Hello all. So, as the title says, the last two cars I have owned, including my current 2007 Cayman S, have both had a similarly annoying issue that I can't seem to track down. My previous car was a 2012 BMW 135i, and I had it back to the dealership several times over this issue, always with a finding of "unable to recreate the problem".
It's not the easiest thing in the world to describe, so bear with me here. Basically the issue is a weird jolt felt through the drive train in certain situations. It usually happens following a gear change or deceleration event when you get back on the power. It feels like something slips and then suddenly grabs in the drive train, all as a part of one split second "event", after which things are normal until I change gears again. It does not do this all of the time, and the old car in particular seemed to do it mostly after being driven over 45 minutes or so which made troubleshooting a pain in the ***. I initially suspected engine mounts, but inspection revealed no problems on the 135i. I have not had a chance to really look at the Porsche, but it did pass a pre-purchase inspection. On the BMW I checked the whole drive-shaft, diff mounts, guibo, etc, and never found any issues. On the Porsche there obviously isn't as much going on in that respect, and I'm not yet fully familiarized with how everything works.
So, in the BMW I basically came to believe that the factory Dual Mass Flywheel was malfunctioning, but decided to sell it before I found out for sure. I'm starting to suspect a similar issue with the Porche, but don't yet know enough to come to that conclusion with any confidence. Does anyone have any insight to lend here?
Yes it does sound like clutch and/or flywheel. You can't really tell for sure without removing the tranny and doing a visual inspection. How many miles since the last clutch change? If you're on the original clutch, how many miles? It seems common that they last 50-60K. Might be time to do the job.
The car has 56K and I don't believe the clutch has ever been changed. It sounds like the more likely cause of the problem itself is the dual mass flywheel, but then you might as well change the clutch as well when you get that far in.
50-60K is an extremely short lifespan for a clutch. My old 540i had 178,000 miles on the original clutch and flywheel when I sold it, and had only started to have minor issues in the last 5K miles. Makes me wonder if there is some sort of design flaw, particularly with the dual mass flywheels they are producing recently, as I never had a similar problem before recent times, but have now seen two in rapid succession. My 135i had problems from the day I bought it, with just over 40K on the clock. That's frankly completely unacceptable in my opinion.
The clutch in this car is also by far the heaviest I have driven on any car in the last 15 plus years. I wonder if there might be an upgrade available that would both last a bit longer, and possibly reduce clutch effort slightly. That would be an ideal end result in my book.
Even before finishing reading your initial post, i was thinking dual mass flywheel.
60k on a clutch is low, but that is a common mileage for folks on here w 987s.
Porsches always seem to have heavy clutches. I've had many both old and new and it is a constant. I've never heard of any kind of upgrade, you'd have to change hydraulics and/or geometry to make the effort lighter.
I have had this happen x2, strange on the same road. In heavy, but speedy (65mph) traffic where you have slow down due to a lane changer, down shift, then accelerate and then you feel like the clutch is slipping then a surge takes over. It is enough for even the wife to notice the surge when the slip stops. I took the car to the dealer finally, but they couldn't produce the problem. The funny thing to me it only happens on the same road and more or less the same area with the same traffic levels. I thought about it for a while and I suspect it is just the stability control system kicking in.
Before you throw a lightweight flywheel on there, you might want to Google "amazing two piece crankshaft" and learn what might befall you if you go that route. For certain a 2.7
Boxster
5 speed has a lighter clutch pedal than a 3.4 Cayman S. Both vehicles that I own. If you want to have 295 HP at your disposal, a 295 HP capable clutch is a requirement. It's really the torque you are controlling, not the HP, but you get my drift. Best of luck to ya.
It's possible the tires are breaking loose and the PSM is killing power to save some rubber. Again, the PSM can fool you into thinking you are not overpowering the tires. I know of a set that wore the rears out in 5,000 miles.
A couple problems here. My BMW 135i has significantly more torque than the Cayman S, especially at lower RPMs. It is on the order of 70 or 80 ft/lbs more in fact, as they routinely dyno at around 340 lb/ft in stock configuration(BMW apparently underrates them on the torque front) Despite all of that extra oomph, which would require an even stiffer clutch than the Cayman S by your logic, it's clutch requires roughly 1/4 the pedal pressure as the Cayman S. Obviously it is very possible to make a clutch that sustains higher torque without the high pedal weight. Whether it is possible on the Cayman without major changes, I am not yet sure. Have seen reports of reduced pedal weights with aftermarket clutch replacements, but they are isolated and it's the internet, so who knows. I do know that it is absolutely possible to have a light clutch pedal with our power levels though.
Second, there is absolutely zero chance the issue is caused by PSM intervention, at least in my case. It does this even on very small throttle applications. In fact, it is more noticeable when you try to drive smoothly and gently than it is when you get on it, as there is less background noise and motion to disguise it.
As for the flywheel, I would be perfectly happy with a deal mass flywheel if it were reasonably durable. But every 50K miles is frankly an unacceptably short service life for so simple a part. I'm hearing lots of conflicting information on single mass flywheels, but personally it seems likely that those who broke a crankshaft were using an unsprung clutch, and most likely driving their car extremely roughly or made a mistake at the track. My money would be on a missed shift or a foot slipping off a clutch pedal. I don't drive that way, and I would be using a sprung clutch if I go that direction, so my fear of a broken crank is quite small. Besides, the engine is going to die from bore scoring and/or the IMS long before that anyway. LOL!
Edit: Just googled the "amazing two piece crankshaft". The only shocking thing I found was that the engine in question serviced 12,000 miles of track use. 12,000 TRACK MILES!!! Good lord, it's amazing the thing hadn't lauched the pistons out through the wheel wells long ago.
