FE Power Forums
FE Power Forums => FE Technical Forum => Topic started by: c9zx on July 04, 2025, 10:23:35 AM
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I'd like to benefit from everyone's experiences with Long and Diaphragm style clutches. I've only used Long style clutches with 60's-70' Fords. And the pedal effort is significant and its can take a toll on mechanical linkage, as well as my left leg. However, they have always worked well. Will the diaphragm style work well and reliably with 6000 + RPM shifts? Will it be easier on linkage and my left leg?
The car is a 1966 Cyclone. Trans is wide ratio, converting to big input and rebuild. Engine will be 462 (if THIS block checks good). TFS heads, ED RPM intake, around 11.0:1 SCR, long tubes (Doug's), Hydraulic Roller cam (looking for peak HP at 6100-6200 RPM if possible), Harland Sharp rockers, 850-950 Holley. Unless I screw something up, it should make good power and make me smile every time I drive it. Thanks for all the input everyone. Chuck S. (OK)
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Long style!
Diaphragm plates are a GM design, not really compatible with older Ford vehicles without some modification.
Modern Long style pressure plates are not the 3000-3500 lb plates of the 60’s. Pedal pressure is not bad at all.
I’d recommend a RAM Powergrip HD. It would be rated for 650 hp and I've never had anyone complain about the pedal pressure.
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The "Long-Style" is the superior design of clutch from the mechanical function intent standpoint. The "Diaphragm" is just a "cheaper" and resultantly "poorer" execution in the design of a clutch; and yes, was originally popularized in U.S. automotive production by G.M.; but today, it's what almost everybody utilizes in O.E.M. production vehicles. This is not only due to the costing advantage, but also it 'does' present a lesser peddle effort in comparison to the Long-Style, which is an important consideration for the O.E.M.'s today and which can prove to be particularly advantageous for those with tired left legs. :)
The problem here, is that the clutch peddle linkage in the Ford products of this period were developed with lever-ratios intended for the Long-Style, and often when coupled to the Diaphragm units presents a foreign feel, often operating in a less progressive nature, more closely to just an "in-out" system; which I do not appreciate. ;)
Scott.
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Experience I had with my diaphragm was that it it wouldn't re-engage above 6k power shits until the rpms dropped. did ok with off the throttle quick shifts.
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I've used diaphragm clutches for decades. They work fine in a Ford application. I'm using a Center Force Dual Friction in my Fairlane. They need to be properly adjusted for the right pedal feel and to make sure you don't over center the diaphragm spring and stick the clutch at high RPM. You have to remove the Ford assist spring from the pedal as this will also cause the clutch to stick. Pedal effort without the assist spring is not very high. You can also put in a lighter spring if you want a lighter pedal effort. Everyone is right in that the factory clutch setup wasn't designed for a diaphragm clutch, but it certainly is easy enough to get it to work with very good results.
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Everyone seems to think that a diaphragm pressure plate makes the clutch easier on your leg, but that's not the reality of it.
The common McLeod 11" Long pressure plate that they use in their clutch kits is an 1800 lb pressure plate. The McLeod 11" diaphgram plate that they use (it has an 11" Long bolt pattern so that you can bolt it up to a Ford flywheel) is 2400 lbs.
If you switch over to RAM, their 11" Long pressure plate is 1800-2400 lbs, depending on which kit you buy, and their 11" diaphragm pressure plate is 2200-2400 lbs, also depending on which one you buy.
You gain nothing by switching to diaphragm, unless your only other choice is a 3000-3500 lb Long style pressure plate from the 1960's.
In the old days, there weren't that many friction materials available, so you had to work with an organic disc and a lot of clamping load. Today, we have better materials including sintered bronze, sintered iron, Kevlar, etc., and it allows the pressure plate load to be greatly reduced.
Never really was a CF fan. A decade or so ago, I moved a lot more drivetrain parts than I do now, and the amount of emails I got from guys wanting to switch because their clutch systems didn't work really surprised me. Now granted, it was from guys with lighter vehicles, like the Cobra replicas, light Mustangs, etc., but once I switched them over to a RAM/McLeod, their issues went away.
I'd have to dig a little bit, but I think with a big input Toploader, your choice is going to be necked down anyway. Trying to get that input shaft to work with a diaphgram pressure plate would be pretty much impossible. Even some of the Long style pressure plates have to have the fingers modified to work with the larger trans.
Both RAM and McLeod offer 1-3/8" clutch kits in a Long style. Again, I slightly favor the RAM for higher horsepower applications.
Specifically to the OP: Instead of doing a big input swap, I'd seriously look at an 1-1/8"x26 input shaft swap. There's a lot more clutch kit offerings and the strength will equal or be higher than the 1-3/8".
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I'd have to dig a little bit, but I think with a big input Toploader, your choice is going to be necked down anyway. Trying to get that input shaft to work with a diaphgram pressure plate would be pretty much impossible. Even some of the Long style pressure plates have to have the fingers modified to work with the larger trans.
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My Toploader is a big in and out. I seem to be able to do the impossible. Seriously, you can have a preference just as does everyone else. I don't know where the leg pressure argument comes in. I know I can't be the only person using a diaphragm clutch with good results with a big in and out Toploader.
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I'd have to dig a little bit, but I think with a big input Toploader, your choice is going to be necked down anyway. Trying to get that input shaft to work with a diaphgram pressure plate would be pretty much impossible. Even some of the Long style pressure plates have to have the fingers modified to work with the larger trans.
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My Toploader is a big in and out. I seem to be able to do the impossible. Seriously, you can have a preference just as does everyone else. I don't know where the leg pressure argument comes in. I know I can't be the only person using a diaphragm clutch with good results with a big in and out Toploader.
Been a while since I dabbled with all the drivetrain stuff. No need to be snarky, Gerry, I don't care to admit that I'm wrong. But to be honest, I never considered Centerforce to really be an option for my customers, so I didn't stay up to date on their catalog. I'm looking at McLeod's catalog now, it looks like they offer the diaphragm plate to fit the 1-3/8x10 input now too. There is a note that the fingers had to be modified, so maybe that's an option that they now offer.
You spent half a paragraph talking about pedal effort. In addition, part of the OP's question was about a clutch that wouldn't take a toll on his left leg. That's why I discussed it.
I do have to ask though, what do you think you're gaining by switching to a diaphragm pressure plate? There is work involved to make them work with an older factory vehicle, so I'm just curious why you think there's a benefit there.
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I do have to ask though, what do you think you're gaining by switching to a diaphragm pressure plate? There is work involved to make them work with an older factory vehicle, so I'm just curious why you think there's a benefit there.
It is a preference. I know they work and they have always worked good for me even in racing conditions. The work involved is nothing more than removing the assist spring and setting up the pedal travel to keep the spring from going over center. Both are quite easy. You are misjudging benign sarcasm for snark. Not everything is an assault.
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I do have to ask though, what do you think you're gaining by switching to a diaphragm pressure plate? There is work involved to make them work with an older factory vehicle, so I'm just curious why you think there's a benefit there.
Not everything is an assault.
Same to you.
I'm still curious as to what the perceived differences are. "They've always worked" doesn't really answer my question.
What I'm getting at is that I don't know why someone would go through the extra steps to install one when a Long style setup works perfectly fine out of the box. If it's not pedal effort, then what is it?
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I'm still curious as to what the perceived differences are. "They've always worked" doesn't really answer my question.
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Again, everyone has a preference and that is all that it comes down to. I'm not trying to persuade anyone one way or the other. My sole input here is that a diaphragm plate is a viable choice. No merits one way or the other.
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I'm still curious as to what the perceived differences are. "They've always worked" doesn't really answer my question.
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Again, everyone has a preference and that is all that it comes down to. I'm not trying to persuade anyone one way or the other. My sole input here is that a diaphragm plate is a viable choice. No merits one way or the other.
Fair enough. I guess.
Usually when someone says that they prefer one thing over another, there's a reasoning behind that. Was just curious as to what your reasoning was/is.
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My thanks to everyone for your input. I've sent an email to RAM asking about availability. Chuck S. (OK)
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An 11" Long Powergrip HD kit for an 1-3/8x10 input is part number 98988HD.
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I still have my old 11" Zoom pressure plate upstairs, and my Mustang equalizer with a big strap welded to it after it bent
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A two disk, 7.25" racing diaphragm, is light years ahead of a Long style clutch. Especially in weight and inertia.
Road racers, where clutches, weight and inertia are extremely important, have used them since before the '70's. 3 disk 5.5" clutches were used in 700+ hp cars back in the '70's, too.
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Thanks Brent.
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I'm using a Center Force Dual Friction
B.T.W. Did you know that the "Dual-Friction" (and if I remember correctly this was initially a C.F. introduced product, and what elevated them as a "top-Rung" player in the market place) type clutch disks, that in the 'original' configuration, had the "organic" composite facing the flywheel and the more exotic material (Kevlar most commonly) facing the pressure-plate? This intention was due to fact that the pressure-plate ring is generally a smaller mass than that of the flywheel but realizes the same forces and hence generally reaches higher operating temperatures and that it was the higher temperature tolerance of the not organic material, which becomes "greasy" as the bonding resins begin to cook, that led to the development of the Dual-Friction product. ;)
But, . . . . . then, the manufacturers realized that the "ductile-iron" pressure-plate rings available on the market as being utilized hadn't been developed for these 'exotic' friction materials and proved that they weren't compatible, particularly from the metal displacement standpoint; so then someone looking for a "quick-fix", got the bright idea of just flipping the friction materials positions (nobody will notice!) and then declaring that you just needed to 'also' buy one their "steel" (friction faced) flywheels for compatibility! ::)
But baby, this has made a lot of money for those in the industry! :o
Scott.
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In the late 80s or early 90s, we stopped putting Centerforce clutches into vehicles at the shop. It was the rage for lifted 4x4s and usually ended up in heartache.
A cheap Zoom purple would last forever, the CF would smoke every time, even in little 4x4 4 cyl trucks and 6 cyl Jeeps. I hope they have improved, but do a couple 4x4s twice and it leaves a bad taste in your mouth.
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One has to give credit to C.F. in creating an increased interest in clutches; which for the most part previously were just something that someone bought like brake pads, solely because they needed it, and generally made their selection based on simple recommendations by another, . . . . "cause it was what they were using". :-\
Beginning back in the earlier '80's, presumably after the "Non-Compete Clause" lapsed after Hays Clutches had been folded into the Mr. Gasket Group, C.F. popped up with a greater some of effort in promotion, colorful shipping boxes, that 'bright' orange painted P.P. hat, and for goodness sake, don't forget the 'jingly little weights', all of which provided tangible identifiers that this product 'must be better' than the others, at least at first glance! Never before had the subject of clutches become such a fashionable consideration! ::)
Scott.
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One has to give credit to C.F. in creating an increased interest in clutches; which for the most part previously were just something that someone bought like brake pads, solely because they needed it, and generally made their selection based on simple recommendations by another, . . . . "cause it was what they were using". :-\
Beginning back in the earlier '80's, presumably after the "Non-Compete Clause" lapsed after Hays Clutches had been folded into the Mr. Gasket Group, C.F. popped up with a greater some of effort in promotion, colorful shipping boxes, that 'bright' orange painted P.P. hat, and for goodness sake, don't forget the 'jingly little weights', all of which provided tangible identifiers that this product 'must be better' than the others, at least at first glance! Never before had the subject of clutches become such a fashionable consideration! ::)
Scott.
Hahaha, a lot of guys I know had to remove those jingly little weights because they caused the clutch to not perform correctly.....
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And then sometimes, they've been known to remove themselves! :o
Scott.
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Long style!
Diaphragm plates are a GM design, not really compatible with older Ford vehicles without some modification.
Modern Long style pressure plates are not the 3000-3500 lb plates of the 60’s. Pedal pressure is not bad at all.
I’d recommend a RAM Powergrip HD. It would be rated for 650 hp and I've never had anyone complain about the pedal pressure.
Very good engagement on these as well with a sprung hub to absorb any chatter. Metallic facing on both sides. It will require a billet steel flywheel. It will chew through a cast iron flywheel in a matter of weeks.
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Running this(see attachments) RAM dual disc behind a 387 and inside a Lakewood scatter shield. Using a hydraulic release bearing. Pedal effort is surprisingly light. Both disc's are organic. TILTON realase bearing works great with the TKO 600.