Noisy gearbox on over run

[james]

I dont know if its just me getting old but I think my gearbox is noisier now when I lift off. It always whined when you close the throttle (which is kinda cool), I'm sure thats normal but it seems to be noisier recently.

I dont remember it ever having had its gearbox oil changed (unless its part of a normal A,B,C service in which case it will have.)

Its not dripping oil onto the garage floor. Could it be worn engine mounts because the noise goes away if I feather the throttle to take up the slack. Or does it just need a gear oil change?

Thanks

[ClarkyBoy]

Sounds like the thrust plate/clutch bearing to me,

I have had a few cars with similar, it will probably run forever with that noise TBH if it is what i think, but a clutch and bearing change will do the job if you are concerned about it.

[Rich H]

K series box always sounds like a bag-of-spanners-in-a-washing-machine-dropped-down-a-flight-of-stairs when on overrun. Worse when the oil is old or low.

TADTS to some extent. New oil quietened mine a bit for a while.

[Gourlay83]

I also think they are all a tad noisey. Worth while changing gearbox oil as its sometimes missed on a service.

Can't see how the clutch/ clutch bearing would be causing it. Unless you only hear it when the clutch is depressed as that's the only time the thrust bearing is used.

Alan

[ClarkyBoy]

i allways thought that the loose spinning noise was cause buy the thrust plate bearing, and when you apply pressure to the clutch it goes away, whether the car is moving or not?

maybe im wrong, but i have allways thought this for some reason, so something must have put it in my head at some point?

[Gourlay83]

Your nearly right,

If there is a noise when the clutch is up its most likely to be the gearbox bearings/drivetrain as that's what's turning. If the noise goes away when the clutch is depressed, that's because the clutch has disconnected the engine from the gearbox, which means the box is no longer turning

Don't mean to correct you Clarky but that's the way I see it.
Alan

[robin]

The gearbox is "filled for life" IIRC (which means filled until you need a driveshaft or a clutch ). There is no harm in replacing oil, but needs to be the right oil. It will probably make it quieter for a while.

IMHO the whole gear train is noisy under engine braking - hence the noise "goes away" when you increase engine speed to match vehicle speed - then the gears are free wheeling. The torque across the gears swaps directions when accelerating vs. engine braking.

There is no such change in torque direction across the release bearing whether you're accelerating or engine braking - in other words it cannot tell the difference between accelerating and engine braking - so I doubt it's responsible for the change in noise when you lift off.

Cheers,
Robin

[ClarkyBoy]

Your nearly right,

If there is a noise when the clutch is up its most likely to be the gearbox bearings/drivetrain as that's what's turning. If the noise goes away when the clutch is depressed, that's because the clutch has disconnected the engine from the gearbox, which means the box is no longer turning

Don't mean to correct you Clarky but that's the way I see it.
Alan

aah, i see, thank you for correcting me - everyday is a school day i suppose!!!



cheers alan!

[james]

So I just need to make sure I dont lift off then. That'll fix it