Clutch Clunk. Me or it?

[doublesnaggle]

I just bought a 99 996 C2. 140k on it. New clutch at 70k.

Im not familiar with the new noises...

When I shift in any gear, I let out the clutch and mix some gas pedal and I hear and feel a low thunk or clunk coming from the rear. Like I am picking up slack in a bad u-joint. (in a car with a driveline) Am I shifting or using the clutch improperly? If I let out very smooth and slowly, it wont clunk.

Ive driven many many standard transmissions. I think Ive heard this before, not sure though... Any advice?

Edited June 10, 2012 by doublesnaggle

[logray]

Sounds like it could be the DMF spring action. Did they replace the flywheel when the clutch job was done?

[doublesnaggle]

Don't know cause the last owner doesn't know. I wonder if I called the shop if they could tell me from a record of repair from years ago...

[logray]

If the dual mass flywheel is toast, you can get all sorts of strange noises and clunks, thuds, etc.

Unfortunately typically if it is anything more than the flywheel causing these problems you are looking at big $$$$ for motor or transmission repair.

It might be possible your slave cylinder is slow or needs to be bled.

But my guess would be flywheel. There is a flywheel inspection procedure when the clutch is replaced, and in addition, it is usually customary to replace the flywheel when the clutch is done at such high mileage and under "spirited" driving conditions.

These are just guesses though, and in the hands of an experienced mechanic who is actually looking at or experiencing the problem might provide an alternate diagnosis.

[fpb111]

Also check the rubber in your transmission mount. When they start to deteriorate they will clunk.

Does it also clunk when you step on the gas, let off, and step on the gas again? check the trans mount.

http://www.autopartswarehouse.com/sku/Porsche/911/OES_Genuine/Motor_and_Transmission_Mount/1999/Carrera/6_Cyl_3-dot-4L/W0133-1891774.html?intcmpid=Product+Listings+Best+Seller

Do you often hear a rattle/clunk when you shut the car off? Check the DMF

TSB 911 (996) 8/02 1360 Dual Mass Flywheel Check procedure

http://www.renntech.....-procedurepdf/

Can the dual Mass Flywheel be twisted approx. 15mm in each direction, left/right, and does it return to approximately its initial position? If so it is good.

Can the DMF be twisted beyond dim stated above without a noticeable increase in the spring force? Or is it fixed (no rotation?) if so bad

Edited June 11, 2012 by fpb111

[porsche34]

Probably the CV joint...cheap and easy DIY.

Good luck

Robert

[doublesnaggle]

It only does it when letting my foot off the clutch. In any gear.

It comes from the rear of the car.

It sounds low and deep, like a thud more than like a clunk.

It feels like slop in the drivetrain.

I don't know what a CV joint sounds like when its sloppy, but I have a feeling thats it. Ill find out how to check it.

I just drove the car from SF to Seattle. The MAF went out the day after I got in Seattle.

It knew to make sure to get me home first. :notworthy:

[JMo]

@doublesnaggle What was the problem? Did it end up being the CV joint(s)?  Im having the same issue with my 2000 996.

[DBJoe996]

For a 2000 - An easy fix would be to change out your motor mounts.  Known to cause shifting and clunking noises from the rear.  Then it would be on to the transmission mount, but that is difficult to do as it requires dropping the transmission.  Could be a CV joint if it appears on one side of the car, or the other.  Other things could be struts, drop links, basically any rear suspension component.  I would start with the motor mounts.

[DBJoe996]

This is also a good solution for clunking and fairly easy to install:

http://www.function-first.com/products/engine-trans/trans-mount-insert

[JMo]

Thanks for the input DBJoe996. Did the mounts and still getting the clunk. Going to start moving through your suggestions and will post the results.

[grmccloskey]

I have the same issue on my 2001 986, 88k miles.  Did the clutch at about 78k.  DMF was checked and met the inspection spec.    It seems to be only in first and second when letting the clutch out fast.  Checked CV joints, they were good but changed them anyway and it did not go away.  Power bled the clutch three times, still there.  Checked trans mounts, seem to be solid.  As long as I baby the clutch there is no bump.  If I drive it like I stole it, bumps or clunks hard enough to hear and feel it.