4th Gear Whine

[Harry]

Hi All,

My car has developed a whine when coasting in 4th gear. Under load the noise goes away.

Any thoughts as to what it is? Am I looking at gear box rebuild?

Thanks very much.


Cheers,

Harry.

[HughH]

harry is it only in 4th or can u hear it in 5th as well under virtually no or very low load

also is it still there if u push in the clutch

[CamBiscuit]

Harry I wouldn't stress too much unless its really bad or its happened all of a sudden. The trans in the ST would wine a bit but I had no sound proofing!

To be on the safe side maybe drain and check your oil for any nasties.

[Lyndon]

I replaced 4th and 5th gear pairs in my 915. They were pitted and made a pretty bad whine. I also found some damaged bearings which would have ended badly if left longer. It made the gearbox much quieter to drive. Now I just have to sort the pinion gear and it should be quiet as a mouse.

[Harry]

harry is it only in 4th or can u hear it in 5th as well under virtually no or very low load

also is it still there if u push in the clutch

Hi Hugh,

I just took it for a spin on the freeway, no noise in 5th, only 4th, and none with the clutch in.

When going around left hand bends at 100 kph a thrumming noise is present as well. I suspect is coming from the diff (the diff is a LSD) and I'm not sure if that is normal for LSDs?

Cheers,

Harry.

[Harry]

Harry I wouldn't stress too much unless its really bad or its happened all of a sudden. The trans in the ST would wine a bit but I had no sound proofing!

To be on the safe side maybe drain and check your oil for any nasties.

Thanks Cam, I'll drop the oil and have a look.


Cheers,

Harry.

[Harry]

I replaced 4th and 5th gear pairs in my 915. They were pitted and made a pretty bad whine. I also found some damaged bearings which would have ended badly if left longer. It made the gearbox much quieter to drive. Now I just have to sort the pinion gear and it should be quiet as a mouse.

Thanks Lyndon, did you do the work yourself?

Cheers,

Harry.

[HughH]

So it sounds like "just" a 4th gear noise, not CV , and if only 4th probably not the crown wheel and pinion or the bearings in the gearbox When my pinion was on the way out you could hear it in both 4th and 5th and occasionally in 3rd. It was noisy for a couple of years before we ended up changing it. I think cams suggestion to check there is nothing nasty in the oil is good and then you could probably leave it for a while. I am not sure about the other noise though not having a LSD - does it only make the noise on left turns or on both?

[Lyndon]

Hi Harry,
I did most of the work myself, although I was designing transmissions at the time so I had a good array of tools at my disposal. Most of it is fairly straight forward if your patient.

[Harry]

So it sounds like "just" a 4th gear noise, not CV , and if only 4th probably not the crown wheel and pinion or the bearings in the gearbox When my pinion was on the way out you could hear it in both 4th and 5th and occasionally in 3rd. It was noisy for a couple of years before we ended up changing it. I think cams suggestion to check there is nothing nasty in the oil is good and then you could probably leave it for a while. I am not sure about the other noise though not having a LSD - does it only make the noise on left turns or on both?

Hi Hugh,

It only makes the noise when turning left, a loud thrum that permeates throughout the cabin.

Cheers,

Harry.

[Terminator]

The LSD was/is noisy, on the 74 Carrera I have same noise thnik it happens when turning either direction at slow speeds though can't say I have ever heard it at high speed.

The 72T that Neville purchased from me had the whine in 5th gear and it went away when I changed the gear. The gear showed no signs of wear to the naked eye.

[Fishcop]

Check clutch pack on LSD...

[Merv]

I assume your gearbox mounts are all good Harry?

[Harry]

The LSD was/is noisy, on the 74 Carrera I have same noise thnik it happens when turning either direction at slow speeds though can't say I have ever heard it at high speed.

The 72T that Neville purchased from me had the whine in 5th gear and it went away when I changed the gear. The gear showed no signs of wear to the naked eye.

Hi Clyde,

Yes, I know the noise you are talking about at low speed, it occurs when you are turning at low speed and apply a bit of throttle.

I never heard the noise at high speed either until recently and it seems to be different to the low speed noise and only when turning left.

Cheers,

Harry.

[Harry]

Check clutch pack on LSD...

Hi John,

Yep, I guess the next time the engine is out I will get the gearbox and diff looked at as well.


Cheers,

Harry.