Then in that case i will stick with the ACT , that TT runs 9's on.

 

After reading over lots of threads like this I'm pretty much set on getting an ACT or comparible single plate.

 

Exedy Twins will hold up to 750HP (HP stat from Exedy catalog) and the smaller diameter (centered weight) creates a lower inertia, allowing very fast up and down shifts for street, circuit, and auto-x. The 7000 RPM launch is where we see people get into trouble. I know these clutches are capable of transfering the power of a launch, it's really just a matter of allowing the heat that is generated to dissapate before attempting to drop the clutch again.

 

well I heard that ACT has grinding/blocking gear issues on high RPM ... If thats the case then issue still not solved.


The only thing that is not good about my Exedy is that you have to wait until its worm which takes about 10 min, if it's not worm then you are out of luck.

 

*cough* cusco is VERY good *cough*

 

I just wanted to throw in a couple of comments after reading this whole thread, which was actually very good reading.

1. Clutches hold torque, not horsepower. When you are shopping for a clutch and talking to vendors/companies, ask them about the torque rating. You should avoid any company or vendor that starts quoting horsepower ratings. Just say "thank you" and hang up the phone.

2. LogicPerformance provided some very good evidence on the quality and design of the Exedy twin plate clutch setup. Whether it was biased or not, I don't think that's the point. Read past any bias and look at the facts. Let me explain...

I have a Materials Science Engineering degree, and also used to work at a job that performed failure analyses on metal parts (not cars or clutches, actually power plants parts). The Rockwell testing that was talked about as well as the warping is all due to the design of the part and the ability of the part to uniformly heat and cool. Any metal plate that is heated/cooled more on one side than the other will warp. (If you don't believe me, buy a big plate of metal, take a torch to it until one side heats up a lot and let it cool...after it cools your plate will look like more like a bowl than a plate.) There are only a few ways to avoid this warping:

1. Attach the plate to another rigid object, making the plate rigid. This will minimize warping somewhat, but this will cause the part to build internal stresses, and eventually crack, if the stresses of heating/cooling are above the yield strength of the material. Or the metal can also fatigue through repeated heating/cooling if restrained by another object. Not really a good solution. This solution really isn't possible on the 'floating' metal disc in the clutch assembly, anyway.

2. Allow heat transfer from the plate to be as uniform as possible in both directions. This is accomplished by created the object perfectly symmetric, but also deals with the environment around the plate. The environment on both sides of the plate needs to be symmetric in its abiltiy to transfer the heat from the plate. If one side is a better heat sink than the other, the plate will warp (if the heat is great enough or the metal is thin enough not to support the stresses). I would guess in the design of a clutch, this would be pretty challenging. I mean, one side leads to the flywheel/engine and one side leads to the transmission. How can you definitely ensure equal heat dissipation in both directions?

3. Use a material for the plate that is either a) strong enough or b) thick enough to withstand the stresses involved in non-uniform heating and cooling of the plate. Non-uniform heating/cooling will impose stresses on the plate, but the properties of the plate (mass, thermal conductivity, etc) all play a role in determining how much heat the plate can take before yielding to the stresses and warping. Obviously, one easy solution is to increase the mass. Maybe a better solution would be to use a better material.

4. Just don't launch you car from 7,000 rpms repeatedly, because no material will stand up to that.

Seriously, though, I'm just trying to shed a little light on the subject. If the plate is too thin that a certain amount of heat begins to warp it, perhaps Exedy needs to go back and look at the design again. Maybe we just drive are cars more agressively than the clutch was designed for.

All in all, I just think LogicPerformace was giving us facts. Use them as you wish, but always seek knowledge about the subject.

Eric

 

As you noticed mattgold is from exedy. We are not bad mouthing exedy at all its a great clutch for 95% of the people out there. But if you make 600hp its a ****ty clutch to run because it warps quickly.

Chris

 

Dear Logic - how many 600 whp Evos do you guys run these days?

 

Grinding gears is just a mitsu trademark

The DSM's did it so I imagine the EVO will have the same problem in years to come.

Chris

 

Why havent you called me back after I left you 3 messages? Do you not want to sell more dynoflashes? Why do you call me to ask the price of a twin disc? Seems like you just come on here to put people down sport, you have not put one piece of useful information in this post and you are supposed to be a good standing vendor in this community. So why not tell us your thoughts on your clutch al.

Chris

 

Well put eric.

 

Bad mouthing Exedy - no - Posting with the intentions to advertise RPS under the guise of "research", maybe.

Was your "research" extensive? No.
Were there identical conditions for all cluthes "tested"? No.
Was the testing contucted with any control of some sort? No.
Did the "research" include all possible "Twin Plates" for objective comparison? No.

Those are critical things that are needed when testing anything... but I digress.

As for this - Maybe it would be more appropriate to say the Exedy is a great clutch for 95% of people... but if you launch your car at 7000RPMs (poorly), and are making too much power for the clutch then you may fall into that 5%. I believe you can destroy *any* clutch put under the right abuse.

Just to take it back to "by the numbers" as your post implies... of the 100's of these clutches Exedy has sold, less than 1% has come back for inspection / warranty / replacement. Of that sub-1% most have been returned due to incorrect clutch / power level and even so - the customers have been treated fairly. I have already seen a destroyed RPS, and how many RPSs are on the market? 10? 20? 1 return from 20 = 5% return rate. Which - now that I think about it - explaines posts like this.

Regardless, Exedy is making an honest effort towards the Evo community, and has already introduced a heavier clamp load P. Plate for the higher HP Evos - and will continue to refine and revamp the parts as the users needs continue to grow.

Sincerely,

-Matt Gold

 

Your talking JDM matt I do not understand And its clearly stated in like 5 posts that exedy's are a great clutch for 95% of the drivers out there. Where do you get your #'s for RPS? Lets see some pics of this failed RPS clutch. Put some back in to your claims.

Chris

 

*cough* Exedy makes it *cough*

-M

 

LoL... The company is getting to me! ^_^

My numbers for RPS are "?"... how many are out there? Maybe you can enlighten us, and maybe *one* of their users can chime in on this.

There is ONE, isn't there?

-M