Allison Transmission Questions
AllisonMan keep your thread going - look at its history - it's been, and will continue to be, a tremendous help to many, many people. Like Bush70 said "PLEASE DON'T let one bad apple spoil it for the people that truly appreciate and need you." I would have said, 'Don't let one spoiled, bad apple ruin it for the people that truly appreciate and need you', because it was obvious to me that icrman was purposely tormenting you. Let's examine his posts and attempt to discern the truth. I do this at the risk of alienating some other members but I knew that AllisonMan would consider terminating his thread as a result of icrman's badgering, and I feel it is important that I do all I can to discourage that.
Things began to deteriorate shortly after icrman started answering questions directed specifically to AllisonMan. AllisonMan took offence and sepisllib supported AllisonMan's position. And AllisonMan politely warned me and others to beware of icrman's answers since he (AllisonMan) did not agree with a few of them.
After icrman discovered that other members thought he was intruding, he became indignant: "Well I didn't see all those posts yesterday, about me butting in on this discussion. I thought all these public forums, were for everyone to be able to write in, and offer some help if they can. This is the first time I have ever been chastised for trying to offer help and extra ideas. I didn't see anything, anywhere that said this disscussion was off limits.
Allisonman is a great help here, and I don't want to make an enemy. But I also have some years of Automatic Transmission experience, though very little on the "Newer Allisons", I have years of heavy equipment, truck, Diesel and gas engine, some aircraft engine, experience. Plus many many years of Machinist experience. So I do know a little bit about mechanics. I also hold an FCC License that atests to my electronics back ground. I do respect the man, but I don't appreciate being chastised for what appears as stepping on someones turf. That is very childish. Sorry I upsetted anyone"
Sepisllig again supported AllisonMan's position.
Then came the following post from icrman, which I knew would jepardize the thread: "Setting up another thread, seems a bit redundant. This one is Called Allison Transmissions. People looking for information shouldn't have to hunt all over the place. Transrand answered my question. It was ignored in my first post. Allisonman takes a whole week or so to come here to answer questions. And besides just like going to see a Doctor, don't you like a second opinion?
Okay I have a question or two. In the Allison transmission electronic shift controller "box" what actually operates the shift solenoids? Is it a transistor? If so what kind is it? And how is it biased? Also what is the voltage and power required to operate the shift solenoids? What kind of processor is used in the controller? Motorola?? I would like to know the material that the planet carriers are made from, and if it is heat treated. Is it specific to a certain model or series that they would use different materials for the carriers or different heat treats? What do they Rockwell at?
How about the clutches, are they paper? Or something else? I would really like the answers, because I don't know the newer transmissions at all"
I think everyone should reread the above post. In my mind, there is no sincere question-asking here - only badgering! Icrman profiles himself as "Machinist/mechanic/engineer". As an engineer, I believe icrman should know where to find answers to his own questions; particularly detailed engineering questions like, what kind of transistor operates the shift solenoids in the controller box. And how is it biased? Really??? Icrman claims to be the engineer, why should he be asking engineering questions of another member who makes no claims of being an engineer that I am aware of. And the planetaries - what do they rockwell at if they are heat treated and on, and on.
When I read the above post I was insulted, and I wanted to apologize to AllisonMan for what I saw as gross rudeness on the part of icrman. But I held silent, hoping this would blow over. It didn't.
Finally let me examine the quality of icrman's answer to the question I asked of AllisonMan since I was warned by AllisonMan to beware of that answer. I asked: "Hi AllisonMan! I am about to install an MT643 into a Cummins powered Dodge pickup but I have recently been warned that this large tranny will rob excessive horsepower and significantly reduce my fuel mileage. I chose this tranny because my engine develops approximately the rated torque (700 ft lbs) of this tranny, and I want the lockup torque converter. Is it true that this will be a bad combination, i.e. large power loss and fuel mileage loss? Can these losses be mitigated by a specific torque converter ratio or by other means. I already own this rebuilt tranny."
Icrman replied: "The losses in the larger transmission should not be too much more than on a smaller Automatic transmission. . . " GREAT! That's just what I hoped to hear; however, I'm still confused since two other Allison technicians I've consulted subsequently disagree - and so does AllisonMan.
So I asked again, hoping for quantitative information: "Thanks icrman! Can we be more specific regarding hp/torque losses associated with an Allison mt643. Is there anything published in this area which would allow me to make a comparison with other transmissions?"
Icrman answered: "It would be a bit difficult to be specific on the losses in the various automatic transmissions available. Unless you have access to a transmission dynomometer, or the engineering data from the manufacture. Modern Automatic Transmissions, and even some of the older Automatics are really very efficient. Too many people are under the false impression that an automatic is less efficient than a manual operated unit. I would say the automatic should actually beat the manual, because manuals in most cases use thicker oil, and have the gear sets constantly running in it. It is like a big cake mixer constantly churning that oil. And that robs power. Where as the automatic has in most cases one variable displacement pump, and the gear sets run in much thinner oil. (Fluid) The gears are not constantly submerged in the oil like the manual unit.
To answer your question the only thing in the larger transmission that would create an increase in drag, is the size of clutch plates, when released there is a certain amount of parasitic drag on them. But I don't think it is enough to be concerned about. If I find some info I'll let you know."
As I see it, this answer is so erroneous it is laughable. Without refuting each statement let me simply point out that icrman believes automatic transmissions are more efficient than manual tranasmissions. I believe that conclusion is so rediculous that it makes unbelievable every word that comes out of his mouth. Thanks AllisonMan, for alerting me to this. Don't worry I did see thru his words and continued hoping you would respond despite his distractions: I said: "Happy holidays, AllisonMan! Thank you for your reply. I was hoping you would reply despite the fact icrman had. I respect your opinion that the MT643 is overkill but allow me to make two points which might mitigate this. First, the fueling of my Cummins has been turned up considerably and is usable as I also have an aftermarket twin turbo setup, enlarged intake and exhaust. Thus, the torque of the engine is approximately 800 ft.lbs. which exceeds the 670 ft.lb. torque rating of the MT643. Secondly, I already own the rebuilt MTB643 and SAE2 bellhousing. I hate to think this must become wasted funds. Therefore, I'd still like to use it IF it does not significantly demise fuel economy and/or engine torque/horsepower. That is why I've asked specifically for your professional evaluation of those two aspects. When you say "overkill" it is not clear to me whether you mean the tranny is simply too heavy or large for a one ton pickup, or whether you mean it is too massive for the Cummins 6bt to rotate efficiently. I understand this 700 pound trans will put me very near my front axel limit, and that I must either raise the body two inches or modify the tunnel to accomodate the SAE2 bellhousing etc. Thanks for your patience. HFletcher"
PLEASE STICK AROUND ALLISONMAN, I DON'T BELIEVE ICRMAN CAN REPLACE YOU!!!!!!!!!!!!!!!!!!!!!!!!!!!!
