Dual disk clutch does not shift slower than a single.

The floater cannot move independent of the flywheel. It is either bolted in place (haisely) or held by 3 large grooves (SB), but it cannot move at a different speed. The only "drag" it is adding is the additional weight on the flywheel. The clutches cannot move independent of eachother. If 1 clutch is slipping past the floater, the other clutch is slipping past at the same speed. There is no other option.

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Im not saying move indepenant of the flywheel. Im talking about the movement of the floater plate within the grooves in the flywheel. There is nothing to pull the floater back from the 1st disk. There will be some friction between the two. The pressure plate can be a foot away. The floater will still be able to make some limited contact with the disc's.

How do you bolt a floater plate in? It has to have some lateral movement.

roachie said:

Im not saying move indepenant of the flywheel. Im talking about the movement of the floater plate within the grooves in the flywheel. There is nothing to pull the floater back from the 1st disk. There will be some friction between the two. The pressure plate can be a foot away. The floater will still be able to make some limited contact with the disc's.

How do you bolt a floater plate in? It has to have some lateral movement.

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On the haisley clutch there were small tabs of a spring like metal that bolted to the flywheel. I'll try to throw up some pictures if you are interested?

Heat is plausible. You also have spinning force trying to seperate the clutches and floater plate. Stick a paperclip on the end of your pencil and give it a good spin. Does it stay completely stationary? There are several different forces acting on a clutch at any given time. How much weight would actually be against the floater plate with no pressure plate pushing against it? The weight of the clutch? The weight of the floater plate? Less, since they are attempting to spin and seperate from eacother? More, from centrifugal force pushing them together? If the pressure plate isn't applying pressure, can the synchros in the transmission even tell that there is additional "friction?" I'm betting there is more parasitic loss from the transmission bearings then there would be from the clutch and float plate touching eachother with no force being applied to either.

Which begs another question.. If you are at a stop light with the clutch pressed in, are you burning up your clutch since the floater plate hasn't seperated from the clutches?

Anyone have pre-mature clutch failure from holding the clutch in at stops (assuming your hydraulics were correct and up to the task?)? I've never heard of it.

Damn it. Vailar was in the thread posting a comment, but not he is gone.. I really wanted to read it!!! I was hoping an expert would chime in and lay this one to rest.

Clutch material has a Lot of effect on clutch shift speed. Ceramic/Feramic clutch material sticks to the flywheel and pressure plate. Because these materials semi-weld together, the synchros are tasked with breaking the friction bond between friction disk and flywheel.

I also noticed that my truck shifted slower when going from 12.25" to 13" clutch.

You guys can reason all you want, a double disk will shift slower than a single disk. A higher friction disk that bites into the flywheel will always shift slower than a lower friction disk.


Why is it hard to get a double disc to shift into reverse???? The dang clutch drags enough to keep the input shaft on the tranny spinning, even when the clutch pedal is fully depressed.

One surefire trick to make a clutch shift faster is to polish and lube the tranny input shaft and internal hub of the friction disk. The easier it is for the friction disk to rattle free from the flywheel or pressure plate, the easier it will be for the input shaft to be slowed down by the synchro to make input shaft speed match output shaft/wheel speed for the selected gear.

Double disk clutches also require a larger 1.375 input shaft. A larger more massive input shaft will require more synchro wear/force to slow down.


A worn flywheel pilot bearing will also cause slow shifting, why??? The minute amount of drag that the bearing places on the input shaft that keeps it spinning with the engine rpm. If a small bearing with literally zero leverage due to it be located near the center of the shaft can cause hard shifts, imagine what a high friction disk located 6.5" from the center of the shaft can do.

I rest my case!

like i said I have seen dd clutches shift slower, usually in 5 speed trucks, mine is a 6 speed, so less rpm loss between gears, which I'm sure helps a lot. Prime example my brother had a dd in his truck 95 12v nv4500, it wasn't the fastest, I put the same clutch (he upgraded i got his old one) in my 04 nv5600 truck it was just as fast as stock. Either it was my fresher syncros or like i said less rpm loss, which equals less syncro work, and the rotating parts don't have to slow down as much.

Big Blue24 said:

Clutch material has a Lot of effect on clutch shift speed. Ceramic/Feramic clutch material sticks to the flywheel and pressure plate. Because these materials semi-weld together, the synchros are tasked with breaking the friction bond between friction disk and flywheel.

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So an organic dual disk clutch will shift faster than a feramic single disk, since there are no friction bonds to break?

Big Blue24 said:

I also noticed that my truck shifted slower when going from 12.25" to 13" clutch.

You guys can reason all you want, a double disk will shift slower than a single disk. A higher friction disk that bites into the flywheel will always shift slower than a lower friction disk.

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Your assuming that the dual disk has a more agressive clutch material than a single disk.. If that is the case, why is a high performance dual disk generally less grabby than a high performance single disk? (IE, compare the Southbend FE to a DD). If the single disk has higher friction than the dual disk, wouldn't the dual disk shift faster by your logic? What gives?

Big Blue24 said:

Why is it hard to get a double disc to shift into reverse???? The dang clutch drags enough to keep the input shaft on the tranny spinning, even when the clutch pedal is fully depressed.

One surefire trick to make a clutch shift faster is to polish and lube the tranny input shaft and internal hub of the friction disk. The easier it is for the friction disk to rattle free from the flywheel or pressure plate, the easier it will be for the input shaft to be slowed down by the synchro to make input shaft speed match output shaft/wheel speed for the selected gear.

Double disk clutches also require a larger 1.375 input shaft. A larger more massive input shaft will require more synchro wear/force to slow down.

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Agreed. However, increased synchro wear does not automatically equal slower shift speeds. You may be asking more of the synchros, but it will function the same way. Just like you are asking more of the stock hydraulics.. Eventually, it may fail, just like the stock hydraulics fail when you add higher pressure plates.

Big Blue24 said:

A worn flywheel pilot bearing will also cause slow shifting, why??? The minute amount of drag that the bearing places on the input shaft that keeps it spinning with the engine rpm. If a small bearing with literally zero leverage due to it be located near the center of the shaft can cause hard shifts, imagine what a high friction disk located 6.5" from the center of the shaft can do.

I rest my case!

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A failed/failing bearing acts a heck of a lot different than a clutch that needs to slide away from a floater plate or flywheel. The bearing has the force of the pressure plate fingers pushing against it, binding against the input shaft. What does the clutch have pushing against it to bind it against the input shaft when the clutch is properly depressed? Completely different forces acting in completely different ways. Better re-think your case.

A failed/failing bearing acts a heck of a lot different than a clutch that needs to slide away from a floater plate or flywheel. The bearing has the force of the pressure plate fingers pushing against it, binding against the input shaft. What does the clutch have pushing against it to bind it against the input shaft when the clutch is properly depressed? Completely different forces acting in completely different ways. Better re-think your case.

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Um he said PILOT bearing. That would make a big difference.

roachie said:

Um he said PILOT bearing. That would make a big difference.

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You're right! My bad, my miss-reading.

But it still creates the same issue. The pilot bearing is in constant contact with the flywheel. It is supposed to allow the input shaft to spin at a different speed than the flywheel, correct? It can never seperate from the input shaft, or the flywheel. The clutch CAN seperate from the flywheel, but not the input shaft.. That is the big difference between the 2, and why a failing PILOT bearing has a lot more effect on how a transmission shifts than a clutch "sticking" to the flywheel.

I mean, everyone does realize you can shift a transmission without depressing the clutch, right? The amazing advancements of modern synchros make that possible... You don't have to break any "bonds" or nuffin.

Boy someone was bored to write all this! if u want speed get a auto. You have to suffer somewhere when u modify stuff. If u make more power u get a clutch that holds and if it takes I second more to shift what have u lost nail-it and grab another gear

I weighed the nv4500 and the G56 clutch that I had laying in the shop. The nv4500 clutch weighed 89. The G56 weighed 94.5. I can't remember what my SBC DD weighed. I want to say 128#, but that's just a guess. The increase in weight provides additional interia for the synchronizer to overcome, making it slower.

I have been "floating" the gears (no clutch shifting, up and down) since I was 17 in every vehicle that would allow. Certain transmissions are more forgiving on that.

Most of the FWD's Ive driven wont allow that.

Ill agree with the material sticking to the plate/flywheel.

The thing is, no one is lying about it. You just havent driven one that is slower. Many dual discs just wont shift fast. I drove a buddy's 98.5 24v with a 5 speed and 3850 South Bend DD a few times. It wouldnt shift as fast as stock, but it wasnt too bad. I cant say why some wont shift as fast, but some just dont. No one is lying or trying to pull your leg. Keep in mind a "street-drag" clutch is probably going to shift better than one made more for pulling.

Eric

Wow, what alot of info in this thread, here's my take, the big lever DD's we make shift slower do to several reason's, bigger springs in the cover, limiting release. more rotating mass the other disc 14 lbs, Stickier friction materials, then throw in some heat your about there. i have a 4200# Iron Dual Disc in my truck when it's cold i can shift pretty good, as soon as it heats up it's a little more difficult but still not to bad. It hold's about everything i can throw at it. I know you cant argue with Physic's, i do get that, my dad has a PHD in Physic's and he remind's me all the time. If it look's good on paper it must be right. LOL

Nobody even mentioned the engagement mechanism. My experience has been that diaphragm clutches shift easier/faster then lever style.
Street Puller

Iron Giant

you are absoloutley right, they just dont seem to hold up in sled pulling. for drag racing that is the way i would go. diaphram clutches work much quicker than lever types.

When I purchased my ConFE years upon years ago. It was slower to shift then stock. I bought the upgraded hydraulics and it helped I believe it helped mainly due to the fact you could adjust the engagement point with the adjustable rod on the master cylinder. Read this again, the ConFE shifted slower! Not slow enough, I could still chirp 3rd and 4th gears. It lasted me 70K miles and 612hp and well over 1150# feet torque that it's rated for. The pressure plate side was fine, the flywheel side and flywheel was all chewed up.

I figured the same would apply to the DD I ordered from SBC. Peter gave me and excellent deal that I could not pass up! It's the 3200# 12CB spring DD.

So I'm going from a full feramic to a ceramic button. It's even slower!. 2nd to 3rd take for ever if you shift over 1800-2000rpm range. it's nearly impossible to get into 3rd with any reasonable speed. It's just not going to happen. 3rd to 4th is doable. I've managed to grab 4th fast enough to snap my belt tentioner. grabbed 5th, sometimes you feel a little grind, and 6th is always fast.

Reverse, it's a pain in the freaking pooper.

These results are the SAME between a trans with 115K miles, and one with 0 miles. I've found that in my old trans adding 8oz of friction modifier did help for a while with the shifting. I'm planning on doing this with my new trans very soon. this is the same stuff you put in your average posi rear end (not the AAM)

I'd have to agree with Valair1. It's the material used. Why? i've never heard of "feramic" before I owned a diesel truck. The folks that used ceramic material had full drag cars and I'm sure they don't touch the clutch while grabbing gears with the liberty trans. Now, kevlar is something you hear folks going to in a DD application on gassers.

Banks folks, what material are you folks running on the clutch disks?

The other reason why the SBC specifically (in my experience) has a slower time to get into gear or even shift is because the disk to drag on the floater plate. Every wonder what that sound could be when you disengage the clutch that metal on metal sliding sound.....

Can someone post pics of the "spring" features on the Hasley DD clutch's floater plate?

BTW, I'm very impressed with this thread. why? there is absolutely no bull chit "yet". Just information and very thought out theorys and responses.

JasonCzerak said:

BTW, I'm very impressed with this thread. why? there is absolutely no bull chit "yet". Just information and very thought out theorys and responses.

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Well...

I think you're completely wrong and have no idea what you are talking about! :hehe::hehe::hehe::hehe::hehe::hehe::hehe: :hehe::hehe:

How about a boat? It probably has 2 dual disks in a Siamese configuration.

there's alway's one in the bunch.LOL

Joe, you an ass. LOL



I'd love to see a close up of the floater, but this is the best I could find (I need to start some work already!)

Folks, when you compare DD clutches, you need to compare apples to apples as well. My SBC is a 12 puck sprung and the haisley's is not where near that.



See my old thread here Competition Diesel.Com - Bringing The BEST Together

I can assure you the street drag disks do not weight nearly as much as the SBC disks I have.

there a have been a few folks that have stated in many clutch threads that a 6 puck un spung will move faster then a spring 12puck. my next clutch will be un spung and 6 pucks. Be it less weight, or less "material to weld" to the flywheel.

Now, if they will be SBC disks or haisley's will depending on how that floater really works in the haisley.


so I should just poney up and go to an auto already! Taking donations for an auto upgrade!