Converting an M931 to a Dump truck

[jjb]

Anyone ever done it? I've seen many threads about bobbing or adding a cargo bed and such but I can find anything converting to a dump?
I was wondering what kind/size dump body. What you used for hydraulics? Electric or PTO?? Ballpark cost for the parts?

I was originally planning on keeping the 931 to play around with then sell it to help finance the 929 but maybe I will rethink that.

Given the price that the 929's bring at the auction its probably cheaper to do the conversion.

Thanks

 

[FireFighterHill]

Im planning to convert mine to a dump with a kit from C&C Equipment and the bed from a ammo trailer. The kit from C&C is about 1600 Bucks and comes with an electric hydraulic pump and reservoir.

 

[m16ty]

If you can find a winch PTO, valve, controls,and pump, that would be the thing to use for hydraulics because it would bolt right up.

You may want to look for a bed off a M817 as they seem to be much more plentiful that a M929 bed. You could always go with a 12' commercial bed also. A compete M817 bed should have the pump, tank, and valving with it but you'll have to figure out how to tie it into the M931 PTO and work out the control linkage.

Pricing is all over the map. It all depends on what you can find. There was a local guy that had some complete M817 beds for $1200.

 

[clews1975]

I am trying to accomplice the same thing that jjb has listed above. I would like to keep it as close to original as possible. any help would be greatly appreciated. Thank you

 

[jcappeljr]

It might be cheaper to buy a winch tractor,and start with that.All you would need then is a bed from a 817/929.I just sold 2 sets of hyds from a 939 series truck for $1000 each.Plus installing the hyds. is a pain. I have put commercial dump beds on alot of military trucks.Its hard to find a 13' civilian bed.I also have a m932 for sale or possible trade + cash.

 

[goldneagle]

According to Jeff Davis the headache rack on the M817 bed would have to be modified to fit a M931. (especially if it has a hardtop on it) (since the cab on the M939 series is wider than the M808 series.)

 

[clews1975]

I am going to buy junk m817 as suggested. problem is they are standard, so pto is different, but can get pto for $500 new. if you can weld setting up pto shaft to pump is a breeze.

 

[Vintage iron]

I maybe able to help with a PTO

 

[tobyS]

I'm working on making a cargo into a dump. I'll try to attach a couple of photo's

 

[tobyS]

hinge for cargo to make dump

Here is where it will pivot (hinge). Note I will make a lot heavier hinge in line with this one but for now it gives me a starting point without a lot of modification.

 

[tobyS]

I know the bed steel is rather light steel for a dump truck so I want to improve it. On my 73 4x4 F66 boomtruck, the bed (diamond plate) has wood under it and between the frame. It really cushions a hard hit. So should I fab that into my dump cargo to make it stronger and less prone to damage?

At times I plan on carrying rather large rocks and sometimes heavy scrap, which damage a bed... so I'm thinking of putting down a 1 1/2" layer of white oak then a steel layer 3/16" plate over that, welded in place.

For anyone looking at the pictures, there will be a c-channel that goes from the front to the angle iron rear, alongside of the existing frame and a telescoping cylinder at the front. I need a PTO.

I can make a different thread, but this seemed the same subject.

 

[m16ty]

You will bang up the bed floor pretty good, and even the crossmembers, hauling big rock. The wood will help greatly but I'd suggest removing the original floor skin first. If you sandwich the wood between the original floor and the new floor, moisture will get in there and can't get out. The wood will rot fairly quick.

 

[trukhead]

I'm contemplating cutting a '56 F700 3 yard dump truck into a trailer with a 90,000 GVW lunnette ring to pull behind my M931A2 on that dandy pintle hitch. I'll leave the dump truck frame long to make it easier to back onto spots,

 

[tobyS]

Trukhead, If you have it and it's not going to run otherwise...go for it. I've made trailers from truck rear ends and they work very well. But be careful about your center of gravity, it's changed significantly and corners or un-even dips in the road let you know if your top heavy. My welder and torch on a ranger bed had to be changed to under slung (lowered). Longer is better for stability, but get it as low as you can so the load is not wanting to roll it over. I think they stopped making 3 wheel ATV's because of the tendency to roll, much like the truck rear end will do with that single pintle connection. By the way, what will you do for brakes? I bet the 700 has no air brake. Semi truck axles are an alternative for air brakes.

M16ty...your right that it is a place to hold water which will cause rot. I wouldn't remove the skin, but I could ventilate it well. On my other truck there is a few spots rotting... it's a 73. I know where there is a place that could treat the wood (white oak) also...they do RR ties. I would weld the top skin on with continuous bead, making it harder to penetrate, but of course not impossible. The bed of my dump trailer shows the wear on the floor (single layer skin) but has yet to bend frame members. It's about the same thickness as the cargo bed, but not as much frame support. Perhaps I should just plan on the bed being destroyed or find another way of reinforcing it like (tight fit) wood cross members underneath, between the steel ones and frame. That wouldn't be near as much work. Darn dump trucks on GL are bringing a premium and they vary a lot in use/condition.

 

[trukhead]

Trukhead, If you have it and it's not going to run otherwise...go for it. I've made trailers from truck rear ends and they work very well. But be careful about your center of gravity, it's changed significantly and corners or un-even dips in the road let you know if your top heavy. My welder and torch on a ranger bed had to be changed to under slung (lowered). Longer is better for stability, but get it as low as you can so the load is not wanting to roll it over. I think they stopped making 3 wheel ATV's because of the tendency to roll, much like the truck rear end will do with that single pintle connection. By the way, what will you do for brakes? I bet the 700 has no air brake. Semi truck axles are an alternative for air brakes.

Thanks for the input on the stability. I had not even give it a thought beyond the axle is biased to the rear of the dump body footprint. Any load in the dump trailer is like BBQ on the rotisserie.

Again, Thought and care need to be considered before each load with said dump trailer.

Thanks again
Dennis

 

[Triple C]

Not to rain on the parade here, cause I LOVE dump trucks but has everyone considered the insurance implications? Modifications to the insured vehicle normally voids the insurance unless you notify the carrier and I would assume they would then re-rate the policy accordingly. When I left trucking, dump truck insurance was not cheap. If you modify your rig without telling them, don't count on having effective coverage in the event of an accident. Sorry, just trying to keep us all safe and happy.

 

[tobyS]

My insurer is informed of my purpose for the dump, which is to haul building brick and clean fill, about 50 loads, from my own town lot to my farm, where I am using the materials for a fill purpose. I am not doing commercial work, but only my own. Thanks for the reminder one must be properly insured.

Trukhead, I go back and forth on a trailer to pull that way but realize the stability issue makes a different design, lower, to be necessary for a 15-20,000 lb load, which I see as no problem pulling for a 23,000 lb truck.

Speaking of a grill, I put a cast iron hemispherical flask (weighs 1500#), that I cook with a wood fire, onto a dually f350. Now completing it as a vending trailer, perhaps for the said lot that I'm cleaning up (across from a Walgreen).

 

[seano11]

No different then hauling a pup behind a tandem dump truck? Why would ya be worried about it tipping over?

 

[tobyS]

Because the center of gravity is acting on a point in the center of the truck, whereas a pup is supported to the outside of it's wheel base. A pup would simulate the 4 wheel support like having a front end, but on a pintle, it rotates on the axis and gives no support, thus a high center of gravity could roll much easier. Notice the roll moment built into a pintle on the trucks. To the extent it could be a problem would depend on many factors, but to cut up a single axle dump and think one can carry the same load, that high up, may find it is not so stable on dips in the road or curves. Not wanting to pour water on the idea, just saying it has limitations with a high CG so de-rating the load is wise.