Clutch Slipping!!! ECU Upgrade Issues
#31
03-04-2005 | 02:02 PM
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Originally posted by 1999Porsche911
The clamping force of the stock Porsche pressure plate is more than enough regardless of HP. If you have burned the clutch, pressure plate or flywheel due to improper engagement of the clutch, then all bets are off. But assuming the clutch system has not been ruined:
If you have a huge amount of power in the engine, your wheels will break long before your clutch even is tempted to slip. There is little chance a clutch will slip with ANY amount of HP even if you are driving on some obscenely large slicks. You are more likely to twist a shaft or axle before the clutch. If a good stock clutch is engaged fully, IT WILL NOT SLIP AT ALL, no matter how much power you are pushing through it. Your weak point is the tires.
The only benefit a better pressure plate has on a powerful car is how quickly it will get the plate to clamp down against the flywheel. Once it is clamped, it is clamped and will not move. If I replace my clutch, it will be with the stock setup.
The clamping force of the stock Porsche pressure plate is more than enough regardless of HP. If you have burned the clutch, pressure plate or flywheel due to improper engagement of the clutch, then all bets are off. But assuming the clutch system has not been ruined:
If you have a huge amount of power in the engine, your wheels will break long before your clutch even is tempted to slip. There is little chance a clutch will slip with ANY amount of HP even if you are driving on some obscenely large slicks. You are more likely to twist a shaft or axle before the clutch. If a good stock clutch is engaged fully, IT WILL NOT SLIP AT ALL, no matter how much power you are pushing through it. Your weak point is the tires.
The only benefit a better pressure plate has on a powerful car is how quickly it will get the plate to clamp down against the flywheel. Once it is clamped, it is clamped and will not move. If I replace my clutch, it will be with the stock setup.
Last edited by Josh; 03-04-2005 at 02:05 PM.
#32
03-04-2005 | 02:05 PM
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Re: And The Answer is......................
Very well said Victor, I could`nt have put it better my self.
Neil
Neil
Originally posted by hhazrati
So the general opinion is that I "might" have too much power/torque for a oem clutch. I have right under 500HP. I know it isn't from bad driving habits, I am very carefull on the street. I don't drag race, ever! The car does see the track on a regular basis, down-shifts are common.
My decision is not to go with the Sachs, and stay with the dealer for the work.
Thanks.
So the general opinion is that I "might" have too much power/torque for a oem clutch. I have right under 500HP. I know it isn't from bad driving habits, I am very carefull on the street. I don't drag race, ever! The car does see the track on a regular basis, down-shifts are common.
My decision is not to go with the Sachs, and stay with the dealer for the work.
Thanks.
My personal opinion is that if you want a good clutch with easy engagement/disengagement (light as stock) and something that has room for growth, I would recommend the Sachs Kevlar/Carbon clutch/pressureplate combination with Aluminum flywheel. I've had several on different 993TT & 996TT that I have owned. They are amazing and the extra revving power you get with the light flywheel will give your car amazing response.
I'll let some of the tuners chime in and put their word in...
#34
03-04-2005 | 05:57 PM
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Like I said I have been doing this a long time and I can assure you that the clamp rating and material DOES make a difference. Not that I want to change a clutch but come down to KC and I will prove this to you on my dyno. Maybe not on a dyno jet but on my dyno I can simulate real load and it does occur if you don't have enough clamp.
Down shifting is not a good indication of clutch strength. Your torque jolts for a second and the car will then go on a down ward spiral. Loading a car on the highway on a high gear or on a dyno with street parasitic the load is harder and longer and continues to increase with wind resistance and gear load. While my car will spin all four wheels in third it is not going to do it in 5th or 6th and you can bet that not enough clamp will pop it. Something has to give and it WILL be the clutch. I am not certain how you can contest this fact? Not trying to be combative but telling someone to use a stock TT clutch in a 700HP kit is irresponsible. It does guarantee you more business for sure.
If Porsche didn't believe in this then the 930 clutch would have been the same as the 934/935 as well as the 956s and 962s. They used a different set up. In fact if you look at the normal G5o clutch compared to the specs of the RS or even the RSR all the Nm ratings for those are higher as you increase HP. These clutches are not just changing the focal points but also the clamp rate. Look them up.
Talk about a hijacked thread!
Down shifting is not a good indication of clutch strength. Your torque jolts for a second and the car will then go on a down ward spiral. Loading a car on the highway on a high gear or on a dyno with street parasitic the load is harder and longer and continues to increase with wind resistance and gear load. While my car will spin all four wheels in third it is not going to do it in 5th or 6th and you can bet that not enough clamp will pop it. Something has to give and it WILL be the clutch. I am not certain how you can contest this fact? Not trying to be combative but telling someone to use a stock TT clutch in a 700HP kit is irresponsible. It does guarantee you more business for sure.
If Porsche didn't believe in this then the 930 clutch would have been the same as the 934/935 as well as the 956s and 962s. They used a different set up. In fact if you look at the normal G5o clutch compared to the specs of the RS or even the RSR all the Nm ratings for those are higher as you increase HP. These clutches are not just changing the focal points but also the clamp rate. Look them up.
Talk about a hijacked thread!
#36
03-04-2005 | 08:34 PM
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Not bad really. Mid 50s, due for some 60s this weekend. Bad part...I am headed to MA for Tech Tactics. I have to give a class, more like 4, on how to build a tranny. It is suppose to snow out there 
Of course they are calling for snow here next wed. Figures gotta love KS.
Of course they are calling for snow here next wed. Figures gotta love KS.
#38
03-04-2005 | 09:17 PM
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Thats the Zone 1, get togehter in Springfiield, Ma. right? Man I sure wish I could make it. I had a shop in Northampton, just north of there.
Hey tell Bruce Anderson and Prescott Kelly I said hello. If you want to got to a good downtown restaurant in Springfield, check out the "Student Prince" on Fort St., I believe. Anyway I hope you enjoy it.
Talk soon Jay Putnam.
Hey tell Bruce Anderson and Prescott Kelly I said hello. If you want to got to a good downtown restaurant in Springfield, check out the "Student Prince" on Fort St., I believe. Anyway I hope you enjoy it.
Talk soon Jay Putnam.
#39
03-04-2005 | 09:25 PM
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Yes sir. That is the one.
I will tell them you said hi. We are giving 4 classes each this time. 7 subject total. Everything from wiring to trannies and more. The idea is more hands on. We will also be doing this at Parade. It will be called Porsche College. You making Parade?
I will tell them you said hi. We are giving 4 classes each this time. 7 subject total. Everything from wiring to trannies and more. The idea is more hands on. We will also be doing this at Parade. It will be called Porsche College. You making Parade?
#42
03-05-2005 | 05:58 AM
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I will try to make it to the Parade, also next year I will try to make Tech Tactics.
I had not missed 1, since they started. Except after moving down here I havent been able to go since. Anyway have fun, will talk soon.
Jay Putnam
I had not missed 1, since they started. Except after moving down here I havent been able to go since. Anyway have fun, will talk soon.
Jay Putnam
#43
03-05-2005 | 07:25 AM
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For Stephen Ph.D.
Stephen:
I think you are making the most sense. I can see your point for a 700HP TT. But in my case, about 500hp, would a Porsche OEM clutch be OK? Was the first clutch (a little) defective, or am I looking at another clutch repair within the next 2100 miles?
I really want to stay with OEM, not do any more HP mods and DE my TT.
Thanks
I think you are making the most sense. I can see your point for a 700HP TT. But in my case, about 500hp, would a Porsche OEM clutch be OK? Was the first clutch (a little) defective, or am I looking at another clutch repair within the next 2100 miles?
I really want to stay with OEM, not do any more HP mods and DE my TT.
Thanks
#45
03-05-2005 | 07:35 AM
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Depends on your driving style. Are you an aggressive driver, do you get on the boost regularly? When? More highway vs. local driving? 1/4 mile races?
how long have you had the extra HP?
Too many questions to ask to warrant whether or not you should stay with OEM.
I say go for the upgrade and be worry free (somewhat). I doubt your clutch was defective...it was probably a combination of your driving style + power increase.
how long have you had the extra HP?
Too many questions to ask to warrant whether or not you should stay with OEM.
I say go for the upgrade and be worry free (somewhat). I doubt your clutch was defective...it was probably a combination of your driving style + power increase.