should i buy a 2.5 or 5 ton truck?

[ke5eua]

59apache, I have though about that as well. I have watched a few videos of these trucks and noticed a lot of flex as you've pointed out. So what is the solution?

Also, it would seem that given the cost of fuel, tires, the tools required to work on something larger, that the total cost for keeping and maintaining the 5-ton vs the 2.5-ton goes up exponentially. I would like something that was easier to work on with simpler tools

So let me throw out a scenario. Let's just say I get the truck and I have the camper part of it set up the way I want. Then I decide i want to live out of it while doing some traveling around the country, on the road. This would require very long periods of steady cruising speeds, higher RPMs. After I have upgraded brakes I think it would suit me better to add more power and quite possibly add another gear to the tranny (I have already read threads where people do this for added speed).. So my question is this, would it be better to add more power to the multifuel engine, say bigger turbo charger among other modifications, or buy a detroit or cummins diesel engine/tranny for it?.. Also take into consideration that I am very interested in the ability to run on WVO, WMO, and WATF as well as regular diesel.

If you are going to spend the money to upgrade brakes, and engine, and transmission just get 900 series with the 8.3 and auto and be done with it.

 

[Mike929]

If you are going to spend the money to upgrade brakes, and engine, and transmission just get 900 series with the 8.3 and auto and be done with it.

I agree. The cost of those upgrades will cover a lot of maintenance on a 900 series, and you have a lot more commercial parts on the M939A2 trucks.

 

[justin22885]

I agree. The cost of those upgrades will cover a lot of maintenance on a 900 series, and you have a lot more commercial parts on the M939A2 trucks.

Besides the engine, what other commercial parts are on it?. Also, the downside I was most put off by with the 5-ton trucks is the need for much bigger, more specialized tools just to work on it, lower fuel economy, and overall size and weight.

Are there any readily available cabover style cargo trucks? I like the M1078 but there doesn't seem to be too many of these in civilian hands? I wonder if it is at all possible for my specific application to convert an M35 to a cabover so to maximize the cargo space without having to go with a longer wheelbase? I do have the knowledge and the skills to design and fabricate a cabover cab, I would still need to change around the steering, some linkages, cables, etc but I think its doable.

Something I should make note of, I am one of those people who love the project itself more than the final product, I do not buy something if I can make myself. I like to tinker so i think just buying an M923 or 939 would actually take some of the fun away. So in my opinion the M900 series already having better brakes, power steering, and more power is more of a downside than a positive.

 

[Jeepsinker]

I'm sorry, but all maintenance schedules being equal, 939 series trucks are junk compared to the deuce.

 

[Mike929]

Besides the engine, what other commercial parts are on it?. Also, the downside I was most put off by with the 5-ton trucks is the need for much bigger, more specialized tools just to work on it, lower fuel economy, and overall size and weight.

Are there any readily available cabover style cargo trucks? I like the M1078 but there doesn't seem to be too many of these in civilian hands? I wonder if it is at all possible for my specific application to convert an M35 to a cabover so to maximize the cargo space without having to go with a longer wheelbase? I do have the knowledge and the skills to design and fabricate a cabover cab, I would still need to change around the steering, some linkages, cables, etc but I think its doable.

Something I should make note of, I am one of those people who love the project itself more than the final product, I do not buy something if I can make myself. I like to tinker so i think just buying an M923 or 939 would actually take some of the fun away. So in my opinion the M900 series already having better brakes, power steering, and more power is more of a downside than a positive.

Justin,
I'm confused, you are worried about cost of a few less mpg, then you talk about fabricating a cabover for a deuce???

(8 to 10 mpg in the M939A2 (not A1) and maybe 10-12 mpg in the deuce.)


Jeepsinker,
I have two deuces and love them, and I'm fairly new to the M939 series (i.e., one month). Anything specific I should be concerned about? I love the way the deuces look and love driving my stock deuces, but comfort wise the M939 is better. I'm tall and not too small. I have to bend down a bit to look under the deuce wiper motors, and the larger steering wheel fills a lot of the available room. The M931A2 I just bought allows me to sit up straight and see out the front windshield, and plenty of room in the cab. I like shifting the deuce, but for a long distance travel I like the much faster M939A2 trucks, power steering, air brakes, and automatic transmission. I plan to convert my M931A2 into an RV. I don't want to cut or change my Deuces. i.e., I bought a tilt steering wheel and was going to put in power steering, but couldn't bring myself to cut on my deuces. Just seemed wrong, in my mind.

 

[justin22885]

My biggest concern with the deuce vs the M939 is really that the deuce looks like it is much easier to work on. That doesnt seem like much, but you dont need nearly as large, robust, or specialized equipment. Also, I'm not just looking for a truck i could drive a couple times throughout the year, but if I am able to bring fuel costs way down using WVO, WMO, or WATF then it is something I would be driving much more frequently and it seems like the deuce is a platform that offers me everything I need in a smaller, lighter package too.

Those are the main reasons why im leaning heavily on the deuce.

If i purchased a deuce now, I would mostly just be driving it around town. I would work on making some improvements to what is already there, perhaps tires and brakes as I go along. I will be going through two phases in the near future, the first phase after its done and able to be used as a camper i will be living out of it as I travel around the united states. Before I purchase land to start building my own house where this vehicle will really shine in coming to my aid I plan to first travel around, see the country a little more to determine where exactly I want to put those level of resources into, and where I want to buy the land to do all this.

So, for the first phase, I will be doing mostly on-road driving, for this I would like to be able to reliably get my top speed up, and probably find tires that are better suited for the road, so the engine would need to be able to handle long periods at cruising speed. This is why i was looking into brake modifications, tires, etc

And to be perfectly honest, I'm not one of these people who cares to own many different vehicles for many different purposes.. as I will be becoming a bit nomadic for a while, I need a vehicle that is going to be more of a swiss army knife as it will be something i will need to come to rely on a lot in the foreseeable future.

And this may sound very corny to some of you, but I can easily become sentimentally attached to a great truck which is why its important for me to find something that can handle anything I throw at. I think the M35 may just be that kind of vehicle.

 

[porkysplace]

My biggest concern with the deuce vs the M939 is really that the deuce looks like it is much easier to work on. That doesnt seem like much, but you dont need nearly as large, robust, or specialized equipment. Also, I'm not just looking for a truck i could drive a couple times throughout the year, but if I am able to bring fuel costs way down using WVO, WMO, or WATF then it is something I would be driving much more frequently and it seems like the deuce is a platform that offers me everything I need in a smaller, lighter package too.

Those are the main reasons why im leaning heavily on the deuce.

I'm others will disagree but WMO WATF ect, is hard on the hydraulic heads and injector pump and will shorten the engine life . So you need to figure your long term costs in repairs compared to costs of clean fuel. WVO is a whole different thing it acts as a solvent and any build-up in the fuel system will be pluging it up . WVO may be alright if it is the only thing you run .

 

[Jeepsinker]

I won't argue that the 939 series trucks are more comfortable for long distance driving or for larger framed people, but I still stand by my statement. Nowhere near as many field repairs are possible on the 939 as a deuce. Two days ago I had a major transmission failure in my deuce. I took the trans apart without removing it from the truck and replaced some major components and had it done inside of a day. Not remotely possible to do that with a 5 ton. And with the deuce you worry about losing brakes or leaking wheel cylinders, with a 939 you worry about sticking brakes or bad diaphragms. Both have head gasket failures fairly commonly. Both have transmission failures commonly. Both have fuel system failures at around the same rate, albeit the deuce does a bit more. But the deuce is the one you stand a better chance of doing a successful field repair on.

 

[Mike929]

I won't argue that the 939 series trucks are more comfortable for long distance driving or for larger framed people, but I still stand by my statement. Nowhere near as many field repairs are possible on the 939 as a deuce. Two days ago I had a major transmission failure in my deuce. I took the trans apart without removing it from the truck and replaced some major components and had it done inside of a day. Not remotely possible to do that with a 5 ton. And with the deuce you worry about losing brakes or leaking wheel cylinders, with a 939 you worry about sticking brakes or bad diaphragms. Both have head gasket failures fairly commonly. Both have transmission failures commonly. Both have fuel system failures at around the same rate, albeit the deuce does a bit more. But the deuce is the one you stand a better chance of doing a successful field repair on.

Not arguing that the deuce is a more simple design that is very easy to work on (i.e., not complex). I thought you were saying the M939 was junk, and was wondering if I missed a failure issue that I missed in my research. I did not mean to offend, just wanted to tap your knowledge of what I needed to keep an eye on with my new truck.

 

[Jeepsinker]

Oh no, I still do mean that the 939series are junk in my opinion. Getting a decent one is hit or miss. I have a field full of both of these trucks and it gets really old keeping all of the 5 tons running. I don't have any problem with the deuces. Every time you start the 5 tons up some of them will have some other stupid problem they didn't have last time.

 

[justin22885]

What Jeepsinker said is exactly the answer I was looking for, about the field repairs. I want a truck that is brutally simple and easy to work on. Taking apart and rebuilding the transmission in the field, how many production trucks from ford, dodge, or chevy can do that, and that is the kind of ease of repair and brutal simplicity in a truck that I need for something I intend to have with me for the next few decades at least. So, I am about 99.9% decided on the M35 (probably an M35A2).

As for the WVO and WMO, would it be better to use a multifuel engine for this, or would it be better to get a more commercially available diesel engine and make the necessary modifications to the engine or fuel delivery system for the purpose of running primary waste oils? As I have mentioned before, I am fine making engine modifications and upgrades, if something is hard on hydraulics, is this because of the higher viscosity of the WMO? If so, wouldnt a heated tank solve this problem? Also if I use WMO I would probably build a centrifuge to clean and filter it.

So given what I am looking to do with this vehicle, in your opinion am I better off tweaking and modifying the original engine, or installing a DT466 or 5.9L cummins engine? And how much of that "brutal simplicity" will I lose going for one of these other two engines?

 

[Jeepsinker]

You are in about the same boat as far as simplicity goes with an old 12 valve or early 24 valve cummins, but I really don't think you need to worry about doing an engine swap yet. People talk a lot on here on how underpowered the multifuel engine is, but you really need to drive one yourself and see what it is like. When I first got my deuce I couldn't figure out why so many people said they were underpowered because it ran strong! Now over the course of another 700 or so hours and 16,000 miles I have lost a lot of power due to what I think is worn injectors. What I'm saying is that once you drive a good running well tuned truck I don't think you'll see much need for an engine swap. And as far as running waste oils goes, it isn't the viscosity that is the problem, its the microscopic dissolved metal and carbon particles that damages things. You are better off running waste vegetable oil only if you can swing it.

 

[justin22885]

Wouldn't building a centrifuge for the oil sufficiently clean it from all those metal shavings? Also, its not so much how much power it actually has that concerns me most, but how short-lived I've heard some people say they are when driving too often at cruising speeds?

 

[Jeepsinker]

A centrifuge will take metal particles out yes, but it will not remove dissolved heavy metals and carbon. If you are worried about engine lifespan, install some 11.00r20 tires and learn to be happy at 48-50 mph cruising speed. That will keep the engine together.

 

[justin22885]

Is there a particular RPM range the engine should be kept at for cruising speeds so not to significantly shorten its lifespan? 2,000? 2,200?

 

[Jeepsinker]

Yes! With the 11.00r20 tires I mentioned earlier you will cruise at 48-50 mph at around 2200 rpm, which is much much easier on the engine than running it at redline (25-2650rpm). I personally never exceed 2300 rpm, even when pulling very heavy loads. Just drive the truck like yo want it to last and it will. And bear in mind that I'm not an old man griping at the young kids about driving too fast or abusing vehicles. I'm 26 and I'm telling you that you just have to drive it sensibly and it'll do what you want and last too.

 

[Mike929]

Oh no, I still do mean that the 939series are junk in my opinion. Getting a decent one is hit or miss. I have a field full of both of these trucks and it gets really old keeping all of the 5 tons running. I don't have any problem with the deuces. Every time you start the 5 tons up some of them will have some other stupid problem they didn't have last time.

What kind of problems are you seeing on the m939a2 trucks? I think a list of

specific issues would add value to this thread. Especially if you fixed something more then once

 

[justin22885]

With the 11.00R20 tires and say an added gear to the transmission (I believe I've seen this mod before), what would the speed be at 2,200?

 

[Jeepsinker]

Nothing I haven't already said or that isn't posted about multiple times in other threads. Stuck brakes, crappy fuel systems that suck air every time you turn around, control box failures, electrical fires ( no fun), ctis problems, air dryer purge valves sticking open, charging system failures (sometimes pcb related as well) fan clutch engagement or disengement issues, cracked power steering hard lines, I'm sure there is more I'm forgetting at the moment but that should cover most of my daily frustrations. Bear in mind that I have over 20 939 series trucks around my house and shop right now and I had every one of them fully functional at the same time once.

 

[porkysplace]

Nothing I haven't already said or that isn't posted about multiple times in other threads. Stuck brakes, crappy fuel systems that suck air every time you turn around, control box failures, electrical fires ( no fun), ctis problems, air dryer purge valves sticking open, charging system failures (sometimes pcb related as well) fan clutch engagement or disengement issues, cracked power steering hard lines, I'm sure there is more I'm forgetting at the moment but that should cover most of my daily frustrations. Bear in mind that I have over 20 939 series trucks around my house and shop right now and I had every one of them fully functional at the same time once.

All are close to 30 years old also.