jacal128

I have a 1986 928s with 68000 miles on it, it has developed a sound that seems to coming from just behind the engine. It is fairly loud. Could this sound be a torque tube going or gone bad or possibly the Thrust bearing? Any ideas would be great. Thanks

Tony

odds are torque tube..or converter bearings

Hilton

First thing to do is measure the crank end play.. that'll either eliminate thrust bearing, or tell you that if the noise is the torque tube, you don't want to spend money fixing.

Black Sea RD

Hi Jacal,

Need a bit more information as in, is this a 5 speed or automatic?

If it's an automatic the best thing to do is to raise the car, remove the lower bellhousing cover and check the front flexplate for a forward bowing. You can do this with a small straight edge laid up against the flexplate. There usually is and at this time release the front clamp pinch bolt and measure how much the flexplate moves back unto the drive shaft. This will usually be 2-4mm.

Next remove the six bolts holding the flexplate to the flywheel and then slide the flexplate back unto the drive shaft making sure there is no longer any contact between the flexplate and flywheel. You have now essentially disconnected the driveline/transmission from the engine.

Next start the car and listen. If the noise is still there then it's probably the engine. If not then it could be the torque tube (TT) bearings, the torque converter housing bearings, or the transmission.

What we have found is that front flexplate load seems to hasten the TT and torque converter housing bearings demise.

As said by another, you should do a crank shaft end play measurement while your under the car to try to determine how your thrust bearing is doing. If it's out of spec it could mean your engine is ready to go soon.

HTH,

jacal128

Going to check this weekend, is it worth rebuilding and replacing bearings while I am down there. Not a everyday driver, just trying to put it back to what this car should be. ( bad previous owner ) Thanks.

Black Sea RD

Hi Jacal,

To rebuild and replace bearings in the driveline will mean having to drop the rear suspension, transmission and TT. A big job.

The first order of business is to locate the noise, determine the thrust bearing's health and go from there.

Good luck and keep us posted,

Dan87951

I just did a torque tube on my 87 S4 which really ended up being the converter bearings. Its amazing how everything amplifes down there so it was hard to pin point the sound. I went ahead and did the torque tube as well because once you remove the trans to get at the converter bearings its only a few more steps to remove the torque tube (plus this isn't a job you want to repeat). If you do decide to take on the work yourself gets some sandwich baggies and marker and label all the bolts as your remove them. It's also a good time to rebuild the transmission lines if you haven't done so already since I'm sure yours are leaking or sweating by now (very simple and cheap). It's also a good time to replace the vacuum line to your transmission, I believe your model year as 2 of them? Also Constantine gave some good advise to determine if its engine related noise or drive train. Good Luck.