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Discussion Starter #1
I hear so many trans builders says that to make a trans live a long life you need to stay away from a aggressive clutch. What about the Centerforce dual friction clutch?. I have done tons of clutch searchs in the past and it seems like the CF DF clutch has a lot of fans that say the pedal is almost like stock but it holds like crazy. So I was just wondering where this clutch fits in as far as agressiveness goes compared to others. Are the twin disc clutchs that use 2 organic discs even more aggressive or is it just a different design?
 

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All depends on the power the car makes. A car that makes 400 HP takes a much different clutch than 800 HP. Also the weight of the car plays a factor. For example if you put a clutch that is to aggressive for 400 HP and is hitting the tire to hard. You pull that out and put it in something that makes 800 it might be right on or little on the light side. But along those lines the transmission for 400 vs 800 HP is greatly different as well.

So specifically talking about the clutch you are talking about. I would say if the car is close to stock power and stock weight the dual friction clutch is to aggressive. If you are making 300-400 at stock or little over stock weight it will be better suited. Rough numbers here, every car is different.
 

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Discussion Starter #3
That makes sense. We are at #3100 w/driver and hope to be about 550hp at the flywheel with our 363.
 

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Ideally, the clutch's holding power should be matched to the power you make with very little reserve. Here's a simplified explanation- let's assume the engine makes 500ft/lbs and the clutch's capacity is 700 ft/lbs. When you launch the car, the clutch is going to draw 700ft/lbs…the 500ft/lbs that the engine is making at wot plus another 200 ft/lbs of stored inertia energy that will cause the rotating assy to lose rpm. That extra 200 ft/lbs makes the launch more violent, but as soon engine rpm is drawn down to the point that engine rpm sync's up with vehicle speed, rpm ceases to drop and that transfer of an additional 200ft/lbs of inertia energy stops. The downside is that after you have lost the rpm and used that inertia energy, that spent energy then has to be paid back in full before the engine can recover the rpm that it lost. That inertia energy transfer which made the car launch harder initially now slows the car, as it reverses and some of the engine's power must be used to recharge spent inertia energy back into the rotating assy. In the end, that temporary 200 ft/lb boost did not actually net you any performance gain.

Why subject your transmission and drivetrain to that extra 200 ft/lbs if it doesn't net you anything?
What if that extra 200 ft/lbs of holding power gets you a broken transmission?

If a clutch with only 600 ft/lbs of capacity were used it would slip roughly twice as long, which means the car would be traveling faster at the point where rpm and vehicle speed finally sync up...less bog. Not only does the transmission see less abuse, but the engine doesn't lose as many rpm after launch and after the shifts...the engine will be pulling from a higher average rpm where it makes more power.
 

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Discussion Starter #5
Weenburner, I have to be honest. I had to read that reply over and over because most of it went right over my head. But the more I went over it, the more I understood what you were saying and it made perfect sense. I never even gave that a thought. I guess I was thinking that a clutch is either clamped or not clamped and never thought above the slippage factor before it actually becomes locked 1-1 or the enertia factor. I love to hear from guys like you that actually understand all of the technical stuff. I appreciate you taking the time to explain it for guys like me that want to learn. Thanks!
 

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That's a pretty big can of wiggling worms there. If you watch the Coyote cars you might be surprised at what you see. Head games and technique. The left foot is in more control of the situation than you might think.
 

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That's a pretty big can of wiggling worms there. If you watch the Coyote cars you might be surprised at what you see. Head games and technique. The left foot is in more control of the situation than you might think.
Is that where you can have a stiff clutch and control the slippage and keep the engine at the rpm you want it by using your left foot to allow/not allow more or less slippage? Some guy told my son years ago to practice his launching and the goal was that as you release the clutch be able to keep the engine in its sweet spot rpm wise with clutch slippage while it is launching and keep it there until the engine and trans meet at the same rpm and the clutch is fully engaged 1-1 and then the rpms can go up from there. Very hard to do! Is that similar to what you are thinking or make any sense?
 

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I've run the CF DF with about 400hp natural and about 500hp supercharged. In my opinion it is too much clutch (~3000lbs base). It hits the tires very hard. If I could do it over I would have used a King Cobra or Ford Heavy duty plate (~2600lbs) with the DF disc. I like the DF disc for bracket racing as it recovers from slip. It has been my experience that organic does not recover if you accidentally drive into the clutch during the burnout or on the starting line.
 

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If I could do it over I would have used a King Cobra or Ford Heavy duty plate (~2600lbs) with the DF disc. I like the DF disc for bracket racing as it recovers from slip. It has been my experience that organic does not recover if you accidentally drive into the clutch during the burnout or on the starting line.
I know this is old, but I've come across while doing a search, ( some people do that ) Ive got a spec stage II in my car now and it's just too tight, Ive got an approximately 360-380HP engine, in a 3,000 pound car, I need a clutch that's not so aggressive, but wondered how long a king cobra would hold up to going to the track as often as twice a month.
 

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Why not just shim the pressure plate to reduce clamp load?
 

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That's exactly what I did with a Ram King Cobra 432 PP. The diaphragm spring didnt go over center at an .028 gap. I guess the track will be the final test. At least then I will know after some of my recent escapades that I found personally embarrassing if this will work at RPM. I figure the disc type and material will tell me if it will hold 500 HP without beating my tranny up to much.
 

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Why not just shim the pressure plate to reduce clamp load?
I thought about it, but figured it would be a trial and error thing, and would just rather get a new one that's more suited to what I need and throw it in.
 

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I know this is old, but I've come across while doing a search, ( some people do that ) Ive got a spec stage II in my car now and it's just too tight, Ive got an approximately 360-380HP engine, in a 3,000 pound car, I need a clutch that's not so aggressive, but wondered how long a king cobra would hold up to going to the track as often as twice a month.
I have tried three king cobra clutches, two from Promotion performance ("blue-printed king cobra with an organic/kevlar disk") and none of them lasted long at all. I made a few decent passes before they started slipping and I only dip into the 11s at 3200lbs. I wasted a lot of time and money and it was really frustrating not being able to make a good pass. You might want to check out weenburner's ClutchTamer with your spec stage 2. Although the stage 2 has a kevlar disk and I think it'll glaze if you slip it. Or maybe try a ceramic disk with the king cobra...I wouldn't use an organic or kevlar disk for drag racing from my experience.
 

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I know this is old, but I've come across while doing a search, ( some people do that ) Ive got a spec stage II in my car now and it's just too tight, Ive got an approximately 360-380HP engine, in a 3,000 pound car, I need a clutch that's not so aggressive, but wondered how long a king cobra would hold up to going to the track as often as twice a month.
Ive used a heavy duty organic disc with that kind of power. I put about 150 high 11sec passes on it (video below). Held no problem and was easy on the starting line. However you cant slip it. I messed up bumping the car in with too much brake pressure and I cooked the disc. The clutch didnt recover. A metallic disc would have recovered.

 

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I thought about it, but figured it would be a trial and error thing, and would just rather get a new one that's more suited to what I need and throw it in.
Local guy I race with Nick5oh on this board shimmed his Spec clutch with great results. He put an AFR headed 302 into the 10s. However he doesnt street drive it.
 

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I have tried three king cobra clutches, two from Promotion performance ("blue-printed king cobra with an organic/kevlar disk") and none of them lasted long at all. I made a few decent passes before they started slipping and I only dip into the 11s at 3200lbs. I wasted a lot of time and money and it was really frustrating not being able to make a good pass. You might want to check out weenburner's ClutchTamer with your spec stage 2. Although the stage 2 has a kevlar disk and I think it'll glaze if you slip it. Or maybe try a ceramic disk with the king cobra...I wouldn't use an organic or kevlar disk for drag racing from my experience.
I have a customer that has what many consider to be a VERY aggressive clutch in front of a G-Force T5- a Ram Powergrip HD. At 2985lbs he was breaking 1st gear often running [email protected] with a best 1.44 60', after adding the ClutchTamer he leaves at 6400rpm and is down to [email protected] 1.35 60' without breaking the T5.
 

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I have a customer that has what many consider to be a VERY aggressive clutch in front of a G-Force T5- a Ram Powergrip HD. At 2985lbs he was breaking 1st gear often running [email protected] with a best 1.44 60', after adding the ClutchTamer he leaves at 6400rpm and is down to [email protected] 1.35 60' without breaking the T5.
I installed the ClutchTamer over the winter and went to the track last weekend but had ignition issues. I look forward to actually seeing what this thing can do!
 

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I installed the ClutchTamer over the winter and went to the track last weekend but had ignition issues. I look forward to actually seeing what this thing can do!
I put one on my car, too. I thought I could maybe get it in the ballpark on the street, but all I do is spin. Weenburner, I haven't contacted you yet because I have no clue what I'm doing!
Sorry for the hijack.
 
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