AndreSantos

Hey guys and gals,

I've wrote here before and got amazing feedback, so I'll try my luck again that someone knows more about this than I do (a lot more).

So, in the list of stuff my 987.2 Boxster S needs done is a new clutch, because every now and there there is clutch slippage.
Quick conclusion: Clutch is worn out, time for a new clutch.

However... I've driven cars with worn out clutches before, and the clutch slippage was predictable and repeatable.
Here it seems to slip sometimes, other times not.
It slips in situations where I wouldn't expect it to slip, but then doesn't slip on a good session with a lot of pushing.
It left me wondering if there might be some other component that is screwed up and the clutch doesn't get enough pressure. (pressure plate?)

Out of the 111-point check Porsche did on my car, the report noticed that the clutch pedal was quite heavy. Wish they gave me more info, but that's what it says.

So... is there any chance a bad master/slave cylinder (I still need to read-up what do each of them do/what's the difference between them) could cause a lower pressure on the clutch? From the little I know about clutches, I would say no. But I don't know that much about clutches, so here I am asking.

If it is the pressure plate, would it make sense to replace only the pressure plate? How to check the wear on a clutch disk? are there spec numbers on how thick the disk is when new?

These are probably some silly questions, but I just came from an hard session of driving and the clutch didn't slip a single time.
I've done zero launches (the car is really not about that anyway) as the state of the clutch is not the best and I don't want to finish it off for the sake of a launch.
However, it slips on weird situations.
Example: Autobahn, 4th gear at around 3k rpm, step on it.... and it starts slipping around 4k (when the camshaft profile changes I'm guessing)
Quickly upshift from first to second and floor it: slippage, but not always.

However, get it rolling in 1st gear and then floor it. No slippage, even if I floor it at 4k rpm or higher. Same for 2nd gear.

Today it snowed a lot, I went to a local park to have some fun and to get used to the car's behavior in a low grip scenario. Ended up staying there for a while and was pretty merciless on the clutch, zero slip. And yeah, I realize, snow = low grip so less force that the clutch has to overcome. But my butt sensor tells me that the forces involved in some situations were much more brutal than a regular autobahn acceleration... and yet, no slip.

So here I am wondering if it can be something else other than the disk, and if it even makes sense even if it is something else, to get the transmission out to fix the clutch and not replace the clutch?

Thank you in advance.
Please no judgement on the driving, I've been driving for a very long time, I'm no hooligan. The area was completely isolated, no danger or disturbance to anyone. Also, I baby my car mechanically and I'm working on bringing it to its best shape again but that's so I drive it like these cars were meant to be driven whenever I can
In short, I have due respect for others and for the machine itself

MrMoose

Hydraulic clutch mechanism can cause a clutch not to release, but I can't see how it could cause one to slip.

If yours is slipping at all, the two most likely issues are either a worn clutch or contamination on the clutch disk from something like a rear main seal leak. Either way it sounds like you need to open it up and replace the clutch.

AndreSantos

I wasn’t aware that could happen, thank you, I’ve already learned something new!

And yeah, I think no matter what’s wrong it’s gonna be figured out and fixed by dropping the transmission anyway

thank you for your help!

I have a follow up question about the hydraulics on the clutch.

it only happened once, but it has happened with the clutch pedal fully depressed (fully pushed down. Sorry if depressed isn’t the correct expression - English is not my native language) that I tried going into reverse and I got grinding like people often get when trying to slot a gear with the pedal not fully down.
it was only that one time.
could this be a sign of failing master or slave cylinders ? (I’ve now read up on their respective functions)

MrMoose

Possibly? Usually hydraulic issues aren't intermittent, but I guess it could happen? I'm no expert, though.

One other possibility I can think of is you just shifted too fast. Reverse isn't synchronized, so theoretically you should sort of wait a bit after pushing down the clutch for the input shaft to spin down before shifting. If the transmission is hot and the oil is thin this takes longer. Some cars are more picky about this than others: I've never had a grind into reverse on the Cayman that I can recall, but older Alfas will regularly do it if you don't wait a second or two to shift after pushing the clutch down.

That or you shifted into reverse while the car was rolling, that would probably do it too.

hueyhoolihan

if you've got the time, just keep driving it. time will tell.

AndreSantos

I wasn’t aware reverse wasn’t synced. Again learn something new
I wouldn’t pop reverse with the car rolling, god knows from when, but from experience I know that’s a bad idea.

The thing is the car was parked. I had just driven 40minutes on the autobahn, parked the car 2 minutes to pickup someone from the airport. When reversing out, I could feel a lot of resistance on the gear going in. I forced it a bit and got the grinding noise :/

It didn’t happen any other time, so for now I’m gonna assume it was my mistake and I didn’t fully depress the clutch.


Whats the worse that can happen ? I remember reading somewhere the clutch disk can eventually break and wreck havoc.

I won’t do many Kms from now till end of Jan, then I’ll replace the clutch.

hueyhoolihan

long before any real damage occurs, i would think that there would be little doubt as to whether or not it's a slipping clutch. the problem at the moment is that the number of slippages is too small to be conclusive is all. IOW, more mileage will intensify the symptoms.

harveyf

I don't know for the Boxster but on most cars, the labor hours to replace the master and slave cylinder are a small fraction of those to replace the clutch, which requires dropping the engine. So it might be valid to change them out first and see if it fixes the problem.
Also, do a Google search with something like "What are common problems with a Porsche 987.2 boxster clutch". I find that when I use Google, it will identify good historical discussions, across multiple platforms, of the issue that may not come to light just by pinging a forum in real time.
BTW I do not condemn snow based car control learning sessions. There is a reason why some of the best rally car drivers are Scandanavian

Racer Boy

A heavy clutch pedal is an indication that the pressure plate is going bad. My 2002 Boxster had a heavy pedal and eventually started to have a slipping clutch. After the clutch was replaced (BTW, the transaxle is dropped, not the engine), the clutch was much lighter. My guess is that you need to replace your clutch.

MrMoose

That's probably unlikely. What usually can happen is if it slips too much for too long, your flywheel gets overheated and starts discoloring or getting micro cracks. Usually you can just get it resurfaced but in bad cases you'd replace it.

Probably a good idea. I'm sure they'll do this, but make sure they check the rear main seal for leaks as well and fix that: oil contamination will quickly cause a clutch to have issues.

AndreSantos

Which seal exactly is the rear main seal?

Racer Boy

The flywheels in our cars are dual mass, and they can't be re-surfaced. They have to be replaced.

The rear main seal is the seal that goes around the rear of the crankshaft and keep oil from leaking from the crank onto the clutch. Most clutch jobs include replacing the rear seal.

XuTVJet

How many miles are on the car?

My recently acquired CPO'd 69K mile 987.2 Cayman had a very heavy clutch pedal. I had never driven a Cayman (or Porsche for that matter) and my salesmen, who has a 997 911 6MT, said the heavy pedal was likely because the clutch was replaced with a heavier duty one. About 100 miles after owning the car, I got a vibration through the clutch pedal. Both my local Porsche dealer and an independent Porsche shop said it was a bad pressure plate finger and the heavy pedal was caused by a heavily worn clutch. The dual mass flywheel was also likely going bad as there were varying vibrations felt at varying rpms while in neutral and under load. I managed to get the CPO certifying dealer to give me $2800 for missing the fact that the clutch, pressure plate, and flywheel were done. When all these parts were replaced, their analysis was correct. The clutch disc, while it never slipped, was on the rivets and was a few thousand miles from no longer working.

Long story short, it is quite likely that the clutch disc is done and the pressure plate may be done as well. I paid $2,800 for a SACHs clutch kit (disc, pressure plate, throw bearing) and an OEM Porsche dual mass flywheel and flywheel bolts installed at my independent Porsche shop. My Porsche dealer wanted $5K and would use the same parts. LOL. The rear main seal was fine and my mechanic recommended not touching it as new ones rarely seal as well as when they're set at the factory.

The clutch/pressure plate system is self-adjusting and as the disc wears, the pedal gets heavier and heavier. The clutch pedal now is way lighter and the vibrations gone. It's a different driving car now.

AndreSantos

Lots of good info there. Thanks for sharing!