New clutch needed
06-29-2008, 11:53 AM
#31
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Don,
It is pretty clear that the problem lied with the PP if it was stock, those will hardly hold 500lbs.ft of torque, I am surprised Andial would keep that setup on a 3.8 twin plug TT. Probably they simply put an uprated Clutch disk there, which is still not enough with a stock PP. I don't understand why was it so tricky to know the issue? Did they not disclose what PP they were using?
Kevin,
What I said initially was that you were using the wrong units, which you were, and later asked how could you determine customer needs from that Force rating that you posted... There is only one way to establish what clutch assembly a customer needs for his engine output and that is by looking at Torque capacity of the clutch assembly not clamping Force, unless you are ready for lengthy physics calculations.
By looking at my BMEP chart, I know that with a high clamping special organic clutch (full face, not puck) and the top uprated PP from Sachs (posted above), Almost all except the most breathed upon 996TTs will do great at 1.4bar with a 100% stock pedal feel. At the dragstrip, things might change by about 20% (grip from 1G to 1.2G on acceleration due to sticky surface).
It is pretty clear that the problem lied with the PP if it was stock, those will hardly hold 500lbs.ft of torque, I am surprised Andial would keep that setup on a 3.8 twin plug TT. Probably they simply put an uprated Clutch disk there, which is still not enough with a stock PP. I don't understand why was it so tricky to know the issue? Did they not disclose what PP they were using?
What I said initially was that you were using the wrong units, which you were, and later asked how could you determine customer needs from that Force rating that you posted... There is only one way to establish what clutch assembly a customer needs for his engine output and that is by looking at Torque capacity of the clutch assembly not clamping Force, unless you are ready for lengthy physics calculations.
By looking at my BMEP chart, I know that with a high clamping special organic clutch (full face, not puck) and the top uprated PP from Sachs (posted above), Almost all except the most breathed upon 996TTs will do great at 1.4bar with a 100% stock pedal feel. At the dragstrip, things might change by about 20% (grip from 1G to 1.2G on acceleration due to sticky surface).
06-29-2008, 03:19 PM
#32
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This is a great thread, very interesting...
I would like to just add a couple of things: Whilst I agree with Jean that the only way to rate the clutches is by the engine torque output they are designed to handle (this is how Sachs do it with a 10% leeway I believe) the BIG problem which Jean also mentioned is that the 97% of people whose engine torque ouputs have been measured on chassis dynos will have incorrect numbers to the point that they are meaningless for this excercise.
Fortunately the set up Jean has highlighted which he and I have is so damn good that IMO it is a no brainer and should be used by anyone with a tuned 993tt. Kevin alluded to cost factors of which I know nothing but certainly cost should not stand in the way of getting this clutch set up which incedentially is pretty new and has only been around for a few years - before this one we were in all kinds of trouble and I can sympathise with the chorus when talking about sintered clutches for the street
, but that used to be the only option for real 750NM engined 993tts....
Jean mentions the set up being just like stock which initially I would agree with but the tech at a new shop I am using drove the car a wanted to know what "race" clutch I had in there so it is "sharper" than stock but you get used to it very quickly and it becomes as easy to drive just like stock
I would like to just add a couple of things: Whilst I agree with Jean that the only way to rate the clutches is by the engine torque output they are designed to handle (this is how Sachs do it with a 10% leeway I believe) the BIG problem which Jean also mentioned is that the 97% of people whose engine torque ouputs have been measured on chassis dynos will have incorrect numbers to the point that they are meaningless for this excercise.
Fortunately the set up Jean has highlighted which he and I have is so damn good that IMO it is a no brainer and should be used by anyone with a tuned 993tt. Kevin alluded to cost factors of which I know nothing but certainly cost should not stand in the way of getting this clutch set up which incedentially is pretty new and has only been around for a few years - before this one we were in all kinds of trouble and I can sympathise with the chorus when talking about sintered clutches for the street
, but that used to be the only option for real 750NM engined 993tts....Jean mentions the set up being just like stock which initially I would agree with but the tech at a new shop I am using drove the car a wanted to know what "race" clutch I had in there so it is "sharper" than stock but you get used to it very quickly and it becomes as easy to drive just like stock
06-29-2008, 04:25 PM
#33
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Don,
It is pretty clear that the problem lied with the PP if it was stock, those will hardly hold 500lbs.ft of torque, I am surprised Andial would keep that setup on a 3.8 twin plug TT. Probably they simply put an uprated Clutch disk there, which is still not enough with a stock PP. I don't understand why was it so tricky to know the issue? Did they not disclose what PP they were using?
It is pretty clear that the problem lied with the PP if it was stock, those will hardly hold 500lbs.ft of torque, I am surprised Andial would keep that setup on a 3.8 twin plug TT. Probably they simply put an uprated Clutch disk there, which is still not enough with a stock PP. I don't understand why was it so tricky to know the issue? Did they not disclose what PP they were using?
06-29-2008, 10:16 PM
#34
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Can Kevin, Jean or anyone on here comment on longevity of clutch/FW combinations? After all, since for most of us (including me) who aren't on racing teams and dearly need a setup that doesn't require that we pull down our engines to repair our clutches every track outing, a clutch/FW assembly with tremendous clamp force/torque handling specs. is meaningless if we have to repair it every few thousand miles even if it doesn't slip for just a single 1/4 run.
My 996TT tuned to 650-700 crank HP/lb-ft has had its Sachs/OEM dual mass FW setup start to slip this past month after 10,000 miles of hard but non-track driving even though it was rated for 800+ lb-ft.
My 996TT tuned to 650-700 crank HP/lb-ft has had its Sachs/OEM dual mass FW setup start to slip this past month after 10,000 miles of hard but non-track driving even though it was rated for 800+ lb-ft.
11-24-2008, 02:36 PM
#35
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How do this disc "special organic facings, part numbers 881864 999973 from the Sachs racing catalog" compare to a gt3RS disc
Would it be the same as "580 lbs.ft if you are using a modified organic plate (street/track) part numbers 881864 999973 " if using the 752 pressure plate
Would it be the same as "580 lbs.ft if you are using a modified organic plate (street/track) part numbers 881864 999973 " if using the 752 pressure plate
11-24-2008, 06:56 PM
#36
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I have the UMW kit http://forums.rennlist.com/upload/p1010158_copy3.jpg
It looks like a 802 disc but thet cant be right i think,does a gt3 RS use a 802 disc if so this combo support 660 nm (500ft/lb).. i think im missing something here
It looks like a 802 disc but thet cant be right i think,does a gt3 RS use a 802 disc if so this combo support 660 nm (500ft/lb).. i think im missing something here
11-24-2008, 11:42 PM
#37
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Rickard I don't know what engine setup you are running but if this 802 clutch (Porsche part number: 996.116.015.30) and pressure plate are working for you it tells me that your torque cannot be above 750NM. As I mentioned in an earlier post in this thread the manufacturer tolerances will take you to 550lbs.ft.
The 973 disc plate does not have springs yet it has almost stock pedal feel.
It is the same as the one in this kit at the bottom of this page http://www.cargraphic.de/index.php?/...,1053/&start=0
And the 764 pressure plate is the one here http://www.cargraphic.de/index.php?/...,1053/&start=3
They can be had at much better prices though.
The 973 disc plate does not have springs yet it has almost stock pedal feel.
It is the same as the one in this kit at the bottom of this page http://www.cargraphic.de/index.php?/...,1053/&start=0
And the 764 pressure plate is the one here http://www.cargraphic.de/index.php?/...,1053/&start=3
They can be had at much better prices though.
11-25-2008, 05:56 AM
#39
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Rickard I don't know what engine setup you are running but if this 802 clutch (Porsche part number: 996.116.015.30) and pressure plate are working for you it tells me that your torque cannot be above 750NM. As I mentioned in an earlier post in this thread the manufacturer tolerances will take you to 550lbs.ft.
The 973 disc plate does not have springs yet it has almost stock pedal feel.
It is the same as the one in this kit at the bottom of this page http://www.cargraphic.de/index.php?/...,1053/&start=0
And the 764 pressure plate is the one here http://www.cargraphic.de/index.php?/...,1053/&start=3
They can be had at much better prices though.
The 973 disc plate does not have springs yet it has almost stock pedal feel.
It is the same as the one in this kit at the bottom of this page http://www.cargraphic.de/index.php?/...,1053/&start=0
And the 764 pressure plate is the one here http://www.cargraphic.de/index.php?/...,1053/&start=3
They can be had at much better prices though.
Thanks Jean
Thats right im not pusching over 750nm right now but im affraid im at the edge so i want to uppgrade a littel, i have the engien out of the car for some winter tune up so i want to uppgrade. I think i will be at 750-800nm
I have the 752 pressure plate so i think the best would be to go to the sinter paddel or 973 disc or change pressure plate for a 764 and use the disc i have
11-25-2008, 01:34 PM
#40
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Jean
The same kit we are talking about FVD lists as max 660nm(http://shop.fvd.de/shop/picture.php?...VD116909_1.jpg), i thougt the kit i bought was holding more then that
so i need to uppgrade the PP or the disc to something better i was hoppening that i did have the 973 disc or something simulra in ther but no..
The same kit we are talking about FVD lists as max 660nm(http://shop.fvd.de/shop/picture.php?...VD116909_1.jpg), i thougt the kit i bought was holding more then that
so i need to uppgrade the PP or the disc to something better i was hoppening that i did have the 973 disc or something simulra in ther but no..
11-25-2008, 01:52 PM
#41
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Rickard
Yes this is how they rate, per my earlier post. However as you can see there is some tolerance levels built into them.
If you will upgrade your engine in any way, you definitely will need the better clutch disc, I would also change the pressure plate at once if cost is not significant. This is the real dyno test
Yes this is how they rate, per my earlier post. However as you can see there is some tolerance levels built into them.
If you will upgrade your engine in any way, you definitely will need the better clutch disc, I would also change the pressure plate at once if cost is not significant. This is the real dyno test
11-25-2008, 02:16 PM
#42
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Rickard
Yes this is how they rate, per my earlier post. However as you can see there is some tolerance levels built into them.
If you will upgrade your engine in any way, you definitely will need the better clutch disc, I would also change the pressure plate at once if cost is not significant. This is the real dyno test
Yes this is how they rate, per my earlier post. However as you can see there is some tolerance levels built into them.
If you will upgrade your engine in any way, you definitely will need the better clutch disc, I would also change the pressure plate at once if cost is not significant. This is the real dyno test
764 plate with 973 disc
Not the sinter plate ?
11-25-2008, 11:42 PM
#43
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11-26-2008, 05:27 AM
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12-23-2008, 02:58 PM
#45
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Jean and Toby,
as you know I have been running a 752PP/973 disc on my 997tt with the modded VTG's. Since install about a year ago I have had no issues with the clutch (5k miles) with many track days, a few 60-130 runs, and a few 0-300kph runs. Now with cooler weather (30-40F) and revised software (more midrange boost) the 752/973 combo cannot hold power in 4th, 5th, 6th gears. Under WOT the engine will just peg the rev limiter like it is in neutral. I plan to go to the next level with the 764/973 and was wondering how much increased clutch pedal effort to expect - I noticed no difference in the 752PP from stock.
Thanks
as you know I have been running a 752PP/973 disc on my 997tt with the modded VTG's. Since install about a year ago I have had no issues with the clutch (5k miles) with many track days, a few 60-130 runs, and a few 0-300kph runs. Now with cooler weather (30-40F) and revised software (more midrange boost) the 752/973 combo cannot hold power in 4th, 5th, 6th gears. Under WOT the engine will just peg the rev limiter like it is in neutral. I plan to go to the next level with the 764/973 and was wondering how much increased clutch pedal effort to expect - I noticed no difference in the 752PP from stock.
Thanks