New clutch required?
 

I got my first clutch slip today in 6th gear with an ambient temperature of 7 degC. I floored it with over-boost off (1.0 bar) from about 50 mph. I couldn’t get it to do it again even with overboost (1.2 bar) in 5th gear downwards.

I can still smell the burnt clutch an hour of driving after it happened.

Does this mean I need a new clutch or is one clutch slip no big deal? Saying that, I did have a similar thing reversing up a steep hill back in 2008 in Switzerland, the smell lasted for about 20 mins then.

I know I have 798Nm torque with my CG544 kit which exceeds the factory clutch tolerances; perhaps I need a whole upgraded clutch kit?

Eg. Cargraphic Clutch

Or perhaps just an upgraded pressure plate?

My car only has 17k miles on the clock so I would rather not change the whole clutch out unless I really need to.

Would appreciate your thoughts...

(also opinions on single mass flywheels please as part of that kit mentioned above)

It's time for the real deal. You need a clutch with more clamping force.

I used to get this in my 996tt and the clutch never did go, it happend about 6 times over the time frame of about 3 years and always happend on the motorway in 6th gear! (i did ask my porsche mechanic about this too and he said it could be due to the fact the plate is not warmed up properly yet and the surface might be smooth at the point that it slipped?)

If your clutch was really gone it would not bite at all and just fly up the rev range without your car going anywhere.

Just keep an eye on it as you never know!

Have a sachs plate sitting there ready and waiting or you could with a lightwieght fly wheel kit as this would help with performance but im not sure about it for a daily drive although some others could advise you on this.

P.S. My old 996tt had exhaust and remap and i got it with 24k miles and sold it with 50k miles and clutch was still fine as I never launched it.

Alex, I'd bet it isn't the clutch. It's the pressure plate. You need something with more clamping force. Unfortunately, the cost of labor is the same, so you'll probably end up doing both. You could do a standard Sachs 2 upgrade for the power level you are at. If you plan on making more power later, spend a little more and go to Sachs 883082 999764.

Thanks for your thoughts guys. That kit I linked to in my OP looks like a Sachs kit to me with a 890Nm pressure plate.

http://www.cargraphic.de/stepone/dat.../PO502a_gr.jpg

Single mass flywheel is what I am debating. Apart from the rattling on idle, does it make for a better driving experience?

Alex, I use an Aasco aluminum flywheel with a Sachs 2 setup. Here are the pros:

1. Noticable ease in rev matching/heel toe shifting.
2. Noticable improvement in acceleration in 1st and 2nd gear.

Cons:

1. Rattle. The rattle can not be heard when you first start up and the engine/transmission is cold. As it warms up in neutral, you start to hear it. When you push the Sports Chrono button, the idle changes, and the sound goes away again. If you start the A/C, even with Sports Chrono, it is noticable, (a la GT3 RS.)

2. Low gear/WOT noise. The Sachs clutch is unsprung...meaning it does not dampen anything from the engine. Under WOT 2000-3000 RPM in a higher gear (ie you are lugging the engine) you will hear rattle.

This setup (Aasco/Sachs 2) is the same as what AWE used. They can also give a pretty good analysis. They ultimately removed the flywheel because some customers were confused by the noises.

Alternatively, you could go with a different setup...Clutchmasters makes a very good setup with a LWFW which apparently is noise free, although some have commented about the very high engagement point of the clutch.

- bob

Another note. I'd definately checkout the setup before you get it installed. Otherwise, you'll be paying for another 10 hours of labor to remove it. :)

There is unfortunately no such thing as a compeltely noiseless LWFW...by definition, the LWFW will allow transmission of engine pulses/noises to the transmission. There have been a few who have swapped transmission fluids to something thicker (Redline Shockproof) but I'm not sure what the safety is over Mobil1 Delvac.

A wealth of knowledge, thanks Bob!

AWE's offering:
http://www.awe-tuning.com/pages/shar...n&IL=996stage2

Looks like a stage2 would be enough. I will try to find out what the Cargraphic kit consists of exactly.

Bob/Alex, thanks for the very helpful thread.
Bob, I would most likely get mine from AWE; on the page that Alex quoted above http://www.awe-tuning.com/pages/shar...n&IL=996stage2

Yours would be the first one on the table: <TABLE border=0 cellSpacing=1 cellPadding=0 width=585><TBODY><TR bgColor=#cccccc><TD>Sachs/A.W.E. St2.5 Clutch Kit w/ LW Flywheel (996T </TD><TD style="TEXT-ALIGN: right; PADDING-RIGHT: 2px">$2,625.95 </TD></TR></TBODY></TABLE>

And if I don't want the flywheel, I would get the second one listed on that table? Would this be the one that feels most like stock? TIA.

<TABLE border=0 cellSpacing=1 cellPadding=0 width=585><TBODY><TR bgColor=#999999><TD>Sachs/A.W.E. St2.5 Clutch: 996T/GT2/GT3, 997T </TD><TD style="TEXT-ALIGN: right; PADDING-RIGHT: 2px">$1,530.95</TD></TR></TBODY></TABLE>

Hi Cannga...

Mike or Todd will be able to tell you for sure, but I think Gene had reported a very stock feeling clutch pressure and engagement using his stock OEM dual mass flywheel with a Sach's 2, and the upgraded pressure plate (part #883082 999764) hence Sach's 2.5 not 2... :)

The Aasco flywheel feels pretty similar, but in a direct comparison, the engagement point is higher than with the OEM dual mass. The engagement range is pretty similar.

Bob,

I changed my setup to a Clutch Masters this week. The LWFW rattle is the same as the Sachs setup. You are correct on the engagement point. It is slithgly higher than stock or the Sachs setup. I've already stalled it a fews times.. hilarious



Alex,

I had the Sachs stage 2 setup with the AASCO LWFW. It lasted about 7500 miles before it slipped. This setup is rated for about 540-550 ft lb of torque. I think you might want to look at the Clutch Masters setup. It is supposed to hold over 800hp with no problems. 2/20-934HRF-AL is the part#. $3225 retail. It comes with an organic/fiber tough disc with a pressure plate rated at 3900lbs of clamping force and a LWFW. If you want to keep the stock drivability, you need to stay with the organic/fiber tough combo.

Do you know the clamping force with that upgraded pressure plate? Sach's website doesn't give any real specifics.

Thanks.

PS: I feel like I should rep you on almost every message you post. Always most helpful info.

Thanks. Below is a table from Sachs showing the rating of the 2 pressure plates, I assume one is of the stage 2 xxxxx752 (torque rating 544 lb-ft with organic disc), and the other one which Gene upgraded to, xxxxx764 (rating 659 lb-ft).

It seems from reading Gene's post https://www.6speedonline.com/forums/...utch-feel.html , he re-used the OEM clutch disc (as opposed to using Sachs xxxxx973)? Is that possible?

Mike, which pressure plate did you use that didn't hold up with your stage 2, xxxx752 or xxxx764?

http://i214.photobucket.com/albums/c...tecopycrop.jpg

Cannga's got the data sheet. If you want to rep someone, Cannga has data comming out of his ears!

I'd + rep for a very useful table, but I guess I need to spread it around before I can hit him again, lol!

bob

I have the 764 pressure plate in mine and it's holding so far. Very stock-like feel and I would say even slightly better (less mushy, better engagement feel). It's the same set-up Dan at SpeedGallery has on his car which he let me test drive beforehand. The boys did a really great job with the install and pricing. Dan knows what he is doing. He's got cup cars up the wazoo sitting around his shop.

I gave it to CANNGA because I hadn't hit him in awhile. :D

i deal with dan all the time , good guy. does he have this in his 997 Turbo or one of his cup cars ? ty

Ha ha Bob. And you got data coming out of your ears AND eyes. As much of a "data gatherer" that I am, you surprise me all the times with the wide range of info you have.
Thanks ruf_turbo.

It was his 996tt that I test drove. Not sure what he runs in his cup cars.

http://www.carbonetic.net/products/single.html

Carbonnetic Carbon Singel plate cultch

Can,

I had the 752 pressure plate from Sachs. It definitely was not enough to hold. My new setup uses a Clutch Masters stage 2 disc with their stage 3 pressure plate.

I am definitely going to get the 890Nm pressure plate whatever. Just whether I go with a LWFW or not. Hmmmm....

Alex, I'm having a hard time recording the video...All the clips sound the same. I'll try again tonight.

bob

If you want stock-like clutch feel, I would stick with the dual mass flywheel.

A Sachs technician today suggested that the vibration is only noticeable at idle with a LWFW, not when shifting through gears. But the benefit in terms of throttle response is really minimal on a car as powerful as a 997TT and it’s not an option he would go for himself.

Alex,

The increase in throttle response is very noticeable. The chatter at idle might really bother you if you are sensitive to noise. The only time you really hear it is during idle. Especially if your AC is turned on. It can get loud. To be on the safe side, I would stick with the dual mass.

Hello,

Sorry for the slow response.

We sell two different kits from Sachs Racing.

The first is what we call the Stg 2.5. It uses the 764 plate that has the same pedal feel as stock, but with higher clamping force. This is the same plate the Gene Lou is using in his 750 car. This aforementioned replaced our standard Stg 2 kit.

Our second option, and one that is not a hot seller, is our Stg 3 kit. This has very heavy pedal feel and a bit overkill in my opinion. This uses a 752 plate and a 944 disc. Tough to modulate, but if you are abusive on clutches, this is the one to get.

Either of these can be used with or without a Lightweight flywheel that is cut to be used with a stock clutch.

We are a dealer for Sachs Racing so our pricing is ultra competitive.

Please email me directly if you have specific questions or would like ordering info.

Thank you.

Mike makes a very good point about the noise, and I agree. In terms of performance, the top cars at the Texas Mile use OEM flywheels almost exclusively. I think the LWFW makes the most difference in heel/toe (toe/heel) rev matching.

- bob

To those who've tried LWFW (and of course, the pro Mike/AWE): we've talked about noise, but how does the LWFW affect the feel and ease of clutch engagement please?
If a LWFW changes speed faster, doesn't it make engagement more difficult?

Thanks for this great discussion. I finally "get it" as far as which clutch to buy. :)

From my experience, the LWFW has made modulating a launch a bit tougher. On the flip side, the rev match (heel & toe) requires much less effort. So to your point Can, engagement is a bit different and takes a little getting used to.

The flywheel will have nothing to do with feel. Feel is based on the clamping force of the pressure plate along with disc type and material.

I'm 99% sure my setup is the same as Mike/Todd's at AWE before they swapped back to the OEM dual mass flywheel.

The engagement point is nearly identical to the stock flywheel, which you know is pretty high compared to other vehicles. The engagement "range" is slightly shorter, but you can still modulate it to inch the car forward up a hill.

There are several that have them on the 996TT that use a clutch stop to make the travel length shorter.

That's the best I can do without having you drive my car (which you are welcome if you ever decide you like the snow :) )

- bob

Really? Interesting...

I have driven a myriad of cars with and without flywheels. Especially on the modern Porsches I don't feel a difference on engagement or modulation if using a clutch plate and disc combo that was similar to stock.

+1 ^^ My experience is limited since I've only driven one. The engagement was high up and found it difficult to modulate. It would take a bit of getting used to as GB said. I don't exactly know what set-up it was but my 2.5 set-up feels like stock, perhaps a little better since you can also feel a more defined clamping, especially in 2nd gear which never felt great.

Gene seems to indicate in one of his posts that he uses the stock clutch disc, instead of the Sachs xxxx973 clutch disc?

Could you comment on this please? What's the advantage/disadvantage of re-using stock clutch disc versus xxxxx973? TIA

BTW, Tom (of Lucent) keeps telling me I need to replace my clutch. When I drive, nothing happens, when he drives, immediately the clutch slips. Hmmmm. I don't dare to ask him anymore how he test drives my car. :eek: :p

There is a modification to the clutch if the engagement feels too high...

You can remove the slave out from the transmission and pull the pin out and cut it to move the engagement point lower.

I will have to call Gene to get a clarification since I sold him the 973 disc along with his 764 plate.

I could be a little overly sensitive, but that is what I have experienced. I think for me, the quicker throttle response affects my ability to modulate the shorter and higher engagement point of my setup. The engagement point is definitely higher than stock.

Ok, I was referring to "feel" as the point where the disc meets the flywheel while lifting your foot.

What you are talking about is the height at which that happens. I understand now.

Ok, I have noticed it slightly higher, but as for what I was calling "feel", that has not changed with or without the flywheel.

Simple misunderstanding. We are on the same page now...