@!&_)*(^% clutch again!!!!!
03-24-2008, 12:33 AM
#17
Rest in Peace
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I understand that the clutch set up in some of the 928's are twin disks, and to be honest I, and my shop has limited exposure to this type of setup.
So take what I say with a grain of salt in reference to the GTS setup.
Over the last 15 years we have done more clutches than I can count.
I first started seeing a trend with some of my long time clients.
They could get 100-150,000 (or how ever many)miles out of a original clutch, we would turn the flywheel, put in a new dealer PP, release bearing and disc.
A year or two would go by (or much sooner) and they would be back in for a new clutch, we would do the same thing with a new flywheel and they would get as many miles out of them as the original ones.
The cars with hydraulic clutches seem to be a lot more susectable to this than the ones with mechanical linkage.
I have a theory, for every thousandth you take off a flywheel = a thousandth of wear you will not get from the clutch.
I could be 100% off base on this, it is just what I have seen at my shop.
But in your latter post you say that all of the GTS clutches have failed, that puts a different light on things, at least for me anyway.
Greg Nettles
So take what I say with a grain of salt in reference to the GTS setup.
Over the last 15 years we have done more clutches than I can count.
I first started seeing a trend with some of my long time clients.
They could get 100-150,000 (or how ever many)miles out of a original clutch, we would turn the flywheel, put in a new dealer PP, release bearing and disc.
A year or two would go by (or much sooner) and they would be back in for a new clutch, we would do the same thing with a new flywheel and they would get as many miles out of them as the original ones.
The cars with hydraulic clutches seem to be a lot more susectable to this than the ones with mechanical linkage.
I have a theory, for every thousandth you take off a flywheel = a thousandth of wear you will not get from the clutch.
I could be 100% off base on this, it is just what I have seen at my shop.
But in your latter post you say that all of the GTS clutches have failed, that puts a different light on things, at least for me anyway.
Greg Nettles
03-24-2008, 12:37 AM
#18
Nordschleife Master
I would go with Carl's Spec clutchs. Go stage II or I for max holding power.
Though the dual disc setup is imo the best way to go with one of his aluminum flywheels.
Though the dual disc setup is imo the best way to go with one of his aluminum flywheels.
03-24-2008, 12:40 AM
#19
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My machinist also has told me that when a flywheel has blue spots or cracks in it it will get "Grains" of hard and soft spots like the grain in wood and will wear unevenly.
They will stay there after it has been turned, which in a very short time will lead to high and low spots on the flywheel.
But once again, I have 0 prof of this.
Maybe Mike S could tell us his thoughts on this issue of hardness.
They will stay there after it has been turned, which in a very short time will lead to high and low spots on the flywheel.
But once again, I have 0 prof of this.
Maybe Mike S could tell us his thoughts on this issue of hardness.
03-24-2008, 12:50 AM
#20
Rocket Pilot
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03-24-2008, 07:04 AM
#22
I understand that the clutch set up in some of the 928's are twin disks, and to be honest I, and my shop has limited exposure to this type of setup.
So take what I say with a grain of salt in reference to the GTS setup.
Over the last 15 years we have done more clutches than I can count.
I first started seeing a trend with some of my long time clients.
They could get 100-150,000 (or how ever many)miles out of a original clutch, we would turn the flywheel, put in a new dealer PP, release bearing and disc.
A year or two would go by (or much sooner) and they would be back in for a new clutch, we would do the same thing with a new flywheel and they would get as many miles out of them as the original ones.
The cars with hydraulic clutches seem to be a lot more susectable to this than the ones with mechanical linkage.
I have a theory, for every thousandth you take off a flywheel = a thousandth of wear you will not get from the clutch.
I could be 100% off base on this, it is just what I have seen at my shop.
But in your latter post you say that all of the GTS clutches have failed, that puts a different light on things, at least for me anyway.
Greg Nettles
So take what I say with a grain of salt in reference to the GTS setup.
Over the last 15 years we have done more clutches than I can count.
I first started seeing a trend with some of my long time clients.
They could get 100-150,000 (or how ever many)miles out of a original clutch, we would turn the flywheel, put in a new dealer PP, release bearing and disc.
A year or two would go by (or much sooner) and they would be back in for a new clutch, we would do the same thing with a new flywheel and they would get as many miles out of them as the original ones.
The cars with hydraulic clutches seem to be a lot more susectable to this than the ones with mechanical linkage.
I have a theory, for every thousandth you take off a flywheel = a thousandth of wear you will not get from the clutch.
I could be 100% off base on this, it is just what I have seen at my shop.
But in your latter post you say that all of the GTS clutches have failed, that puts a different light on things, at least for me anyway.
Greg Nettles
I think that a lot of resurfaced flywheels tend to have a surface like sandpaper, causing accelerated wear during engagement of the clutch.
We used to deglaze the flywheel with scotchbrite disks. Of course if your flywheel is fried, this is not an option, but your machine shop should be able to create a better finish on your flywheel.
03-24-2008, 09:21 AM
#23
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Kevin,
I fried my stock clutch a couple of years ago, stomp on it in third and if it hooked up, the clutch would slip. Nasty, nasty smell that burnt clutch is. The spec stage 3+ seems to work well, I had Motorsports in Utah make a kevlar clutch with a heavier pressure plate. It has held up well for a couple of years now, and doesn't feel a whole lot heavier than the stock pedal effort.
Now for the downsides....You will have to "slip" the clutch a bit more in reverse or it will "chatter". 1200 to 1500 rpms works very well and smooth. It is not as smooth in stop and go traffic as stock parts, but I survived Chicago Friday rush hour traffic fine. The spec unit will do about the same, is a little less "friendly" to drive. You will do fine with either.
One more time, the stock single disc clutches will not hold up well with high power and aggressive use of that power. Dual disc seems to hold better, but it was easier plugging in a single disc replacement.
Luckily the clutch is easy to replace if you have a x-pipe. Just sucks about the $$$$.
Jim
I fried my stock clutch a couple of years ago, stomp on it in third and if it hooked up, the clutch would slip. Nasty, nasty smell that burnt clutch is. The spec stage 3+ seems to work well, I had Motorsports in Utah make a kevlar clutch with a heavier pressure plate. It has held up well for a couple of years now, and doesn't feel a whole lot heavier than the stock pedal effort.
Now for the downsides....You will have to "slip" the clutch a bit more in reverse or it will "chatter". 1200 to 1500 rpms works very well and smooth. It is not as smooth in stop and go traffic as stock parts, but I survived Chicago Friday rush hour traffic fine. The spec unit will do about the same, is a little less "friendly" to drive. You will do fine with either.
One more time, the stock single disc clutches will not hold up well with high power and aggressive use of that power. Dual disc seems to hold better, but it was easier plugging in a single disc replacement.
Luckily the clutch is easy to replace if you have a x-pipe. Just sucks about the $$$$.
Jim
03-24-2008, 03:10 PM
#24
Race Car
Hmm, I guess I'm lucky so far? My GT's clutch is still holding fine and I estimate to have about 450rwhp/rwtq. I believe the clutch hasn't been touched since before the S/C was installed and this car has one of the largest number of miles with a supercharger installed. Gotta take it to the dyno when I have time to verify the power numbers.
Dan
'91 928GT S/C
'86 928S 5-spd w/LSD *sale pending*
Dan
'91 928GT S/C
'86 928S 5-spd w/LSD *sale pending*
03-24-2008, 03:55 PM
#25
The Lady's Man
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03-24-2008, 04:34 PM
#26
The Parts Whisperer
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Another option I would consider is having the pressure plate modified for more pressure. Clutch Masters can do this (909) 877-6800. I have tried several friction disc materials and although they may work on a race car I would not want them on my street car.
03-24-2008, 05:05 PM
#27
Race Car
Dan
'91 928GT S/C
'86 928S 5-spd w/LSD *sale pending*
03-24-2008, 05:23 PM
#28
Rocket Pilot
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03-24-2008, 05:26 PM
#29
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Kevin,
I fried my stock clutch a couple of years ago, stomp on it in third and if it hooked up, the clutch would slip. Nasty, nasty smell that burnt clutch is. The spec stage 3+ seems to work well, I had Motorsports in Utah make a kevlar clutch with a heavier pressure plate. It has held up well for a couple of years now, and doesn't feel a whole lot heavier than the stock pedal effort.
Now for the downsides....You will have to "slip" the clutch a bit more in reverse or it will "chatter". 1200 to 1500 rpms works very well and smooth. It is not as smooth in stop and go traffic as stock parts, but I survived Chicago Friday rush hour traffic fine. The spec unit will do about the same, is a little less "friendly" to drive. You will do fine with either.
One more time, the stock single disc clutches will not hold up well with high power and aggressive use of that power. Dual disc seems to hold better, but it was easier plugging in a single disc replacement.
Luckily the clutch is easy to replace if you have a x-pipe. Just sucks about the $$$$.
Jim
I fried my stock clutch a couple of years ago, stomp on it in third and if it hooked up, the clutch would slip. Nasty, nasty smell that burnt clutch is. The spec stage 3+ seems to work well, I had Motorsports in Utah make a kevlar clutch with a heavier pressure plate. It has held up well for a couple of years now, and doesn't feel a whole lot heavier than the stock pedal effort.
Now for the downsides....You will have to "slip" the clutch a bit more in reverse or it will "chatter". 1200 to 1500 rpms works very well and smooth. It is not as smooth in stop and go traffic as stock parts, but I survived Chicago Friday rush hour traffic fine. The spec unit will do about the same, is a little less "friendly" to drive. You will do fine with either.
One more time, the stock single disc clutches will not hold up well with high power and aggressive use of that power. Dual disc seems to hold better, but it was easier plugging in a single disc replacement.
Luckily the clutch is easy to replace if you have a x-pipe. Just sucks about the $$$$.
Jim
Kevin
03-24-2008, 05:33 PM
#30
Rocket Pilot
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Thanks,
Kevin