Unusual Clutch Behaviour

[mattatk]

OK, I've had my '01 Boxster S (986) for almost a year now. As my first Porsche I wasn't too sure how firm the clutch should feel. My clutch wad quite firm but manageable. Driving yesterday, I shifted down to second & felt something give in the clutch pedal. Now the clutch is much lighter but still operating. I can't feel any slippage & I performed the funtional check on the clutch pedal (pulling up on it to feel for play) & it's all good.

Should I be concerned? Should I investigate further?

Cheers,

Matt

[RFM]

A cracked diaphragm spring belongs to the possibilities, unfortunately the gearbox must be build out to verify this.

[mattatk]

Ouch!! At work now, I'll look into it further later in the week. I guess you can get a replacement diaphragm separate to the whole clutch unit. I really don't want to pull it apart if the car works ok now. When I drove to work this morning I noticed a slight vibe in the clutch pedal when fully depressed. Otherwise the clutch behaved well. Does anyone have any tips for further diagnosis?

Cheers,

Matt

[dh986320S]

I had the same problem last summer on my '03 S. Clutch pedal had progressively grown stiffer, then driving to work felt the pedal give. Clutch still engaged with no slippage, albeit much further in the pedal travel. Ended up being a cracked pressure plate.

[SA321]

I had the same problem last summer on my '03 S. Clutch pedal had progressively grown stiffer, then driving to work felt the pedal give. Clutch still engaged with no slippage, albeit much further in the pedal travel. Ended up being a cracked pressure plate.

i had cracked plate at about 20k mi. the change in pressure of peddal was sudden but there was a lot of slipage though and pedal would not come back but that was due to a lot of dust which got on axel and would lock clutch release bearing

[mattatk]

dh986320S,

Interesting that you say that, the engagement point of the clutch did feel higher up. I don't think there's any slippage, the clutch just seemed to be much easier to use! Having said that I felt like it had lost a bit of power, which could be attributed to minor slippage.

More to follow...

[mattatk]

Further...

I did a bleed on the clutch hydraulics whilst waiting for clutch parts to ship to me (in Australia). As per the manual, I had the clutch pedal fully depressed for the bleed. I am curious though, it doesn't tell you when to release the clutch pedal in the process. Do you seal everything up & then pull the pedal forward (as I did) or when the pressure from the bleeder is still on the reservoir? Also, is it OK to apply the pressure on the reservoir with air only, or should the bleeder have fluid in it?

I did remove quite a few bubbles from the line athough there were no previous signs of leaks in the system. The clutch feels good when driving, the pedal is lighter. Initially I had to help pull the pedal back up each operation, but it is slowly getting firmer & springing back to upright position now (is that because I didn't bring the pedal back whilst there was pressure in the system from the bleeder?).

Unfortunately the clutch does slip in high gear uphill with plenty of throttle applied, so I am going to proceed with a full clutch replacement when the parts turn up.

[Wayne R. Dempsey]

Unfortunately the clutch does slip in high gear uphill with plenty of throttle applied, so I am going to proceed with a full clutch replacement when the parts turn up.

BINGO. There's your culprit for sure - the pressure plate. If you haven't replaced the clutch before, I have a lengthy article available on it here: http://www.pelicanparts.com/techarticles/Boxster_Tech/77-BODY-Window_Regulator/77-BODY-Window_Regulator.htm

Things like this are why I recommend replacing the pressure plate along with the disc and throw out bearing all at once. Some people cheap out and replace just a worn disc.

-Wayne

[mattatk]

Thanks Wayne, I had noticed that it was best to replace all components & had ordered the Sachs three piece clutch kit & extras to change everything except the flywheel (gulp, I hope!!). The clutch really feels a lot better after the bleed but definitely slipping, hence my plan to change it out.

I appreciate your advice.

Cheers,

Matt

[Wayne R. Dempsey]

Let us know how it turns out!

-Wayne

[mattatk]

Off on leave for 2-4weeks so I won't tackle the job till late Jul-Aug.

I'll grab my wife's camera & grab some hi-res photos for anyone interested.

Thanks again!

[mattatk]

Gathering final intel on my first clutch job. Quick question for the experts:

Both the Bentley manual & workshop manual state that you need to remove the drive axles from the car for tranny removal, but I read an online article stating that you can simply disconnect the inner CV joints from tranny. Is this possible?

[Loren]

Gathering final intel on my first clutch job. Quick question for the experts:

Both the Bentley manual & workshop manual state that you need to remove the drive axles from the car for tranny removal, but I read an online article stating that you can simply disconnect the inner CV joints from tranny. Is this possible?

That is what the Bentley manual means - disconnect at the CV joints.

[mattatk]

Family duties kept interrupting!! Spent 1/2 day & got as far as removing transmission mount brackets, was going to work into evening but I broke my 1/2" adaptor socket for my wrench! Looking forward to getting into it tomorrow. Found that the muffler can be removed without pulling the rear bumper off but it is fairly difficult to access/find the top bolts holding the muffler to the bracket. Bentley manual didn't really show the location of the bolts.

Unfortunately I found one inner CV boot damaged. Looked inside the boot & looks pretty clean. Obviously I'll be hassling Pelican Parts for a new boot, but is there an easy way to tell if the bearing inside has copped any damage from dirt/debris ingestion?

[mattatk]

OK finally got time to get stuck into it. The clutch disc looked reasonable, the pressure plate looks OK, the flywheel is slightly discoloured (heat damage?). There appears to be quite a lot of black dust deposit on the release lever & throwout bearing in the transmission casing & at the base of the engine casing behind the flywheel (RMS leak maybe?). The IMS is caked in black deposit. Not sure if it's oil or clutch dust, anyway I'll pull the flywheel to check the RMS whilst it's convenient.

Edited July 27, 2010 by mattatk

[mattatk]

HELP?!

All done & back together!!

Did a bleed as per the Bentley manual (had the clutch pedal in for it). But now the clutch pedal doesn't come back to the release position, definitely no feel, stays stuck down or up if pulled on (maybe no system pressure?). With pedal in (engine running) I try to engage a gear & the gear lever resists (feels like the clutch isn't engaging?) No sign of leaks in the usual spots.

Can anyone shed any light please?

Edited July 29, 2010 by mattatk

[mattatk]

Bled the clutch again today, well tried & with 20psi pressure bleeder attached & clutch pedal depressed, no flow out the bleed nipple. Deduced that the master cylinder is not porting fluid down to the slave (bleed nipple), so it must be broken or blocked. No leaks in the area & will take a while to get my replacement from Pelican Parts, so I experimented by cycling the clutch pedal whilst bleed pressure was attached. Heard a gurgling noise in the footwell & clutch pedal began to get some feel. Disconnected the bleed & pumped the pedal some more. Much more feel although still sticking down a bit. Lowered the car & clutch worked normally albeit sticking slightly. Will try again tomorrow to bleed a bit more. I think I've either cleared a blockage or air lock (?) or the master cylinder is working intermittently. So I'll order one from Pelican anyway to be safe.

Thanks all for the input so far...