Porsche Enthusiasts Club Forum

Hi all
I have a problem with a transmission rumble on my 1991 944 S2.
The noise starts at about 30 mph and gets steadily louder as my speed increases. It's present in all the higher gears and when the transmission is loaded and unloaded.
I've tried the usual trick of changing the transmission fluid but to no avail.
I'm not sure if it's coming from the transaxle or the torque tube.
It's not the sort of whine that indicates the diff is worn, more a sort of low frequency rumble.

Anyone had a similar problem or any thoughts on what it could be?

Neil

Possibly a torque tube bearing. First I'd be dropping the driveshafts & checking the CV joints as well.

Sure its not a rear wheel bearing? I thought my box was on the way out but it was just an incredibly noisy wheel bearing with the same symptoms you describe.

If it's road speed related, I'd go for something between diff and wheel bearing. If it's engine speed related, torque tube is a possible....

Perhaps try getting up to speed, dip the clutch, put into neutral and see what noises are present with different parts of the drive train loaded or unloaded... Weaving from side to side can help tell you if it's a wheel bearing.

Good luck

Thanks for the replies guys.
I've had the rear on axel stands and I can't detect any play in the rear wheels to indicate bearing problems.
The noise does seem to be road speed related, I don't seem to get any noise in first gear, but when it's up to speed and in neutral I still get the noise.

Exactly as I was, no play in the bearing at all. Same noise symptoms. I'll still have my money on a rear wheel bearing

Please don't read this as patronising in anyway as I'm genuinely trying to help, but have you ever heard a worn wheel bearing? The noise you describe fits exactly what I've heard on 2 previous cars, with the solution being to replace the wheel bearing in each case. On the first occasion, I was worried it was something terminal, but on the second occasion, I knew what it was straight away.

Cheers,
Bryan

Hi Bryan
No offence taken at all, I appreciate your help.
As well as an absence of play I couldn't hear any noise when I rotated the rear wheels with the car on axel stands.
Did you decide it was a wheel bearing purely from the noise the car made on the road or could you hear anything with the rear wheels off the ground and the wheels rotated by hand?
I am almost tempted to change the wheel bearings anyway as a first step, as it won't cost as much as a refurbished torque tube, diff or gearbox.

Cheers
Neil

Thanks for the info Jim, I've ordered the 12 point spline drive I need to disconnect the driveshafts so that I can check the CV joints.
Cheers
Neil

Worth checking the CV joints & gaitors at the same time. Also repacking with clean grease. Filthy 'orrible job but worth doing. Note that officially the bolts are stretch bolts & shouldn't be reused. Either replace or use some Loctite.

If those bolts have not been touched for 25+ years then be prepared to cut them all off! The spline heads on mine were rusted and there was nothing left for the tool to grip on

I bought these bolts for the 968, I believe they're the same on the 944 -£1 each plus postage.... https://www.ebay.co.uk/itm/181856392919

Hammer the triple square bit into the bolt head before you try to undo them that will give you best purchase...

Good luck

After problems with my Mondeo daily driver I've finally managed to get around to looking for the cause of this rumble.
Removed the drive shafts and checked the CV joints, all OK.
Next took off the caliper and disc and so that only the hub was left on. When I turned the hub by hand it made a terrible racket and I could actually feel it grating as it turned. Definitely the wheel bearing so you were spot on pilch and briggy.
Replaced the bearings on both rear wheels and now they are smooth and silent, job done.
Many thanks for all your helpful replies guys.
Neil

Excellent stuff, no doubt the cabin is a much more pleasurable place to be in now

Great stuff. Glad it was something relatively simple. Sounds like you did the work yourself, which makes it all the more satisfying.