I seem to be posting more and more here but still bear with me...

I have a noise on my car, you can only hear it after 15mph and below 25mph and it being loudest at 20mph. It's a humming noise and is definitely noticeable in the car.

I thought wheel bearing on the passenger side was the obvious choise but the one on the car is new... Never mind, check the other side. Also new!

I jacked the car up and started it in 4th gear to spin one wheel at a time at 20mph. Drivers side = silent, passenger side = humming noise... Despite it being new I thought I'd change it anyway so I know 100% it's new and been fitted correctly.

New wheel bearing made no difference so thought driveshaft then, the driveshaft was fine but had a spare so was easy enough to check. Changed over the driveshaft and its exactly the same still... I now think hmm, the only other choise is the gearbox then!

I've had the noise on the car with the brakes all removed on the passenger side also so the only thing turning is the bearing and driveshaft.

I took the car to the gearbox specialist and asked him for advice. He says 100% that's not gearbox at fault because if you go along the road 25mph put it in neutral the noise stays on... As well as a few other things. Followed by "it's not often I'm wrong but I have been in the past, don't get me wrong I'd love it to be the box and take your money off you, but that's not like any gearbox noise I've heard"

We also checked the gearbox oil just incase, it's still like new and had little to no metal filings in.

What do I do?!

for a start you donate you 312 / 256 set up to me ..... after that if you push your clutch down while driving does the noise stay or disappear ....

how loud is the noise? is it possible its something else none transmission related but at the passenger side? with the drivers side wheel in the air spinning if you go to the passenger side can you still hear the noise or not ?

Live with it?

for a start you donate you 312 / 256 set up to me ..... after that if you push your clutch down while driving does the noise stay or disappear ....

how loud is the noise? is it possible its something else none transmission related but at the passenger side? with the drivers side wheel in the air spinning if you go to the passenger side can you still hear the noise or not ?

I could sell things from the car to make money but Don't want to just yet!

the noise stays on the car all the time (between 15 and 25mph) doesn't matter what gear or with or without clutch.

With the wheel in the air spinning you can hear the noise but its louder sitting in the car.

I could sell things from the car to make money but Don't want to just yet!

the noise stays on the car all the time (between 15 and 25mph) doesn't matter what gear or with or without clutch.

With the wheel in the air spinning you can hear the noise but its louder sitting in the car.

lol i said donate .... not sell

you could push clutch down whilst driving and turn the engine off if the noise remains its 100% transmission

suppose there are also 2 other options

1 - never drive between 15 and 25 mph

2 - huge sub in boot and turn the radio riight up

Have you got slightly deformed tyres? I know when my last set were on their way out, I was getting a lot of road noise particularly at sub 30mph speeds, and it turned out the tyres had small flat spots / deforming.

I've ruled out tyres, brakes Etc as the noise stays on the car with the passenger side up I the air with the wheels and brakes off the car.

Could it be a noisy diff?

Putting it in neutral will not stop the driveshaft turning in the diff. It just means the gearbox is disconnected from the wheels. Technically the diff is always connected to the wheels.

Get someone to sit in the car to recreate the noise with the wheels off the ground and poke around at the gearbox and wheel bearing with your ear up against a long screwdriver. Shouldn't be too hard to locate where the noise is loudest. Just remember to use axle stands and don't get squashed in the process

+1 thats the best solution to this is to get your ear on the box.

Good luck