Dual disk clutch does not shift slower than a single.

[Tate]

Bingo. But, it's not enough to be of any concern, right? So if they seperate enough at a stop light, why not enough during shifts?

Because you have 7000 lbs. of truck stationary that the dragging of clutch discs won't over come. We are talking about 100 lbs. of rotating mass that the friction will over come with a disengaged clutch.

Obviously anyones arguements won't make you a believer that some DD's shift slower than singles. So if you are ever up in Alberta, feel free to come take my truck for a spin and feel the difference.

 

[MD-LUCKY]

What is providing the centrifugal angled force?

I'm assuming a single disk has alot more room for the clutch to disengage the flywheel than a dual disk... not sure though?

I'm certain is does.. The question is, does it matter? They don't have to "seperate" from eachother to prevent shifting (even at high speeds). The synchros can overcome light contact with low friction. Once they are seperate, even if only by .00001 an inch, it doesn't matter if they can continue another 5" beyond that, or .0005". They are seperated.

For some people that may be true, for others you simply need a clutch to take more load. I went from a single FE clutch to a dual FB, not for a smoother shifting clutch but to hold more load.

Thats the point though. The dual disk material isn't as aggressive as the single disk. If it's friction we are talking about, the clutch with MORE friction should shift slower, right?

Yes there is still some friction, but not as much. I'm sure there are lots of factors that affect how much the input shaft continues to rotate. Clutch material, amount of mass spinning with it, space available to disengage, etc.

Exactly!! The question is, can the synchros handle the additional rotation... Either do to:

1: Additional friction (either in a single or dual disk)
2: Additional weight (either in a single or dual disk)

The answer is yes. RPM is a MUCH bigger factor than weight or friction. Or, more accuratly, RPM brings the additional weight and friction in as a factor.. If the transmission synchros can handle the force of a gas engine at 5200rpm (or higher) the same transmission can handle the additional weight and friction of a diesel RPM. The reason we know this is true is that the additional weight, even DOUBLING the weight of the factory clutch, is still more centrifugal force at 5250 in a gas engine then 3200 in a diesel.

The real question is: how do high performance GAS engines shift at 8,000 rpm after installing a dual disk? (any why don't they claim it is slower?)

I can think of two things that are different between shifting at a stop light or while racing.

The first difference is rpm, while racing the rpms are higher during the shift, therefore there is more inertia to keep the input shaft spinning.

No no, I'm talking about clutch wear at the stoplight. IE: If the clutch and floater plate are not seperating from eachother, they should be constantly burning up at stops, right?

It would be like driving down the road resting your foot on the brake..

Constant contact = warped and burned.

We seem to handle the theory that they seperate at a stop, but for some reason a few folks are claiming that they don't fully seperate during a shift. Maybe. But, if they don't fully seperate during a shift, why do they seperate during a stop?

The second difference may be better explained if I use an example:

While driving to work one morning in my 5 spd Fox body mustang, I was making a hard run up to speed and during my quick shift from 3rd to 4th, a coiled up 5' black snake slide out from under my passenger seat.

Why did it slide out? Because when I stabbed the clutch in, the car stopped accelerating, as the car slowed down for this brief 1/3 of a second, the snakes inertia overcame the friction between itself and the floor and it continued forward.

The same thing happens to the clutch plates, as you stab the clutch in, and they start to slip inbetween the pressure plate and floater plate and between the floater plate and flywheel, the inertia of the clutch plates cause them to continue forward and maintain contact with the forward surface.

Maybe this small increase in friction between the plates at precisely when your trying to speed shift your transmission is enough to make it take longer to slow down the input shaft? I don't know?

But I do know that I hate snakes

You lost me at snake. Because I effin hate snakes. Terrified to death.



Okay maybe not. The question is, can the synchros over come that friction at 3200 rpm... with no pressure plate pushing against it... with no force other than that SPILT SECOND that you stabbed the clutch, while spinning at different speeds?

The engine RPM and clutch RPM change at different speeds, right? So, if there is so little friction between the clutch and pressure plate / floater / flywheel to keep the transmission RPM and engine RPM equal, why would it change the shifting?

If it does change the shifting, then question becomes why doesn't a high friction material clutch stick more (and shift slower) than a low friction clutch?




If that is the answer, then I've GOT to hear how a high friction single disk clutch shifts FASTER than a low(er) friction dual disk. ?

 

[MD-LUCKY]

Obviously anyones arguements won't make you a believer that some DD's shift slower than singles. So if you are ever up in Alberta, feel free to come take my truck for a spin and feel the difference.

Which clutch you running?

Is it going to shift slower than my current 3600 12cb south bend dual disk, or will it be slower than my old haisley 6cb street drag dual disk?

I'm pretty close to Canada.. I may just take you up on that.

 

[Tate]

I'm certain is does.. The question is, does it matter? They don't have to "seperate" from eachother to prevent shifting (even at high speeds). The synchros can overcome light contact with low friction. Once they are seperate, even if only by .00001 an inch, it doesn't matter if they can continue another 5" beyond that, or .0005". They are seperated.



Thats the point though. The dual disk material isn't as aggressive as the single disk. If it's friction we are talking about, the clutch with MORE friction should shift slower, right?




Exactly!! The question is, can the synchros handle the additional rotation... Either do to:

1: Additional friction (either in a single or dual disk)
2: Additional weight (either in a single or dual disk)

The answer is yes. RPM is a MUCH bigger factor than weight or friction. Or, more accuratly, RPM brings the additional weight and friction in as a factor.. If the transmission synchros can handle the force of a gas engine at 5200rpm (or higher) the same transmission can handle the additional weight and friction of a diesel RPM. The reason we know this is true is that the additional weight, even DOUBLING the weight of the factory clutch, is still more centrifugal force at 5250 in a gas engine then 3200 in a diesel.

The real question is: how do high performance GAS engines shift at 8,000 rpm after installing a dual disk? (any why don't they claim it is slower?)




No no, I'm talking about clutch wear at the stoplight. IE: If the clutch and floater plate are not seperating from eachother, they should be constantly burning up at stops, right?

It would be like driving down the road resting your foot on the brake..

Constant contact = warped and burned.

We seem to handle the theory that they seperate at a stop, but for some reason a few folks are claiming that they don't fully seperate during a shift. Maybe. But, if they don't fully seperate during a shift, why do they seperate during a stop?



You lost me at snake. Because I effin hate snakes. Terrified to death.



Okay maybe not. The question is, can the synchros over come that friction at 3200 rpm... with no pressure plate pushing against it... with no force other than that SPILT SECOND that you stabbed the clutch, while spinning at different speeds?

The engine RPM and clutch RPM change at different speeds, right? So, if there is so little friction between the clutch and pressure plate / floater / flywheel to keep the transmission RPM and engine RPM equal, why would it change the shifting?

If it does change the shifting, then question becomes why doesn't a high friction material clutch stick more (and shift slower) than a low friction clutch?




If that is the answer, then I've GOT to hear how a high friction single disk clutch shifts FASTER than a low(er) friction dual disk. ?

Can you define centrifugal for me, because maybe our understanding of that term is dfferent. My understanding is the force of a mass away from the center of a spinning object; ie. in a radial fashion. You seem to be using it inplace of inertia, which is what we are dealing with here.

Also, the discs and plates don't seperate completely. Ever hear the metal on metal sound with your foot on the clutch? Thats the plates and discs dragging on each other, even with your clutch fully depressed.

 

[Tate]

Which clutch you running?

Is it going to shift slower than my current 3600 12cb south bend dual disk, or will it be slower than my old haisley 6cb street drag dual disk?

I'm pretty close to Canada.. I may just take you up on that.

I've got a 3250 diaphragm 12cb sprung hub in the 12v, and a 3600 lever style 6cb unsprung hub. The 3250 isn't too bad, but the 3600, its faster to float the gears.

 

[MD-LUCKY]

Can you define centrifugal for me, because maybe our understanding of that term is dfferent. My understanding is the force of a mass away from the center of a spinning object; ie. in a radial fashion. You seem to be using it inplace of inertia, which is what we are dealing with here.

I don't think I can define centrifugal force without using the term inertia. Sorry.



IF:

Also, the discs and plates don't seperate completely. Ever hear the metal on metal sound with your foot on the clutch? Thats the plates and discs dragging on each other, even with your clutch fully depressed.

THEN:

If that is the answer, then I've GOT to hear how a high friction single disk clutch shifts FASTER than a low(er) friction dual disk. ?

 

[MD-LUCKY]

I've got a 3250 diaphragm 12cb sprung hub in the 12v, and a 3600 lever style 6cb unsprung hub. The 3250 isn't too bad, but the 3600, its faster to float the gears.

See, that was a conversation we had a few pages back.. I think your 3600 lever MIGHT shift slower because of the way the lever clutch functions. But, that is a result of the pressure plate style, not the fact that it is a dual disk.

 

[Beets]

the noise you here when you have the clutch pressed is the Floated plate.

 

[cetanefreek]

I can say for sure that my 3850 South Bend DD lever type pressure plate, 12fb friction disk clutch shifts WAY slower than any of the single's I've had in it, enough so to the point that I avoid driving it in any kind of traffic, and if some rice burner wants to play I have to choose between letting him run off thinking he burned me or do a 3rd gear boosted launch, anything else just takes too long to shift to even be worth it.

as for the why, all of my theories have been stated by others already so I won't waste your time there, but if you ever make it down to the Boise/Eagle area look me up and I'll let you take mine for a spin and you can see for yourself.

 

[TheNatural31]

I think it's great that yours ain't slower. If you want to drive down to Texas....and I mean deep South Texas you can run my........SB 3600 Sprung Diaphragm!

Noticably slower than any single!!

 

[MD-LUCKY]

Okay, I'll drive all of your trucks...

But, should I also drive kman9090, smokinggoat04, 12v ford, jt prouhpet, 1slomm, and everyone else's pickup that was exactly the same, or faster??

There has to be an explanation why some are slower and some are faster... right?

 

[roachie]

The simple fact is, you havent driven a truck with a pulling clutch in it.
By your reasoning I could rip the tires off my truck in every gear. Busting gears with my DD is like trying to cram the stick in gear sitting still with the clutch engaged.

Your paper clip on a pencil analogy is wrong. The paper clip is unballanced and will find its way off of the pencil. The clutches are ballanced, so they are neutral.

In my head a haisley drag clutch with 3250, diapham press. plate, spring assisted floater, organic disks, 6 puck, and in a 6 speed would be lightening quick.

My 3850 lever, lever, ceramic, 12puck, lug floater plate, and has a bronze flywheel, with my 5 speed is SLOW. I dont care if somebody sits on the dash and shoves with both feet, you wont get 3 to 4 any faster than floating them.

Seems that the gear ratio has alot to do with it. Look a OTR trucks, you can just rip the damn gears in them. Closer ratios with less of an RPM difference between them for the syncos to overcome.

With that said, there is nothing to make the 1st disk separate from the floater. There is nothing to make the floater come back on a lug style floater plate. Even when they plates are pulled back 0.001". You know good and well the plates will mover fore and aft some, just skiping along the surface is enough to make the shift slower.

 

[MCummings]

My dual disk shifts plenty quick.

Here's a clip of shifting with my right foot to the floor...

YouTube - Dodge Diesel 3500 Dual Disk Clutch

I don't understand how some hang, and some don't... Mine doesn't.

Merrick

 

[cetanefreek]

this is my second clutch of this type, and the second NV5600, with both clutches and both transmissions it has never changed, I used to think all DD clutches were like this until this thread popped up. which in turn seems to de-bunk most of my theories.

on the other hand one of the guys at the shop drove my pickup both times right after he installed the clutch, and he told me that southbend suggested he slip the hell out of the clutch to break it in.

so here's another thought, what are the chances that those of us who have slower shifting also have slightly heat-warped friction and/or floater plates?

that would mean that we would need the increased pressure plate travel to release the clutch fully, as in the pressure plate has enough load to press the friction disc's flat while the clutch is engaged, but when you disengage the clutch the friction discs have warped just enough to spring a little out of true and cause drag, therefore causing a slower shift.

just throwing that thought out for consideration.

 

[malibu795]

subscribing

 

[MD-LUCKY]

The simple fact is, you havent driven a truck with a pulling clutch in it.
By your reasoning I could rip the tires off my truck in every gear. Busting gears with my DD is like trying to cram the stick in gear sitting still with the clutch engaged.

Yup. That's pretty much what I'm saying. I don't know if my 3600 12cb counts as a pulling clutch or not though? I won't ever use it as one, either way. I've said this several times: I think there is a plausible explanation as to why a lever clutch would shift slower.

Your paper clip on a pencil analogy is wrong. The paper clip is unballanced and will find its way off of the pencil. The clutches are ballanced, so they are neutral.

Neutral (or close to it) at 0*. Is you engine and transmission sitting 0*?

In my head a haisley drag clutch with 3250, diapham press. plate, spring assisted floater, organic disks, 6 puck, and in a 6 speed would be lightening quick.

Agreed. But, in my head, it would be the same as any other clutch. (lever style not included.)

My 3850 lever, lever, ceramic, 12puck, lug floater plate, and has a bronze flywheel, with my 5 speed is SLOW. I dont care if somebody sits on the dash and shoves with both feet, you wont get 3 to 4 any faster than floating them.

I'm still rolling the lever style around in my head. Could be a few factors that makes this completely plausible. Agreed!

Seems that the gear ratio has alot to do with it. Look a OTR trucks, you can just rip the damn gears in them. Closer ratios with less of an RPM difference between them for the syncos to overcome.

Also agreed. Maybe a 6-speed shifts easier than a 5-speed in general, no matter which clutch is used?

With that said, there is nothing to make the 1st disk separate from the floater. There is nothing to make the floater come back on a lug style floater plate. Even when they plates are pulled back 0.001". You know good and well the plates will mover fore and aft some, just skiping along the surface is enough to make the shift slower.

No it isn't. It is enough to create theorhetical increased work for the synchros (much as the additional weight does), but it doesn't equate to the transmission shifting slower. Lets get real here.. A "perfectly balanced" (as you pointed out) cylinder spinning on a balanced shaft with roller bearings, and no pressure pushing against it or the floater plate... How much friction is there?

Which still leaves 1 question un-answered, if all over the above is true and causes additional friction:

If that is the answer, then I've GOT to hear how a high friction single disk clutch shifts FASTER than a low(er) friction dual disk. ?

(a single disk has nothing to "pull" it away from the flywheel, either.)

 

[roachie]

Your singe disk will either be pulled away form the flywheel while attached to the pressure plate. Or stuck to the pressure plate. (for an instant)

A dual is 2x that. Stuck to the flywheel and to the floater. Or any combination. Has the possibility of 3x.

0* they are not. I would doubt that at that low of an RPM with the tiny time frame they have that gravity will have much say in the matter.



Is there a corilation of the slow clutches and fast ones to those that do and dont have a bronze insert?

Hmmmm, more questions.

 

[GOT-Torque]

so here's another thought, what are the chances that those of us who have slower shifting also have slightly heat-warped friction and/or floater plates?

that would mean that we would need the increased pressure plate travel to release the clutch fully, as in the pressure plate has enough load to press the friction disc's flat while the clutch is engaged, but when you disengage the clutch the friction discs have warped just enough to spring a little out of true and cause drag, therefore causing a slower shift.

just throwing that thought out for consideration.

I know when I had my clutch out after maybe 10 pulls and a couple street launches that it looked like hell. I've got some pics somewhere, it scares me to look at them. I was hoping it would last longer as a 3850 unsprung FB 12 puck but I'm probably on borrowed time now. I just put it back in as funds were low and decided to run it until it don't run no more...

However, it always shifted slower...

To answer your question:
If that is the answer, then I've GOT to hear how a high friction single disk clutch shifts FASTER than a low(er) friction dual disk. ?

There are twice as many contact surfaces that must break free from each other...

 

[MD-LUCKY]

edit in: This was in response to Roachie's post.. You where too quick.



My next question would be this then:

What is the minimal amount of force needed to turn the input shaft (with clutch) on our transmissions?

AND

Is the friction between the floater plate / flywheel / pressure plate and clutch with ZERO pressure against it (pressure plate fully released) enough to turn the input shaft alone?

If it takes 1 ftlb to move the input shaft, and the friction between the clutch and whatever source is only able to generate .75 ftlb with 0 pressure from the pressure plate, it would be a mute point, correct?

If that is the case.. Then why wouldn't a transmission that is built extremely light (lets say, a high rpm race transmission) have MORE difficulty shifting with a dual disk clutch at high RPM? Once again. Why are we diesel folk the only ones that experience this?

 

[GOT-Torque]

light transmission, light clutch = less inertia on the input shaft. Takes less work from the synchros to slow the input shaft down...

Here's a thought, maybe those cars and rice rockets that say a dual disk is just as fast is because the transmissions are light enough that the speed of the shift is solely based on how fast you could stab the clutch and grab the next gear. I know my mustang could literaly be shifted as fast as you could work the clutch and shifter. The installation of a dual disk may very well have slowed the shift down 20%, however the actual shifting time is so short that you can't tell?

If you add 20% to the time it takes to shift a 3/4 ton truck it is noticeable?