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About a year ago I had a complete rs 4.0 clutch and everything associated with the clutch replaced and installed. Since I've done about 24 track days and 4k total miles, maybe 2k of those track.
About 4 events ago I noticed my clutch action getting sticky and was making some noise when cold. 2 events ago it became hard to remove from gear when hot and I would get a grind a couple times a day on random shifts. (Synchros??)
Being overly **** rentantive with maintenance I have the shop pull the tranny. They (and based on research here) suspected an issue with the fork, throw out bearing, pressure plate, or guide tube.
First, they drained the tranny and inspected the fluid and magnet. Fluid was very normal in color (I replace every 6-8 days). Very low amount of material on magnet. Nothing abnormal.
Next they removed the clutch assembly. They found the pressure plate, flywheel, and clutch disk to be perfect. Very little wear and no issues. I also inspected myself and found no abnormal issues at all.
However, the throw out bearing is shot, it's wobbly like the bearing races are shot, and there is abnormal wear on the ears, the guide tube has a groove on it, and the fork has odd wear from the shot tob. The groove on the guide tube was causing the sticky feeling and the issues with the clutch disengaging at times.
Theory is something caused the tob to get wobbly (bad part or something), that caused an incorrect angle of engagement which eventually caused the wear on the guide tube and the clutch fork.
So question for the experts... Any other theories what happened here? Is this just a bad tob, or was there some other issue??
Upside is outside the labor to pull the tranny the parts are not expensive (by Porsche standards). Much cheaper than a tranny rebuild which was my worst fear. Oh, and the seal on the diff side of the tranny housing is seeping a bit so that will get replaced.
Sorry to hear about your problem. Unfortunately I don't have any information on the matter, but will subscribe to see what the problem was. Education is necessary!
Looks quite normal for an ex E60 M5 guy. Do a search on SMG clutch issues.
Guide tube has galling present so will make the action sticky or sometimes lock up. Normally due to lack of proper lubricant on install. Poor choice of materials rubbing together is the bottom line.
p.s trouble with lubrication is that it attracts clutch friction material dust and that makes a grinding paste hence why I said material choice is poor. A phosphor bronze bush or Teflon sleave would work much better as they are 'self' lubricating.
You could try a Teflon coating, same as they use on piston skirts?
About 4 events ago I noticed my clutch action getting sticky and was making some noise when cold. 2 events ago it became hard to remove from gear when hot and I would get a grind a couple times a day on random shifts. (Synchros??)
I have same symptoms as you and a new clutch is going in today, I will report back on the condition of the old clutch components (BTW thanks to Sharky for his valued advice)
Exact same issue here with 4.0 Clutch on '10. TOB was toast, fork worn, guide tube has a ridge preventing full displacement of the pressure plate. Friction surfaces look new, but metal fingers on clutch are cracking at base. Symptoms were sticky shifts at low RPM, grinding while shifting in anger. Overall annoying because we rebuilt the transmission thinking this was all synchro issues....which while worn, were not that bad - not worth a rebuild. Lucky next owner will be getting a nice fresh drivetrain. FML.
Seems like the to bearing is the fulcrum under loading. What's a more robust way to cure it. Looks like guide tube is made of plastic and held by skimpy screws. Is that correct from pics? Mike
Seems like the to bearing is the fulcrum under loading. What's a more robust way to cure it. Looks like guide tube is made of plastic and held by skimpy screws. Is that correct from pics? Mike
It's steel. The clutch assembly slides on it.
Theory is either bad TOB or bad grease or poor grease application or grease just dissolved under high stress and temps....
no rotation, that's taken care of by the release bearing which slides on this guide tube.
It does see a side load in aligning the bearing as the fork moves through a slight arch. Main load is the compression of the pressure plate diaphragm springs.
We need some one with a machine shop to produce another steel guide tube then sleave it in phosphor bronze or plastic sleave.
Its a common problem on stick shift or SMG (automated manual) cars (Fezzers nd BMW etc) due to the trend to high power/torque cars needing heavy duty clutches with high clamping forces and exasperated by quick gear changes (automated or track use) causing the galling.
Is it likely that this issue is specifically caused by the 4.0 parts?
I have all stock components, including the dual mass flywheel, and I beat the snot out of my car on the track regularly. I have the reverse shudder, which is most likely the TOB, but don't have any issues with a sticky clutch or getting the car into gear. Perhaps this was exacerbated by an ill-timed rev matching technique?
05-07-2015, 02:44 AM
Clutch Issue - Any thoughts to cause
