M1078 How do you make it a 4WD or am I missing something???

[Lugnuts]

This is the second time it happened. The M1078 got stuck and one tire alone spun killing any forward or reverse progress so I am writing the question, HOW DOES ONE ENGAGE THE DIFFERENTIALS INTO 4WD OR IS IT MY IMAGINATION THAT THESE TRUCKS REALLY DON'T COME WITH 4WD?
The first time it happened I said I would get back to it and never did. I did a search on this site, been all around the truck, went through the manual superficially,

 

[dronsen]

The truck is full-time 4x4. Activating transmission MODE helps by transferring power from 70% rear/30% front to 50/50, but the Achilles heal of these trucks are lack of diff lockers. Acela has them for sale - or FMTV Truck Sales last time I checked - best mod ever (except high speed gears).

 

[Lugnuts]

The truck is full-time 4x4. Activating transmission MODE helps by transferring power from 70% rear/30% front to 50/50, but the Achilles heal of these trucks are lack of diff lockers. Acela has them for sale - or FMTV Truck Sales last time I checked - best mod ever (except high speed gears).

Thank you for your response. Please instruct me about MODE activation . I assume you are speaking of the MODE button on the shifter

 

[Third From Texas]

Thank you for your response. Please instruct me about MODE activation . I assume you are speaking of the MODE button on the shifter

Button on the trans control.

BUT...there are a number of restrictions. It's in the truck operator's manual. Do you have that TM?

 

[Lugnuts]

Button on the trans control.

BUT...there are a number of restrictions. It's in the truck operator's manual. Do you have that TM?

I do not but I will promptly go see if I can locate that Operators TM unless of course you have it conveniently by you.

 

[Third From Texas]

And these trucks are not really 4x4. They are technically more along the lines of AWD. Pity they didn't see fit to incorporate lockers and give the trucks actual four-wheel locking capability

 

[Third From Texas]

And these trucks are not really 4x4. They are technically more along the lines of AWD. Pity they didn't see fit to incorporate lockers and give the trucks actual four-wheel locking capability

Don't have it on me and I'd hate to tell you wrong info. But you can screw the truck up if you don't follow the procedures/restrictions on Mode use (ie: not a good idea to slap it into mode going down the highway, etc).

 

[Lugnuts]

And these trucks are not really 4x4. They are technically more along the lines of AWD. Pity they didn't see fit to incorporate lockers and give the trucks actual four-wheel locking capability

Thanks. Check the other post from dronsen and he listed where the lockers could be obtained from.

 

[Third From Texas]

https://tfsweb.tamu.edu/uploadedFiles/TFSMain/Preparing_for_Wildfires/Fire_Department_Programs/Career_Fire_Department_Programs/Firefighter_Property_Program/TM-9-2320-365-10%20Operators%20Manual%20M1078%20series%202,5%20ton%204x4.pdf

 

[Third From Texas]

Thanks. Check the other post from dronsen and he listed where the lockers could be obtained from.

Yes, the army never spec'ed them and it would have been nice. As far as I know the lockers available are not air or e-lockers (they are "locked") . Most folks only slap on in the rear unless the truck is full-time off-road because lockers will cause you outboard wheel to "skip" in a tight turn).

But I'm NOT the guy to ask about lockers.

 

[Ronmar]

What year is your truck? The manuals are available in the manuals section on this forum, which is the first section on the main steel soldiers page. I think it is on the second page under present conflict vehicles...

The LMTV is full time All wheel drive with as mentioned a 70/30 torque split.. this means that if traction becomes unbalanced, all the engine torque can esacpe out of one wheel as you discovered. Also as mentioned mode button will lock up the center diff and limit you to 5th gear. This should result in 2 wheels spinning, one front, one rear.

these trucks are begging for a diff lock or a traction control...

 

[Third From Texas]

these trucks are begging fir a diff lock or a traction control...

So much this. I wish Bryce had pursued his air locker quest at the manufacture level.

 

[Ronmar]

So much this. I wish Bryce had pursued his air locker quest at the manufacture level.

Because they are air brakes, I think a simple traction control(brake the spinning wheel to force torque elsewhere) is very feasible. I have drawn up one simple circuit to do this, I just don’t have time to play with it yet...

 

[Lugnuts]

What year is your truck? The manuals are available in the manuals section on this forum, which is the first section on the main steel soldiers page. I think it is on the second page under present conflict vehicles...

The LMTV is full time All wheel drive with as mentioned a 70/30 torque split.. this means that if traction becomes unbalanced, all the engine torque can esacpe out of one wheel as you discovered. Also as mentioned mode button will lock up the center diff and limit you to 5th gear. This should result in 2 wheels spinning, one front, one rear.

these trucks are begging for a diff lock or a traction control...

I don't have the year on the truck by me. Thanks for answering.
I went to the Operators Manual and they did mention shifting the MODE switch but weren't clear as to what happens. So the center diff locks or the transfer case? If you have only 2 axles front and rear then what locks?

 

[Lugnuts]

Because they are air brakes, I think a simple traction control(brake the spinning wheel to force torque elsewhere) is very feasible. I have drawn up one simple circuit to do this, I just don’t have time to play with it yet...

If you are not going to use it for personal gain (which is quite alright) might you post your idea? I thought on the same issue but these things are electrically monitored beyond useful as it is in my opinion.

 

[Ronmar]

The center differential we are referring to is in the bottom of the transfer case. in the round section at the bottom where the drive shafts connect is a planetary gear installed as a diff that gets you that 70/30 torque split(mechanical advantage/70% towards the rear). There is also the P7 clutch pack that when engaged locks the planet carrier to the ring gear(locks up gearset) so you get a 50/50 torque split.

As for the traction control, I think I would like to see how it works first ever play with fiddle or split brakes on a tractor or dune buggy? You brake the wheel that is spinning which forces torque back toward the wheel that has traction. I do this as often as I lock the rear diff on my tractor... I am envisioning a simple counting circuit and a transistor driving a solenoid air valve. The issues of course are doing this in a way that cannot possibly interfere with the existing braking function and of course measuring wheel rotation in a way reliable enough to survive being buried in mud in close proximity to a spinning wheel...

 

[Lugnuts]

The center differential we are referring to is in the bottom of the transfer case. in the round section at the bottom where the drive shafts connect is a planetary gear installed as a diff that gets you that 70/30 torque split(mechanical advantage/70% towards the rear). There is also the P7 clutch pack that when engaged locks the planet carrier to the ring gear(locks up gearset) so you get a 50/50 torque split.

As for the traction control, I think I would like to see how it works first ever play with fiddle or split brakes on a tractor or dune buggy? You brake the wheel that is spinning which forces torque back toward the wheel that has traction. I do this as often as I lock the rear diff on my tractor... I am envisioning a simple counting circuit and a transistor driving a solenoid air valve. The issues of course are doing this in a way that cannot possibly interfere with the existing braking function and of course measuring wheel rotation in a way reliable enough to survive being buried in mud in close proximity to a spinning wheel...

Thank you