Allison Transmission Questions

Discussion in 'General RVing' started by AllisonMan, Apr 5, 2003.

  1. dbarton291

    dbarton291 Senior Member

  2. Rick from Paso

    Rick from Paso New Member

    Re: Allison Transmission Questions

    Dan, Thanks, that's what I've been looking for! I got tons of manuals with this old eagle, but nothing in the way of service manuals. I try to do my own service and repairs. I have a 1996 FL70 with the same mechanical Cummins 8.3, I have all the manuals for that truck but it has a Eaton/Fuller road ranger 9 speed. Automatic trannys are a real mystery to me, my hat's off to you guys who work on them. I wonder if I can get some service manuals from Spartan. Many of the systems are the same as in my truck ie. air brakes, compressor and so forth, but my FL70 has tons of room to work under and on top of, this thing is awful to crawl under! Triple E, I did crawl under and saw the real drain plug! Thank you all so much for your help!! (India?)

    Regards, Rick from Paso
     
  3. Triple E

    Triple E Senior Member

    Re: Allison Transmission Questions

    Rick, this is a big secret. Danny and agent 99 covers this globe to protect us from evil. So keep it quiet. ;) :clown:

    :8ball:
     
  4. dbarton291

    dbarton291 Senior Member

    Re: Allison Transmission Questions

    Yeah, and 99 is way hotter in person :)

    I'm in Delhi tonight, eating Chinese food and watching cricket. I got to help diagnose some vehicle problems here in a fleet. Conditions here around most heavy vehicles and the related servicing of them are....um..... different.....very different.
     
  5. dbarton291

    dbarton291 Senior Member

    Re: Allison Transmission Questions

    Well, it's evening here, 11:00PM. It's 1:30PM eastern time back home.
     
  6. dbarton291

    dbarton291 Senior Member

    Re: Allison Transmission Questions

    Back in the USA again. Whew.
     
  7. Londonjack

    Londonjack New Member

    RE: Allison Transmission Questions

    Hi, AllisonMan! I was planning to consult with Indy, but the Factory closed for Easter weekend; I was Googling, found YOU, and see that I would have to wade through 41 X 25 back posts to see whether you've already answered my issue, so I hope that you will either answer directly or point me to prior post(s) that has my answer.

    I have a 1983 Bluebird Wanderlodge with 3208 Turbo CAT and a 4-spd. Allison, with 4:89 rears.
    It won't shift to 2nd until it has hung awhile @ 15 mph (approx 2300 rpm). Same 'hang' before shifting to 3rd @ 25 mph (2300 rpm). This seems to take 'forever'. Then she takes off like a scared rabbit before it shifts into 4th @ 40-42 mph (and drops back to 1800 rpm), but feels sluggish, possibly lugging a bit.

    I want the shifting points to occur far faster, except for 4th, which I'd like to be able to control by foot pressure, if possible, but have it shift no sooner than about 45 or 50 unless I totally back off fuel.

    The shop that has my bus now has no clue how far to turn the screw(s) in the valve body which I'm told will adjust shift points. I'm a non-mechanic, but did own some Class 8 trucks back in the day.

    Could you kindly speak to just how my mechanic should 'tune' the valve body adjustment(s) for shift points so as to get me up to road speed faster, and without 'hanging' at the top R's of 1st & 2nd, and delaying that last shift and lockup in 4th?

    Could you also speak to whether swapping the 4:89 rear end for, say, a 4:11 (or higher speed) would enable me to avoid dragging along in the lower two gears (possibly even without adjustment of the valve body) ?

    Also, do you think that we ought to be looking at the governor, or is this shifting delay most easily remedied by either the valve body adjustment or by going to a higher ratio rear end?

    Having driven Class 8 steel haulers, I always preferred to employ "progressive shifting" -- that is, just get her moving in each gear enough so as not to lug in the next gear, but winding the rpm's progressively higher with each succeeding gear. To me this is easier on the equipment, results in a much smoother ride, and never, ever tops the tachometer in the lower gears.

    I would like to have my Allison shift similarly, and much sooner, rather than winding out to 2200-2500 in first, etc., so that it sounds like I am needlessly over-revving the engine in (and unnecessarily prolonging driving in 1st & 2nd gears -- which is happening, but not by my choice !

    Does doing city driving in 3rd only prevent upshifting, or does it somehow ALTER the shift points because of that manual selection of range three? (I swear I feel a difference, almost as though there is at least one additional gear in there, splitting [or shifting?] much more to my liking, and had I discovered this before the trip to the transmission shop, I'd have more insights to pass along to you.)

    Finally, I plan to convert to an air throttle as soon as possible. Would that cure any of the issues I have presented here? (The present accelerator's cable seems to stick at times, and push only with considerable effort . . . )

    Thanks in advance for your every consideration, AllisonMan!
     
  8. dbarton291

    dbarton291 Senior Member

    Re: Allison Transmission Questions

    Here's my advice:

    1. Get your vehicle to a shop that is Allison authorized. If it's at a place that doesn't even know about turning the shift collars, I wouldn't want them touching my transmission. It should be one of the MT series transmissions. An MT643, or 647 depending on the engine power.

    2. The engine may or may not be making adequate power and turning the proper RPM. Remember, this vehicle is 27 years old. I would have the shop perform a stall test to make sure the engine is making power, and its proper RPM before making any transmission adjustments. A lack of top end power, or RPM will make the condition you describe of "hanging" before shifting.

    3. The axle ratio is independent of the ability of the transmission to shift and not "hang".

    4. The air throttle will not effect the "hanging" issue and will decrease your ability to modulate shifts with your foot.

    5. Once you're sure the engine is making full power and RPM, then you can slowly decrease the shift points by turning the adjusting collars further down(down their "ramp"). This will decrease the pressure the shift spring is making on the shift modulator valve it sits against. By turning the collars down, I mean you will be turning the collars further down the "ramp" shape they have. The collar will actually sit further out in the bore as you lower the shift point. If I remember correctly, the 1-2 shift valves are in the bore closest to the selector valve, then the 2-3, then the 3-4. The last bore you see on the side of the valve body with the shift adjusting collars is the trimmer regulator valve.

    6. If the transmission modulator is an air modulator, you really won't have much control over your shift points with your foot. The air modulators are pretty much either on or off. If you have a cable modulator, make sure it's adjusted correctly. I've posted the link to the MT mechanics tips booklet here a number of times. Here it is again: http://www.allisontransmission.com/publications/pubs/MT1357EN.jsp

    7. Driving around in D3 prevents upshifting to fourth. It does not affect the shift schedule otherwise.

    8. You might check the governor filter and clean it. You can find its location in the mechanics tips booklet. Doesn't sound like you have a governor failure or problem to me.

    Well, now ya know what I think and a little of what I know. I hope it helps some. I always did like messin with the MTs and HTs.
     
  9. Londonjack

    Londonjack New Member

    Re: Allison Transmission Questions





    1. I had it to the local Allison shop one Saturday, and have far more confidence in the moxy of the man who has my bus than the former. I'm also afraid of their labor rate and 'big shop' propensity to gouge.

    My current trannie mechanic does cars all day long, and some garbage trucks - at least to the extent of gross shift failures - so this shouldn't be a total mystery to him. He simply lacks a word of advice, which is what you're hopefully going to supply. :8ball:


    5. I did not see a diagram of the valve body "collars". Could you point me directly to one (instead of an entire user's manual)? And could you kindly suggest the amount of change to ramp (percentage-wise or other measure of movement down the ramp) the collars should be moved? (This, so that we don't have to drop the fluid 2-3 times to even get close to what we want....?)



    So, If I want him to split the difference (between current setting on 1-2, so that it shifts closer to 9 or 10 mph than 15; or current setting on 2-3, so that it shifts at, say, 18 rather than 25 or 26), is that a mere matter of approximately eyeballing a halfway point between 'zero' and current setting?



    I just want my man to have some hint as to how far to turn the collars. ;)



    6. I hear you saying that there now exists a certain measure of foot throttle 'feel' or foot control over shift points, but that with an air throttle, I would lose that control. I think I would hate to lose that, but I don't have much if any control as things are (were before the new cable to trannie). Besides, the guys on the Wanderlodge Owners Group (WOG) to a man swear by the air throttle, and rave that it's the singlemost important improvement they have ever made to their enjoyment of driving their Bluebirds.

    My guess is that they get foot-tired when driving long distances, and many cruise controls aren't working, for whatever reason(s). Also, in the case of older, cabled controls, they probably are just too sticky, and make hard work out of acceleration, reaching existing shifting points, etc.


    I only hope that it doesn't lead to too abrupt or hard shifts....



    Thanks again for your kind and prompt response, Sir. BTW, I once played music on a big name band with the famous Dee Barton, of Stan Kenton fame.... :)
     
  10. dbarton291

    dbarton291 Senior Member

    Re: Allison Transmission Questions

    1. Okay. Make sure the engine's making full power and RPM first, or this is all really a waste of time.

    2. If your guy works on cars and garbage trucks all day long, he has seen shift collars before. Drop the pan and he'll see them right away. If he doesn't recognize shift collars, he may be a great guy but isn't as savvy as you think. I don't have a picture of just shift collars. They kind of look like a ramped ring with notches in it.

    3. Nobody can truthfully say how many notches you need to drop those collars to get the MPH you want. The shift specifications for the valve body are based on output shaft RPM, so tailoring like you want to do takes some trial and error. My recommendation is to first see where they are. If the collars are all already down at the bottom, you can't get what you want. If the shift springs have enough adjustment in them as they are now, I would start by dropping 2-3 notches and see what happens(they only have seven notches on each one). If one doesn't have 2-3 notches of downward adjustment left, take it to the bottom notch and leave it.

    I really recommend you don't get into trying to change springs. If you get the upshift point too low, the downshift point also gets low and the vehicle may lug on a hill. You don't want that. Things break under those conditions.

    I know this isn't exactly what you were asking for, but I hope it at least helps get you started and helps you avoid a couple of pitfalls.
     
  11. C Nash

    C Nash Senior Member

    Re: Allison Transmission Questions

    Danny, In checking a neighbors MH with the Allision Trans I found it full of water. Water will come out the overflow on the trans with engine running and the dipstick is milky Is the trans cooled by going through the radiator? The MH has not been in water. Radiator was low in coalent. Thanks
     
  12. Triple E

    Triple E Senior Member

    Re: Allison Transmission Questions

    Nash, Danny has stated that if the transmission cooling water has anti-freeze in it and the anti-freeze gets into the internals of the transmission, the transmission will have to be rebuilt. I guess anti-freeze will destroy the bonding agents in the Allison Transmission. :( :dead: :sleepy: :disapprove: :( :dead:

    :8ball:
     
  13. LEN

    LEN Senior Member

    Re: Allison Transmission Questions

    Nash, the trans has a radiator hook/welded to the engine radiator. There was a period of time where a crack formed between the two and anti freeze got to the trans and EEE is correct it only takes a few minutes and the trans needs a rebuild. Do a search on a couple other sites and you will find the problem and which coach's and motors are involved. The cure is new or rebuilt radiators with the fix and a rebuild on the trans.

    LEN
     
  14. dbarton291

    dbarton291 Senior Member

    Re: Allison Transmission Questions

    Yup, anti-freeze destroys friction clutch plates. Sounds like the radiator had a leak between the trans cooler and the engine part of the radiator. Gotta get a new radiator and rebuild the trans.

    I've seen people try to flush the trans and put in new fluid. Every time I've seen somebody try it, the trans eventually failed. Better to fix it now than have it fail on the road somewhere.
     
  15. C Nash

    C Nash Senior Member

    Re: Allison Transmission Questions

    Thanks, that is the answer I was expecting.
     
  16. H2H1

    H2H1 Senior Member

    Re: Allison Transmission Questions

    Nash I know that wasn't the answer you was looking for. But now you know what you have to do. I hope this one you are working on and not yours.
     
  17. Allison Expert

    Allison Expert New Member

    Re: Allison Transmission Questions

    Hey dbarton, something else to keep in mind on that older motorhome with the MT....Moving the collars will change the output rpm about 20-30rpm in either direction. To take out the trial and error part of changing something, putting the pan back up and repeating that process, if he has it at an Allison shop already, they could just pull the valve body and put it on a test stand and calibrate it that way.....Just a thought :)
     
  18. dbarton291

    dbarton291 Senior Member

    Re: Allison Transmission Questions

    Um true....but....read the thread. He's not at an Allison shop. Doesn't want to go to an Allison shop. The guy that has it doesn't have a valve body test stand.

    20-30 output shaft RPM is generally correct. However, the owner is talking is MPH. You gotta take the output shaft rpm, and the axle ratio, and the tire revs per mile to change that 20-30 output shaft RPM into miles per hour the customer actually sees. Then, what if some springs have been changed over the years. That 20-30 output shaft RPM may change. This guy is looking for a quick, free answer. I'm not getting out my slide rule, I mean my calculator for this one.

    I was teaching the MT in service training classes 30 years ago. I haven't lost all my marbles yet....maybe.
     
  19. Allison Expert

    Allison Expert New Member

    Re: Allison Transmission Questions

    dbarton, I wasn't saying that you don't know what your talking about, it was just another idea for the guy to think about. Excuse the hell out of me for trying to suggest another avenue.... :angry:
     
  20. H2H1

    H2H1 Senior Member

    Re: Allison Transmission Questions

    well I think both of you are real smart and glad both are on this forum. I know that if I need advice I can ask here. Bury the hatchet we need both of you. :laugh: :laugh:
     

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