M915A2 highway speed

[trashauler]

Looking at a few M915A2's. Both have 60 series Detroit, Allison auto, and 4:56 rears. Anyone know the max speed on these?

 

[trashauler]

If anyone else was worndering it is 58mph. Purchased and drove one back to the shop today.

 

[Ferroequinologist]

I thought the A2's could do 80...

Other than that, how do you like it?

 

[BKubu]

I know you did not ask me, Adam, but, since I own an M916A1 and an M916A2 (the M916A1 is equivalent to his M915A2) I can say that I am sure the truck brought a smile to his face. They have power to spare...430 HP, 1400+ foot pounds of torque. Unfortunately, no A/C in the M915A2 and M916A1. My M916A2 has it, though.

 

[trashauler]

Great truck! Definitely plenty of power. I am sure with a gear ratio change you could get more speed out of it. For what I will be using it for 58 is more than plenty.

 

[wreckerman893]

I thought the A2's could do 80...

The M915's that had the CAT transmission in them would bump 80 if the fuel was turned up to 2350 RPM. My former Convoy Commander can attest to that because I passed him in West Texas in a CUCV that was running wide open. He was not amused.

 

[quickfarms]

What rom are you turning at 58?

 

[trashauler]

It was running about 2150 @ 58

 

[FreightBoss]

I see this is an old thread but I was curious...I have an M915a2 that I have been using commercially. I was on the turnpike and was passed by another M915 he must have been doing 70 an active duty towing equipment. My M915a2 does 58 @ 2150 so I would have to get a new rear end to get more speed...did later model 915's come with a different rear end?

 

[M543A2]

There must be some big differences in both power and speed. A friend of ours used his to tow-bar a disabled M62 wrecker for us. It was slow, foot on the floor going over hills with down shift after downshift and even not able to get up suitable speed on level ground. The truck had no issues with fuel filters, etc. We used our M35A2 to tow the truck back to the owner (we did not want to put the road miles on the power train) and once we got into overdrive we never dropped out of it over the same route taken with the 915. We had a hard time understanding why the big cubic inch motor was worth it after our experience with this truck. The trip is about 30 miles. We have done head work to the MF engine and turned up the fuel in our M35. In now over 5 years of using it that way to tow other trucks and pull a Ferree 18 ton tandem axle dual wheel trailer we have never had an issue with it, but we use the power with sense. So, with that experience, it is good to see that evidently there is a way to get more power in the later trucks.
Statements from my experience! Regards M543A2

 

[NDT]

The newer M915s have an overdrive Allison.

 

[dmetalmiki]

Just curious. what is the target M.P.G. for the quicker truck running a mile a minute?

 

[Monkeyboyarmy]

There must have been something wrong with the pump on that 915, probably a stuck aneroid valve. We had a 916 that looked like it had a new pump on it....would not do over 30 empty. Changed the pump and ran like new. Sorry I have no info on the A2's........yet.

 

[73m819]

I drove a 915 from NJ to NE and back, it did 70 mph (had to work at it just a bit) and got 6 mpg till I tried to suck the bottom out of the tank, then it really worked to do 65, it was happy doing 60.

 

[Scott88M]

I drove M915s in a transportation unit. The original with 16 spd cat trans could do mid 70's easy. The A1/A2 had a 5 spd Allison and could hit maybe 60. We were one of the first units to get A3's and if i remember right were at least mid 60's then i got out of the Army.

 

[GFD200]

We have a 915A4 and it'll do every bit of 80. We have a 916A2 and that big old thing will barely do 55-58. Anyone have a site to get gears for the 916 so we could look at a swap? We'd like to get it up to 65-70 if possible.

 

[FreightBoss]

Has anyone tried a different rearend on the M915a2. I was thinking a 3.73:1 to run highway speed at a lower rpm...any thoughts?

 

[Fireman451]

What rear end gear ratio does the m915a1 have ? Good for hauling ?

 

[Jericho]

AF had some brand new ones a few years ago, ran them on the long haul route into the missile fields in the Dakotas, I used to laugh as they passed me on the wide open straight as an arrow highway, they seemed to travel in groups 2 and 3 trucks, I was doing 70 and they passed me regularly at full steam, I used to stop at the front gate and ask if the Trans Commander was in, thought he would like cell phone video of his rough riders , Taken from the much maligned ( by the Trans Squadron guys ) Jet Engine Maintenance Six Pack truck , as we got waxed. We both worked for the LOgistics Group Commander, He would just chuckle !

 

[74M35A2]

Series 60 engine is a nice piece. First OTR truck engine to normally see 1 million miles before rebuild. Great power, cold starting, etc... Oil pan is nylon/fiberglass, pretty slick. Engine control computer on the latest DD15's and such are liquid cooled by incoming diesel fuel. Can get turbo compound option which adds 10% power (50hp) directly from the turbo turbine to the flywheel for an efficiency increase.

Sorry, somebody said Detroit Diesel and I got all excited....