968Forums.com
when is an aluminum flywheel not your friend? - Printable Version

+- 968Forums.com (https://968forums.com/forum)
+-- Forum: FIXING MY BABY - OEM REPAIRS (https://968forums.com/forum/fixing-my-baby-oem-repairs)
+--- Forum: OEM REPAIR & TECHNICAL (not modifications) (https://968forums.com/forum/oem-repair-technical-not-modifications)
+---- Forum: Clutch & Flywheel (https://968forums.com/forum/clutch-flywheel)
+---- Thread: when is an aluminum flywheel not your friend? (/when-is-an-aluminum-flywheel-not-your-friend.html)


when is an aluminum flywheel not your friend? - flash - 08-21-2008

everybody knows i have been running the 12 lb fidanza aluminum flywheel for about 5 years now, and loving it - it has not been without complication though - it required paying a lot more attention to shifting, having to blip the throttle between gears on down shift, make faster upshifts, rev it higher to take off, deal with the rattles, yada yada



it also meant a shorter lifespan on clutch disks - i complicated matters by installing a 3200 lb Sachs pressure plate, upgrading from the 2600lb stock unit - this mean faster engagement, but at the cost of fragging a disk at PIR at 100mph



so, i came home and put in the same thing i had, because there was no other choice at that time - this led to the development of the new spring center disk - last month i finally put the disk in my car, using the same pressure plate and flywheel - i cleaned them up a bit, but did not surface or rebalance, since they had just been done about 20 driving hours earlier



well, the downshift from third to second was UGLY - it felt like the trans was coming out of the car - if i let it coast down, and let the clutch out slowly, it was fine - if i revved the gears up to speed match, it was fine - all other shifts, both up and down, were great - rattle greatly diminished and now livable - however, the car was not really drivable the way it was



one other car with a light flywheel, albeit a different one, exhibited this symptom, and guess what? same 3200 lb pressure plate - none of the OEM plated cars had the problem



so, out came the clutch AGAIN - yanked it out monday with no fuss - off went the flywheel for surfacing and it and the new pressure OEM plate for balancing - got it back tuesday morning and began putting it back together



just as i was torquing the last pressure plate bolt, ZIP - stripped a hole - i had done this once before, and heli-coiled it, but did not do all of them - ok - out of heli-coils, so off to the hardware store for more - ok - repaired the hole - back together again - ZIP! 2 more stripped - ARRRRRGH! - i had second guessed myself - i should have done them all - the flywheel had seen the pressure plate removed 5 times now, and that was just too much for the aluminum threads



moral of the story comes in 3 parts



1. with an aluminum flywheel, using the spring center disk, you MUST use the OEM disk (which pete can still get, but is not sold anywhere over here) - you CANNOT use the replacement Sachs unit that everybody sells - the OEM unit is more expensive, but it is the only thing that will work



2. first assembly is fine with the aluminum threads, as long as you VERY gradually go around tightening the bolts down, one turn at a time, going all around a dozen or so times - it's a pain, but if you don't rotate the flywheel around that many times, you WILL strip a hole - the same goes for disassembly - that's how i got to the first failed one



3. when replacing a clutch on an aluminum flywheel, you need to heli-coil the threads - the aluminum just isn't up to the task or re-torque



finally got it together last night about 9 - quick test drive shows things to be better - not sure i like the soft stock pedal feel, but i am pretty sure i can get used to it - i'll get to drive it more today and break in the disk and really see how it is



as a side note, the 3200 lb pressure plate which i am currently having surfaced, and is a great upgrade for a DMF, and the standard clutch disk, both of which have almost no time on them, will likely be up for sale very soon

when is an aluminum flywheel not your friend? - Eric_K - 08-21-2008

I have been racing the last 4 years on a lightweight Fidanza & 3200lb Sachs pressure plate with no issues. The secret is running a durable disk, I switched to a Spec StgII kevlar disk after destroying the stock disk in early 2004. The stock style disk is not ideal for track work. After eating 2 of them I wasn't going back.

when is an aluminum flywheel not your friend? - flash - 08-21-2008

yeah - i have a very durable disk in there now - there were 2 issues i wanted to resolve - the rattle is diminished, where the kevlar would not help that - i also wanted to have a more durable disk, which i now have



i think the fidanza just may be too light to be happy with everything else - not sure it is going to cook in or not - i just drove it again, and tried getting it hot (i could smell it) - not a lot better than yesterday, but better than with the 3200 - i can get used to it, but i don't like it



kevlar is cool for track - a bit aggressive though for the street - i may have to go that route though



i will probably put in the rs barn 18 lb unit in this car, using the 2600, and relegate the fidanza and 3200 to the track with a kevlar puck style disk