Single Disc VS Triple Disc RACE EXPERIENCE++++

[Fishin Guide]

I have a DTT in the truck.



As far as the better clutch material, I have no idea. I have not been able to slip my TC under and circumstances.



Now, with all that said. I think the real differences in the TCs are in the fluid coupling. With my TC, it is much tighter than my buddies ATS. He has to get an early lockup or I will flat out run him. When my TC locks, it is not harsh or abusive. With his, it is a sudden drop in RPMs. Now he is able to get the RPMs up quicker. Sure sounds impressive! :-laf



One note, he shifts locked to lock under throttle. The shifts are smoother than at 1/2- 3/4 throttle. We have come to the conclusion that the TC slips a little and results in a smoother shift. If I shifted my truck lock to lock without billet shafts, there would be pieces on the floor. So maybe the fluid acts as a spacer until it's forced out and full lockup occurs? But no matter the design, the TC is mathematically the strongest clutch in the trans.



If you stacked 100 clutches on top of each other and applied the force to a 12" circle and did the same with one clutch fiber and applied the same force to both, witch would holder better? From my racing days, I have my own opinion.



BTW, the 5 disc unit that was referred to earlier is a Mercedes design I believe. It's in a car and has much less power, torque and weight. It's not even a reasonable comparison. Besides, smooth shifts are key, not lockup strength.



I have heard more about TC carnage with the triple disc convertor, especially in regards to flexplates. There is simply more mass there. And it's spinning along at a pretty good clip. So, if it gets loose, it may do more damage. I don't know.





Have fun with whatever choice you make!!



Dave

 

[justinp20012500]

Why do people say the TC clutch is the strongest in the trans?





Justin

 

[Hohn]

The holding power of the clutch is a function of:

-- coefficient of friction (lining material)
-- normal force (line pressure)
-- diameter (leverage)

Even if the first three factors are all held the same, a larger diameter clutch will hold more. This is because it gets "leverage" from it's larger diameter, with respect to torque.

At least, that how it makes sense to me...

 

[justinp20012500]

Forgot to ad...



2 billet cover singles burnt in 2 years.



1 billet triple and I am still pounding it on the pulling track.

 

[Will Manchester]

I posted this a while back on another thread, hopefuly this will help you make an educated decision!



Here is a technical explanation (a bit long) of holding capacity, this can be applied to TC's, manual clutches, clutch packs inside a transmission, etc:



When looking at holding force between 2 surfaces, the equation is F=uN (or Force = static coefficient of friction * the Normal Force applied to it). Notice that surface area is NOT part of this equation.



Your normal force (lb, kg, etc) is the combination of the pressure (psi) created by the pump & VB combo and the surface area (in^2, m^2, etc) of the piston (technically, the OD of your lockup clutch and ID of the piston bore). Pressure * area leaves you with a force (lb/in^2 * in^2 = lb).



The coefficient of friction (a dimensionless variable) of a clutch in an automatic transmission will vary by its composition, however the range is very small (somewhere between . 14 - 17). What you are looking for is something that will have a long life, wont burn easily, and most people want an engagement that isn't too harsh.



So, you multiply the normal force times the coefficient of friction, and you get a force. But we are looking for the torque holding capacity. The equation for torque is T=F*D (or Torque = Force * Distance).



Force is what we derived above.



Distance can be a bit tricky to define if you want an exact number (it involves some calculus). Distance is defined as the length (in, ft, m, etc) from the center of rotation to the point of interest. With a clutch, there is not 1 specific point on the clutch where all the force is being held. However, virtually all of your lockup clutches are about 1 inch wide (give or take just a little). You can make a very good approximation by using the center point of the friction itself (example: ID=10", OD = 12", therefore D=5. 5"). If you had a friction that was 3" or 4" wide, this approximation would not be very accurate, but I have never seen one to date.



You should have enough info now to calculate your holding capacity for a locking torque converter with a single disk! Just make sure your units all match up. Ultimately, you'd like to have a number represented in lb*ft. (not lb*in!).



If you are looking at the holding capacity for a multi disk application, modify the fist equation for finding holding force between surface: F=xuN, were x = the # of frictions in the converter. Therefor with a given line pressure, a double disk TC will hold 2x the torque, a triple disk TC will hold 3x the torque, a quad disk TC... you get the point!



Bottom Line: You can only significantly alter the holding capacity of a clutch pack in 3 ways (assuming that we are constrained by size limits - which we are).

1. The number of clutches in a clutch pack.

2. The pressure applied to that clutch pack. (You are not going to double or triple your pressure, btw)

3. Both!



All of the calculations above assumes that the TC is fully locked up. Imagine a 600HP truck accelerating in the fluid coupling, an the VB commands the lockup signal: the TC clutch is now having to make the engine RPM match the transmission and driveline RPM. This is where slip usually starts, and your "u" is now a dynamic coefficient of friction, which is MUCH small than the static coefficient of friction. To combat this problem, the VB is "valved" properly for the application and converter being used. If you "slam" the fluid into the piston, it is easier to ensure a lockup w/ minimal slip. If you ease the fluid into the piston for a nice cushy lockup, you greatly increase the risk of slip occurring and never reaching lockup (the dreaded TC shake). A triple disk has 3 disks all doing the same amount of work as the 1 disk in a single disk converter (remember F=xuN). Therefore, your single disk converters will typical rely on a VB that uses much higher line pressures (BTW, this pressure is common to the entire transmission, not just the TC) and be valved for very quick lockup. Look at all the sled pullers out there using a manual transmission: they all use multiple clutches and a pressure plate with BIG springs - this will ensure that the clutch "grabs" when they are done spooling their turbo and fully release the clutch pedal.



Oh, and one last thing - surface area. Surface area does not do much in terms of holding capacity, but does play a role in longevity of the friction and its ability to trap ATF. The wider the friction, it has more area to "wear" and absorb heat. However, the pressure seen on the friction itself is reduced as the surface area increases - this increases the likelihood of the ATF behind the piston can compromising the seal between the piston-friction-cover. The narrower the friction, the greater the likelihood for burning the clutch and shorter life, but you will have a better seal. Most TC designers have found a nice balance.



----------------





For all you manual transmission guys out there, same principal applies here. Your pressure comes from the springs in the pressure plate itself. However, the coefficient of friction has a much broader range here (look at the SB line up - same pressure plate on all there single disks!).

 

[Graphic man]

i am going to add my $0. 02



i run a 3 disc now ATS

and i am going to go back to a single DTT



reason: 3 disc is too lose on the bottom end and when it goes into lock-up it is to harsh and it feels like i can drive through 2-and 3 shifts



the single is a little tighter on the bottom and mid lock up is lock up so once it is locked it there to stay



you can read 800hp+ threads and see no slipping (jet pilot)



i spent years drag racing and went through a few converters, but these are diesels and things are in reverse for stall speeds and slippage compared to gas motors.



don't get me wrong the 3 disc is still an awesome piece, but i just don't think it is what i am looking for, i think 600hp+ (when i am done) the converter just wont cut it. (unless you shift lock)



i don't think you will be disappointed in any choice you make



just my $0. 02



Scott

 

[JVolpe]

WM



There you go again. Now I have to dig up all my old college books and see if you are pulling my leg(LOL). Well, maybe I'll just take your word for it.



I have not been able to make my triple disc tc slip or have yet to break anything, flex plate is the only thing not billet and that will be soon.

 

[Will Manchester]

reason: 3 disc is too lose on the bottom end and when it goes into lock-up it is to harsh and it feels like i can drive through 2-and 3 shifts

Scott, what you are referring to here is a function of the stator and has absolutely nothing to do with the locking portion of the TC. The stator's job is to change the direction of fluid after it leaves the turbine and enters the pump. Fluid exiting the turbine is flowing opposite engine rotation. For the pump to efficiently pick up the ATF, the fluid needs to be flowing in rotation with the engine. The shape of the fins in relation to the discharge angle of the turbine and how the fins are sloped to redirect the fluid GREATLY effects the drivability of the vehicle. The stator happens to be the only thing that all of the aftermarket manufactures (specifically speaking to the diesel truck market) are changing inside the TC's as far as drivability is concerned (pump and turbine are not changed). If you were to put a DTT stator inside your ATS converter, it would drive just like a DTT converter and have 3x the torque holding ability in lockup. The opposite is also true.



Call up ATS, they can probably work with you to get a lower stalling converter. I believe that they have made some major changes to the stator in the last year. You could also call up DTT and see if they can put one of their stators in your current converter. It would be a LOT cheaper than a whole new converter! Its probably only a couple bills to do a cut/clean and a new stator.

 

[biggy238]

Nice reprint on the ATS info. . It's the whole reason I started the thread.



Maybe it's the mechanism i'm curious about. Yes, mathematically, surface area yields more friction, but only if the same force is applied equally to each disc, otherwise you have what I consider floatation.



I guess i'm going to have to hunt up some trucks using the other 3. . I know where a Goerend is that just blew his dana 70, if that's an indication of whats getting to the ground.



I hate to say it, but that ATS acted exactly how I expected a built transmission to run, having never been near one before. 1,2,3, occurring in rapid succession, making use of the torque and shifting at appropriate points, and then using 4 and 4th lockup for top speed. He did however hold 3rd with the od button.



ATS doesn't seem to lend itself to a home built transmission like what AK discussed.



I think i've pretty well made my decision about the TC.



My next question, which some of you have discussed already, how does ATS andle it's VB's?? Do they just custom taylor them to your needs?? I noticed the others seem to have different style to choose from.

 

[Will Manchester]

I think you will find with any TC, when you gain in one area, you will loose in another. It has been my experience that the manufacturers selling triple disk converters tend to have a higher stall than the single disk guys (I’ve only been in ATS and Suncoast equipped trucks) and rely on the lockup for the grunt work. The single disk manufacturers rely heavily on a tight fluid coupling.



The higher stall allows for much better every day putsin around. Smoke is minimized and acceleration is much better under most circumstances. Taking off from a stop with a higher stall converters is also much easier. Usually, with the higher stall converters, they will be a bit less efficient (mathematically speaking) when you are going WOT. For the best of both worlds, use a lockup switches (or little black box). With some electronics to control lockup, you can tow, spool up BIG turbos, and get 100% efficiency very quickly as the 47-RH to current transmissions can all be modified for lockup in all gears. You choose when to lock it up.



The low stall converters are usually very efficient (mathematically) and the fluid coupling is very firm, feels like you are locked up. And typically there is little drop in RPM on lockup. The low stall can be a pain to drive around with a fueled up truck when you are trying to control the smoke. Getting a heavy load started from a dead stop can also be very difficult. However, once you get 1600+ RPM’s, an efficient fluid coupling rocks! Its all about getting that first 600-700RPM over with. I actually drove one truck that when the front wheels were put up against a curb could not build enough RPM /boost to climb the curb!



Where do we all spend 99% of our time driving?



You also need to look at a TC as a stand alone unit – it will work with a stock VB or modified. The VB will effect how fast (and how much you feel) the TC engages which can be modified a great deal for the drivers needs. The only other thing that the VB controls (as far as the TC) is line pressure. Line pressure is line pressure – if the TC is getting “x” amount of line pressure, the entire transmission is getting “x” amount of line pressure. So, you need to contact the manufacturer that you have decided to go with and have them build it to your needs/specifications. Someone who is towing horses is going to want a VB that has moderate increases in line pressure & timing – drag racers/sled pullers are gonna want to take it to the limits. They can ALL tweak you out a VB that will suit your needs.

 

[rrausch]

ATS's Valve Body is tailored to their trans. I wouldn't mix and match TC's and VB's from different manufacturers. Now having said that, I believe ALL aftermarket 47RH, 47RE and 48RE VB's are stock Mopar units which have been reworked, it is just that ATS reworks theirs to fit the TripleLok TC.

 

[Turbo Thom]

FL8DOSE... ... ..... One company in Fla, I won't call any names, they're in Fort Walton Beach, builds the 5 disc. No war here.



. . Preston. .

 

[mcoleman]

In answer to the question on the DTTs running locked or unlocked. I've ran my DTT locked at the track for 50,000 miles now with no issues. It's a 12 second truck and has pulled numerous 1. 6 short times but will stay in the mid 1. 7 range even with a easy 15 pound launch. The transmission also behaves very well for daily driving and towing.

 

[Lsfarm]

Street vs Racetrack

The reason that so many race trucks are running triple disc converters is because they are RACE trucks. These trucks need rpm off the line to get enough air flow through the exhaust to light their big turbos. Once the truck leaves the line at say 2500-3000 rpm the TC is locked [tripple disc] and then the rest of the way down the track the trans shifts locked to locked. When the TC is locked there is a huge rpm drop, the TC lockup clutches are in effect acting like a third gear clutch pack, or an OD clutch pack. These are multiple disc because they must pull down the engine rpm and torque. A lot of clutch surface area is needed both for wear surfaces and heat dissapation.



Just think what it would be like to drive a truck with a very loose fluid drive and have to lock the TC as soon as possible just to realize the performance that the truck has. This is just what a stock TC is like, and it is because of the loose stock fluid drive and reliabilty issues that most transmissions are upgraded. This is not for the daily driver, at least not for me or any of my customers.



Now those living at high altitude, and who have a large turbo with lots of lag, with tall tires and 3. 55 gears, a looser TC is an advantage. For that purpose a designed-for-your-truck TC is available.



The original reason for the triple disc converter [as it was advertised] was to allow for good TC lockup with stock or near stock line pressures. This sounds good, and with stock lockup pressures having extra discs makes sense. BUT in practice it didn't work. And now all the high performance transmissions run about the same line pressures.



WHY?? because the TC lockup is only one of FOUR clutches engaged when the truck is in OD, or one of three when in third locked. And as stated in a post previously the TC clutch is the strongest in the transmission. .



When in OD, the rear clutch, the third gear clutch, the OD clutch and the TC lockup clutch are all engaged. What was found out by the early triple disc experiment and advertising was that if the line pressures were NOT turned up, then one of the other applied clutches slipped due to inadequate pressure to keep it applied. So the reliability of the low line pressure transmissions suffered, and the line pressures were turned up to keep the rest of the trans alive.



With adequate line pressure to hold the rear clutch, third gear clutch, and OD clutch the TC clutch [single disc] is still the strongest in the trans. So adding extra TC discs in not needed.



But the Triple Disc advertising had to say something to sell the product so it has fallen down to this: if one is good then three must be better.



So why are the race trucks running multiple disc TC clutches?? because the amount of rpm drop and slippage to be overcome when running a loose fluid drive and then locking the TC requires a lot of surface area, and wear surfaces. The rpm drop is similar to a 1-2 shift or a 2-3 shift.



Think about a stock TC, when the Lockup clutch engages, under load the rpm drop is around 5-600 rpm with stock or mild increased HP. This is why our stock TC lockup clutch doesn't last very long in a stock trans. With a much tighter fluid drive, the rpm drop is minor, around 1-200 rpm with very little associated wear or heat.



There is nothing wrong with a triple disc TC, they do create more TC clutch lining wear, and need more frequent ATF and filter changes [my opinion] because of the extra worn off clutch lining suspended in the ATF, but that is just an additional maintenance item.



I personally don't feel the need for extra lockup discs except for a race truck set up with a loose fluid drive.



My experiences and opinions. Greg L

 

[justinp20012500]

I am still having a hard time understanding why people say the TC clutch is the strongest clutch in the trans...



Heres some back ground...



The rear drum in a 47re has 48. 3744 square inches of friction applied with approx. 100-125 psi of fluid.



The stock single disk TC clutch has approx 34 square inches of friction material that is applied with 55-70 psi of fluid pressure.

 

[biggy238]

The Diameter of the rear clutch is smaller than the TC clutch diameter. . Even if it has more friction area, it doesn't have the leverage (moment Arm) available to it that the TC clutch has.



Well. . I wonder If i need to look at this. . What stator efficiency id s used for the ATS triple? (just this one as I have ridden with one of these installed-only reason)

Just think what it would be like to drive a truck with a very loose fluid drive and have to lock the TC as soon as possible just to realize the performance that the truck has. This is just what a stock TC is like, and it is because of the loose stock fluid drive and reliabilty issues that most transmissions are upgraded. This is not for the daily driver, at least not for me or any of my customers.

I'm already living this nightmare. . i'm more than familiar with it. And every day this RPM drop gets smaller and smaller as the TC slips more and more.





Now back to the Flex plate rupture. . This is a function of drag racing as Greg L described it??? This does make sense as lockup with a low (stator) efficiency would cause a considerable shock wave through the driveline.



I guess my biggest problem right now is taking the theory here and turning it into tangible evidence.





Maybe I'll present this scenario. My normal beat is 5 miles of 6% up and downs with 3 lights. My only city driving (almost every weekend) is 27 stop lights of approx 1/4 to 1/2 mile spacing. Ofcouse Street racing is what i'm building this for. I can't afford strip racing or even pulling. I also live in a very mountainous rural area so low speed coupling is a big aspect. Short bursts of high power is definately needed. Sounds like I need to make some calls.



What converter is going to handle this situation better? (mechanics, not brand) (supposed) Stator efficiency, disk combo... . ?? I liked the fact that the ATS locked at 30mph and stayed that way.

I guess it's rhetorical now... Maybe I'm beyond help LOL.



Thanks to you all... especially for the fact that you adhered to my requested guidelines. Feel free to keep going though.



I hate to do it but i'm thinking strongly of not chancing it and going with what I already know is what I want.

 

[I-6DZL]

Do you realize you can enjoy a tight converter for running around town, and also enjoy the convenience of having a converter lock up from 30 to stock setting, all while having the OD shift controlled at your point of interest ??



DTT converters can be locked up from 2nd through OD, no problem. Do you need a DTT converter locked up in 2nd or early 3rd?? NOPE, do you want it?? Not likely... ...



A truck with a tight converter that cannot pull itself over a curb is a FLAT OUT JOKE!!!! That truck has to be sooooo overfueled it absolutely pathetic, and deserves the loosest converter possible.



Like was said before, one needs to choose a converter for their truck. Overfueled, over turbo'd trucks need a loose converter.

Properly tuned fuel - turbo'd trucks will get more enjoyment from a lower stall converter.



The way i see it is you have more than enough info to make your decision. Don't regret the decision you make... ..... I regret the first decision i made for an Auto, thus i run a tight single disk in MY truck, and smile EVERY DAY to and from work, stop light to stop light.



Either way you look at it, it's all about having fun... ... ..... just have fun!



Curtis

 

[MD500E]

It really comes down to personal choice. I have experience with a full ats triple disc truck as well as 3 dtt trucks, ranging from 89 to 93 race converters. I personally prefer a tighter converter most of the time. My favorite if the dtt 91, although there are times I cant get a trailer moving from a stop without a smoke fest.

 

[fox]

Looking at your power adders, you are seriously under AIRED! You need twins.

I can't imagine trying to pull a trailer with a set-up like that. Maybe a few blocks.

All in fun, you should only pull trailers at night, with a spot light on the EGT gauge!!!!

 

[biggy238]

Who would need a spotlight. . The Exhaust Manifold would be glowing bright enough to light everything up



And Really... I don't mind the Idea of having the truck lock at 30 and staying that way.



Beggars can't be choosey. The boat i'm in has sunk low enough to the water that i'd take just about anything to help me feel better. :{ At heavy throttle I drop 300rpm between the transmission and lockup. I'm working on the money for the build right now... My driving tendency is driving hard from a stop and then cruising, like I said. . short bursts and then constant speeds.