Exedy Hyper Carbon Clutch

[71RS/SS396]

Anybody used an Exedy hyper carbon triple disc clutch? I've been researching clutches for my track car project and would like to run a triple disc clutch but, the car will see some limited street driving and I know most triple are tough to drive on the street but, the Exedy is suppose to be tolerable. I'm looking for feedback from anyone that has used one.
http://www.horsepowerfreaks.com/part...iple_Disc/7047 (http://www.horsepowerfreaks.com/partdetails/Exedy/Clutch/Clutch_Kits/Hyper_Carbon-_Triple_Disc/7047)

[andrewb70]

Anybody used an Exedy hyper carbon triple disc clutch? I've been researching clutches for my track car project and would like to run a triple disc clutch but, the car will see some limited street driving and I know most triple are tough to drive on the street but, the Exedy is suppose to be tolerable. I'm looking for feedback from anyone that has used one.
http://www.horsepowerfreaks.com/part...iple_Disc/7047 (http://www.horsepowerfreaks.com/partdetails/Exedy/Clutch/Clutch_Kits/Hyper_Carbon-_Triple_Disc/7047)

If you are going to spend that kind of money on a clutch, you might as well look for a true carbon/carbon design, instead of the carbon/steel. The problem with carbon/steel clutches is that it is very easy to warp the steel floater plates because they can't tolerate the heat like the carbon can.

Andrew

[71RS/SS396]

Any suggestions on a carbon/carbon clutch? Are they usable on the street?

[andrewb70]

Any suggestions on a carbon/carbon clutch? Are they usable on the street?

Before answering those questions, what is it that you are trying to accomplish? How much power will the engine be making? What is the intended purpose of the car?

Andrew

[71RS/SS396]

The car is primarily going to be used as a track car in ASCS and open track days, but it will be street driven for some of the events. The current engine is a modified LS7 aprox. 550-575 hp, but I plan to up the power in the future once I improve my driving skills. Kyle Tucker is building the car and I've had conversations with him about the benefits of a lighweight low inertia clutch with regards to shifting. I've driven his test car and the triple in his car is way to aggressive for me for the street but shifts very nice once your rolling, it's pretty much like a switch so that's why I started looking at alternative options and Chuck Mallet suggested this clutch.

[andrewb70]

Tim,

It sounds like you are looking for a clutch that is not exactly a racing clutch, but one that will reduce the moment of inertia (MOI) as compared to a stock style clutch. Before we go further, lets quickly review the three basic elements of what determines a particular clutches torque capacity.

1. Spring pressure. This is straight forward; the stiffer the spring, cetiris paribus, that is acting on the pressure plate to clamp the disk against the flywheel, the higher the torque capacity.

2. Disk surface area. This is also fairly straight forward; the greater the surface area, cetiris paribus, the greater the torque capacity. Surface area can be achieved either by changing the diameter of the disk, increasing the number of discs, or any combination there of.

3. Coefficient of friction between the disk and flywheel/pressure plate. The greater the friction, cetiris paribus, and higher the torque capacity.

MOI is a function of two variables: the mass and the diameter. The diameter will determine the center of the rotating mass, which is much like the concept of the center of gravity.

Now, the lower MOI of the entire driveline (crank, flywheel, clutch, transmission internals, u-joints, driveshaft, rear axles, wheels, tires) the quicker the everything will be able to positively accelerate or negatively accelerate (decelerate). Remember that MOI is a function of diameter as much as the mass, thus, when you look at the list of the various components, the flywheel and clutch are the "low hanging" fruit out of the rest of the components. In other words, it is the most easily altered component of the whole drive line system (wheels and tires being the other components) that can be changed that will result in a significant impact on the MOI of the entire driveline.

Let's look at the extreme examples: a NASCAR race car and the new Cadillac CTSV. Current NASCAR rules state that the clutch disk diameter may not be less than 7.25" and carbon clutches are not allowed. So the basic NASCAR bellhousing kit looks like this:

https://static1.pt-content.com/images/pt/2012/01/15029781_151-1.jpg

The starter is mounted on the bellhousing and engages a small ring gear that is mounted on the clutch cover. Components are a light as possible, given the restraint of the rules.

The CTSV clutch looks similar to this:

https://static1.pt-content.com/images/pt/2012/01/DSCN1271_900-1.jpg

It is a massive dual disk clutch assembly that on the CTSV is mounted to a very heavy dual mass flywheel. I don't know the exact weight, but I would not be surprised if the flywheel and the clutch assembly is over 70 pounds. Compare that to the NASCAR set-up which is probably less than 20. Also remember that MOI is not only about the weight but also the diameter.

The basic moment of inertia formula is: mass x distance squared

Given that formula you can see that changes in diameter will result in greater reductions in MOI than changes in mass.


So where does this leave you? Hopefully all this will give you a better understanding of how the various components work together, and you will see that clutch selection is filled with compromises. The lower the MOI, the quicker the car will accelerate, but it will also be hard to drive on the street and will buck and jerk when you are trying to drive gently at low speeds. The greater the MOI the smoother the driveline will feel, the easier it will be to drive on the street, at the expense of ultimate acceleration.

You have to be brutally honest with yourself about how the car will be used. If this car will be used primarily (95% race and trailered to events) for ASCS and open track days, then you should go with a low MOI clutch and live with the issues that are associated with those set-ups. If, on the other hand, you will drive this car on the street 95% of the time and do 1-2 events per year, then you should really think about a clutch set-up that will be easier to drive.

Now, lets get down to some specific recommendations. If money is no object, and you want a low MOI clutch that will live on the street, then there is only one option:

http://www.lgmotorsports.com/Tilton-Triple-Carbon-Clutch

That is a Tilton triple disk, carbon/carbon clutch on a lightweight flywheel. You can specify the power level, which, in this case, is altered by changing the spring. You can also alter the weight, but if this is truly going to be a 95% track car, then go with the lightest assembly (14.9 pounds) you can. The carbon/carbon clutch will wear great and can be shimmed as the disks wear. Completely rebuildable, etc...

Quarter Master also offers a triple carbon/carbon set-up, but none of their vendors seem to have packaged it as neatly together as LG has done with the Tilton components.

A much less expensive, but a very good system is sold by Pfadt:

http://www.pfadtracing.com/catalog/product_info.php/cPath/26_36/products_id/240

It uses a Quarter Master (QMI) 8.5" clutch in a dual disk configuration with what QMI calls Rally disks. They are thicker than the typical disks that are used on the metallic triple disk clutches. The flywheel that is used with the Pfadt kit will also accept 7.25" clutches, so you can change the set-up later, either to a carbon/carbon clutch or metallic 7.25" assembly.

A good "compromise" would be the RPS carbon/carbon:

http://www.lgmotorsports.com/RPS-Billet-Carbon-Twin-Disk-Clutch

Higher MOI than the Quarter Master or the Tilton, but should have great driveability.

Hope all that helps...

Andrew




The car is primarily going to be used as a track car in ASCS and open track days, but it will be street driven for some of the events. The current engine is a modified LS7 aprox. 550-575 hp, but I plan to up the power in the future once I improve my driving skills. Kyle Tucker is building the car and I've had conversations with him about the benefits of a lighweight low inertia clutch with regards to shifting. I've driven his test car and the triple in his car is way to aggressive for me for the street but shifts very nice once your rolling, it's pretty much like a switch so that's why I started looking at alternative options and Chuck Mallet suggested this clutch.

[71RS/SS396]

Thanks for the info, it gives me a few more options.

[andrewb70]

Thanks for the info, it gives me a few more options.

If you just want options, there are dozens of options, but how will you gauge what is right for you? LOL

Andrew

[71RS/SS396]

I will have to mull it over, likely no matter what I decide it will be some sort of compromise it always is. I'm going to ask Kyle which quarter master triple he has, so that may eliminate one choice. Money isn't the deciding factor but I certainly would hate to spend 4K-6K on a clutch and be disappointed with it ,but I also don't want to cheap out and then end up spending the money later anyways.

[andrewb70]

I will have to mull it over, likely no matter what I decide it will be some sort of compromise it always is. I'm going to ask Kyle which quarter master triple he has, so that may eliminate one choice. Money isn't the deciding factor but I certainly would hate to spend 4K-6K on a clutch and be disappointed with it ,but I also don't want to cheap out and then end up spending the money later anyways.

Clutches are most certainly an exercise in compromises. Also remember that clutches are wear items that will ultimately need to be replaced, or at the very least, rebuilt. Again, you need to be brutally honest with yourself as to how the car will be used. Good luck on your project.

Andrew

[71RS/SS396]

As I stated earlier the car is for track use I have plenty of cars to cruise in. I want this one to be purpose built for the track other than the little bit of street driving I will have to do to participate in the events everything else on the car has been designed and built with that in mind.

[andrewb70]

As I stated earlier the car is for track use I have plenty of cars to cruise in. I want this one to be purpose built for the track other than the little bit of street driving I will have to do to participate in the events everything else on the car has been designed and built with that in mind.

Then I would really consider the Tilton carbon/carbon. It will have the best street manner of any racing clutch. I also believe that the LG / Tilton setup includes a throw out bearing, but you'll have to double check that. If it was in the my budget I would definitely use that setup.

Also check with QMI. They may have a similar setup for less money.

Andrew