M920 TM needed

[Andy1234]

Title sez it all, I bought an M920, and I intend to drive it home. An idea of the differences between it and an M818 would be helpful .

I believe the TM # is 9-2320-273-10.

Thanks,

Andy

 

[papercu]

They are on LOGSA if you have trouble downloading PM a address and I'll send a CD. Wayne

 

[Andy1234]

They are on LOGSA if you have trouble downloading PM a address and I'll send a CD. Wayne

Found it! Thanks!

I have it saved as a .pdf file now, so if anyone else needs it I can email it.

Andy

 

[papercu]

There is also a training TC over at Tc 21-305-3_training Program for the m939 Series 5-Ton Tactical Cargo Truck_1 August 1997 Wayne

 

[M920]

Title sez it all, I bought an M920, and I intend to drive it home. An idea of the differences between it and an M818 would be helpful .

I believe the TM # is 9-2320-273-10.

Thanks,

Andy

Hi Andy,

Congrats on your new M920 truck! As you know....it has the CAT 7155 "slap-shift" transmission in it and it is actually quite diffrent to drive than any other tranny out there.
When I first got mine, I thought that it was like a manual valve body equiped automatic..... Well, that made for some pretty rough shifts!!!!

So you definately have to let of the accelerator when shifting the air shift controller!
What happens when you take the lever on the controller out of it's notch is this:
The air operated valve body disconnects the front and rear clutches in the transmission and a brake stops all the gears! Now the air-shift solenoids move the shift-forks and engage the straight-cut gears in the selected gear. After this is completed the rear clutch re-engages and speeds up the gears and allows the front clutch to re-engage and complete the shift!
(I was always AMAZED that this thing even works!)

Now here is where you have to be cautious:
This transmission will shift whatever is selected on the controller in the cab at WHATEVER SPEED!!!!! You can go 60MPH in 16th gear and select 1st AND IT WILL GO IN!!! (at least for a VERY SHORT MOMENT! Lol) Worse.....YOU COULD EVEN PUT IT IN REVERSE at that forward speed!!!!
I don't want to worry you, but I think it is good for you to know.

Just remember that this transmission does not have any way of knowing, what speed the truck is going down the road and it is therefore entirely up to you to select the right gear for the speed.

Now there is a feature on the shifter that lets you only shift 2 gears up or down at a time between 1st and 9th gear and only 1 gear at a time between 10th and 16th gear.
But there is also a little lever that you can pull up and now IT WILL FREELY GO IN TO ANY OF THE 16 FORWARD OR THE 2 REVERSE GEARS AT ANY SPEED!

It also does not help that the shift controller in the cab seems to work backwards from what you would expect. (1st gear is in the front and 16th towards the back)

Oh and before I forget, the clutch is just that, A CLUTCH! It does not act like a torque converter so just like you would "ease" of the clutch on a standard transmission truck to take off smoothly you have to "ease" on the accelerator pedal with this setup.
If you just push down on it like with an automatic transmission (and this is easy to do since there is no clutch-pedal) it will engage "BRUTALLY" just like if you slipped of the clutch on a standard!

So just be cautious when you first start driving it and remember that if you put it in the wrong gear on accident the only way to disengage it and keep the engine from reving way up is to pull the shift lever back out of it's notch.
So it is simple....Shifter in the notch: clutch engaged....shifter out of the notch: clutch disengaged.

Unfortunately in the beginning, my normal reaction to misshifts was to push in the clutch, but the place where you would expect it to be, is occupied by the Jake-brake pedal. (which generally makes matters worse when depressed at the wrong time!) Lol

Despite all the above.....it is actually a nice transmission to drive....once you get used to it.....

I hope this will help you on your trip back and feel free to contact me if you have any more questions or (heaven forbid) run in to any trouble. Lol

Soni

 

[Andy1234]

Wow! Thanks, Soni! You read my mind as to the next set of questions that I had!

When you start out, do you use 1st, or is it ok to start in a higher gear, like 4th or 6th?

Thanks,

Andy

 

[M920]

Wow! Thanks, Soni! You read my mind as to the next set of questions that I had!

When you start out, do you use 1st, or is it ok to start in a higher gear, like 4th or 6th?

Thanks,

Andy

Andy,

yeah.....5th or 6th is as low as you want to go when you are empty or bobtailing. Once rolling the shifter will let you skip gears up to 10th gear....so if you start in 5th....it will let you go: 5th...7th...9th...11th...12th...13th...14th...15th...16th (which btw is overdrive)

If you start in 6th.....it will let you go:
6th...8th...10th...11th...12th...13th...14th...15th...16th

Also....because of the factory detroit lockers in the rear tandems the truck will act kind of jerky when making a sharp turn while coasting. It feels weird but it is normal and there is no reason to worry about it.

Make sure and post some pics from your trip!


Soni

 

[M813rc]

If you want the paper -10s for the M920, Milman61 on Ebay had them NOS last I checked.
I'm old fashioned, I always like to have a paper copy of the manual in the truck with me..

Cheers

 

[reb87]

Make sure you let the air get above 80 psi before using the transmission. Also there is a button by your right knee (on the tranny shift tower) that must be pushed in (like the air parking brake) to activate the transmission. If the transmission is not shifting good like one of mine you may need to keep the pressure over 100psi. The best way to shift is to let off the accelerator right after the first "poosh" of air (there are two "pooshes" one taking it out of gear and one putting it in the next gear)

 

[M920]

Wow! Thanks, Soni! You read my mind as to the next set of questions that I had!

When you start out, do you use 1st, or is it ok to start in a higher gear, like 4th or 6th?

Thanks,

Andy

Oh and one more thing to look out for: The Transfercase holds very little oil for it's size and you have to make sure it is to the fill level or you burn up the bearings.
Also it has a little oil pump mounted on top, across from the input shaft that pumps oil to the top of the T-case.
This pump can be disengaged for cold weather use by switching a spacer from one side to the other....make sure it is in the "summer mode" (the spacer needs to be on the end of the pump, not between the pump and the T-case!)

Look it up in your TM if my explanation does not make sense to you.

Soni

 

[Floridianson]

Wow! Thanks, Soni! You read my mind as to the next set of questions that I had!

When you start out, do you use 1st, or is it ok to start in a higher gear, like 4th or 6th?

Thanks,

Andy

Don't know what motor you have but level ground no trailer I start in 8th and skip two gears at a time. So 8th to 10th to 12th and so on.
The clutch starts to engage at approximately 775 rpm and is fully engaged at approximately 1100 rpm. The selection of the correct gear ratio must be made to prevent a long period of time in the 775 to 1100 rpm range. If the truck engine does not accelerate above 1200 engine rpm in three seconds or less go to a lower gear.

 

[emr]

I am no expert on that truck, But I can tell U differences between an M818 or from bumper to pintle, they are both green though...But thats about it. ...But I sure would LOVE to have one, good luck and enjoy it...