Stock flywheel, what is the life expectancy?
 

Hello guys,

my 2002 S is in the shop for an IMS upgrade plus a oil pump drive upgrade and while the transmission is out, the technician checked over the clutch and flywheel.

the car has 66,000 km, or 41,000 miles. Oil changes at regiously low intervals. Tech inspections 4 times a year.

Bothe the IMS and RMS were sweeting, but no real leaks. Whatever oil leaked was down in the bell housing. It did not drop a spot in the garage all winter.

He said the clutch looks great, but the stock dual mass flywheel needs to be replaced.

I asked why it fell apart, and he said it was somewhat normal wear and tear. some last longer then others. He said it was obvious the drive train was not abused because even after 3 seasons of track events, the stock clutch was in good shape.

I searched these forums for flywheel comments, and besides the "single mass flywheel" and Boxster Spec threads, I could not find much.

I trust my mechanic, he is an upright guy, very longtime PCA member, and a longtime poster here. I just want to hear more of others experiences with flywheels.

Please share. :)

-Michael

Flywheel life expectancy same as clutch's. It can last forever (229K miles in ahem one case (Mine!) or it can fail sooner, sometimes much sooner.

Generally the flywheel suffers when the clutch wears out and results in slippage which overheats the FW and if enough the surface gets hard spots and will not resurface properly and will chatter and grab.

Added: If the clutch disc wears too much the rivets can wear grooves in the flywheel and if too deep resurfacing not an option and the FW's toast.

Another failure mode, more rare, is the "dual mass" feature fails.

There is a test in which the tech measures the amount of movement the dual mass mechanism allows. There's a pretty definite callout for what's acceptable and what's not. I don't recall the numbers but a knowledgeable tech should know them or be able to get them and perform the test.

Also, visual inspection may turn up a reason to replace the FW. Maybe there's obviously damaged hardware, like cracks, or the ring gear's damaged, or some of the little tabs that the crank sensor use to detect position of crank and misfire conditions missing.

Your tech is right. It varies. Some car owners have the FW fail early, most of the time through no fault of their own (which I'm sure is the case in your situation) or through their fault due to misuse, abuse, mistreatment.

Take pics of the old FW and post.

Sincerely,

Macster.

for what it is worth. I am not sure if you have the same Duel Mass as my 99/996. But the car has 103K on it. I just did the IMS and clutch also, I cleaned the FW up really well with anything I could find that would cut it. Put it all back together and its fine. The clutch feels great

I dropped in at the shop and took a look at it. We pulled out a brand new LUK replacement for comparison. After the intial movement in the new FW, when you turn it in either direction, it "self centers" and regains it's original position.

On the FW from my car, it was easier to turn and did not return to it's original position.

We looked at the clutch though, and it looked really good.

The tech said, if the clutch was gone, it would be an easy suggestion to replace the FW with a lightweight variant, as they ship with the clutch. But since the clutch still looks within spec, it was up to me. Twice the price for the LW....

Considering all I am having done... I said stay with the dual mass. The deep sump kit is an option that is more attractive IF I take that extra step.

Obviously your FW's dual mass feature no longer functional. Time to replace the FW.

I have read posts by at least one Porsche engine expert that IIRC cautions against using a lightweight flywheel. These engines do not have a crankshaft dampener. This function apparently is part of the dual mass FW's functionality.

If you take away the stock FW there's no crankshaft dampener function and I'm not sure that's a good thing for these engines.

Sincerely,

Macster.

Interesting. I guess my budget led me to a possibly better decision then my heart would have.

Read this thread in the 996 forum:

Is LWFW safe after LN Bearing retro fit?

I think this is a link to the thread:

https://rennlist.com/forums/showthre...ferrerid=46040

Sincerely,

Macster.

Again, great post.

The cons of the LWFW are outweighing the pros in this application.... for myself personally.

It seems that while adding racier parts to a street car at a piecemeal pace is once again proving itself to produce mixed results.

An old adage rears its head.....Either buy and integrated comprehensive performance package, or a purpose built car to start with.

Update:

IMS bearing, and RMS seals replaced. New flywheel, Pagid Yellows and new fluid, and two new CV boots....

Much more then I wanted to spend... but...piece of mind and regular maintenance are worth it.

For the record, after removal and inspection, my original IMS was in perfect condition, but the IMS and RMS were sweating a bit of oil, which collected in the bell housing. Not a drop of oil ever fell on my garage floor.

I guess, in my case, track driving, and frequent oil changes/maintenance can claim to be a recipe for a healthy IMS.

now... if I can sqeeze the lemon any more and afford those new track-only wheels.....

Hi MikeBat.
Im hoping you can help me identify the cause of an issue I have with my 2005 997 Carrera. Its a manual, with 130k on the clock, 2nd clutch since 56k, im the 4th owner so can only vouch for the clutch treatment since 40k when, when I bought it. So the car runs perfect except for one annoying and obvious sign of its age. Driving on the freeway, top gear, cruising on a constant throttle. If I lift off, and then apply throttle again their is a jolt as if slack in the transmission is taken up. If I go on off the throttle I can make it very obvious, and it will do it in any gear, but its more obvious in top gear. Its clear their is some serious play in the system somewhere. The most common suggestion is engine mounts (replaced) then transmission mount ( just replaced with aga tool) yet no change. Ive gone through thoughts its inner CV joints, but now im thinking its the DMF, and the play is the discs moving without spring retention, which is what you mentioned in saying the old DMF didn't return back to center. Its begs the question, before you replaced the DMF did you have this play? Im wondering if you can help me solve this problem, which would seem obvious (not that many things between crank and wheels) yet I cant find anyone who have a clear answer beyond a list of things to replace. Thanks for any help you can provide!!

Hi thanks for searching, but this thread is almost 10 years old. You should get better results in the 997 forum

If you are sure the engine mounts and transmission mounts are good then check the CV joints for excessive play. If they are ok then my WAG would have to be the flywheel, the dual mass feature has failed. I seem to recall there were other symptoms of the dual mass feature having failed. You sure when you take off from a stop and as you let the clutch out and it begins to enage there is no clunk? And shifts up and down are also clunk free?

Last but not least while this probably doesn't play a role in what you are experiencing I have to mention it is very important the brake and clutch hydraulic fluid (the two systems share fluid) be flushed/bled every 2 years. Letting this go even -- my experience with my Boxster -- really affects clutch operation and this in turn negatively affects shifting quality.

I agree it sounds like flywheel and/or clutch disc is failing. If you have >60K miles on this clutch it's probably time to replace it.
one other thought is something in the differential.