Clutch Chatter in Reverse

[x030399]

1984 944, 85k miles

I bought the car in 1999 with 65k and, as far as I know, the original rubber center clutch. The clutch was fine while I owned it and I put about 5k on it, then bought a 1986 951, and gave the 1984 to my parents. They put a new Sachs turbo clutch into the 1984 in 2001. I sold the 951 in 2003, my parents bought a 2004 911, and gave me back the 1984 944.

Ever since I took it back from my parents, I have had a problem with MAJOR clutch chatter in reverse, and, if you're not careful about blipping the throttle, a MAJOR chatter on 3-2 downshift.

It's a lot worse when cold, and is if feathering the throttle right, I can avoid it when the car's warm and reversing on flat ground. But even when warm, it's impossible to back up a hill in reverse without shaking the bejeeses out of the car, and thinking that the whole drivetrain is gonna fall out.

Asked my parents, and they said they never noticed a problem. I suspect that the problem was there ever since the Sachs clutch, but my parents didn't notice because they back out of a downhill driveway, and they don't do any aggressive 3-2 downshifts.

Any idea what this might be?

I've learned to live with it, and make sure I don't park with the nose downhill, but is a clutch job in my future?

p.s., re-built transmission was installed May 2008 due to failed bearings, and still the same symptoms. Motor mounts seem fine b/c it idles smooth as silk at 900 rpm.

[mikepellegrini]

I'm not entirely sure what precisely you mean by clutch chatter.

The only thing I can think of is engine mounts. When they're toast, the engine flops around (somewhat) when you engage the clutch. No vibration at idle? Huh. I think I'd check the engine mounts anyway, just to be sure.

[Jeff Laurence]

A fierce clutch is sometimes the result of oil on the friction material. Was the rear engine seal replaced with the clutch?

[John_AZ]

Originally Posted by x030399

1984 944, 85k miles

I bought the car in 1999 with 65k and, as far as I know, the original rubber center clutch. The clutch was fine while I owned it and I put about 5k on it, then bought a 1986 951, and gave the 1984 to my parents. They put a new Sachs turbo clutch into the 1984 in 2001.

I am somewhat confused.
The NA disc is 225mm and the Turbo disc is 240mm IIRC.

Did your parents put in a NA disc that is similiar to a racing disc for track and not for street? I'm doing my clutch now and looked at Kevlar linings and decided to go with street friction material because of the potential problems you are describing. Maybe just change the disc-$200 to $350 and a lot of time.

GL
John_AZ
1988 924S 60K + 1987 924S 113K

[x030399]

Maybe I misspoke. My understanding is that the 951 does not use the same rubber center clutch that the NA did, and that you could put a non-rubber center Sachs clutch, that is functionally similar, but maybe not identica to the 951 clutch.

That non-rubber Sachs clutch is what was put into my car in 2003, 6k miles ago.

When I say clutch chatter, maybe a better way of explaining it is clutch "earthquake" i.e., as you gradually start moving (in reverse), there's a rumbling chatter, and if you keep going without seriosly feathering the throttle, it increases to the the point the whole car starts an earthquake-like banging vibration that will shake you fillings out, and probably drop the tranny out of the car.

I did do research elsewhere in the meantime, and seems it's not a unique problem. Found plenty of other non-Porsche cars that have the same problem, and apparently, it's either a flywheel with burnt patches on it, or oil on the clutch friction material.

Prolly B, because the receipt for the repair doesn't say anything about the rear seal being done when they put in the clutch.

I guess I'll live with it until I have enough $ to do a new clutch, even though this one is brand new.

thks!

[John_AZ]

If we think the clutch spring disc put in the 944 in 2001 or 2003 is good with only 6K miles and you did not mention oil dripping from the rear of the engine down to the floor I will offer my second guess.

Your torque tube bearings (4) are about to explode and before this happens, you will get the vibration you describe. Quote-

"When I say clutch chatter, maybe a better way of explaining it is clutch "earthquake" i.e., as you gradually start moving (in reverse), there's a rumbling chatter, and if you keep going without seriosly feathering the throttle, it increases to the the point the whole car starts an earthquake-like banging vibration that will shake you fillings out, and probably drop the tranny out of the car."

"Earthquake like banging" makes me think the torque tube is bad.

A similiar thread, bad outcome:
Help! Noise when shifting into 3rd

I am not convinced you have oil on the disc. The flywheel protects the disc in the recess and oil from the seal would drip on the garage floor. You could have ruined the disc if the heater control valve at the rear of the engine leaks colant at the pivot or the heater hose above the bell housing leaks coolant on to the clutch. ???????

GL
John_AZ

[x030399]

Hmmmm, interesting point about the coolant leak. The hose from the block to the heater valve (that tiny 4" sucker) blew catastrophically 3 weeks ago. I was only a mile from home and was able to limp home, but the engine compartment was totally soaked. I fashioned a replacement from a Napa hose and all is well now, but I'm wondering if that could have ruined the clutch friction material.

This problem has been going on for the last 4 years, and my problem is no worse than before, so I guess that coolant bath incident didn't mess up the clutch any more than it was before.

There's zero oil leaks, as evidenced by my bone dry garage floor, so does that means the rear seal is ok?

If it's the torque tube bearings, would the problem be less when the car is warm? When it's stone cold, the earthquake is the worst. Even trying to back up on a level surface causes it. When the car is warm, I have no problem backing up on a level surface, but if I'm trying to reverse up hill, it still occurs.

thks, scott

[John_AZ]

Originally Posted by x030399

There's zero oil leaks, as evidenced by my bone dry garage floor, so does that means the rear seal is ok?

If it's the torque tube bearings, would the problem be less when the car is warm? When it's stone cold, the earthquake is the worst. Even trying to back up on a level surface causes it. When the car is warm, I have no problem backing up on a level surface, but if I'm trying to reverse up hill, it still occurs. thks, scott

Before I continue. Did you have to top off the coolant reservoir before the big "blow"? Could it have been leaking for a while down the bell housing on to the clutch disc?

Rear seal.
It should be fine. Even if you were to go under your car and check if the seal weeps down the rear of the oil pan, it would not harm the disc.

2nd part.
Again if I have 3 chances to win like at a carnival...

Now it sounds like your transaxle. It is less of a RPM or Speed issue.

Have you checked your transmission fluid? How old is it?

If you want to check your transmission to rule out Rack and Pinion wear,
You can spend a couple of hours and remove the passenger side inspection plate.
I just learned of this recently and have not done it myself.

Remove 9 or so bolts after you remove the CV joint
There is another bolt inside of the transaxle hub to remove.
Once removed, grab the R&P for sloppyness and missing teeth.
Check the back of the inspection plate for metal particles.

Put back together and reseal with Permatex 574-no "O" ring required.

If you find damage, look for a good used. The new R&P alone is +-$1000
http://www.944online.com/cgi-bin/ASI_Store.cgi?Product+skukey_1000550+9441+transmis sion-9441

My chances are over and GL
John_AZ

[John_AZ]

Another idea.
Put the rear of the car up on jackstands.
Block the 4 wheels
Start the car
Gently shift the car in forward and reverse while having your hand on the torque tube-requires long arms or a friend.

Any vibration?
If you feel vibration it could be the TT bearings or the TT shaft "very minutely" bent during the transaxle replacement or clutch job.

Next check the CV joints for loose bolts. This will also cause a lot of vibration.

Next check the transaxle mounts.

Here is another web site on the R&P:
http://www.tech-session.com/kb/index.php?article=1

GL
John_AZ

[x030399]

Well, thanks for the ideas, but as I mentioned, the problem was there with the previous transaxel, and I just put in a completely rebuilt tranny (for a different reason), and same problem. Tranny fluid is brand new, along with the new tranny.

That makes me think it's not the tranny. It scared the heck out of my mechanic after he had the new tranny in and thought he did something wrong. I told him no, that's the way it always was. Tranny's fine.

I'm being more and more convinced that my parent's mechanic had greasy hands and accidentally got some oil on the friction material when he was handling the new clutch.

[x030399]

Oh, sorry, also missed the question about topping off coolant. No, I hadn't had to put any coolant in the car the previous 9 months before the heater hose blew.

I was under there Thu putting in new radiator fans, and it's bone dry everywher, exept for some slight weeping of flourscent dye around the a/c compressor (had it topped off last summer.)

[John_AZ]

I found a site from Centerforce clutchs that has a diagnostic PDF.
http://media.centerforce.com/DiagGuide/DiagnosticGuide04DL.pdf

GL
John_AZ

[x030399]

1984 944

Wow, thanks John!

Based on that OUTSTANDING clutch diagnostic site, looks like I have either burnt spots or oil on the friction material.

Seems either way, I'm going to have to replace the clutch to fix it.

Like I said earlier, I've learned to live with it, and around it. But I did get in a situation where I needed to reverse up a 5% grade, and barely made it out.

Anyone know what is a reasonable cost for an indy to replace a clutch?

[John_AZ]

Originally Posted by x030399

1984 944
Anyone know what is a reasonable cost for an indy to replace a clutch?

Please explain what an "indy" is?
Maybe:
1. I live in Indianapolis
2. I used to live in India
3. This is my nickname
4. "indy" is slang for mechanically challenged and the shop usually gouges me.
5. An independent shop-A shade tree mechanic-My cousin-A friend of a friend who can change his oil?

Anyway, Shops charge 12 to 14 hours labor. A Member, mikeran, just has his "87 changed for $1600, parts and labor. This is CHEAP. If the shop runs into any extra problems, price goes up. I have seen prices as high as $3200 P & L and lots of WYAIT stuff. Make sure they resurface the flywheel and do a balance on the FW & PP or you may spill your coffee and vibrate more than before.

Many shops do not want to work on 944s and many have no experience with our car quirks.

GL
John_AZ

[x030399]

Ummmmmm......my meaning of "indy" is "independent mechanic / shop" i.e., non-dealer, non chain (e.g. Aamco, Midas, Lee Myles, etc.)

Sorry, thougt that was a well known acronym among car enthusiasts.

Well, anyway, thanks for the advice, your $1,600-$3,200 range was what I wanted to know.

thks, scott

[x030399]

p.s., that cost is what I was afraid of. Seem's crazy that I had a completely re-built tranny put in for $2,000 parts and labor, and the clutch is more.

Ah well, that's why my octogenarian parents decided to go with a brand new Porsche.....couldn't stomach putting more money into the car than it was worth!