MTV Engine and transmission swap

[TheDrashStash]

I've been toying with this idea for a while now and been trying to do research if anyone has attempted an engine swap in a FMTV of any kind. I know lot's people swap out HMMVW engines all the time but found nothing on FMTV's.

What: Detroit Diesel 8v71 318HP with manual transmission replacing the CAT 3116 and Allison in a M1088

Why: Besides being the coolest kid on the block, I'd have a V8 2 stroke beast that's easily rebuildable and a manual transmission that wont leave me stranded in North Carolina with a faulty speed sensor wire harness (This happened). I also have a 74 Ford L9000 with everything I need minus a transfer case.

What are your thought on this, good idea or bad?

 

[simp5782]

What transmission are you going to find that has a .65 od ratio that the Allison has. Only an RTOO14613 meets that in the bigger truck transmission
Most are .73 on a manual for their OD which isn't going to get you over 50mph.

You could use a T1138 for the OD transfer case but I think you would be slinging drivelines from the faster spinning

 

[TheDrashStash]

What transmission are you going to find that has a .65 od ratio that the Allison has. Only an RTOO14613 meets that in the bigger truck transmission
Most are .73 on a manual for their OD which isn't going to get you over 50mph.

You could use a T1138 for the OD transfer case but I think you would be slinging drivelines from the faster spinning

I've thought about this and I may have to end up getting 3.07's in it to make up for that loss in gearing. I'll have to look at what's already in the ford to see if I can use it. I know you put a 350 big cam in one of your trucks, and there's another L9000 here with a big cam next to the truck with the Detroit

 

[coachgeo]

I've thought about this and I may have to end up getting 3.07's in it to make up for that loss in gearing. I'll have to look at what's already in the ford to see if I can use it. I know you put a 350 big cam in one of your trucks, and there's another L9000 here with a big cam next to the truck with the Detroit

Just do what Brazos did and leave the trans..... (just rebuild tranny so it will last another 20yrs) and put in a cummins It worked extremely well by all reports

 

[simp5782]

I've thought about this and I may have to end up getting 3.07's in it to make up for that loss in gearing. I'll have to look at what's already in the ford to see if I can use it. I know you put a 350 big cam in one of your trucks, and there's another L9000 here with a big cam next to the truck with the Detroit

Didn't put a big cam in an LMTV as 14liters isn't going to fit and would tear the axles and everything they are hooked to apart.

 

[TheDrashStash]

Didn't put a big cam in an LMTV as 14liters isn't going to fit and would tear the axles and everything they are hooked to apart.

That's what I thought too. Say the Detroit fits, how hard would it be on everything downstream?

 

[TheDrashStash]

Just do what Brazos did and leave the trans..... (just rebuild tranny so it will last another 20yrs) and put in a cummins It worked extremely well by all reports

That's an option, but I'd like to get a manual in there if I can. It'd be a blast to ride around in. I'd just need a linkage that reaches all the way back to the trans

 

[Third From Texas]

Why not get a truck that has all the goodies you want, and slap an LMTV cab onto it.

Because....

 

[chucky]

Would any of the manual fuel pump international motors like dt360 or dt466 fit down in there you can get the same hp out of them as the 3116

 

[BERZERKER888]

Talk to Bryce.. he has driven a BAE lmtv with the Cummins diesel…fast fast fast

 

[TheDrashStash]

Why not get a truck that has all the goodies you want, and slap an LMTV cab onto it.

Because....

Man, the last thing I need is another truck lol. The idea is that I use what I have on have and not spend loads of money. I already have the engine and transmission

Talk to Bryce.. he has driven a BAE lmtv with the Cummins diesel…fast fast fast

Is this the same Bryce that sells loads of 3.07s?

 

[TheDrashStash]

Took another look at the Detroit today and it's way taller and wider than a 3116. (35 inches wide) But momma didn't raise a quitter. I think it'll fit if I cut out where the 3rd passenger sits and build it up. I'll get the Detroit pulled out this winter because the truck it's in needs to go to the scrap due to the frame rusting out so I'll get better measurements then

The transmission is a Roadranger RTO9513 which apparently I can flip some gears around and get a final ratio of .644, but I'll have to do some more research on that

 

[simp5782]

Took another look at the Detroit today and it's way taller and wider than a 3116. (35 inches wide) But momma didn't raise a quitter. I think it'll fit if I cut out where the 3rd passenger sits and build it up. I'll get the Detroit pulled out this winter because the truck it's in needs to go to the scrap due to the frame rusting out so I'll get better measurements then

The transmission is a Roadranger RTO9513 which apparently I can flip some gears around and get a final ratio of .644, but I'll have to do some more research on that

You can but you will want to add about 5 inches of insulation or the whining noise alone will chatter your teeth cause you think it's going to explode

 

[BERZERKER888]

Man, the last thing I need is another truck lol. The idea is that I use what I have on have and not spend loads of money. I already have the engine and transmission



Is this the same Bryce that sells loads of 3.07s?

yes..

 

[TheDrashStash]

You can but you will want to add about 5 inches of insulation or the whining noise alone will chatter your teeth cause you think it's going to explode

Yeah, might not be the best way to do it. Looks like with my 13 speed I have with a T1138 I'd get a ratio of .63 combined which would be good for me. But at 2400 engine rpm the driveshafts will be turning 3779 rpm which is a little fast

 

[TheDrashStash]

I think Wes's suggestion with the double overdrive transmission is the way to do it, along with a hemtt transfer case. If I do that I wouldn't even need 3.07s to cruise at 65

 

[TheDrashStash]

Just a test fit and there's definitely enough room for a floor mounted clutch pedal

 

[Nomadic]

That is a good looking pedal.

 

[Ronmar]

Another thing that might also be considered if you are choosing different trans ratios would be to loose the 2:1 in the geared Hubs. That would simplify the axles and half the required driveshaft RPM at speed…

 

[TheDrashStash]

Another thing that might also be considered if you are choosing different trans ratios would be to loose the 2:1 in the geared Hubs. That would simplify the axles and halve the required driveshaft RPM at speed…

Has this been done before? The axels that go to the spider gears aren't that big, but the 2:1 halves the torque going through it. Would it not be a weak spot if you got rid of the gears?