M939 series truck N14 swap

[RPMRPM]

I’m looking for info one a M939A1 or A2 series truck N14 mechanical engine swap if anyone has done it how much work it was, the cost, time, etc. the one I’m dropping in has a Jake if that matters thanks ahead of time

 

[DeMilitarized]

@simp5782 Would be your expert. He swapped a 400 bic cam into his m923a1. From what I've read you need to raise the cab and hood 2 or more inches and swap the transmission and most likely the transfer case. (Transmission is weak and transfercase will crack with the torque. Oshkosh 55000 transfer case is your go to.

 

[simp5782]

If you use the stock transmission you don't have to move anything. It's SAE 2. The NHC250 bellhousing will swap over. You however do have to center the bellhousing onto the N14.

Stock transmission isn't going to last very long doing rodding or working.

Transfer case won't hold up in low range period

You must raise the front hood mount for the jakes to clear.

You must cut the front cross member and weld in a plate for the front mount on the engine to bolt to.

Any other larger transmission install has to have the cab raised and its own mounts done

 

[DeMilitarized]

I’m looking for info one a M939A1 or A2 series truck N14 mechanical engine swap if anyone has done it how much work it was, the cost, time, etc. the one I’m dropping in has a Jake if that matters thanks ahead of time

An a2 truck will be different than an a1 truck because an a1 truck has a doghouse.

 

[RPMRPM]

If you use the stock transmission you don't have to move anything. It's SAE 2. The NHC250 bellhousing will swap over. You however do have to center the bellhousing onto the N14.

Stock transmission isn't going to last very long doing rodding or working.

Transfer case won't hold up in low range period

You must raise the front holdout for the jakes to clear.

You must cut the front cross member and weld in a plate for the front mount on the engine to bolt to.

Any other larger transmission install has to have the cab raised and its own mounts done

Ok, what would you recommend transmission wise I might turn the fuel up on the N14 a bit nothing crazy though since the jump from about 650 ft lbs to about 1,800 will be plenty, mostly gonna be a off-road camper setup built off the M934 expandable van so it’s quite a bit heavier than a cargo truck, obliviously there will be stuff in the camper, and possibly towing a max of 20k behind it (vehicle & trailer)

 

[RPMRPM]

I’m looking for info one a M939A1 or A2 series truck N14 mechanical engine swap if anyone has done it how much work it was, the cost, time, etc. the one I’m dropping in has a Jake if that matters thanks ahead of time

Also who do you guys recommend for insurance on something like that

 

[simp5782]

Ok, what would you recommend transmission wise I might turn the fuel up on the N14 a bit nothing crazy though since the jump from about 650 ft lbs to about 1,800 will be plenty, mostly gonna be a off-road camper setup built off the M934 expandable van so it’s quite a bit heavier than a cargo truck, obliviously there will be stuff in the camper, and possibly towing a max of 20k behind it (vehicle & trailer)

If you are going with a turned up engine it's just gonna be cheaper and easier to buy a 920. Slide your 934 box onto it.

920s are 30ft long. About 4ft shorter than a 934. That is easier remedied by adding some frame to the rear.

920s also have lockers in both rear axles.

You can sell the rear winch for 2500 and the pusher for 1500 and recoup some money. Or put a 13spd in it.

There are 920s with automatic 7spd Allison's available as well.

 

[DeMilitarized]

I agree with simp. A m920 probably won’t have as good offroad capabilities but wayyyy easier to just buy a m920 with a 7 speed and a big cam 400.

 

[simp5782]

I agree with simp. A m920 probably won’t have as good offroad capabilities but wayyyy easier to just buy a m920 with a 7 speed and a big cam 400.

A 920 is just as capable as a 934 offroad with the same load.

Time you ditch the winch and pusher you lost around 2.5tons of weight. So the 920 is then around 25k.

934A0 is around 30k with the box

It'll be a little heavier with double the power and better gearing.

Even more agility if you add a long arm air ride to it like the HET uses. It is designed to be used with the axles the 920 has.

They make air locker front axles that come in the front discharge cement mixers you could swap in as well. This is the idea I have for my 920. All 8 digging if you need it and it'll go.

Even a HET will go pretty well offroad till you lose momentum.

 

[RPMRPM]

A 920 is just as capable as a 934 offroad with the same load.

Time you ditch the winch and pusher you lost around 2.5tons of weight. So the 920 is then around 25k.

934A0 is around 30k with the box

It'll be a little heavier with double the power and better gearing.

Even more agility if you add a long arm air ride to it like the HET uses. It is designed to be used with the axles the 920 has.

They make air locker front axles that come in the front discharge cement mixers you could swap in as well. This is the idea I have for my 920. All 8 digging if you need it and it'll go.

Even a HET will go pretty well offroad till you lose momentum.

So it’s 8WD the middle axle isn’t a drop axle? I think I’ll defiantly have to go that way, also do they have CTIS? And if so are they reliable or are they like the 900 and 800 series trucks

 

[DeMilitarized]

So it’s 8WD the middle axle isn’t a drop axle? I think I’ll defiantly have to go that way, also do they have CTIS? And if so are they reliable or are they like the 900 and 800 series trucks

No CTIS. If you really need CTIS then you are definitely taking that truck in the wrong spots. It is a 6x6 truck with a drop axle but I believe he was saying was to add another drive axle. They are fairly simple and bulletproof from what Ive read and experienced with my m915. Simp had some issues with the 6x6 breaking on his m916 but not sure if that applies to the m920.

 

[RPMRPM]

No CTIS. If you really need CTIS then you are definitely taking that truck in the wrong spots. It is a 6x6 truck with a drop axle but I believe he was saying was to add another drive axle. They are fairly simple and bulletproof from what Ive read and experienced with my m915. Simp had some issues with the 6x6 breaking on his m916 but not sure if that applies to the m920.

Ok, gotcha so swap the drop axle for another drive axle

 

[DeMilitarized]

Ok, gotcha so swap the drop axle for another drive axle

I personally wouldn't if you don't need to. Seems like a lot of hassle and tire wear for minimal results.

 

[rd3war]

I'm working on making a M916 into a expedition / camper vehicle. It has plenty of power with the Cummins big cam 400. I have a S-280 shelter to go on the flat bed. The M916 or M920 would be a good platform to start with if you want something this big... they make the 5 ton look small.

 

[RPMRPM]

I'm working on making a M916 into a expedition / camper vehicle. It has plenty of power with the Cummins big cam 400. I have a S-280 shelter to go on the flat bed. The M916 or M920 would be a good platform to start with if you want something this big... they make the 5 ton look small.
View attachment 882998

View attachment 882999

I’ll have to look into one when since I love the look of that build are those the 53” tires on yours? Also are there any differences I need to be aware of between the M916 and M920 trucks or any other models In their series

 

[RPMRPM]

also do any of you guys suggest a specific dealer or individual to buy from ive been looking at some of the trucks from Adelmans truck parts their all oil field trucks and prices really well, but I’d you think I should look somewhere else let me know @simp5782 @DeMilitarized @rd3war

 

[RPMRPM]

Al

also do any of you guys suggest a specific dealer or individual to buy from ive been looking at some of the trucks from Adelmans truck parts their all oil field trucks and prices really well, but I’d you think I should look somewhere else let me know @simp5782 @DeMilitarized @rd3war

Also would a M911 be another viable option there a lot more of those in my area that I’ve found although that one dose have a Detroit not a Cummins saddy

 

[simp5782]

also do any of you guys suggest a specific dealer or individual to buy from ive been looking at some of the trucks from Adelmans truck parts their all oil field trucks and prices really well, but I’d you think I should look somewhere else let me know @simp5782 @DeMilitarized @rd3war

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[DeMilitarized]

also do any of you guys suggest a specific dealer or individual to buy from ive been looking at some of the trucks from Adelmans truck parts their all oil field trucks and prices really well, but I’d you think I should look somewhere else let me know @simp5782 @DeMilitarized @rd3war

@simp5782 may have a few for sale. The m915 is the 6x4 version of the m916 sits taller and has 6x6. The m920 is a longer version of the m916 with a drop axle. There are may diferebt types of each truck available such as a1 a0 a2 a3 a4r2 ext. A dealer will be much more expensive than an individual.

 

[simp5782]

Al

Also would a M911 be another viable option there a lot more of those in my area that I’ve found although that one dose have a Detroit not a Cummins saddy

No. They are hard to find parts for. Also very slow and overwidth. You need a permit everywhere