Dual disk clutch does not shift slower than a single.

[MD-LUCKY]

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...

Good point.. Torque distributed over surface area, right?

Same reason you can run a less aggresive material with a dual disk.. You have more surface area to take the torque load.

So whats better at breaking those bonds. A light single disk with a more aggressive material, or a heavier dual disk with a less aggressive material? Inertia, right?

So wouldn't a more aggressive (6cb) dual disk shift SLOWER than a less aggressive (12cb) dual disk? Then why do people "report" the opposite?

I love this stuff. Really boggles the ole noodle.

 

[MD-LUCKY]

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?

But under that thought we have to throw the last 2 pages of this thread right out the window!

Thats basically saying shift time has nothing to do with bonds, and floater plates sticking, and clutch material.. Only weight.

Because, if it DID have something to do with all of those items.. The installation of a dual disk in ANY application should show a noticable decrease in shift speed. Right? Regardless of the application, additional bonds and friction would cause slower shift speeds.



Taking it a step further:

If that is correct, you should notice MUCH, MUCH slower shift speeds in a car. Why?

Less throw distance = less time for the "bonds" to break and the clutches to seperate before you hit the next synchro gear.


You take any of these theories and apply them to any other motorsport.. And they just don't pan out. That is weird, no matter where you stand on the subject.

 

[Tate]

But under that thought we have to throw the last 2 pages of this thread right out the window!

Thats basically saying shift time has nothing to do with bonds, and floater plates sticking, and clutch material.. Only weight.

Because, if it DID have something to do with all of those items.. The installation of a dual disk in ANY application should show a noticable decrease in shift speed. Right? Regardless of the application, additional bonds and friction would cause slower shift speeds.



Taking it a step further:

If that is correct, you should notice MUCH, MUCH slower shift speeds in a car. Why?

Less throw distance = less time for the "bonds" to break and the clutches to seperate before you hit the next synchro gear.


You take any of these theories and apply them to any other motorsport.. And they just don't pan out. That is weird, no matter where you stand on the subject.

Smaller clutches, the bonds between the disc and pressure plate/floater/flywheel would likely be weaker, so the synchros would be able to break them easier when it tries to slow the input down.

I'd be curious to know if the bronze inlay makes a difference, as my 3600 lever has the bronze inlay, and it is noticably slower than my 3250 diaphragm, which is sans bronze.

 

[smokingoat04]

In my eyes lever vs. diaphram is not a concern. I've had both, both could bark tires on the 4th to 5th shift. My truck may be a freak, it has an 130,xxx mile nv5600, stock fluid no additives. It's smooth, not notichy, and between a stock clutch, 13" feramic single, Mitchell 4000lb 12 cb un sprung lever type DD, and the Haisley street puller (diaphram dd), they all shift great. No noticeable differences, except engagement, and the floater rattled on the mitchell. Other than that, I could pass all clutches off as a single.

 

[MD-LUCKY]

Smaller clutches, the bonds between the disc and pressure plate/floater/flywheel would likely be weaker, so the synchros would be able to break them easier when it tries to slow the input down.

But you had to see the fault with that logic as you typed it. Everything in a car transmission is smaller, including the synchros. Yet, I can't find a single example of a dual disk causing slower shifting in a car. (even if there are 1 or 2 gripes out there, there is nothing like the diesel community). What gives?

I'd be curious to know if the bronze inlay makes a difference, as my 3600 lever has the bronze inlay, and it is noticably slower than my 3250 diaphragm, which is sans bronze.

Don't really know there. I'll do some research and see if I can come up with anything.

 

[JFlagg]

When my Mitchell DD was brand new, it shifted just as fast as the stocker it replaced... The only time that the shifting suffered was after the floater disc started to crack, most likely warping it and causing drag. I always heard that DD shifted slower too, but never put any thought into the matter since mine didn't.

On a different note, I think this may be the longest thread on CompD that everyone maintained their cool and we haven't had any heated arguments, just detailed and intelligent ones. We even had competing clutch manufacturers giving out good info along with their honest opinions without them bashing each other. Sure wouldn't have had that if this was a cam discussion LOL Maybe this is a start to that CHANGE Obama promised us? I sure hope me commenting on it doesn't jinx it....

 

[smokingoat04]

Jeremy your WRONG!!.................j/k Anyways like he said my mitchell got slow after I busted the floater. It was warped pretty bad, so I understand why. I think the slow ones are misadjusted, and drag. If they are fully releasing, all the other factors shouldn't make such a dramatic difference.

 

[JFlagg]

Jeremy your WRONG!!.................j/k Anyways like he said my mitchell got slow after I busted the floater. It was warped pretty bad, so I understand why. I think the slow ones are misadjusted, and drag. If they are fully releasing, all the other factors shouldn't make such a dramatic difference.

Yeah, when it 100% it shifted as good as stock. I raced with it a few times and banged throught he gears about as fast as your can get a NV5600 to go, but after I warped and cracked that first floater plate it was never right again... even after a replacement. Got a whole new one going in now, so hopefully I'll know more in a few weeks.

 

[MD-LUCKY]

I'd be curious to know if the bronze inlay makes a difference, as my 3600 lever has the bronze inlay, and it is noticably slower than my 3250 diaphragm, which is sans bronze.

I tried like hell to find a reason bronze would make a difference, but I just couldn't come up with any...

I still think it may have something to do with the lever style pressure plate. The way they function, it seems slightly more plausible that they would shift slower.. I'd love to know if anyone has a single disk lever pressure plate, and their opinion of how it shifts.. I'm almost willing to bet that it shifts slower than diaphram style. But, that is a function of the pressure plate, not the amount of clutches.

 

[Tate]

I tried like hell to find a reason bronze would make a difference, but I just couldn't come up with any...

I still think it may have something to do with the lever style pressure plate. The way they function, it seems slightly more plausible that they would shift slower.. I'd love to know if anyone has a single disk lever pressure plate, and their opinion of how it shifts.. I'm almost willing to bet that it shifts slower than diaphram style. But, that is a function of the pressure plate, not the amount of clutches.

It could very well be the pressure plate causing the slower shifts. I'd imagine why they say that the DD's shift slower is that a good chunk of them are lever style. Not sure of any manufacturers of lever style single discs. Diaphragm pressure plates haven't been on our DD's too long. When I bought my first clutch, the lever style was the only kind I could get from SBC.

 

[roachie]

Ive seen lever style singe disk drag clutches though.

The bronze inserts are very suspect now....

 

[cetanefreek]

I didn't take the time to look it up, but doesn't bronze melt at a lower temp than steel or iron? I do know it's softer, and it would seem to me that that would make it easier for it to bond to the friction plate, softer metal that melts easier would stick to the plate more readily..... or I may be drunk, I've had a lot of rum tonight.

although that would not explain a slower shift unless you were slipping the clutch enough to cause sufficient heat to braze the bronze to the ferrous material in the friction plate right?

unless the bronze is so soft that just the pressure on the friction disk from the pressure plate is enough to make it stick to the bronze inlay.... although that does not seem plausible to me.

 

[Mudn_1]

I can definetely say my DD doesn't shift any slower now!

I went to the track tonight a backed my best time of 14.7 @ 93 with a single disc, with a 14.8 @ 97, I am still not used to the clutch and how it doesn't give much so needless to say it came out a little too hard and I let off and got back in it! this was like a 2.3 60ft and a 9.7 1/8th!

it back halfed well and still pulled a close time to before with a 4mph! there is definetely more in the truck if I can just get off the stinkin line smoothly!

it bucked fuggin so hard I wasn't expecting it, and I guess I wasn't expecting it to grab soo quick!

will never own a single disc again! LOVE IT!

oh yeah there was a third gen there (04.5 i think) with just a smarty and a SB dual disc and he ran a 14.3, which I though was impressive

P.S.- stock hydraulics and 3600 6cb

 

[Scooter's Roofing]

I put a lever sprung 12cb DD on my 98... NV4500. I couldn't shift it any faster using the pedal than not using the pedal. We double checked everything, had Peter on the phone checking pressure plate lift on the press, etc. installed another one... same issue.

installed an FE and it shifted worlds faster! so, yes, in that instance, the DD shifted a TON slower than a single!!!

now, on my 04 6sp... had a 3250 diaphragm solid 6 puck. shifted very fast

 

[Valair1]

a diaphram clutch has alot less moving parts .

 

[XLR8R]

On our silver '05, which I've always shifted at the track without lifting, the 3250 DD lever-style (in comparison to the stock LUK) takes noticeably more arm effort to shift, with some of the gear changes taking more time as well.

There is certainly more RPM float (easily 2-300) during no-lift gear changes, which combined with the clutch's holding power makes it a lot easier to bark the 37"s.

 

[Scooter's Roofing]

more intertia on the input shaft is going to cause slower shifting, that's just simple physics

 

[MD-LUCKY]

more intertia on the input shaft is going to cause slower shifting, that's just simple physics

Too simple.

You've taken the role of synchros out of the equation (or, more accuratly, you've assumed they are not able to handle increased inertia.)

My transmission was rated to handle 550ftlbs at the input shaft. Is it capable of handling additional torque? Yup. Does additional torque put additional strain on the transmission? Yup. Does it function differently? Nope.

 

[JasonCzerak]

Too simple.

You've taken the role of synchros out of the equation (or, more accuratly, you've assumed they are not able to handle increased inertia.)

My transmission was rated to handle 550ftlbs at the input shaft. Is it capable of handling additional torque? Yup. Does additional torque put additional strain on the transmission? Yup. Does it function differently? Nope.

The syncro's can handle it sure, but they have to handle things differently with different input load to slow down.

They design the trans to slow down xyz weight with an abc size/style/etc synco. Now you have more weight, So, maybe the design needs to be changed. I suppose tho, the higher RPM's with a smaller clutch in a gasser operation would negate this to a point?


Maybe this analogy can be applied some how. Braking system.

Brakes are designed to stop the truck well from 108mph. I suppose this pertains to the gassers, cuz now we can run the trucks to 145+. Will the OEM brakes work? Yeah, Will they slow the truck down at the same rate? No. Redesign the brakes for the application.


My main argument here is that I can no longer do the 2nd to 3rd shift worth a damn if I'm over 2500rpm. 3-4th and so on is "ok" but I tend to grind gears even with fully depressing the clutch, with upgrade hydrolics with the master shaft about 1/2 the width of a 1/2" nut. So I'm pressing the clutch further then stock. (take a nut, grind 1/2 it down, and use it as a stopper to prevent the shaft from turn on the eye-hook)

Yeah, I have more HP, however, I have a lagger turbo then stock, so there for I have less HP in 2nd gear then I did with the stock turbo, there for, that gear will accelerate slower.

However, I do recall that my ConFE did shift slower then my stocker. So I'm leaning toward the material if anything.

 

[MD-LUCKY]

The syncro's can handle it sure, but they have to handle things differently with different input load to slow down.

They design the trans to slow down xyz weight with an abc size/style/etc synco. Now you have more weight, So, maybe the design needs to be changed. I suppose tho, the higher RPM's with a smaller clutch in a gasser operation would negate this to a point?

Yup. Thanks kind of the point I've been harping on for a while now. These synchros handle a heck of a lot more in their gas engine application due to RPM than they do in our diesel engines. In fact, the gas engine RPM centrifugal force is greater with a stock clutch than a diesel engine with a dual disk clutch. I even DOUBLED the weight of the clutch, which I'm not sure is 100% accurate. I should have weighed my stocker clutch, then weighed both dual disks for a comparison. If the opportunity ever comes up again, I will be sure to get those weights!!

Maybe this analogy can be applied some how. Braking system.

Brakes are designed to stop the truck well from 108mph. I suppose this pertains to the gassers, cuz now we can run the trucks to 145+. Will the OEM brakes work? Yeah, Will they slow the truck down at the same rate? No. Redesign the brakes for the application.

My main argument here is that I can no longer do the 2nd to 3rd shift worth a damn if I'm over 2500rpm. 3-4th and so on is "ok" but I tend to grind gears even with fully depressing the clutch, with upgrade hydrolics with the master shaft about 1/2 the width of a 1/2" nut. So I'm pressing the clutch further then stock. (take a nut, grind 1/2 it down, and use it as a stopper to prevent the shaft from turn on the eye-hook)

Yeah, I have more HP, however, I have a lagger turbo then stock, so there for I have less HP in 2nd gear then I did with the stock turbo, there for, that gear will accelerate slower.

However, I do recall that my ConFE did shift slower then my stocker. So I'm leaning toward the material if anything.

Maybe. But, shouldn't the most aggressive material shift the slowest then?

So, shouldn't a super aggressive FE shift slower than a less aggressive dual disk? But, we just don't see that happening... Or, at least many folks are reporting that as happening.

Just like in the gasser world. It just doesn't happen. No one reports slower shifts.. Just us diesel guys.

Which REALLY begs the question:

Does anyone know of a lever style pressure plate in any gas application?? I think we may have found our magic bullet.