q's about clutch options

[Reaper1]

I'm saving up for a newer clutch in my car. The current set-up is overpowering it under certain load situations, so an upgrade is inevitable.

I don't really WANT to run a ceramic due to their tendancy to be on/off engagements. I'd rather run a Kevlar type disc.

My first question is what experieces have people had with this type of clutch with a decent amount of power(in the 300lbft range for max torque)?

Secondly, the only one I've found that is carried by one of the TD vendors uses a HD dual diaphragm pressure plate. With the better clutch disc I don't think this is needed, but if it is I'm worried about wear and tear on the thrust bearing in the engine. I can deal with a bit heavier pedal(although I'd like to stay away from that), but I don't want to have to worry about crank walk and thrust bearing issues. Has anybody had any experience with this?

This car is primarily a street car that sees *some* track time.

Thanks for the input.

[Reaper1]

Hmm....nobody has any experience with Kevlar discs?

[MiniMopar]

I have TU's Kevlar unit. I think it's a Clutchnet clutch, based on the picture. I've been driving on it for almost a year. I have mixed feelings about it. Also, I haven't made it to the track yet.

The clutch was and is still chattery when engaged under light load at low RPMs: backing-up and crawling in heavy traffic. It shakes my hood pretty violently, though I have poly bushings in all three mounts. Under load, it is very smooth.

I've launched it hard many times on the street without issue. I have been having issues with the engagement point, but I think the issue is the adjuster or something else. Compared to the 6-puck ceramic I had in my CSX before, the clutch is a bit more street-friendly. It is not as grabby. I just wish it didn't chatter so much. Also, the ceramic is only good for 30-40k miles. I'm hoping the Kevlar will last longer.

[GLHNSLHT2]

I have a spec Stage 3 six puck ceramic and fidanza flywheel in my SHelbyZ. I love it. THe pedal is lighter than a stock T1 clutch. It's very easy to modulate. I was making 280ftlbs @12psi and I've been turning it up the last couple weeks. So far I'm at 20psi so I'm sure I'm making quite a bit more than the 280 I was. It's holding fine.

[slasky]

I have the TU 4 puck ceramic and I love it. It did not take very long to get used to on the street.

[Reaper1]

If I have to go ceramic I will. I've driven them and they aren't "tooo" bad, but I'm more concerned with getting a good launch at the track than streetability as far as engagement goes. I can drive them OK on the street. As stated before that just takes a little getting used to. For the track though, because I race on street tires, I find it is almost needed to slip the clutch a little to get off the line cleanly. Not only to not shock the driveline so much, but also to keep the tires from spinning to oblivion. I might just have the wrong impression of how this might work at the track though...That whole wearing out thing is kind of interesting. I would have thought that they would have lasted longer...hmmm, something else to think about.

My other concern, like stated before, was the pressure plate. I don't really think that an extremely heavy PP is needed if a good disc is used in my application. I'm concerned about the stress this would put on the crank thrust bearing...is all of that REALLY necessary?

Russ, are you using the HD PP also with that disc? If so, how does it compare to the stock one? I'm pretty sure I've driven a car with one and it was HEAVY!! As for it being chattery, I'm only running the solid bobble strut. I have plans to run a PB front mount as well, but so far the stock mount is OK.

I'm interested in the "spec Stage 3" clutch. I'd like more info about it.

I was also looking at the 6-puck ceramic. Something I've always wondered...why is it that the "stronger" clutches have less pucks? This might seem like a trivial question, but it's something I've not really looked up.

Thanks for the input and experience here. I really do appreciate it!

[GLHNSLHT2]

The spec moves the fulcrum points in the PP so it has great clamping force but is easy on the pedal and thrust bearing. Less pucks gives the puck more clamping force per square inch which makes it hold better.

[Reaper1]

Nice! Next dumb/lazy question, where do I find where to get one?

[MiniMopar]

Russ, are you using the HD PP also with that disc? If so, how does it compare to the stock one? I'm pretty sure I've driven a car with one and it was HEAVY!! As for it being chattery, I'm only running the solid bobble strut. I have plans to run a PB front mount as well, but so far the stock mount is OK.

The PP is what TU sold it with. It was speckley-blue in color and is made by Sachs. It feels about the same as a T3 PP to me. You could ask Chris about it.

I was also looking at the 6-puck ceramic. Something I've always wondered...why is it that the "stronger" clutches have less pucks? This might seem like a trivial question, but it's something I've not really looked up.

I think it's because the disc/flywheel are wearing just as fast as the pucks. The fewer pucks there are, the more force is imparted by the PP to each puck. There is a bit of "digging" happening between in the pucks and the steel and perhaps pushing on the pucks harder gives you more overall friction than having more puck surface. This is the opposite effect that you get with tires and the road (i.e. the car weighs the same, so why does have more rubber with less force per sq in cause them to grip better). From what little I remember from Dynamics, predicting frictional force varies wildly with the materials in question. Plus there are other forces at work too. Anyway....

I also imagine that having 6 pucks instead of four will make it a bit less chattery since the pucks will tend to dig less.

[GLHNSLHT2]

www.specclutch.com. SHould have a list of vendors or email them. They're very good about getting back to you.

[TurboRon25]

I think it's because the disc/flywheel are wearing just as fast as the pucks. The fewer pucks there are, the more force is imparted by the PP to each puck. There is a bit of "digging" happening between in the pucks and the steel and perhaps pushing on the pucks harder gives you more overall friction than having more puck surface. This is the opposite effect that you get with tires and the road (i.e. the car weighs the same, so why does have more rubber with less force per sq in cause them to grip better). From what little I remember from Dynamics, predicting frictional force varies wildly with the materials in question. Plus there are other forces at work too. Anyway....

I also imagine that having 6 pucks instead of four will make it a bit less chattery since the pucks will tend to dig less.

Friction still puzzles me. Static and dynamic friction formulas don't care what surface area is, only the normal force.
But tires have alot to to with contact patch. Wider is better than long and skinny (maybe the tire deforms less?). Plus the ground is not smooth, the pavement is like a bunch of little teeth biting into the rubber.

I have TU's Kevlar unit. I think it's a Clutchnet clutch, based on the picture. I've been driving on it for almost a year. I have mixed feelings about it. Also, I haven't made it to the track yet.

The clutch was and is still chattery when engaged under light load at low RPMs: backing-up and crawling in heavy traffic. It shakes my hood pretty violently, though I have poly bushings in all three mounts. Under load, it is very smooth.

I've launched it hard many times on the street without issue. I have been having issues with the engagement point, but I think the issue is the adjuster or something else. Compared to the 6-puck ceramic I had in my CSX before, the clutch is a bit more street-friendly. It is not as grabby. I just wish it didn't chatter so much. Also, the ceramic is only good for 30-40k miles. I'm hoping the Kevlar will last longer.

HOLY COW! I had the same problem with my carbon-kevlar disk. I think it was clutchnet, some Polish sounding guy with a Polish sounding name answered the phone, it was the HOT econo street setup in the FMML days (6 years ago). I ran it with a TIII pressure plate from like, dealers direct or something like that.
I thought the problem was my flywheel the whole time. We were short on time and turned it on a brake lathe. yeah, I know. I even swapped out the flywheel years later with a ground one (when I tranny swapped) but it still shook the car like hell when you were being easy. I thought that maybe the damage had been done and that I effed up the clutch. It probably was the ficken disk the whole time!!

Ron

[Reaper1]

The coefficient of friction does not care about surface area, only about the two surfaces and the force holding them together. Thermodynamics do, however.

Wider tires work better for handling due to tread flex, sidewall deflection, heat dispersement, and keeping a more constant patch on the road.

Taller tires can work just as well, if not better in some cases, than wider ones for straight line acceleration.

It takes more force to break static friction than dynamic becuase of what is going on on a microscopic and molecular level. Once there is slippage, it is easier to keep the two surfaces sliding.

There is more to this explination, but I'm out of time at the moment. Once you atart messing with the formulas and do a couple of experiments it becomes a LOT more clear and easy to understand these concepts.

[MiniMopar]

Yes, I do remember that static > dynamic. However, I also remember that these "coefficients" are not only difficult to predict but are also not constant, even at the same temperature. It's like sliding your foot on dirt and then kicking your heel down. The force imparted is the same, but the dynamics of what is going on changes drastically.

Anyway, I think there is some of that with the 4 vs 6 puck clutches. You sacrifice more clutch (and flywheel) longevity with the 4 puck in exchange for more grabbing force with the same PP.

[Reaper1]

I also think that a dual disc clutch would be nice to have...though I don't know how much that would cost. I could keep a fairly ligth pedal and have a LOT more grip from the clutch!

Ideas on that anybody?

[RJ138]

I have the TU 4 puck ceramic and I love it. It did not take very long to get used to on the street.

What PP did you use with that clutch?

[Chris W]

We now offer several different pressure plates as well as disk options in our clutch lineup.

Pressure Plates
Stock TIII- Natural color
Ultimate- Blue (40% Increase over stock) Adjusted pivot points requires marginal peddle pressure increase
Extreme Yellow (20% Increase over Blue) Adjusted pivot points requires marginal peddle pressure increase
Dual Diaphragm Red (100% over stock TBI pressure plate) NOT recomended for street use.


By offering different levels of options it enables our customers to fine tune their selection to match each unique application. If you need assistance in choosing the right combinatiion for your vehicle don't hesitate to give us a call and we will be happy to work with you over the phone.

Chris-TU
602-76-BOOST

[moparzrule]

I've driven a TU 4 puck ceramic clutch (blue PP), took me about 5 minutes and 3 take-offs to get used to it. I now have a 4 puck, waiting to go in my car.
In my daytona I had a dual diaphram plate with an 8 puck ceramic (no idea what brand), wasn't that bad. I like a stiff pedal though. Never snapped a cable like most people say you will do, I believe thats just a myth that started because 1 person's snapped and it got gossiped down the line.