R34 Gtt Gearbox Knocking

[B-Boi34]

Hi all,

I have done a few searches but not found much info.

My gearbox has developed a knock. You cant hear it when driving & the gearbox still feels good, no crunches or anything.

You hear the knocking when parked in neutral with the clutch out, if you push the clutch in the noise stops. Its not always there, just sometimes, if I park it & the noise is there after turning it off the next time I start it up its gone.

I cant tell if it knocks with engine speed, I cant hear the knock over the exhaust with a little bit of throttle.

Does anyone know what it could be? should I drop the oil? its only a few months old.

Thanks in advance.

[breaker1845]

Are you able to get it up on a hoist and have the car running in neutral, inspect the operation of the clutch fork? The noise is probably still there while driving just can't hear it.

I'd say the gearbox is fine and you are probably having an issue with the fork or something clutch related as you mentioned the issue is due to operation of the clutch.

Anyway to fix the problem you will have to remove the box so best to run fresh oil anyway once you know the problem is fixed.

Best to get under there and check it out, could be another component causing the noise and intermittent occurrence does not help.

[GTSBoy]

Input shaft bearing would have to be a reasonable candidate for a noise that changes when you load the clutch.

[Kinks]

it's either clutch or gearbox input shaft. Changing the gearbox oil is a good idea if you can't remember when it was last done, but probably will not change the noise. Could just be a noisy throwout bearing on the clutch which really doesn't matter unless it is quite a loud noise. If it's only a soft noise like you describe it is OK to ignore it until the clutch wears out (or until the noise gets worse).

I think you can check for throwout bearing by putting slight pressure on the clutch and seeing if the noise disappears.

[B-Boi34]

Thanks for the reply.

Next time it makes the noise I will put slight pressure on the clutch.

Is the idea that the gearbox is still turning with only a little pressure on the clutch & if the noise goes away that rules out the gearbox?

[GTSBoy]

Is the idea that the gearbox is still turning with only a little pressure on the clutch & if the noise goes away that rules out the gearbox?

Not really. Throwout bearings make the most noise when they're unloaded. Load them up slightly and they shut up, unless they're well gone.