LMTV Transmission won't engage

[Oxyacetylene]

Mine was really lurching at a stop when shifting from 3-2. Would jump forward about a foot! Was also straining while at a stop. The throttle pedal lift resolved it. Went to lube and adjust and found where the pedal connects to the floor had been poorly repaired with some green rubber goo. With much effort, removed the goo and welded a panel after removing the small rust hole. Remounted and lubed the vulcanized hinge and viola. A fine example of a 5 minute job turning into a 3 hour task.

I'd like to see some pics of the pedal area you repaired, and the linkage adjustments. Mine apparently had rust holes in the floor and they patched over it with an aluminum plate, and formed an aluminum piece to hold the rear of the pedal, then riveted it all down. I think it makes the rear of the pedal sit a little higher than normal and I thought about redoing it all some day.

 

[tburk49760]

No pics sorry. Bent up a 8" square piece to fit, put a 1/2" lip to weld to the engine hump and direct bolted epithet pedal through the floor with fender washers on both sides of the sheet metal. Works way better...

 

[aleigh]

This thread is gold, the LMTV I just picked up has the same issue, the pedal is not returning to a idle without pulling it up. No problems going into gear thankfully, but it sure wanted to destroy the car in front of it at red lights.

I had a glance at it this morning and didn't see a spring / whatever is causing the pedal to "return". Is it just the throttle linkage / spring on the engine that pushes the pedal through the wire? The pedal does look bent - but I couldn't tell if they are made that way, it does not look "broken", but it is bent about halfway up, sort of perfectly.

What's the consensus on a fix for a stock pedal setup?

 

[tennmogger]

The non-return to idle on my truck was a dragging cable between pedal and linkage up under the dash. If you remove the dash and follow the cable from the pedal up to it's top end, well, you can't reach it or see it. But, you can dribble oil down the center wire of the control cable, right to the top of the cable sheathing.

That lubing fixed my non-returning throttle pedal.

Bob

 

[FSRD]

My lmtv M1078 will not go into high. I can drive in lo just fine but when switched into high the truck won't move. I can hear the transmission shift into great and the engine rpms will go up but the truck won't move. Any solutions on what to do to fix it? Thanks!

 

[Suprman]

You can drive it after pressing the mode button? Or pressing arrow down till its in 1 low range?

 

[coachgeo]

somewhat inside joke........ but then again.... actually logical ... question; are both driveshafts attached?

 

[FSRD]

I can push the mode button so that the mode is on which means it's in low gear and it will drive just fine through all five gears in low. If I then push the mode button to put it into high gear whether it's already in law or a neutral then the truck won't do anything I can hear the transmission go in but the truck doesn't move. It feels like it's not engaging into high.

 

[FSRD]

somewhat inside joke........ but then again.... actually logical ... question; are both driveshafts attached?

No the front drive shaft is not attached.

 

[Suprman]

Thats your problem. And mode is not low range it justs locks the center diff making it 50/50 awd. You have to arrow down to 1 for low range.

 

[coachgeo]

EDIT..... LOL... ok didn't have this post finished in time...... you posted driveshaft not connected before I got this posted. Oh well... it happens. As stated below.. don't think "HIGH and LOW" it will totally confuse you. What I wrote below may still be educational to you though (or confuse you more lol)

I can push the mode button so that the mode is on which means it's in low gear and it will drive just fine through all five gears in low. If I then push the mode button to put it into high gear whether it's already in law or a neutral then the truck won't do anything I can hear the transmission go in but the truck doesn't move. It feels like it's not engaging into high.

if drive shafts are attached; Easier said than done, jack up one wheel on one each axle ... just in case prepare for it being able to drive off of them. Put it in Highway Mode (it is NOT a high gear). Watch to see if one wheel up in the air does NOT spin. If that is the case then look at driveshaft in a safe way. If drive shaft spinning on both but one in air tire on one axle not spinning then something is amiss in that axle. If one drive shaft is not moving then you got something amiss on output section of the tranny to that axle. You see in highway mode the transmission.. like a differential will send all power to the side that is slipping.

If an axle or part of tranny output to one axle is not working (spinning somewhere in the line but not providing drive forces) then the tranny provides all power to that one that it thinks is spinning... which in the line somewhere is not actually putting any forces to the wheel due to whatever is broken (or disconnected) thus you don't move. In Offroad mode the tranny is locked like a locking differential thus no matter how much slip; power is sent to both axles..... allowing truck to move by only the one axle that everything down the line between tranny internals and wheels is still working.

 

[FSRD]

Haha that would be the problem. I put it in high then into drive check the front drive line to see if it was turning and sure enough it was definitely turning so I guessed if one drive shaft is not attached he sends all the power to it. I thought that might be the problem that's what I get for thinking instead of checking.

 

[frank8003]

LMTV transmission is Allison 3700 SP 7-speed automatic with integral single speed transfer case?
View attachment LMTV Allison codes SA3360EN Shift Selector Codes.pdf

 

[Suprman]

MD3070PT trans. Wtec 2 till 97 usually unless upgraded and wtec3 98-2003ish.

 

[coachgeo]

LMTV transmission is Allison 3700 SP 7-speed automatic with integral single speed transfer case?
View attachment 666619

this will help explain what it is... http://www.allisontransmission.com/en-gb/transmissions/models/3000-series

was just contemplating contacting a fellow I know to see if can get him to help explain how this mechanically geared 6 speed 3000 series transmission becomes a 7 speed when adding the AWD transfer case and calling it a 3700 series. Least I think it is mechanically only 6 physical gears. Think it is so if that is the case how does it become 7 when adding Tcase.

Im not sure if the Tcase on the back ADDS a gear below first gear (which I doubt right now but certainly have been wrong many thousands of times) or if it is actually an underdrive that splits a few or all of the 6 available gears available inside a 3000 transmission. Another words get the feeling ratios get reduced inside the Tcase by an underdrive gear. Splitting would explain while all the sudden gears on the keypad are lost when your in Offroad Mode. I'll try to talk Ted into coming in here and explain or at least explain to me and I'll report back second hand.

 

[Suprman]

You start in 2nd and have 6 forward gears. 1st is low range.

 

[coachgeo]

You start in 2nd and have 6 forward gears. 1st is low range.

Yes.. but the 3000 series transmission this is based on only has I believe 6 mechanical gear ratios available.... so what magic inside the Tcase all the sudden makes it 7 ratios. That is what am going to ask Ted.

 

[tennmogger]

You start in 2nd and have 6 forward gears. 1st is low range.

That single line, one sentence, is more definitive than many posts of paragraphs of speculation.

 

[coachgeo]

Since most folk call their boats, trucks, cars, bikes and so on.... a girl... guess we should oblige her desires to be " understood". Don't all woman say.... they like to be "understood". Certainly seems iIf you don't understand them they get mad at you more often.

So think I'll stick with trying to "understand" her..... but to each her own. Hopefully, Ted will oblige the request for help in understanding the inner workings.

 

[Johno176]

Tennmogger: right on.