Educate me on the dump...the M929 / M930

[tobyS]

I run the gate and wings to get the extra 2' of support on both the 929 and 817. I haul materials like construction debris/ I recently hauled about 30 loads of stone from a basement after I took the building down. I never weighed but was probably close to design max. The 817 is gone, but It did fairly well for stability with a load, having the duals. The 929 I have now had 14.00 GT AT2 that under load, were scary. Now I run the 395 Michelins. Went from 9700#/tire to 12,500 and smaller diameter with a wider contact surface.

If you have a 925, that would make a great donor but with the extra length, you can overload it.

 

[LCA078]

Air shift PTO with direct mount pump,not sure of the PSI or tank volume. I hired the job out because I work full time and I wanted it done for the spring.they did a great job it has all the good stuff .

Very cool. I'll probably do my own mainly because I don't know of a shop around me that could do the conversion to my spec. But doing it myself also means it might be a while...

tobyS: I can get easily get take-off 14ft and 16ft dump beds so agree I have to be careful. Not a bad thing when hauling 'fluff' as mentioned before but definitely not good to 'fill her up' with roadbase/gravel. That's why I'm trying to do my homework here.

 

[Glenngineer]

Very cool. I'll probably do my own mainly because I don't know of a shop around me that could do the conversion to my spec. But doing it myself also means it might be a while...

tobyS: I can get easily get take-off 14ft and 16ft dump beds so agree I have to be careful. Not a bad thing when hauling 'fluff' as mentioned before but definitely not good to 'fill her up' with roadbase/gravel. That's why I'm trying to do my homework here.

With my truck we had to bridge up and over the transfer case to do the front mount hoist because the case goes above the frame

 

[Glenngineer]

With my truck we had to bridge up and over the transfer case to do the front mount hoist because the case goes above the frame

My weight tag is blank ,does that mean I can carry anything or nothing LOL

 

[LCA078]

With my truck we had to bridge up and over the transfer case to do the front mount hoist because the case goes above the frame

That's a really nice setup and your shop does quality work. I see the box guides sticking up from the frame but did you also beef up the frame? I can't make out what was added to the frame in the lower right part of the pick...just to the right of the box guide.

 

[Glenngineer]

That's a really nice setup and your shop does quality work. I see the box guides sticking up from the frame but did you also beef up the frame? I can't make out what was added to the frame in the lower right part of the pick...just to the right of the box guide.

That's a rubber strip that gets glued to the frame to prevent wear and noise on bumpy roads.

 

[LCA078]

That's a rubber strip that gets glued to the frame to prevent wear and noise on bumpy roads.

I'm referring to the added steel I circled in red in this pic. I'm assuming the item circled in green is a guide for the bed to sit square but I don't know what's circled in red.

 

[Glenngineer]

I'm referring to the added steel I circled in red in this pic. I'm assuming the item circled in green is a guide for the bed to sit square but I don't know what's circled in red.

That's the safety bar that swings up to make sure the box can't come down and squash me.

 

[LCA078]

Ahh- your truck has ABS and ASB.

Anti -lock Brake System
and
Anti-Squash Bar

I like it

 

[Lukes_deuce]

Since you have a 925, Ill give you my set up. I have a 923a2 with a 10 ton dump hoist fabricated under the stock bed. I had a large backyard project to tackle and I wanted to keep the troop bed for its functionality after the project was done. I like my set up. I haul about 7 yards at a time with the troop seats in place. It was topsoil, fill and crushed concrete. The 7 yards of crushed concrete routinely came in at 17,000 pounds. Also at this amount of material, the material would fall out of the space between the top of the drop sides and bottom of the troop seats. I placed a 2x6 in the gap as a temporary fix. The troop seat bed is not the best dump truck bed. I will take the quirks of a drop side troop bed for my situation. I need to be able to side load pallets and you cant do that on a dump truck.

As for hauling the weight and handling it, my truck did well with 14r20s and 16r20s with 70psi. I never felt the truck was over its capacity or really struggling. Besides being a little slow, I got my job done and moved about 300 yards of material.

I wouldnt use the troop bed for anything bigger than 1.5" stone. You will bend the floor with heavier materials.

 

[LCA078]

I will take the quirks of a drop side troop bed for my situation. I need to be able to side load pallets and you cant do that on a dump truck.
...
I wouldnt use the troop bed for anything bigger than 1.5" stone. You will bend the floor with heavier materials.

I agree that drop sides are a good feature to keep. Luckily, my M923 with troop bed and drop sides is in pretty good shape. My M925...well, it's not so much in good shape. It was used as Volunteer Fire Department water truck and i think either they used some type of fire retardent or had a battery spill over in the bed as the bed is pretty much rusting out on the front half. I originally bought it as a non-running parts truck but after buying my ranch, I think I need a dump bed. I think I can get the 925 in running order and I'm looking for a salvage dump bed to replace the rusted out troop bed. Like most of my projects, it's all about finding time to work on it....

 

[LCA078]

If you have a 925, that would make a great donor but with the extra length, you can overload it.

Help me understand a bit more of the extra length statement. Are you referring to the length of the frame that extends past the rear axle? I know the wheelbase for a M929 or M931 is the short version at 13' 11" and the wheel base for the M923/M925 is a foot longer at 14' 11" but I'm guessing you're referring to be cognizant of the stress issues where the bed pivot point is at the end of the longer frame? Or do you just mean that with an extra bit of frame length, I can add more material to a longer bed and thus overload it?

 

[Glenngineer]

Help me understand a bit more of the extra length statement. Are you referring to the length of the frame that extends past the rear axle? I know the wheelbase for a M929 or M931 is the short version at 13' 11" and the wheel base for the M923/M925 is a foot longer at 14' 11" but I'm guessing you're referring to be cognizant of the stress issues where the bed pivot point is at the end of the longer frame? Or do you just mean that with an extra bit of frame length, I can add more material to a longer bed and thus overload it?

A longer frame has the potential for a larger box which could be overloaded if filled to capacity ,but the problem with the shorter frame is getting enough weight transferred to the front axle so it is carrying it's proper share of the load. I have not put a load on my M931A1 yet but I believe that getting a load on the front axle will be a problem .With a dump box 16-18 inches past the back of the tires is max.

 

[Tow4]

The box on my M929 looks like it is about a foot forward of being centered over the tandems. I'm looking at a picture but I can measure it. Most of the civi dump trucks I've seen have the tandems near the rear of the box in addition to the box being much longer. They also have much higher capacity steer axles. You can get some of the load transfered forward, but with the bed being mostly centered over the tandems, it's going to be hard to do without moving something. Then you have to worry about overloading the steer axle.

 

[Jbulach]

That’s the problem I have on my M925a2, that I put a dump hoist on. I just cant get the weight on my steers that I want. The bed and frame handle 12-13 ton no problem, but I start pushing the legal limit on the bogie. This is why I have been trying to find the factory rating for the front axle. I would eventually like to move the spare to the front bumper, slide the bed as far forward as possible then chop the extra off the rear of the frame. Then would look at getting some of the brake proportioning back to the front axle, so it can do it’s fair share as well.

 

[Tow4]

Our biggest problem is the weight of the truck. My M929 is about 26K empty. Any M939 derivative with similar dump bed and hydraulics is going to be the same. To compound the problem, our axle ratings are also lower. You really can't do anything about these things.

For example, the fellow I had deliver 17 tons of crusher run in NC last year had a Sterling tandem axle dump truck. He said the truck was rated for about 58K GVW (I don't remember the exact number) but he limited the weight because of the grades in the mountains. His truck probably weighed about 20K empty.

I would either buy a civi dump truck or just make more trips. It's going to be hard get more with these trucks because they aren't designed for it.

 

[tobyS]

Help me understand a bit more of the extra length statement. Are you referring to the length of the frame that extends past the rear axle? I know the wheelbase for a M929 or M931 is the short version at 13' 11" and the wheel base for the M923/M925 is a foot longer at 14' 11" but I'm guessing you're referring to be cognizant of the stress issues where the bed pivot point is at the end of the longer frame? Or do you just mean that with an extra bit of frame length, I can add more material to a longer bed and thus overload it?

I was referring to the size of box and likelihood of putting a lot bigger box on the 925 frame. With lots bigger box, eventually someone tries a lot bigger (weight) load. If you keep that from happening then you have a 40% or so bigger bed to do your work....which can be really handy. Maneuverability is less for tight spots and NEVER forget about backing in low (transfer case). Don't expect to have much power backing and you won't be disappointed.

 

[Bjmca]

Here’s a couple shots of the M929 dump hoist system. They use a dual cylinder design with a roller ramp system to assist with the initial lifting, which is the hardest part.

I had a fellow tell me the rear tailgate in ”rock” position is designed to be able to knock down the dumped pile while backing up. That’s also why the bed dumps at such a steep angle. I have not confirmed this ad I don’t have a manual. Anyone able to verify that?

 

[Glenngineer]

That’s the problem I have on my M925a2, that I put a dump hoist on. I just cant get the weight on my steers that I want. The bed and frame handle 12-13 ton no problem, but I start pushing the legal limit on the bogie. This is why I have been trying to find the factory rating for the front axle. I would eventually like to move the spare to the front bumper, slide the bed as far forward as possible then chop the extra off the rear of the frame. Then would look at getting some of the brake proportioning back to the front axle, so it can do it’s fair share as well.

On my truck I moved the spare to the tail gate so I could get as much weight on the front as possible

 

[LCA078]

The box on my M929 looks like it is about a foot forward of being centered over the tandems. I'm looking at a picture but I can measure it. Most of the civi dump trucks I've seen have the tandems near the rear of the box in addition to the box being much longer. They also have much higher capacity steer axles. You can get some of the load transfered forward, but with the bed being mostly centered over the tandems, it's going to be hard to do without moving something. Then you have to worry about overloading the steer axle.

I think part of problem is the M929 is on the short frame wheelbase (same as M931) and there's not enough room to have a decent size bed and room for a spare. If the extra foot of M923 wheelbase was incorporated, the load would shift forward