m923a2 recreational vehicle upgrades

[BigDumbMike]

Hi y'all,

In 2020 I bought a m923a2 that was converted into a bugout style RV by a legend (RIP Bruce). After adding some off-grid capabilities, wife and I lived in it full time in 2021 and drove it all the way from Southern Florida through South Dakota, Wyoming, Montana, Idaho, Nevada, Utah, Arizona, and New Mexico (where it currently resides). We had some of the best times of our life on the trip but also more than our fair share of nightmare scenarios that I want to try and avoid.

Truck is super heavy... comes in at about 21 tons. It's height is 13'6". This thing is frankly too heavy and too high to take confidently into super gnarly terrain (we collapsed a poorly maintained dirt road with a washout on a mountainside in Wyoming). Acknowledging this, I am interested in making it more "highway safe" even if doing so limits (but does not eliminate) its hypothetical offroad capabilities. I don't see us driving it more than 20 feet in from the nearest dirt road unless conditions are near optimal.

First, we had a tire blow out and I was wholly unprepared to swap in a spare. Fortunately, the tire exploded and we came to a stop literally in front of a mechanic. Since then, got all of the gear necessary to swap in the spare if need be. However, we are using the old stock (standard) tires (14r20) and frankly I just don't trust them. I'm considering a full swap that is more resistant to side wall cracking. Would 395s be the move if my overriding concern is durability? If I don't plan on moving the truck for a while is there anything I can do to make the tires last longer? The 3 tire replacement I did was expensive but a full replacement is a bullet i'm willing to bite... just don't want to do it until i plan to use it frequently. Where's the best place to source these tires price wise?

Second, going down significant or prolonged grades in a 21 ton behemoth was always a white knuckle affair. I didnt always feel confident dropping the truck into low gear and on more than one occasion I had to be very careful not to smoke the brakes. I read on this forum that it is possible to install an exhaust brake on the cummins 8.3L that is in the m923a2 (https://www.steelsoldiers.com/threa...-exhaust-brake-ramps-and-hitch-m923a2.138372/). I would have this installed by a professional commercial diesel truck mechanic facility but was wondering if they would need advisory/special parts to accomplish this.

Third, and least importantly, at 21 tons it doesn't take much of an incline to send me to 20mph (or less) max speed even with the turbo. Anything I can do to give it more oomph? There were many times we had traffic backing up behind us (which gave me anxiety because I don't want to bother other people) and literally got passed on the highway by one of those oversize load modular houses on a tractor trailer.

Also, if anyone has any ideas for other things I could do to make the ride more reliable/safe, I'm all ears. We just had our first child last year and I need to be a bit more responsible...

Thanks in advance!

 

[Karl kostman]

You bought a relatively big truck, and sounds like you added another 10K pounds to it I am not sure what you were expecting? The blow out, it happens but your only not prepared once! I am not sure what you mean by making the truck more road worthy? Are you talking comfort? Drivability? Please explain that part further? The power issue? Lets think about this just a little, you have large truck that is heavy and has a 250 HP engine, you can see where I am going here. When you start boosting things like Turbocharger boost, and dumping more fuel into the engine than it was ever designed for your potential for problems multiplies significantly, and we are NOT talking small problems, we are talking engine destroying problems! You would also have a lot more to monitor concerning the engine health while driving, and EGT along with RPM will by your primary gauges. Sorry you dont have an EGT yet but you start boosting HP you will have one! I am not trying to talk you out of your line of thinking but our trucks are all designed to operate within a certain envelope of operations and to provide a long reliable life in doing so, straying to the outside of this envelope is done at your own risk, you had better know what your doing and had really better know your NEW limitations, they are going to have a whole new meaning!
Good luck!

 

[ToddJK]

I agree with Karl on this one. These trucks have some great capabilities but highway/expressway is not one of key functions these trucks were ever designed for. Slow speeds off road and rough terrain is more so the line of thinking. The easiest and most likely the most sure way to keep a good reliable truck and a slight performance boost, put it on a diet and take some weight off of it.

For tires, the 5 tons can take quite a few different sizes, but I've seen them with the stock standard NDT's up to large tractor tires. The 395's are a good tire size, but I don't think any tire will necessary last longer than the other as far as UV and dry rot protection, ect. I think any tire will do, newer the better or in some cases, newer tubes the better. Keep the tires covered by a tarp or custom tire covers when not in use and it doesn't hurt to use some rubber/tire conditioners every so often, those two things will help against dry rot and protection from the sun.

-Edit-

One thing to consider is perhaps keep the 923 as an overlanding truck, change the set up to shave some weight and trailer a small rig like SXS or small truck/jeep to explore area's while keeping the 923 on solid ground/main roads.

 

[simp5782]

For increased braking power install a pacbrake exhaust brake on the A2.

@profo has a highly modified 927a2, intercooler, bigger turbo, weighs around 34k and it has a time pulling hills out west and the engine is maxed out fuel wise. The 8.3 is not powerful. So you are not going to get up a mountain fast.

I have an intercooler aluminum radiator combo you could upgrade it with.

You can add air bags to the rear of the truck for a better ride as well.

 

[Elk1111]

I get to drive by this behemoth at least a couple of times a week and also had the pleasure of speaking with this wonderful couple when they left the truck in New Mexico. My hat is off to anyone that’s willing and able to take a trip like they did and I for one am jealous of the truck and the awesome journey they went on.
I don’t think towing a jeep would slow the truck down much and I would just try to stay off the interstates and enjoy the journey for what it is. There are lots of people traveling in a motor home towing vehicles but this truck is special and I wouldn’t change a thing besides working on the engine a bit to get more power and plenty of gauges to monitor it.
Pirelli makes a new 14x20 tire that would last you quite a long time compared to the Michelins that are on it now. I think 395s would look a bit small for it.

 

[BigDumbMike]

Thank you all for your responses. Please don't take me the wrong way - I am not under any illusions that I can turn this thing into something it is not - was just wondering if i could safely add marginal upgrades for longhaul driving.

Point taken on adding oomph to it - I guess I'll just have to live with the crawl up hill. Putting it on a weight diet isn't really feasible - Adding some pictures but you'll have to take my word for it - basically the entire living quarters is a steel box with all steel interior (think milsurplus bunks etc.). Taking any of this stuff off would be doing it a disservice in my opinion.

Sounds like the exhaust brake is doable. Definitely going to look into this more so thank you for the additional input on that.

Will replace all tires before next big drive and get some custom tire covers for UV.

I already added air ride seats to it - I don't care about any additional comfort driving it (that's part of the fun), just safety.

I think next time we long haul adventure we'll get a 4x4 and wife will drive behind me with the kiddo - I am pretty aware of the limitations as far as offroading at this point from trial and error. The plan is definitely to use this as a mothership and then something else to get further out for shorter trips.

Elk I'll DM you if OK.

 

[simp5782]

Thank you all for your responses. I am not under any illusions that I can turn this thing into something it is not - was just wondering if i could safely add marginal upgrades for longhaul driving.

Point taken on adding oomph to it - I guess I'll just have to live with the crawl up hill. Putting it on a weight diet isn't really feasible - I'll upload some pictures but you'll have to take my word for it - basically the entire living quarters is a steel box with milsurplus (think metal bunks, submarine-style doors, etc).

Sounds like the exhaust brake is totally doable, though. Definitely going to look into this more so thank you for the extra input on that.

Will replace all tires before next big drive and get some custom tire covers for UV.

I already added air ride seats to it - I don't care about the comfort driving it (that's part of the fun), just safety.

Elk I'll DM you if OK - didn't know you were on here...

You can get a 923a1 firewall housing, cab mounts,engine mounts and jackshaft and install a big cam into it. That's 400hp.

Alot of work but you wouldn't crawl up hills.

 

[BigDumbMike]

You can get a 923a1 firewall housing, cab mounts,engine mounts and jackshaft and install a big cam into it. That's 400hp.

Alot of work but you wouldn't crawl up hills.

Thanks I'll look into this as well. There were quite a few times where I wasn't hitting the minimum speed on interstates. Cops didnt seem to mind (most i saw taking their phones out for photos lol). Fortunately people could go around me because multiple lanes. Sometimes back roads just aren't an option due to weight limitations on bridges/etc.

 

[davidb56]

you could make that railing on top of the cabin removable, hinged, or 1 foot shorter to give you some clearance.

 

[BigDumbMike]

you could make that railing on top of the cabin removable, hinged, or 1 foot shorter to give you some clearance.

Thanks i've definitely considered that but not quite sure how to do it and it's not going to be incredibly meaningful clearance. the railing is removable and attaches via 1.25" steel pegs that screw into threaded nuts welded to the roof. I can't add any more width - the original modifier made the dimensions maxed out for federal highway travel. I must keep the rails - the usable rooftop in the middle of nowhere is amazing. If i take the rails off i would need to weld off the brackets that hold them in place to get more than 1" extra clearance. Even if the height was reduced by 1 foot I'd still be incredibly sketched out taking it over uneven terrain... if this thing tips in the middle of nowhere it would be catastrophic I think.

Attaching some more pictures because i figure y'all might find them cool. First tunnel is Red Canyon in Utah on way to Bryce - listed at 13'6" clearance... I mistakenly said the truck is 13'6 - i meant 13'4.

I've been meaning to do a whole writeup of the trip with a truck-focus for these forums - which were instrumental in me getting the truck road ready. Life got in the way but I have to make time.

 

[BigDumbMike]

You can get a 923a1 firewall housing, cab mounts,engine mounts and jackshaft and install a big cam into it. That's 400hp.

Alot of work but you wouldn't crawl up hills.

This would raise my total truck height i assume? if so can't do it

 

[simp5782]

This would raise my total truck height i assume? if so can't do it

Nothing changes you are just making the truck an A1 rather than an A2

 

[Weldman]

Nothing changes you are just making the truck an A1 rather than an A2

Seems to be easier to just buy a A1 and put everything over from the A2 on it minus the engine with few mods.

 

[simp5782]

Seems to be easier to just buy a A1 and put everything over from the A2 on it minus the engine with few mods.

It depends really. You still have to pull the engine on the a1 truck and redo the front mount then swap in a big cam etc. If 923s were still 3 to 5k like they used to be sure it would be cheaper to do it that way. Also depends on how much down time you can have. A2 has ctis which is a good thing for camper trucks to have as well.

If the camper has a crawl thru from the cab to the rear then it's a lot of extra work to swap to a whole other truck etc

 

[BigDumbMike]

It depends really. You still have to pull the engine on the a1 truck and redo the front mount then swap in a big cam etc. If 923s were still 3 to 5k like they used to be sure it would be cheaper to do it that way. Also depends on how much down time you can have. A2 has ctis which is a good thing for camper trucks to have as well.

If the camper has a crawl thru from the cab to the rear then it's a lot of extra work to swap to a whole other truck etc

I have a lot of down time (probably at minimum a year) but i lack the skills to do any of this myself and it's not the highest and best use of my time (better off working to pay someone else to do it). CTIS is borked and i gave up trying to fix it - seemed like a liability as well - did the whole 4 month trip without it. Camper does not have a crawl through unfortunately.

I added a lot to the existing truck that would probably make it a mega hassle to swap trucks. Second alternator to charge the camper batteries when driving, conduit along frame of truck to bring wires back from the front of the truck to the house batteries, air ride seats, custom battery box that sits under the truck, propane tank, etc.

 

[DeMilitarized]

Hi y'all,

In 2020 I bought a m923a2 that was converted into a bugout style RV by a legend (RIP Bruce). After adding some off-grid capabilities, wife and I lived in it full time in 2021 and drove it all the way from Southern Florida through South Dakota, Wyoming, Montana, Idaho, Nevada, Utah, Arizona, and New Mexico (where it currently resides). We had some of the best times of our life on the trip but also more than our fair share of nightmare scenarios that I want to try and avoid.

Truck is super heavy... comes in at about 21 tons. It's height is 13'6". This thing is frankly too heavy and too high to take confidently into super gnarly terrain (we collapsed a poorly maintained dirt road with a washout on a mountainside in Wyoming). Acknowledging this, I am interested in making it more "highway safe" even if doing so limits (but does not eliminate) its hypothetical offroad capabilities. I don't see us driving it more than 20 feet in from the nearest dirt road unless conditions are near optimal.

First, we had a tire blow out and I was wholly unprepared to swap in a spare. Fortunately, the tire exploded and we came to a stop literally in front of a mechanic. Since then, got all of the gear necessary to swap in the spare if need be. However, we are using the old stock (standard) tires (14r20) and frankly I just don't trust them. I'm considering a full swap that is more resistant to side wall cracking. Would 395s be the move if my overriding concern is durability? If I don't plan on moving the truck for a while is there anything I can do to make the tires last longer? The 3 tire replacement I did was expensive but a full replacement is a bullet i'm willing to bite... just don't want to do it until i plan to use it frequently. Where's the best place to source these tires price wise?

Second, going down significant or prolonged grades in a 21 ton behemoth was always a white knuckle affair. I didnt always feel confident dropping the truck into low gear and on more than one occasion I had to be very careful not to smoke the brakes. I read on this forum that it is possible to install an exhaust brake on the cummins 8.3L that is in the m923a2 (https://www.steelsoldiers.com/threa...-exhaust-brake-ramps-and-hitch-m923a2.138372/). I would have this installed by a professional commercial diesel truck mechanic facility but was wondering if they would need advisory/special parts to accomplish this.

Third, and least importantly, at 21 tons it doesn't take much of an incline to send me to 20mph (or less) max speed even with the turbo. Anything I can do to give it more oomph? There were many times we had traffic backing up behind us (which gave me anxiety because I don't want to bother other people) and literally got passed on the highway by one of those oversize load modular houses on a tractor trailer.

Also, if anyone has any ideas for other things I could do to make the ride more reliable/safe, I'm all ears. We just had our first child last year and I need to be a bit more responsible...

Thanks in advance!

1. 395 mvt is the best tire I belive for these trucks overall. Good speed rating, is cheap, and is good on and offroad. Don't hop much also.

2. Valve springs are a must for the exhaust brake

3. If you want max power out of that 8.3 let me know. Probably get you from 250 to 400 or 450. Pyro head studs valve springs compound turbo s475 or ht4b over stock, intercooler. ext. Not cheap but definitely get much more pull up hills. Probably 3-4k in costs

 

[simp5782]

1. 395 mvt is the best tire I belive for these trucks overall. Good speed rating, is cheap, and is good on and offroad. Don't hop much also.

2. Valve springs are a must for the exhaust brake

3. If you want max power out of that 8.3 let me know. Probably get you from 250 to 400 or 450. Pyro head studs valve springs compound turbo s475 or ht4b over stock, intercooler. ext. Not cheap but definitely get much more pull up hills. Probably 3-4k in costs

8.3 doesn't have enough air to spool an HT4B
Maybe a 3b if it's lucky. They are both reverse rotation turbos though

 

[DeMilitarized]

8.3 doesn't have enough air to spool an HT4B
Maybe a 3b if it's lucky. They are both reverse rotation turbos though

Compounds plus modifying the intake system a bunch

 

[simp5782]

Compounds plus modifying the intake system a bunch

Still won't have enough air

 

[DeMilitarized]

Still won't have enough air

Enough fuel to run them you mean?

It has been done before on the facebook groups.