I believe my 2008 C2, with 47k miles, is in need of a clutch replacement. While familiarity plays a part, I believe I notice a tiny bit of slipping coming on. Also, first gear is just beginning to be a very slight struggle to engage. Not much, just enough that I'm noticing something is changing. My question is, I am finding plenty of clutch kits offered, but many appear to offer the disk, plate and throughout bearing. If flywheel replacement is commonly recommend, why so few kits with flywheel included? Do I really need to replace the flywheel? Same question for slave cylinder. The indi shop has offered a great labor quote, but wants the car in and out without waiting on parts in the middle of the project. Thanks in advance for any advice.

 

47K miles ain't many miles. While a clutch can go out at any time usually they last more than 47K miles unless there is clutch abuse going on.

A test for slippage is with everything up to temperature in 4th or 5th gear at around 2.5K RPMs or so just floor the gas pedal. If the clutch is slipping you'll notice engine RPMs going up without a corresponding increase in vehicle speed.

If this occurs the clutch is slipping and needs to be replaced. No need to repeat the test as this just subjects the flywheel to possible overheating.

For the struggle to engage 1st gear this can be due to the brake/clutch fluid being due to be flushed/bled. This is due every 2 years regardless of mileage. Do not dismiss this as a ploy to enrich the dealers. I let my Boxster's brake fluid go just 2.5 years -- at the time I was unaware of this -- and only when the clutch became hard to engage smoothly -- which was quite contrary to its normal behavior -- and when almost every shift felt like the clutch pedal was not fully depressed and I took the car in thinking either the clutch was due to be replaced -- with over 250K miles on it -- or possibly the transmission was due to be rebuilt -- with the same mileage on the transmission -- the SM manager looked up the last brake fluid/flush and bleed and noted it was 2.5 years ago and suggested before a new clutch or any transmission work be done to have the brake/clutch fluid bled. I agreed and the the results were remarkable. The clutch was once again back to its smooth self and shifting was also smooth and crunchy free.

Might note brake behavior before and after this flush/bleed was unchanged.

Might also note that the Boxster now has almost 305K miles and it is still on its original clutch and transmission. My 996 Turbo has 148K miles and is on its orignal clutch, too. At 120K miles the transmission was out for an RMS repair and the clutch disc had no measureable wear. I expect the Turbo clutch to last at least a couple hundred thousand miles and I wouldn't be surprised to have it least 300K miles, if I keep the car that long.

So, if you have not had the brake/clutch fluid flushed and bled in the last 1.5 to 2 years my recommendation is to have this service done and then see how the shifting and clutch behavior is like. This fluid service won't resurrect a slipping clutch though, but it can prevent unnecessary transmission work or unnecessary clutch slave cylinder replacement.

If a new clutch is necessary this doesn't always mean a new flywheel is necessary. The flywheel can be resurfaced if the tech believes it required and as long as the dual mass mechanism passes the movement test and the flywheel is otherwise in reusable shape -- no signs of overheating or other degradation -- the flywheel can be reused.

Unless you are experienced at evaluating a flywheel or just willing to gamble my advice is to leave the question of flywheel replacement up to the tech. He should have seen a number of Porsche flywheels and can make a good recommendation based on his experience.

 

Thanks Macster
The brake fluid had been changed inside of the past year, but does need to be changed again following a track day that say a little boiling of the fluid.
I'll try the 4th or 5th gear pull tomorrow. I suspect it will pull well.

 

Also, if you've never changed your transmission fluid, at 8 years old, it would be worthwhile to do this as well. A lot of us have had excellent results from using Mobil 1 PTX and it has dramatically improved the shift into 1st gear when the car is stopped. Sunset Porsche sells it for a good price.

 

Thanks Petza914
At this time I'm inclined to change transmission fluid, brake fluid, clutch slave cylinder, clutch disc, pressure plate and throughout bearing. Leaving the flywheel unchanged makes me a little nervous, but the $1k spend, which around 50% feel would be unnecessary, is a gamble I'm working to get comfortable with.
Thanks to all for the advice.

 

You can do the slippage test first. The condition of the fluid won't cause the clutch to slip. If you find the clutch is slipping no need to do the brake/clutch fluid flush until *after* the clutch is replaced.

If you find the clutch is not slipping then I think a brake/clutch fluid flush/bleed is a very good idea.

Tracking subjects the brake fluid to extremely high temperature and I do not know what effect this has on the fluid but it can't make it better.

As a precaution if the clutch is not slipping then I'd recommend a brake/clutch fluid flush/bleed.

While my auto tech buddies always advised me to show up at the track with fresh oil in the engine brake fluid never came up for much discussion. The "tracking" involved auto-crossing and except in rare cases speeds -- one track had a pretty long straight that the faster cars were able to really buidl some speed -- were not high and brakes never got real hot.

If tracking involves driving on a real race track at "race track" speeds I'd probably err on the side of caution and do a brake/clutch fluid flush/bleed a few days to a week before the event.

 

Agreed Macster -
I always do a flush/fill with high temp brake fluid before a track day. I'm passing on the test and simple going to go for the aforementioned replacement parts/fluids. Appreciate the advice from all.