08-21-2008, 10:12 AM
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
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
94 Midnight Metallic Blue Cab Porsche 968 w/deviating cashmere/black interior and WAY too many mods to list - thanks to eric for creating www.968forums.com
"It isn't nearly as expensive to do it right as it is to do it wrong."
(This post was last modified: 08-21-2008, 10:27 AM by flash.)
