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Clutch Rattle

 
Old 01-14-2009, 07:08 PM
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Tampa 928s
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Default Clutch Rattle

I have a clutch rattle unless I lightly press my pedal down and it goes away. I dropped the lower bell housing and found the release arm is loose on the throw out bearing. Since this is my first time with a clutch how should I proceed or is this normal with no pressure on it.
Also on a past thread I mentioned if would grind in reverse and first but not all the time. It was brought up that the center plate need to be adjusted. Should I drop the assembly and check everything out or would a pedal spring adjustment solve the rattle.
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Old 01-14-2009, 07:25 PM
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dprantl
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Have you checked the plastic bushing on top of the clutch arm? That can cause the arm to rattle around.

Dan
'91 928GT S/C 475hp/460lb.ft
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Old 01-14-2009, 07:30 PM
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It's on my 82 are you talking about the bushing on top of the torque tube housing for the shifter, it's almost new. The picture where my screw driver is is loose.
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Old 01-14-2009, 07:32 PM
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Originally Posted by Tampa 928s View Post
It's on my 82 are you talking about the bushing on top of the torque tube housing for the shifter, it's almost new. The picture where my screw driver is is loose.
No, not the shifter ball cup. I meant on top of the clutch arm. The bottom of the clutch arm is pushed by the clutch slave cylinder. The top of the arm goes over a ball on the bellhousing. There should be a plastic bushing that fits into the arm which goes around the ball.

Dan
'91 928GT S/C 475hp/460lb.ft
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Old 01-14-2009, 08:40 PM
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there are 3 flat headed pins that stick out the back of the pressure plate make sure to use a piece of wire under these about 2mm thick B4 you release the pressure plate bolts this will help you remove the top of the release arm from its pivot. The arm slides off the plastic bushing, then the new bushing is pressed on the arm slides back on.
Also remember that the throw out bearing is spinning at engine speed the whole time, so if water gets into the clutch it will quickly damage the TOB and or the pilot bearing. Water can come in from the top where the release arm pivot is attached. From your pictures it does look rather rusty
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Old 01-14-2009, 08:43 PM
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Tampa your pointing to the release bearing. Yes it would be loose in relation to the clutch fork. But with the slave cylinder push rod installed the fork would not have any play. Clutch looks well "used". Could be the center plate going out of adjustment because of the worn pressure plate.

Looks pretty corroded. Maybe the disc's are frozen to the input shaft?
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Old 01-14-2009, 08:48 PM
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Yep the clutch release arm ball cup at the top. That fixed the rattle of the same description on my GTS.
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Old 01-14-2009, 08:53 PM
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Where do I look for thr ball cup can't see much in there. Would you drop it, after reading a few threads it seems like this can be a real pain on some cars.
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Old 01-14-2009, 09:17 PM
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The adventure begins the arm is completely off of the ball. I used a bore scope and the arm is not attached to the ball you talked about. Damm I guess I need to do some research on how to do this do they have a book for clutch dummies?
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Old 01-14-2009, 11:54 PM
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If your arm is off the ball, chances are that the plastic bushing is gone. Just get a new bushing (cheap) and put it into the arm, then use a crowbar to push the arm back onto the ball. Using vaseline on the inside of the bushing will help installation. You should be able to do this from the top. I was able to just get in there by leaning over the driver's fender. Some are able to lie down on top of the engine and replace it that way.

Dan
'91 928GT S/C 475hp/460lb.ft
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Old 01-15-2009, 12:49 AM
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Yes you can access the ball from the top. Remove the air cleaner housing at the back of the motor and you will easily see the top of the bellhousing. can be done in about an hours time and makes a difference in clutch action.
JIM
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Old 01-15-2009, 12:50 AM
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Yes you can access the ball from the top. Remove the air cleaner housing at the back of the motor and you will easily see the top of the bellhousing. can be done in about an hours time and makes a difference in clutch action.
JIM
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Old 01-15-2009, 01:18 AM
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Guide tube is dry, you need lube between the arm and the TO bearing both on the rubber pad and where the arm bears against the TO bearing. WSM recommends Moly, "White paste" and Moly, respectively. PP fingers and thrust bearing are probably dry as well, along with the stub shaft.

As for the rattle, it could be an issue with the ball, as has been said already. In my case an issue with the ball resulted in buying a new upper BH, so definitely check it out. I am nearly done with a massive site update that I hope to post in the next week or so, if in the meantime you want pics beyond the ones below let me know what you want to see and I'll see what I can dig up.

1. View of old release arm ball from above, air filter housing off
2. Updated release arm, ball, bushing
3. Ruined bellhousing
4. Wider shot of belhousing

Another possiblity, I think your clutch may be in the early stages of the same failure that I experienced. I had the same thing for quite some time, a thin scrape/rattle that would go away if I touched the clutch pedal. The noise didn't change over months of driving and I figured it was probably just a dry thrust washer brushing on the PP fingers. Well, my TO bearing finally seized up. My running theory is that as the TO grease drys up, it tends to make the thrust washer slip more and more until that dries out. That's when you begin to hear the noise. Touching the clutch pedal creates just enough extra resistance to get the past the resistance of the TO bearing, it begins spinning and all is quiet. It gets harder and harder to turn the TO until it seizes. In my case that last step, going from a small slightly annoying noise that I could only hear leaning out the open door to a SCRREEEE of a seized TO in a few hundred miles. Fortunately that was on the tail end of my return from Sharktoberfest and the subsequent week of short commute driving.
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Old 01-15-2009, 03:20 AM
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nice set of pictures Dave !
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Old 01-15-2009, 08:17 AM
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Thanks for the pictures, looking at the rust is there a way to lube the aforementioned areas with out dropping the clutch. Or should I just go ahead and pull it. Remember I have headers and had to loosen one side to drop bell housing. I'm still a little hazy on adding the copper wire so the clutch will not release. On one picture it looked like a copper fuel pump washer.
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