Transmission Noise

[Neil-yaj396]

I've mentioned to a few of you that above 30mph driving in a straight line something in the drive train of my Coupe makes an annoying 'whiring' sound. Even a slight application of left hand lock stops it dead, whereas application of right hand lock does not really effect it unless you are cornering tightly when the noise eases a little. The noise persists if you knock the car into neutral or drop the clutch at the above speeds.

I changed the gearbox and final drive oil (using both drains) for Red Line 75W 90 in July, and although this has improved the gear changes noticeably, it has not quietened the noise.

Chris M mentioned CV joins and I've tried a few full lock turns in 1st & reverse with no grumbling caused. As above the noise is at it's worst when driving in a straight line at speed, excepting the impact of left hand lock as above.

I'm sure a few of you will have a good listen at the weekend for me, but posting this as a heads up.

Neil

[A Ross]

Hi Neil,

I'll have a listen on the weekend - I think the problem could be one of a number of things. Starting from the inside working out; 

1 Play or wear in the diff bearings
2 Inner CV Joints worn
3 Outer CV Joints worn
4 Play or wear in the Front wheel bearings

If it's happening in a straight line and not when cornering its more likely to be an inner rather than an outer problem. Noises doing anything other than going deadahead are more likely an outter problem. It might be a bit elementary, but check theres nothing fouling the wheel or anything else on the drive train.

Alex 

[Nigel]

Back in the day, my colleague and I became quite good at identifying which wheel
bearing was causing noise. We placed bets with each other! And we got it wrong a few times!

From your description Neil, it's likely to be a wheel bearing.
The change in sound on various cornering points to this.

Happy to have a listen over the weekend.

Nigel

[Neil-yaj396]

A wheel bearing would be a good outcome rather than the final drive being worn out. I even have 2 new bearings in my spares box. Here's hoping for a diagnosis at the weekend!

[WestonE]

Hi Neil

Also consider the bearing supporting the transfer shaft from the gearbox to one of the CV joints. Disconnect the CV slide off the gearbox coupler and spin it listening for grumbling rumbling bearing. Circlip to remove it. Read the numbers off it check outer diameter inner diameter and thickness with a digital vernier. Pop the numbers into a browser and choose an online bearing supplier.

When side loaded it will be quieter hence a possiblity.

Eric