Grinding noise on full (or almost full) lock

[Bela]

Hi Guys,

I have recently started to get a grinding noise from the rear end when the car is on full or almost full lock.

I have shown this to a mechanic who believes its coming from the diff, but there is no sounds such as whining or grinding coming from the diff when driving along apart from the above scenario.

has anyone come across this before?

I have a 3.25:1 LSD fitted

thanks in advance

[Brianmoooore]

The actual diff. only does anything when the car is on appreciable lock, or when a wheel loses grip. When your car is driving along at any speed over about 15 -20 MPH, the diff. is just baggage and does nothing much. Any whining noise from a diff. comes from the bearings or crown wheel and pinion, and is nothing to do with the actual diff.
Do you have the correct oil in the diff? If you use an ordinary oil, without the required friction modifying additives, then it will make noises when forced to work.

[Bela]

Hi Brian,

Thank you for your comments.

I have realised something I missed off from my post, I meant to say when the steering is on full lock (or close to it) I get a grinding noise from the rear end.

Regarding an oil change, this has been advised by my mechanic who has uprated the oil in several E46 M3 diffs as they start to make diff noises at their later stage of life.

My concern is if its coming from the diff as my mechanic has pointed out or if it is wheel bearing?

I only get the grinding noise when steering is on full lock or close to full lock.

[BenHar]

If it's a LSD as you say, it may be the inner wheel tyre skipping slightly as the diff locks up.

Ben

[Bela]

Hi Ben,

yes is an LSD, would the tyre skipping make a grinding noise (sounds like metal against metal).

Wish I could record the noise in action, but I have broken my throttle cable
One on order, will post up a video as soon as the cars back on the road.

Thanks