Clanking sound when pressing/releasing clutch

[wwdwgs]

It's 1987 944s with 98K miles.
There is a clanking sound when I either press or release clutch pedal.
It happens when I normally press/depress clutch pedal. If I press/release the pedal slowly, the sound is minimized.
It seems that the sound is coming from the rear of the car.
I don't know if the clutch is original (rubber center) or not.
Is there any way to look at the clutch if a borescope without raising the car?

[944 Ecology]

Not much chance of seeing inside the bell housing without raising the car, unless, of course, you drop the entire driveline. Even with a borescope, you will not have much of a view.

[walfreyydo]

Well its a long shot but since you said the sound comes from the rear, you can check the drive shaft coupler that mates to the trans through an inspection port on the trans bellhousing. The allen head bolts should be secure and the coupler should be centered between the drive shaft splines and the trans input shaft splines.

Does it make the sound while under load (taking off from a stop sign for instance) or when stationary? With the car idling in neutral? What about with the car turned off?

Knowing these details will help narrow down the source.

[wwdwgs]

the sound appears when pressing and depressing clutch pedal during driving and when stationary or in neutral.
Sometimes sound is minimized or is gone altogether, if I work the clutch very smoothly.
I also noticed, the jerk/sound is present when I quickly let off the gas pedal under acceleration (in gear).
I don't recall any sounds when the engine is off.
Now the car is on jack stands.

[universeman]

Steelman makes a thing called a Chassis Ear which is a set of microphones on long wires that run to a sort of mixing board. You attach the microphones (magnet or cable tie) to areas where you think the sound is coming from. Then you hop in and put on the headphones, do the thing that makes the noise (really good for road noises) and turn the selector to the various microphones, to see which one is the source of the noise.

Might help you narrow it down.

[wwdwgs]

Walfreyydo,
Thanks, I'll check that some time later.
Universeman,
I've heard of them. I don't foresee using this too often, therefore I hesitate to buy it.

[walfreyydo]

Does it make the sound when the car is off and you press/release the clutch pedal?

I am trying to determine if you have an issue with the clutch assembly/throwout bearing (makes sound even with car off) or if its only present when the engine is running which would indicate an issue with driveshaft/torque tube bearings/trans.

[wwdwgs]

No sound when the car is off.

[944 Ecology]

It may be that the rubber center has come apart and the metal ears (designed to help you limp home) are doing their job. Another test would be to drive a fixed speed (say 30 mph in 3rd gear) and alternate a slight lift and then a slight push on the gas pedal. If you hear a clunk, then it's the rubber center clutch.

Another method (if you have the car on jack stands) is to try to rotate the torque tube drive shaft coupler (engine not running and trans in neutral, of course) to see it there is more than about 1 degree of rotation. If so, time for a clutch.

Here is a picture (stolen from another forum) showing the metal tabs involved:

[walfreyydo]

Good advice from George on the possible disintegrated rubber centered clutch. If its not that, then I would be looking at torque tube bearings, trans mount, driveshaft coupler, trans bellhousing bolts potentially loose, or possibly axles (unlikely if the sound also occurs while in neutral, which I think you indicated it does).

If possible a video would be helpful, if you can shoot from outside the car while someone is pushing/releasing the clutch. Try to narrow down the location of the sound as much as possible, if you can.

[OK-944]

You say the sound is coming from the rear of your car? Do you think its clutch related...or just "jerk related?" In other words, when you're smooth on the clutch, the sound does not happen, but if you're a bit more strident with it and/or the accelerator pedal, you get the sound...and its from the rear. Sound right?

Hmmm...could be CV joint related? Or something simple like the CV bolts backing out? Maybe something loose back there...like parking brake components? Possibly a loose exhaust hanger or heat shield is clanking away when the car is "jerked around?"

Re-reading your post, it does sound more clutch related. But does it happen even when you are not shifting between gears? Something involving the shift rod linkage over the tranny? Am trying like heck to avoid suggesting that it could be something inside the tranny. But have you checked your tranny fluid level recently?

[wwdwgs]

Walfreyydo,
I'll get the video - probably before this weekend. I'll try to get to the other areas.... will post any and all findings.
Ok-944,
I haven't checked the tranny's fluid.

[wwdwgs]

sorry, no video...
I got to drive shaft coupler and rotated it.....
.....about 1/5 to 1/4 turn......
At the end of rotation, there was that clunking sound.
There was almost no play moving drive shaft front to back.
didn't check it's allen bolts yet....

[wwdwgs]

the video ...

https://cloud.degoo.com/share/yPxMyQCFadia8dF2Uixzyg

[walfreyydo]

Maybe I am mistaken but the driveshaft should not spin at all with the clutch pedal released (assuming that no one has their foot on the clutch when you took the video). The driveshaft splines should be engaged with the clutch disc and flywheel and the shaft should not move, not even a little.

Since there is movement in the driveshaft, it leads me to think the rubber center on your clutch has disintegrated, allowing that movement of the driveshaft which normally shouldnt be there, and also likely the sound of the "catches" on the clutch disc hitting (a failsafe built into the clutch disc if the rubber center fails).

Seems like a clutch job is in order (and while you are in there rear main seal). I would deal with the clutch first and then see if the sound persists. Make sure you get a Sachs clutch without the rubber center.

[944 Ecology]

Yep, time for a new clutch.

Non turbo, first time, plan on 15 hours. Turbo, first time, plan on 24 hours.

If you screw it up the first time, second time will be quicker due to fasteners already loosened, etc.

[wwdwgs]

Walfreyydo,
your assumption so correct - neutral gear only. Yes, the clutch with springs. BTW, this is the first car in my life that has a clutch with a rubber center.
George,
You're SO encouraging....exhaust, gear box, tube, shifter.... I glanced over clutch replacement procedures on Clark's garage....lot's of fun... plus my favorite - rust.
Thank you for your support!

[walfreyydo]

When I did my clutch I also did the rear main seal, and rebuilt the torque tube. Rebuilding the torque tube isnt 100% necessary (unless the bearings are worn and making noise), and there are also options to buy a rebuilt torque tube, if needed.

The clutch job will require removal of the transmission, linkage, exhaust, bellhousing (speed/ref sensors, slave cylinder as well) and sliding back the torque tube to access the back of the engine. It is one of those jobs that is the hallmark of any 944 DIY enthusiast (meaning its a big job and not a ton of fun). Major sticking points (for me) were the removal of the clutch fork pin, removal of rear main seal (more difficult than you would think).

Torque tube rebuild/replacement was also a huge job in and of itself - if you decide to go down that path it will require dropping the rear suspension (which means its also a good time to look at updating/upgrading or re-indexing the torsion bars for ride height adjustment or replacing for increased stiffness/spring rate).

I tackled both the clutch/rms and tt rebuild over the course of an entire winter - taking my time, ordering parts as I progressed and didnt rush through it (and thereby potentially making a mistake). I researched each step as I went, making sure I knew exactly what potential pitfalls I faced for each step. When I hit a snag I would do some searching on google/forums for information on how others overcame said snag.

There are many guides on doing a clutch job, not only on clarks but also on pelican parts tech articles and on jurgen's many youtube channel guides (search for irina25661). These are invaluable resources for the DIY 944 owner, and I made sure to thoroughly study these before embarking on the project.