m813 over the road reliability

[moose]

Hi there everyone. I was hoping to get some honest input from some 5 ton owners about the actual reliability of these trucks. My plan is to buy and use an m813 to haul a sand rail, and tow a 33 ft. toybox trailer at the same time. Round trip would be about 800-900 miles, and I plan on making 3-4 of these trips per year, in addition to some 300 mile trips to go hunting etc. The truck would be mostly towing on the freeway, but also off-road in sand, mud, and some rough trails. My question is basically how reliable this would be, assuming all maintanence and pre-trip inspections were done correctly, on time, and well. I don't mind working on my equipment in my garage, but when I go to play, I want to play, not work on my truck.
Additionally, I would want to set the truck up with the larger 53 inch super single tires, and some extra gearing in the hopes of being able to cruise at 75mph without straining the motor too bad or over revving it. I know that the Cummins 250 does not like higher rpms.
So please, let me know what you all think. I appreciate and value your input.

 

[Alredneck]

If maintenance is done they are just as good as any other old truck.

I recommend going to radial tires. Upsizing to 395s or 14s. 395 would be the best for towing and still get you around the 60+mph mark. Also for less wear and tear and awesome mileage, 22.5s Budds wheels bolt right up. A 385 is close to a 11r20 mainly wider. I have 22.5s on a M54 and love how it runs on the street ( use to run awaiting rebuild ). 53s are heavy and towing wise will not pull the truck and the load behind it at the speed your looking for. Check out Jwallers thread on turbo upgrade. I am working on one as well for my M814 tractor build plus a 9 or 13spd fuller swap. He has been helping me with mine and we have been sharing info on some of the myths we have come acrossed through our searches.

 

[area52]

Reliable? Yes for a 40+ year old trucks. You are not gonna find any better gears for these axles. As said above, 53" tires will suck the power out of your Cummins. Also think about braking at those speeds, these trucks do not have anti lock brakes or discs either.

 

[moose]

You both mentioned that the 53's would not be a good choice, so maybe the 46 inch super singles with a brake upgrade and a switch to air brakes instead of air over hydraulic. I am more familiar with regular air brakes with the slack adjusters anyways. The turbo comment from Alredneck is very interesting, but makes me wonder if that would hurt the reliability since the motor was designed as a non-turbo motor. Obviously, the trans swap sounds like a great idea. and I have heard a lot of good comments about the Fuller trans. Switching to a different trans will require modifications to bellhousing, and the transfer case I assume. What have you had to do to get your Fuller trans to work? Again, thanks for the info.
What about mods to the motor? I'm planning on upgrading the filters to the spin on type, running the best fluids I can find, and reducing exhaust back pressure. What type of turbo have you tried, and at what boost level? I assume low boost to match the piston design and compression ratio.

 

[Burgerboy13]

I think a 5 ton would not be the best choice for what you are intending to use it for,

just my

 

[sigo]

Burger, why is it not a good choice? Is it the load described? The speed? The distance involved? What do you suggest instead?

I am interested in the subject as well, considering I am a new 813 owner. I've given some thought to longer distance trips as well.

 

[M813A1]

As a M813A1 owner I will tell you that the 1400 R 20's will suck the power out of the NHC 250 Cummins !! My truck would make 63 mph on the road empty but when I had it loaded or was pulling an loaded trailer !! I would recommend a 395 or a 1200R 20 tire that way you will have enough speed and not loose your pull power !! The bad thing is that the 5 Ton Truck is gear bound and there is not alot of choices of gears out there to choose from !! But I would imagine that if you found compatible Rockwell commerical carrier sets it would be possible to change the gears !! Good Luck to all !!

 

[Recovry4x4]

Maybe a 916 tractor converted to cargo config would be better suited for highway duty. I'm not sure about that 75 MPH goal. If you could settle for 62 or so, it would be the perfect truck sans any comfort but pushing one to be able to run 75 and stop as well is going to get costly.

 

[73m819]

"and some extra gearing in the hopes of being able to cruise at 75mph without straining the motor too bad or over revving it. I know that the Cummins 250 does not like higher rpms."'

These trucks were designed in the late 40s, first built in the early 50s NEVER designed for a speed over 50 or so and long distance travel, trust me there is a MAJOR pucker factor blowing a steer tire at 60 and leave the road, start using and pushing something well past its DESIGNED limits will break things and KILL people

If you went to do what you went GET A PETERBUILT
Use the truck what it was designed for, it is a safe and reliable vehicle, use the truck as it was NOT DESIGNED for, it is a WEAPON

Just think how it will feel when you have tell the family of the person that you hurt or KILLED, SORRY, I just wented to GO FAST.

 

[moose]

OK, good point on the safety factor and the original design of the truck. Would you all agree that a 65 mph cruising speed, with air brakes, would be a safe goal? I could live with that, but trying to run 55 on freeways that the traffic goes 80(75mph speed limit in AZ) would drive me crazy. When I get on the road to go riding in the desert, I am anxious to get there and have some fun. I know that I will want to push it, but I will make sure that I am safe and not damaging my equipment. My point is that I could live with a 65mph cruise speed, and I deffinitly don't want to hurt myself or anyone else on the road. I am not interested in giving MV owners a bad name.
Does this sound like a reasonable goal? and what mods could I make to achieve this modified goal? I want to keep the mid-sized tires to achieve a higher overall gearing and the added ground clearance for when it needs to go off road. AZ has some tough dirt roads that lead to some great areas.

 

[O.D. Fever]

I talked to the local Cummings mechanic about a turbo upgrade and he said the engine does not have piston coolers and a turbo would toast the motor. He also said 10 percent over injectors would be ok.

 

[73m819]

"with air brakes, would be a safe goal? I could live with that, but trying to run 55 on freeways that the traffic goes 80(75mph speed limit "
these trucks (m54,m813) have one circuit hyd. brakes, with air assist, NOT AIR BRAKES, loose a wheel cylinder, blow a line, ect., = NO BRAKES IN A HURRY

 

[EMD567]

The **** truck was built to run 50 MPH. At 50 MPH, it will carry you, anything that you want to put in the rear, and anything that you would like to tow, all at 5.6 MPG, to the moon. If you wish to go faster, it will cost you more in mods and work, then a truck that is designed to go 75 MPH. Buy a used OTR tractor, put a bed on it, and use that to haul your toys at 75 MPH.
My 814 drove down from NJ at 50 MPH, and folks had no problem going around it.

 

[jasonjc]

Befor you do anything, even hook a trailer to it, go do a 800mile drive. You will never want to do it again. I drove about 550 miles in one day, it was all I could do to get out of the truck when I got home. The truck ran fine at 50-54mph on the flats 30mph on hills, and trafic went around me fine.

 

[Westech]

I ran my M813A1 from Wisconsin to Haspin IN and that was a bitch. It will pull 50 - 55 all day and I could not even tell I was towing 5K camper. But its a hard ride, the gears SUCK. The 3-4 shift is HUGE!! The money you will spend to get a 813, fix it up you could have got a sweet older OTR tractor and slapped a bed on it. Remember.. heater stink, no AC, Brakes are so so, wipers dont work great, cabs leak air and water and can turn in to a oven or a freezer seats are hard on the driver, no radio, really.. there is sure a neeto factor on driving a military truck... and I did in Active Duty but OTR for get it!

 

[Recovry4x4]

65 will be in the ragged edge. I did 643 miles in a deuce last week and although I've conditioned myself for it over the years, it was ideal weather for a long ride. The 813 is no more comfy than a deuce with the exception of power steering. Converting to air brakes will cost thousands. Adding a turbo correctly of updating to a 400 will cost thousands. Updating tires and rims will cost thousands. Settling for 55 will cost maintenance and will net you durability and the enjoyment of seeing things on the road that you've never seen before (moving at 80 mph). If you must have the higher speed and must have the cool factor and must have the AWD, purchase and M916 and add a bed. Trust me, you are not the first person that wanted to travel at 75 and wouldn't be the first to get there but it's gonna cost money to get there.

 

[drgreg]

I love my M813A1 and I like my 16.00-20s, but I would not want to use it as you intend. I max out at 67mph, on the freeway. And that is pushing the truck hard. I don't think the Mil-surplus tires are rated for more than 50 or 55mph.
Every trip in these trucks is an adventure, for good or bad. I would not want to have my weekend plans messed up with a repair or breakdown.
A lot of people like to drive/ride these trucks for a short distance, but the long trips are enjoyed mostly by a few select wackos.
I would go any distance for a Military Vehicle Event, but I would find an alternative method for just transportation. (even with every mod listed)

 

[hairba11]

one othr thought with everyone wanting to go faster, i helped recover a 816 from oklahoma city to st. louis, mo
it was about 800 miles and 12 hours.

the truck had good power and the roads are reletively flat, and we were making about 52~54 mph.
after about 500 miles, the gear oil in the axles started to boil and spray out. the chase pickup was the one who noticed. had to slow down and pull into a truck stop ans let everything cool down.

 

[kurt802]

I don't drive 55. 45 mph is fast enough for me and I like my 10 Titan NDT tires all at 50 psi. Nobody bothers the "King of the Road" going 45 mph. It's good to be the King 50 mile round trip with a load of fire wood has been my longest trip. That was long enough. Lots of short trips are more enjoyable for me.

 

[466Navastar]

moose - you are not hearing the advise these gentlemen are offering

these trucks are antiques made to go SLOW even when new....... - you want to go fast...so like was said -buy a KW or Peterbuilt......if you want to build a MV something - buy a wrecked Peterbuilt and put the MV body on it...otherwise I fear you will forever be trying to out drive the truck and never enjoy it - for what it is......and possibly kill people in the process....