Triple Disk vs. Single Disk

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Triple Disk vs. Single Disk

Postby Begle1 » Wed Mar 14, 2007 7:11 pm

Alright, I have no idea. Trying to decide between the Goerend unit, which is a triple disk for $550, and the DTT, which I take is a single disk, for $750.

I was under the impression that triple disks were always better, but after reading through some of the articles on DTT's forums that ignorant illusion seems to have been dispelled.

Why isn't the triple disk automatically stronger? I got that it isn't, don't quite understand why... What are differences in operation and performance between the two?


Hmm, never read about any of this before. It seems like under full power, where your line pressure is maxed, then the single disk is more than adequate for holding your power. The triple disk is stronger, but the single won't slip until over 900 horsepower. Likewise, they say that on a normal engine the single has better off the line speeds, for some reason I can't quite grasp... The consensus seems to be that the triple disk is better for holding onto a very quick spool up, but on trucks with laggier turbo's the single disk has enough time to catch up without slipping, and is actually faster. And for pulling or really putting a load on, the triple disk seems to be a benefit.
This all sound close to correct?
1990 D-250 Regular Cab: Tweaked injection pump, built transmission, a cataclysmic charlie foxtrot of electronics, the most intense street-ran water injection system in the country, and some more unique stuff.
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Postby DLittle » Wed Mar 14, 2007 7:27 pm

I think that you are looking at 2nd gen convertors with a lockup tranny. our trannys have no lock up. Are you still using the stock tranny or are you switching to a newer one ?
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Postby Begle1 » Wed Mar 14, 2007 7:38 pm

No, I'm looking at the non-lock-ups.. I think both companies chop off a few hundred to not include the lock-up clutches.

http://www.dieseltrans.com/dodge/price_list.htm

DTT chops off $325...
Another reason why the 727 is best. :twisted:
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Postby DLittle » Wed Mar 14, 2007 7:53 pm

The term single disk and triple disk is refering to how many clutches are ava. for lockup. It doesn't pertain to our convertors.
Dana

1992 W250 auto, 290 k, stock for now SOLD
1973 W100 SWB, D70,D60, 5.9 Twin Turbo SOLD
1993 W250 193k, Auto, TOTALED 10/30/2009
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Postby Begle1 » Wed Mar 14, 2007 9:22 pm

Damn it all. Why the heck didn't you point that out to me before I asked and made myself look like a moron?

Now I'm embarrassed... :oops: :evil:

(Well, was the rest of the post accurate, at any rate?)
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Postby Cschafer » Thu Mar 15, 2007 9:08 am

DTT uses single disk converters and makes them hold. They do this by greatly increasing line pressure to increase clamping force. The problem with that is that when the 47rh or re shift to third one clutch pack (forget witch one) and a band lock and unlock at the same time. One apply's one let's go. The trans is made to kinda slip them a little when it shifts. When you increase pressure neither one will give and it puts added amounts of stress on the input shaft and in some cases will break it. That's why most DTT's run billit inputs. Now other companies shift kits increase line pressure a little but get there firm crisp shifts without raising line pressure on the third shift. Without the added line pressure a single disk will not hold when pulling or high horspower as well and a triple disk is needed. Now on that note I was told by goerand on my 96 that his sigle disk will be fine for me at 350 to 400HP. But no none of the first gen transmissions have lockup. Get a good efficent torque converter for a lot less money then a lockup unit and go out and have some fun :P
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Postby Begle1 » Thu Mar 15, 2007 3:41 pm

But the entire "single or triple disks holding more power" argument only applies when the trans is in lockup, right?

I don't get how the "disks", which I take are clutches, are so important for performance when non-lockup transmissions don't even have them. Are guys engaging lock-up while pulling sleds or doing the quarter mile?
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Postby Cschafer » Thu Mar 15, 2007 6:10 pm

quarter mile yes and some sled pullers but no it does not pertain to first gens at all. It's such a big issue because when your in lockup and floor it up a hill and you slip the lock up clutch it will warp it and make it chattery and not function correctly. So then you will need a new converter.
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Postby Begle1 » Thu Mar 15, 2007 6:37 pm

Where are guys engaging lockup in the quarter mile?

I've always heard that engaging lockup while under hard acceleration was the best way around to wreck your transmission. Which, I guess, would make all the fuss over the clutches logical, wouldn't it...

Still, what would lock up get you in the quarter? Gasser dragsters don't like it, I would think that the lock up is a way to make up for too high gearing and not enough powerband, and guys engage it once they get to third gear and are 2/3's-1/2 of the way down the track?
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Postby Cschafer » Fri Mar 16, 2007 9:26 am

It's preference really. Locking up won't hurt a trans that is upgraded. Some say that the increased shift harshness is is hard on it. My dad's 94 with the mystery switch on dropes about 2 sec 0-60. When my 96 locks up the truck gains about 12 mph without changing rpm. If you have the power then 100% power transfer is faster. If it lugs the truck and takes it out of the power band it will be slower.
90 W250,bank$ intercooled,I.I. Silver Bulit, 38mm ex. gate, a-1000 supply, 6x.018's, MIA AFC lever, 366 spring, 2 stages of laughing gas, 486/1005 on the gas. sold
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Postby dpuckett » Tue Mar 20, 2007 9:28 pm

ANd since our power band ENDs where most gassers' begins, we need the lock up as soon as we can get it. When you have 3-4x the revs, it makes a difference.
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Postby Begle1 » Wed Mar 21, 2007 5:44 pm

I still subscribe to the theory that if you can use lock-up in the quarter, then something isn't happening right... Engaging lock-up's almost as bad as engaging overdrive... It just ain't right... :evil:


The problem is that we don't make any sort of RPM. To add lock-up I'd be spending around an extra $500 on just the converter, then $1000 for the 47/48 RE, and I might be able to get $500 back on my 727...

Before I try to figure a way to get enough power that lockup is a liability, could anybody tell me if the P-pump guys use it in the quarter?
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Postby Cschafer » Wed Mar 21, 2007 7:50 pm

I have to wonder what therory you have to say putting all the torque to the ground is just not right?

Yes my 96 uses it in the quarter. It locks up at about 50-55 and that is the hardest the truck accelerates and that is with a built tranny. With the stocker it really didnt accelerate at all untill lockup. It would just rev to the govener when it was floored.
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Postby Philip » Wed Mar 21, 2007 9:15 pm

Begle just think of a lockup converter the same way you do a clutch. When it is engaged. There is no slippage. Everything your engine is making is going out the tailshaft.

When it is unlocked. You have a normal fluid coupling of a torque converter. Our 1st gens were given very loose converters by DC. It normaly will not allow anywhere near full power threw the trans. The effiency rating on our stock converters might be 60% if we are lucky. You can have two 1st gens with the same mods to the engine with the only difference being the transmissions. One stick and one auto. The stick truck will dyno higher HP everytime.

You have a 727 trans which also means you have 3:08 gears. Your truck is begging for a OD trans of some type. Trust me. :D
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Postby Begle1 » Wed Mar 21, 2007 9:40 pm

The apparently obsoleted theory is that a transmission can't accelerate as fast in lock-up as it can while slipping, due to the combination of weakness in the lock-up clutches and the lack of a torque multiplication effect. Lock-up's good for highway cruising, but it wasn't good enough for hard acceleration. Since the goal of the quarter mile is to accelerate throughout the entire race, the lock-up is more of a crutch for a lack of power band than a way to put more power to the ground. The same thing applies to overdrive, for different reasons.

But with all of these triple/ single disk arguments going on, it seems that some bastard disproved the above theory years ago by making lock-up way stronger than it used to be, back while I was under the impression that the "disks" were some sort of reference to stator construction...


I guess the conclusion is that my current goal is to make the 727 as effective as possible in the Cummins application. The key is to increase the power band of the Diesel by as much as possible, under which case the VE is my biggest enemy.

And so, before I try to design something, I'd like to know if the P-pumped guys lucky enough to have a (relatively) wide powerband also use lock-up in the quarter. Because if they do, proving that lock-up is a crutch gets pretty impossible.

Regardless, since my Goerend's is ordered, that's the boat I'm in. And I'm not really disappointed regardless, considering how much cheaper and simpler parts are for me this way.

The above "simpler and cheaper" logic also applies to intercoolers and overdrive. :P
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