M915A1 Governor Help

[ryanaubra]

I recently purchased a civilian model 915 tractor, rare bird I'm told. It has the same 400 Cummins/Allison, and basically everything else that the military version has, with the exception of being 12Volt and paint. It has a governor on it that limits you to around 58 mph that feels like it is in the trans, and not the fuel system. Anyone have any experience with these governors? I have owned multiple 800 and 931 series tractors, but this is my first 915. Thanks.

 

[tktsales]

If this has the Allison Trans there is no way the trans can really limit your speed. Some off road trucks do have modified valvebodies to block the trans form going into high gear but I don't think you would get 58 mph with this truck if that were the case.. The Cummins fuel pumps typically governor the engine speed to 2100. Check your throttle linkage and make sure when you push the pedal to the floor the linkage on the fuel pump is actually going to full throttle and make sure the modulator cable for the transmission does not bottom out which will limit the movement of your throttle as well.

 

[WillWagner]

Before electronics there was a way road speed was governed by use of an air actuated plunger on the pump, the pump had what was similar to a VS body, the same but not, it looked different, I can't recall the acronym. Take a pic of the pump

You should do what was posted in the above post too. The lever on the pump needs to break over. If it doesn't, before you go messing with rod adjustments, look under the pedal, there is a throttle stop bolt screwed into the floor.

And, at 58, what RPM are you at? Could be gear bound.

 

[simp5782]

Rpm governor Is set to 2150 more then likely on the BCIII . With 4.90 gears on 11R22.5s with that allison being a direct drive more than likely its doing 57/58@ 2150rpms. According to the rpm calculator.

You can shim the governor spring, up the tire size to 395s 85 20s like some people do to increase speed. Re gear it to 4.11s or 4.30s. Or go with the 7speed allison some of the 915s got upgraded too

Or swap In the cat 7155 you have and itll do 69 at 2150rpms

 

[NDT]

There were no civilian M915A1s. 58 mph is against the governor, that is all any of them will do. Just takes a little longer to get somewhere that's all.

 

[Floridianson]

The walking beams on the 915 are shorter than the ones on the 916 and up. It will not allow you to run 53's so be happy and as Wes said put on some bigger tires and gain a little but still walk up hills. My 915A2 with Allison HT740 same way gear bound with 4.56 rear gears so I spend a little more on fuel if I go out of state but walk up hills at 55mph. If I remember right the front drums are smaller than the big boys so no grinding on the drums to make the HEMTT rims work and run the 46's. What are your plans for the truck as the tire size might through off some trailers?

 

[Tow4]

I think the red line is 2300 RPM for the BCIII. I run about 60 MPH at 2150. Anything between 56 and 60 MPH feels good as a cruise speed.

 

[Floridianson]

Thought the seven speed was computer controled. Still don't know what it will be used for as local then 55mph is not all that bad. Best would be gear change new correct tires. Don't use the truck much now but on the edge looking at a gear set change for me.