think it’s brakes as it recently passed an MOT and iirc they attended to the rear brakes. I can check the prop centre bearing but I have a feeling it may be wheel bearings. I recently fitted a stereo ( that was fun), perhaps I just need to turn it up a bit louder….

[SCP440]

I recently fitted a stereo ( that was fun), perhaps I just need to turn it up a bit louder….

That is a dangerous plan, if it is the wheel bearings they are warning you they need replacing. Leave them at your peril.

[Major_Tom]

I recently fitted a stereo ( that was fun), perhaps I just need to turn it up a bit louder….

That is a dangerous plan, if it is the wheel bearings they are warning you they need replacing. Leave them at your peril.

Depends what music he's into, certain wavelengths of sound might create a resonance feedback within the molecular structure of whatever part is at fault and it could reabsorb its worn materials and mend itself. Possibly.

[Major_Tom]

I haven't had my coffee yet.

[Jasonmarie]

I haven't had my coffee yet.

You really should have coffee before 9am , I am on my 2nd cup by then ………

[tejb1]

You can eliminate the prop centre bearing by spraying it with WD40 (other brands are available) as that will *temporarily* stop the noise.

[Mc Tool]

I haven't had my coffee yet.

yeah nah !, sounds like the last thing you need