KEP pressure plate theory on clamping force

[Tippy]

Beginning to think these units wear out quick.

Awhile back, I sold IMR-Merlin my KEP stage II I had lying around. Back up a little though. After buying a new one, I found out KEP could have rebuilt the one I already had. So, I thought it'd be perfect to sell to someone and have it rebuilt saving a lot of money and everyone would happy.

We work a deal and I ship it KEP for rebuild. KEP had to replace the pressure plate due to the eroding of face material from the 6-puck metallic disc I had. While they inspected it, KEP calls me and tells me that the diaphragm is only holding to a stage I, that'd need replacement. Then, they tell me some other parts need replacing too. Damn! Now we're getting close to the cost of a new one. IMR-Merlin and I sort it out, and we proceed to rebuild.

Fast forward, I recently changed to a higher flowing IC and 75mm TB with 3" IC tubing throughout. Suddenly, 3rd gear doesn't hold. A stage II is rated for 650ft/lbs of torque - coupled with running a Kevlar disc, should yield higher.

It really bummed me out, because this is the 2nd time on the dyno where the clutch can't hold.

But lately, I noticed my pedal felt easier. Why?

That got me to thinking. These units probably have quick wearing parts allowing the diaphragm to lose pressure. If you think about it, only so many thousandths of wear can reduce spring force.

Anyone else experience this?

I think this may be an issue with these. I feel KEP needs to use harder materials.

I know what you're thinking, why don't you call KEP?! Well, I wanted to hear if I'm the only one thinking this or others have noticed/experienced the same.....

[lite75]

A metallic disk will hold better than a kevlar but don't expect smooth engagement.

[Rawknees'Turbo]

Originally Posted by Tippy

Back up a little though.

Yer so nasty, JustTheTIPpy!!!

Originally Posted by Tippy

But lately, I noticed my pedal felt easier. Why?

Why? Because your left leg was jealous of your right arm - Popeye for both!

Originally Posted by Tippy

I feel . . . (the) needs to use harder(ing) materials.

Yer really so nasty, Bro!!!


You're welcome!

[GJF]

Organic/metallic disc is all I use. They engage nicely without 4 or 6 puck sintered bronze engagement.

You don't see Kevlar used in race clutches, and there is a reason for it. Kevlar is real slippery by itself. If you overpower them they heat up and smear and usually stick to the pressure plate and or flywheel.

Kevlar is a very smooth engaging disc, but they are only for mild power. If the disc wears past its minimum thickness then you will have a lighter pedal.

[Ken911]

i have a kep 2 in mine also was going to send it back case it looks kinda glazed before it goes back in. Where is a good place for an organic/metalic disc. the last one i got was organic/ kevlar from imagine auto. this time it's getting an aluminum flywheel also.

[GJF]

Stock 930 will work. But I usually use the 996 or 997 unsprung disc.

[Ken911]

Ok thanks!!! Getting far enough along with the house to start thinking about the car again.

[Tippy]

All good points and will consider.

There's still something about these prematurely losing pressure.

If my disc looks fine, I guess I'll take it up with KEP.

My car is weekend driving at best. Don't think it should lose clamping force so quick.

[Ken911]

You know I had to adjust mine pretty often. I was driving it daily and it needed adjusted about once a month

[GJF]

Before you can make any statements like:

Prematurely losing pressure.......... with this statement being said....
What is the spring rate at the proper installed height?
What is the disc thickness?
What is the thickness of the pressure plate shoe? It could be worn as well.
Is the disc within spec or is it worn passed?
If the operator overpowered the clutch, the depending on the degree of temperature the diaphragm could have been compromised and lost spring tension due to excessive temps.
Bottom line if the clutch is abused or the wrong combination its not the manufactures fault.

[TurboKraft]

We find KEP is quite optimistic with their torque ratings.
Did a car recently that came in with a KEP alum plate and their organic+puck disc. By their rating, we should have been fine up to about 560tq at the wheels, but it slipped at 505wtq.

Conversely, Sachs is more expensive but conservative with their ratings. This that are claimed "up to 500tq at the flywheel" will hold 525wtq.

[mark houghton]

My KEP stage 1 worked fine for the maybe 12K I had on it before it got kind of "toasted" with everything else...and I mean everything. Never had to adjust the clutch after the new installation. I had no issues and loved it.

It might be for sale, with the disc and TOB for half price of new.

[Tippy]

Been reading around. I was always under the impression that Kevlar holds better than organic. Apparently not.

Another thing I read, if oil hits Kevlar, it usually dies easily. I'm pretty sure you can "burn" oil off organic discs since I never had problems on old Chevy's that had leaking RMS's and other gaskets. Anyways, I had a not so stellar install of the RMS - maybe oil got onto the disc?

I guess I'll pull it down and find out what is really going on. I'm going to see if KEP will give me the specs for the hardware that holds the diaphragm on and see if they are within spec. It sure does feel a lot easier than it did new thinking the parts have worn.

TBD

[xbmwguy]

hey tip. i thought the same thing when i went from stock to the stage 2.i think you just get used to it. i am on my second organic disc and its holding 627#s torque. left leg gets a little stronger

[Tippy]

Wow! 627 wheel tq?

What brand disc are you running?

[GJF]

Any organic disc. 930/964/993/996/997 it doesn't matter. Sachs preferably....
My gawd tip! I told about this a year or so. When
You going to listen? I have never steered you wrong before

[Tippy]

LOL, my bad!

[Ollies930]

Does anybody have any experience with SPEC Clutches? They list many different options on their web site all the way up to 980ftlbs, all with single disc.

[xbmwguy]

It's the kep organic

[GJF]

Juan tried them a while back. I don't think anything they sent held power even close to their claims. Hopefully he will chime in to clarify.