American Powertrain Science Friction Clutch roasted after 200 miles

[69ProTouring]

Was hoping I could get some advice for someone who might have experience with different clutches on the market.

I have a 69 Road Runner.

I'm running a Gary Stanton Gen III Hemi 7.0L, 605 HP, 550 ft/lb of torque. Here it is -> http://www.bpeusa.com/BPEGS75600SRT8.asp
I also bought my complete drivetrain from American Powertrain, which included a Hydramax Hydraulic Clutch Kit with a Science Friction Street Slayer ClutchKit. The clutch kit was rated for 545 - 755 ft/lb of torque.

Anyhow, I had a shop install it, and drove it around for a couple hundred miles, but I had 2 problems. 1 - The clutch pedal was stiff! Was like driving around doing leg presses. 2 - I barely lifted the clutch pedal off the floor and it would engage. It just didn't seem right so I took it to another shop to drop the transmission and take a look. Here is what they found (pictures below). Clutch is fried! I don't really know what to make of this. I really didn't drive it hard, and only put about 200 miles on it. I'm not sure if it could be that it was installed improperly and it was constantly rubbing or what. I really didn't drive it hard. Not sure if I should get a different type of clutch either. I've seen dual clutches on the market, not sure if I should go that direction. Anyone ever seen anything like this? Any ideas?

Appreciate the advice. Thanks!

 

[5.7 hemi]

I have the same clutch set up and htb, and want to know did the shop get the .150-.200 clearance from the face of the htb to the fingers? Doesn't seem right to me that you'd have this kind of problem.

 

[coloradodave]

I'd like to see the flywheel surface as well. What is your rear end gear ratio and tire size? It's been my experience that ceramic puck style clutches will show some discoloration to the friction surfaces of the pressure plate and flywheel that don't hinder the operation of the clutch. The heat build up on your pressure plate looks to be excessive, like there wasn't sufficient clearance given to the throw-out bearing when the hydraulic set-up was installed. Can you show us a picture of the diaphragm fingers where the bearing engages? As a side note, the pedal pressure with a correctly set-up hydraulic clutch should be relatively easy. Will look forward to your pictures.

 

[69ProTouring]

Really appreciate your help. Here is the picture of the flywheel. I asked the shop to send me the other picture.

They said they're going to call me today, so hopefully I hear some information.

In terms of replacing this clutch, do you think I should go with the same one? McLeod, Centerforce? Here's the McLeod I was looking at - http://www.summitracing.com/parts/mcl-75321/overview/

 

[lewtot184]

i haven't messed with manual trans in years but in my opinion that's the wrong disc for something to drive. i even wonder if a diaphragm pressure plate is good for 600hp. i think i'd look into one of those twin disc set-ups with organic facing on the discs.

 

[69ProTouring]

Here are the other pics of the diaphragm fingers.



- - - Updated - - -

i haven't messed with manual trans in years but in my opinion that's the wrong disc for something to drive. i even wonder if a diaphragm pressure plate is good for 600hp. i think i'd look into one of those twin disc set-ups with organic facing on the discs.

That's what I was kind of wondering myself. It's supposed to handle up to 650 ft/lb of torque according to the spec sheet. the twin disc clutches seem to be able to handle a lot more (700+). It doesn't seem right that I'd have to go that heavy duty would it?

- - - Updated - - -

More pics the shop sent me.

 

[lewtot184]

i think the clutch disc face material is wrong for the application. a clutch disc that will be driven needs to have some "flexiability" to it. from what i can see you have something that's more of a totally engaged or disengaged scenario; other wise a race disc. i've never known a diaphragm clutch to be able to handle high torque loads. you need some professional advice.

 

[5.7 hemi]

Call Tony @ AmericanPowertrain, good guy to deal with.

 

[moparstuart]

is this a Kevlar surface ??? My American Power train Science friction is Kevlar I have about 2000 miles on it now with no problems

 

[69ProTouring]

is this a Kevlar surface ??? My American Power train Science friction is Kevlar I have about 2000 miles on it now with no problems

These are the ceramic pads. The kevlar surface seems to be much more forgiving.

 

[5.7 hemi]

There is a break in period for the ceramic clutch disc. You didn't just get in it and start hammering on it, did you? You need about 500 miles of stop/go before you drop the hammer.

 

[69ProTouring]

There is a break in period for the ceramic clutch disc. You didn't just get in it and start hammering on it, did you? You need about 500 miles of stop/go before you drop the hammer.

Looking back, yeah I probably did a bit.

 

[moparstuart]

There is a break in period for the ceramic clutch disc. You didn't just get in it and start hammering on it, did you? You need about 500 miles of stop/go before you drop the hammer.

yup they told me 500 miles break in on the kevlar also

 

[Jeremiah]

In my experience you would have to get that thing WAY hot to make the flywheel look like that. That means slipping at high RPM. You would have to ride the clutch for a loooooooooong time to get it that hot. Did you smell the clutch burning? Did you see the tach "flash" when you hammered it? That is all signs of clutch slippage from what I have seen in my own car with the disc was starting to slip.

 

[moparstuart]

In my experience you would have to get that thing WAY hot to make the flywheel look like that. That means slipping at high RPM. You would have to ride the clutch for a loooooooooong time to get it that hot. Did you smell the clutch burning? Did you see the tach "flash" when you hammered it? That is all signs of clutch slippage from what I have seen in my own car with the disc was starting to slip.

or did some ya hoo at the first shop that did the install take it out for a joy ride and fry the hell out of it

 

[coloradodave]

As with others here, I believe that the pressure plate was not exerting it's rated pressure on the disc and that the disc was constantly slipping, creating tremendous heat. The diaphragm fingers look good, as does the hydraulic T/O bearing, but if you only put 200 miles on it it is entirely possible that it was not adjusted correctly when installed, and still looks good. American Powertrain is a great company to work with, so I would start there; not accusing them, but telling them you are looking for an answer. I would pay to send the complete set-up back so that they can test the pressure plate and T/O function. The fact that the pedal pressure was extreme leads me to believe that something was amiss in the bellhousing. Per American Powertrain's site, that ceramic disc doesn't require a break-in period. They also tout the easy pedal pressure, so I think you'll either have your answer to your problem, like a defective part, or a professional opinion stating it was installed incorrectly. Please keep us informed of what's happening with this. I think that according to what you've told us and A/P's site, this was a decent choice for your car.

 

[hangn0ut]

That type of pressure plate is noted for having a light pedal. They actually would have the pedal get lighter the farther in it went. Until it went overcenter and went to the floor and stayed there. That the pedal was stiff I think points to the release bearing. Did you get any feedback from the pedal? Did it feel rough? Uneven? Did it make noise? Was the pedal travel excessive? Or too quick? Wrong bearing perhaps. While the pucks look racy, the disc looks street with a sprung hub and probably a marcel. Marcel is a slightly wavy disc between the two sides of the disc. It provides a cushion effect. The flywheel looks smoked. Hope it can be saved. If it had been run with an organic disc, you would have smelled it burning right away. I love McLeod.

 

[69ProTouring]

So it's been a while since I've dropped an update on this topic. To let you know what kind of nightmare this has been, the transmission has been in and out 3 times, and i'll save you the suspense, it's going to have to come out again.

The first thing we did when this happened, was we change all the part out exactly as they were before. The idea was that the first person who installed it must have installed it incorrectly. What we found, however, was the pedal was still far too stiff. Wasn't going to work long term. We did find that the first guy set up the shims so that there was no clearance between the bearing and the fingers, so it was possibly riding that the whole time which was making it slip. Possibly causing what we see in the pictures above.

The 2nd time it was out, we tried to use a different master cylinder. I found a wilwood that had a longer throw, 1.4 inch rather than 1.2. The problem in this case was that the clutch needed 3/4 inch to release, and we set it up with .1 inch clearance. So when we were getting it installed, we discovered that the throwout bearing didn't have a long enough throw to push the 3/4 inch that it needed. The only way to get it to work was if the bearing was riding on the fingers like it was before. It would work, but we'd roast the clutch again.

The 3rd time (and i have pictures below), we decided to use the McLeod racing throwout bearing. What a nice piece compared to the American Powertrain piece of junk. The throw on the bearing was long enough and allowed us to get enough clearance. And finally, the clutch was installed, and the pedal was nice. Sooooo much nicer than the American powertrain powermax setup! But today, i saw a drip under the transmission, and sure as ****, the throwout bearing is leaking. The throw must be too far for that one as well even though it's not pulling all the way out like the hydramax one was.

We called up McLeod, they said they have a twin disc clutch that only needs a 1/2 inch of throw to disengage rather than the 3/4 that the Science friction needs.

I feel completely taken and ripped off by American powertrain. I'm most likely going to change everything out again. I will let you know what setup we go with once this finally works, but I am done getting ripped off by American Powertrain.

Bearing pictures.