Anyone have a Kevlar clutch disc?, If so, what's your experience...good/bad??? Options

[wbergtho]

I have a V-8 car with 500 HP and the stock 930 OEM Sachs disc is starting to slip. I have the KEP Stage 1 930 pressure plate and was told that it would hold 550lbs of torque (with a stock disc). My engine puts out 470 ft. lbs of torque...so this set up should work according to KEP. However, it has only 9-10K miles on the stock disc and it's starting to go already. (Maybe that's about right...considering the amount of performance I have and my driving style?)

I am considering going to Clutchnet's Kevlar disc. Renegade swears by this type of disc for their high HP V-8 applications. I remember Scott telling me about how wonderful and streetable they are. Nice smooth OEM engagement and much higher torque holding capabilities...and long lasting durability to boot. He said that the Kevlar discs need to be broken in gently for approximately 500 miles.

Anyone out there have a Kevlar disc in their car?...If so, how has it worked for you???

Thanks for the feedback!

Bill

[skline]

I had one of those in my Chalon with the V8 and I liked it. I had no problems with it at all and it held very well. If it is an option for you and you do really need it with the power you are running, I would say do it. The only thing with them is if you dont have them adjusted right, they will chatter on you. It's cool cause that is how you know if it is adjusted correctly. I say Do It!

[rick 918-S]

Bill we discussed this on the phone but I thought I would share this for the benifit of the others. I have a Kennedy Stage II with a kevlar and organic mix disc without spring hub. I've only driven the car once. There may be a learning curve or a break infor the disc but mine chattered on engaugement. I had a custom 6 puck 6 spring Kevlar disc last time I had the car together. I liked that one better. It also chattered when I first used it. but after 10 or so engaugements I either figured out how to let it out or it wore in. I think I would rather have the spring hub center though. I'll be changing that out next time around.

[PRS914-6]

Two things make for a smooth engagement.....The "wafer" built inbetween the disks friction surfaces (the reason you can squeeze a disk with your fingers) and the spring centers.

Personally I would NOT use a puck style disk . They are usually designed for racing and more "on or off" situations.

Here is what I did for my 3.6. I had Kennedy build me a stock looking 911 disk but actually a race disk. It has more METAL in the friction material and has a higher coefficient of friction. The advantage of that is you can use a stock pressure plate (911) and get 15-20% more holding power without going to a puck style. Think about when your brakes are worn to the metal and they grab more. Also, my first gear is way taller than stock and this will minimize glazing.

The disk is also only "wafered" on the pressure plate side. The advantage of that is the disk does not have to slide on the input spline every time the clutch is used. Basically it releases quicker but still allows smooth engagement with one sided wafered.

Talk to Kennedy some more and I'm sure they can give you some creative solutions. I was not williing to have a stiff clutch pedal for the street and I made that very clear to them. Basicallly I wanted my cake and eat it too. Hopefully I got it....

[drive-ability]

I have herd they are great, however I had one and it chattered from the first engagement. Went with a stock 930 and it was softer but fine. Tried again with a new kevlar (both through renegade) which was warranted , my pp and flywheel were checked by KEP and it still chattered. I went back to the 930 and love it..I don't have any idea but I still have the disk but have had no luck. ...

[wbergtho]

The disk is also only "wafered" on the pressure plate side. The advantage of that is the disk does not have to slide on the input spline every time the clutch is used. Basically it releases quicker but still allows smooth engagement with one sided wafered.

Are you talking about the marcel (think wave washer) that is sandwiched in the middle of the stock OEM Sachs disc? Or are you talking about the grooves that separate the pucks or disc material?

I think you are talking about the former. Maybe I should have Kennedy replace my OEM material with a more aggressive (higher coefficient of friction) material and have a continuous lining all the way around like the stock disc. Sounds like that is what you have done. I'm trying to imagine half a marcel on the pressure plate side only. Did you have Kennedy use your stock disc core to build up what you currently have?

Thanks for the input guys.

Bill

[Twystd1]

Just finished the 500 mile break in on a Kevlar clutch from Clutch Masters.

The car is a 240SX with a J Spec turbo engine doing about 415HP to the wheels.

And much like many of the high performance clutches I have had built for my friends over the years. This one chattered bad for the owner of this car.

Funny thing is... After I drive the same car for 20 minutes. The chatter is GONE.

I find the most drivers with Kevlar, ceramic arimid, or sintered iron clutches don't know how to break in the clutch. THEREFORE CHATTER.

They also slip the clutch way too much between gears. Get hot spots on the disk, PP and FW. Warp the marcel. And ulitimately create the chattering clutch they then blame on the manufacturer.

Personally. I baby the clutch for a hundred or so engagements/ dis-engagements.
Then I slip the clutch HARDCORE for 8 - 12 seconds in a one minute time frame and heat up the friction material until I can smell it. I usually get it in 2 or 3 second gear slips from a stop.
That is ONE heat cycle. And only needs to be done once.
And only needs to be done of the clutch is chattering.

Then I drive normally and let the clutch assembly cool off to ambient and park it for a half hour.

DONE.
That will typically take all the chatter away for ever. or until a driver continues to slip the clutch between gears in a consistent pattern and heat the clutch up during normal driving. And of course..... the chatter comes back.

I have a notion of why this happens. And no facts to back it up. I have simply been here so many times. And fixed so many clutches for friends and racers. This is simply what I know.

AND..... Some clutch packages just chatter... Period. And I can't make em work. Then I just change out the friction material and resurface everything. With my specs... Specs that are "known good" specs.

And if ya need a custom clutch.. I know peeps. It ain't real cheap. Yet they work every time. And I do like Kennedy. Great products.

Clayton

[PRS914-6]

Yes, the Marcel. Sorry for not explaining it too well. Only the pressure plate side. When looking at the disk, it clearly has more metal. Another tidbit....The lining is special and has a metal backing making it explosion proof. It also makes it thicker so Kennedy had to machine the pressure plate (Sachs) a little to maintain the proper finger location and angle. They also added some extra tabs on the pressure plate that connect the inside plate to the cover. They have a tendancy to bend when shoving a lot of HP through them.

If none of this makes sense, I'll post some pictures

[drive-ability]

Just finished the 500 mile break in on a Kevlar clutch from Clutch Masters.

The car is a 240SX with a J Spec turbo engine doing about 415HP to the wheels.

And much like many of the high performance clutches I have had built for my friends over the years. This one chattered bad for the owner of this car.

Funny thing is... After I drive the same car for 20 minutes. The chatter is GONE.

I find the most drivers with Kevlar, ceramic arimid, or sintered iron clutches don't know how to break in the clutch. THEREFORE CHATTER.

They also slip the clutch way too much between gears. Get hot spots on the disk, PP and FW. Warp the marcel. And ulitimately create the chattering clutch they then blame on the manufacturer.

Personally. I baby the clutch for a hundred or so engagements/ dis-engagements.
Then I slip the clutch HARDCORE for 8 - 12 seconds in a one minute time frame and heat up the friction material until I can smell it. I usually get it in 2 or 3 second gear slips from a stop.
That is ONE heat cycle. And only needs to be done once.
And only needs to be done of the clutch is chattering.

Then I drive normally and let the clutch assembly cool off to ambient and park it for a half hour.

DONE.
That will typically take all the chatter away for ever. or until a driver continues to slip the clutch between gears in a consistent pattern and heat the clutch up during normal driving. And of course..... the chatter comes back.

I have a notion of why this happens. And no facts to back it up. I have simply been here so many times. And fixed so many clutches for friends and racers. This is simply what I know.

AND..... Some clutch packages just chatter... Period. And I can't make em work. Then I just change out the friction material and resurface everything. With my specs... Specs that are "known good" specs.

And if ya need a custom clutch.. I know peeps. It ain't real cheap. Yet they work every time. And I do like Kennedy. Great products.

Clayton

Clayton,
I did try the slipping method you talked about when we spoke some time back. It helped a bit but only for a short time. I really did hammer the disk hard. I now use a 930 and since I don't slam the clutch much its holding up great..
John

[sww914]

I have a carbon kevlar 6 puck no springy thingy with a stock pressure plate and a beat up flywheel. The flywheel has hot spots on it going right through to the back because it's so thin.
The clutch chattered the first time I drove the car, since then it's been perfect.
I don't slip the clutch at all between gears, and I don't do quick take offs from a standstill much, 5mph in the pits you know.
Keep in mind this is a full throttle only kind of car, I don't know how well the clutch would work on the street, I think it would do well with me driving, but I'm very easy on clutches.

[wbergtho]

Thanks for the knowledge & feedback. It seems that the overall response is semi favorable for the kevlar disc. I may try one and if it doesn't work well....I'll get a 6 puck spring centered hub with an aggressive material.

Regards,

Bill