[SILVY968]

A few days ago I noticed that when I press in or release the clutch the pedal has a vibration that transfers into my foot.

I thought it was the linkage, so I lubed it up with white lith. grease, but no change. Then I noticed that when I am in neutral, and press in the clutch, the vibration goes away.

When I am in any gear and rolling and press in the clutch I feel the vibration.

Any ideas what this could be?

I hope that it is not the release bearing, but I think that if it was related to the clutch pieces that it would not go away with the trans in neutral.

Does this point to the transaxle?

Any info would help.

Thanks

Brian

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[flash]

likely it points to the torque tube bearings, most likely the front one - the shaft keeps spinning, even when not in gear, until you step on the clutch



you should be able to ascertain this by use of a stethoscope



repair can be done by shipping yoru torque tube to 928 international - about 500 bucks plus shipping and R&R - unfortunately this requires removal of the transaxle

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[SILVY968]

Flash,

Please clarify.

Isn't the torque tube spinning wether that trans is in neutral or a gear?

The vibration is not there when I clutch in and out of neutral; but is there when I clutch in and out of any gear.

Doesn't that eliminate the torque tube bearings because they spin in both cases?

Brian

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[SILVY968]

Flash,

Just found a reference to, what sounds like my problem on 968.net.

They found that the vibration was caused by a lack of grease on the clutch activation fork inside the clutch housing.

Exactly where is the clutch inspection cover, and what type a grease should I use?

Will the white lith. grease be OK?

Thanks,

Brian

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[sasilverbullet]

I'll be watching this closely, my car does exactly the same thing...

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[flash]

the drive shaft inside the torque tube spins until you step on the clutch, regardless of gear position



i think i did not fully understand what you were first saying



ok - when in nuetral and you step on the clutch, it goes away

when in gear and you step on the clutch it's still there



a couple of things could easily be doing this - first, check if it does it in all gears

second, see if it is at any particular rpm point - third, see if it does it sitting still AND rolling - before i go pointing you in a very expensive direction, let's check those things and see what's happening



the clutch activvation fork thing is generally a "notchy" feeling as you engage it, and not so much a vibration

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[sasilverbullet]

That's what i have, a 'notchy' feeling...

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[Greimann]

[quote name='sasilverbullet' date='Aug 28 2005, 08:58 AM']That's what i have, a 'notchy' feeling...

[right][post="9281"]<{POST_SNAPBACK}>[/post][/right][/quote]

Most likey you have a release fork shaft that has been brinelled by the needle bearings. You'll need to replace the shaft and bearings for a fix.

   

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[BruceWard]

Lets try to make sense of the symptoms

when I press in or release the clutch the pedal has a vibration that transfers into my foot.

There is a vibration, the question is whether or not it is anything to worry about or a normal vibration. Personally I find that I can become worried about vibrations or sounds that others would not notice and are not a problem. Do you feel the vibration if you place your foot on the clutch without pressing in?

I thought it was the linkage, so I lubed it up with white lith. grease, but no change.

I assume you lubed up the shift linkage?

Then I noticed that when I am in neutral, and press in the clutch, the vibration goes away.

Pressing in the clutch breaks the link from the back (transaxle and torque tube) to the front.

When I am in any gear and rolling and press in the clutch I feel the vibration.

So you feel the vibration while rolling but not while sitting still with the clutch in.



Do you also feel the vibration while sitting still in neutral?

Any ideas what this could be?

It could be many things, perhaps not even related to the clutch or transaxle. Our 968s are rough compared to a luxury sedan. The clutch pedal is connected to the clutch via hydraulics which should not carry a vibration so I suspect you must be feeling this other than through your foot. Or if you are feeling it through your foot it could be coming from anywhere.



If you only feel it while rolling then tires, balance or alignment could be the culprit.



The mounts for the transaxle and torque tube are designed to reduce vibrations. They are getting old now and may allow more of the vibration to transfer through. The flywheel is an early dual mass flywheel designed to remove vibrations from the drive train, the rubber in it also ages and could be transferring additional vibration.

I hope that it is not the release bearing, but I think that if it was related to the clutch pieces that it would not go away with the trans in neutral.

Since the vibration changes based on gear I would think it is not caused by the clutch since it functions the same regardless of gear.



How is the vibration effected if you put the 968 in neutral then rev up to 4K and depress the clutch?

Does this point to the transaxle?

I hope not and do not see any reason to focus on it.

Just found a reference to, what sounds like my problem on 968.net.

They found that the vibration was caused by a lack of grease on the clutch activation fork inside the clutch housing.

Exactly where is the clutch inspection cover, and what type a grease should I use?

Will the white lith. grease be OK?

This picture is taken through the clutch inspection port which is on the bottom of the bellhousing and shows the clutch fork inside







There are a few rubber covers on the bell housing that allow you to look in. But if you want to lubricate the fork I suggest removing half of the bell housing which requires removal of 12 or 14 bolts and will look like this after removed







The fork has two bearings connecting it to the needle which is the axis it turns on. When I replaced my clutch those bearings were badly damaged. If the bearings are what you plan to lubricate I would replace them as well as lubricating. I needed to replace the needle as well.



Dave G is an lubrication expert. I would direct all lubrication questions to him.



While replacing my clutch I learned that Zims http://www.allzim.com offers a service of rebuilding clutch forks for about half the price of a new one. They weld on new material and reform it to the original shape. I sent my fork to them for inspection but they sent it back saying it did not need to be rebuilt this time.



This is what the fork looks like







The left end releases the clutch, the middle turns on the needle and the right side is pushed by the slave cylinder.

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[flash]

ok, so i should have said the shaft keeps spinning, even when not in gear, until you step on the clutch, this is while when sitting still - i misread that the first time, and then followed by not being clear in to whom i directed my response



hence the specific questions



the notchy feeling of the pedal would happen regardless of movement of the car, it would really be limited to the pedal, and would not be a vibration



vibrations are tricky things - a lot of things can cause them - first we have to know if it is a vibrations or not but:



alignments will not cause vibrations - shocks and struts can



tire balance can, but it will be speed related and not differing with gear change



tire wear pattern can, and may not be speed related



it could easily be the transaxle - an input bearing could very easily cause a vibration



a pilot bearing can too



the driveshaft bearings could still be the problem and even be somewheat gear specific, because of load - a vibration could show up in a lower gear and not in a higher one becaue the side load on the bearing goes down in a higher gear



if it is rpm specific, it could be a number of things - clutch, flywheel, balance belts, bad cylinder, fouled plug, bad ignition wire, the list is endless



again though, before jumping to any conclusions we need to know the answers to the questions



so, in addition to the above questions, only one of which appears to have been answered so far, where exactly do you feel the sensation? hand, foot, butt, back?

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[SILVY968]

ok, here goes:

To clarify I'll restate with answers to the questions from BRUCEWARD and FLASH.

I do not feel the vibration when I place my foot on the clutch pedal when I do NOT press it in.

I lubed the linkage from the pedal to the input to the hydraulic cylinder at the pivot points and where the return spring slides along its pin, not the shift linkage.

I feel the vibration rolling or sitting still as long as I am shifting in our out of a gear.

I checked out the car rolling and stopped with the engine at 4000 rpm.

When I press in the clutch in and out of neutral I DO get the vibration. It seems to follow engine RPM and not gear selection or speed of vehicle.

I do not feel any vibration when sitting or running in neutral or any gear, only when I am pressing the clutch in or out. It is not felt until it get about 24% in or out of the clutch. I do NOT feel any vibration if I gently touch the pedal.

I only feel the vibration through my foot, and it feels like it is more notchy that vibration.

It almost feels like trying to slip a pipe through an ungreased rubber boot., but it does have a component the you could say vibrates if you stop at a point in the clutch travel, where you are neither fully in or fully out of the clutch.

I get no slip and the car performs normally.

This feeling in the clutch is only felt in the pedal and happens when I press in the clutch to shift and let it out. It is NOT gear or car speed related. It IS related to RPM, as it does NOT seem to happen at low speeds, hence my statement that it does not happen in neutral, at neutral the rpm's are low enough that I did not feel it.

The only thing consistent is that it happens at about 3K RPM and higher and I only feel it in my foot when I press the clutch pedal in and out.

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[flash]

you have a PM

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[Dave]

Y'all are fortunate. That vibration through my clutch pedal was the 135k mile original clutch completely letting go. Amazing how you can just jam it into 2nd with the engine off and use the starter to get moving and running enough to limp into the shop <img src="/forum/images/smilies/968/smile.gif" class="smilie" alt="" />

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[flash]

actually, after talking with brian, i think that's where he is too, only this is already the second clutch (changed at 63k)

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[SILVY968]

Flash, et al



As mentioned, Flash was cool enough to get me on the phone and diagnose a bad clutch. I'm going to contact REDMOND EUROPEAN up here is Seattle and schedule the work. Flash also pointed me to the correct OEM parts at a great price.

I appreciate the help from all of those who responded. Thank You.

I'll keep the forum posted after the repairs.

Hey Flash...the first round in on me at NAMM.

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[BruceWard]

Brian,



I hope that you have the right diagnosis. Personally I would not change the clutch until I felt it slip.



What specifically determined the clutch to be at fault?

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[rustech]

The vibration seems to definitely be something out of balance under the bellhousing (and without symmetrical pressure) pushing back erratically against the fork which modulates the slave cylinder (back pressure) and so is felt in the pedal.

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[SILVY968]

BruceWard,



The clutch was a prime suspect because the vibration was happening under all conditions as long as the revs were above 2-3K. This pointed to a chunk of clutch breaking off and putting the assembly out of balance. Flash and I looked thru my service records and found that the first clutch lasted 63K and now I am at 130K, so it was time. Flash felt that a chunk of the clutch had broken off, which was causing the vibration.

What questions can I answer to erase any doubt; As this is my daily driver? If I take it in once to check and then a second time to repair it it will cost double for a car rental, plus the shop schedule may be full and Flash was worried that if the clutch ran too long in this condition it could damage the flywheel; another large expense I would like to avoid.

Any extra diagnostics that you can think of would be appreciated.

Brian

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[BruceWard]

The chunk shown below fell of my clutch. I felt the clutch slip about a mile before this happened.







I experienced strong vibration at low rpms until I let the car cool down. Then I felt mild vibration when starting and no vibration after the clutch was released. The piece jammed between the clutch and pressure plate within 10 miles of the initial failure making it impossible to press the clutch pedal.



In my case the pressure plate side of the clutch failed before the flywheel side. The pressure plate was damaged but the flywheel side was fine. If the flywheel was to be destroyed a new DMF would add at least $800 to the cost of replacement.



I have not read anything you have posted that makes me think you are in imminent danger of a clutch failure.



I do suspect that opening up the bellhousing and changing something would fix the vibration. Although it might do nothing more than shrink your wallet.



If you were closer I would suggest you come over and we take out those 12 bolts to have a look. All that is needed is a jack, two jack stands, and a wrench. Although a socket set with extensions and a universal joint makes removing the bolts easier.

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[flash]

here's something to think about though: if you would change the friction disk more often, you could avoid changing the pressure plate for a very long time - there is no need to change it if the surface is smooth and the spring rate is still good - if you wait until it slips, it's too late



i suspect he has a similar condition to the one pictured above, though likely not as big a chunk missing



the pedal is dead smooth when not running and at lower rpm - it's an un-evenness in engagement while running that led me there - in any case, it certainly seemed the problem is there in that assembly, and not elsewhere



certainly yanking the pressure plate and looking is a quick way to see, but then if you have it apart, you may as well do the clutch anyway at that mileage, so it's really a moot point - besides, he'd still need the flywheel lock tool and the new pressure plate bolts (since you can't safely reuse the old ones)

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