New (used) IH 7500 Dump Truck purchase, modification & fix up

[mrmikey]

Overhand should be same as I am thinking of shortening C/A and frame both by 2 feet

Yup, I misread your post and thought you wanted to shorten up the overhang.
I still think I'd wait till you get the body tho, as the saying goes, s++t happens and if your luck is like mine.....

 

[Hay Dude]

So I need to figure out what to do with shortening frame and dump body overhang.

Is there a “rule of thumb” for overhang of dump box past truck frame so it won’t hit the tow hitch?
Can a 12’ box fit and dump correctly on a 10.5’ of frame, etc.?

We got the frame blasted, primed & painting finished.

Now I have to find a dump body. The existing frame from back of cab to end is 12’. The last 12-18” of frame has enough rust that I feel it needs to be cut off. If I’m only left with 11’ or 10.5’ of frame, whats my max dump body length?

Seems like 11’ dump would be perfect, but need to be open to 10’ or 12’ if a great deal comes along. Really prefer 11 or 12 to 10. So much more room/capacity.

 

[Rustyiron]

I'd be patient for a 11' or 12' and leave the axle alone and pay an additional $1000 for the right body just to not fool with moving it and the can of worms the it might open.

 

[mrmikey]

It's been awhile since I've actually mounted a single axle (retired for 2 years, worked for purchasing for the previous 5) so don't quote me verbatim .
I'd say the frame length you have now is perfect for a 12' body, the single axle configuration (CA) not so much . If you do go with a 12', you're going to have to watch your front axle weight, it'll be so easy to overload it.
We used to mount the body 12" or so from the spill plate to the center of the hinge. Any more than that, you're possibly getting into issues clashing with the pintle and the also of the body hanging up if you're spreading and try to lower the body if you're not empty.
Another thing to keep in mind if your body has too much overhang is to watch that you don't end up with the dump cylinder hitting the bottom edge of the body when the cylinders extended.

Looking at the pic, you don't have enough to cut 12-18" off the end, you'd be into the rear spring perch or is it an optical illusion? If you find a body that would work with the frame as is, is there a way you could reinforce the end of the frame? A doubler perhaps that can go a couple of feet forward to catch the rear perch bolts, I would assume there is a cross member there which would be a PIA to remove and shorten?
What did you say your CA is now?
Found this online if it helps any:

 

[aczlan]

It's been awhile since I've actually mounted a single axle (retired for 2 years, worked for purchasing for the previous 5) so don't quote me verbatim .
I'd say the frame length you have now is perfect for a 12' body, the single axle configuration (CA) not so much . If you do go with a 12', you're going to have to watch your front axle weight, it'll be so easy to overload it.
We used to mount the body 12" or so from the spill plate to the center of the hinge. Any more than that, you're possibly getting into issues clashing with the pintle and the also of the body hanging up if you're spreading and try to lower the body if you're not empty.
Another thing to keep in mind if your body has too much overhang is to watch that you don't end up with the dump cylinder hitting the bottom edge of the body when the cylinders extended.

Looking at the pic, you don't have enough to cut 12-18" off the end, you'd be into the rear spring perch or is it an optical illusion? If you find a body that would work with the frame as is, is there a way you could reinforce the end of the frame? A doubler perhaps that can go a couple of feet forward to catch the rear perch bolts, I would assume there is a cross member there which would be a PIA to remove and shorten?
What did you say your CA is now?
Found this online if it helps any:
View attachment 785720

From earlier he currently has 144" of frame and 108" CA, that sheet would seem to suggest that he should really have a 2nd axle under a 12' box and he could lose 6" CA.

Aaron Z

 

[Hay Dude]

My C/A is 108” (9 feet). I would have to slide the rear axle forward to get rid of the last 12-18” of frame because the rear hangers are on that last 12-18” of frame that is in bad shape.
The rear spring hangers on the back of the frame were left full of asphalt for many years, trapping water in them. One spring hanger has a fist sized thin area. No problem to replace. The other side rear spring hanger was full of asphalt and caused the frame to rust almost all the way through the outer frame to the inner frame.

My thinking was to slide the rear axle forward enough to a healthy steel spot (probably 12-18” forward).
This might still allow a 12 or 11’ body, but I am not 100% sure. If I have 11’ of frame (132”), I would think a 12’ bed would still be ok. Now if I shorten the frame to 10.5’ (126”) I am not positive a 12’ bed would work as I would have 18” of dump body overhang.
I have seen 11’ beds, but they are usually found on lighter contractor style dump trucks.
I need a “high walled” dump body with 32”-48” sides.

BTW front axle rating is 16,000lbs, so pretty strong up front.

I had not thought of possibly reinforcing the last few feet of frame onto the rear……not sure if it’s enough.

 

[mrmikey]

that sheet would seem to suggest that he should really have a 2nd axle under a 12' box

That's what I was eluding to in the previous post without coming out and actually saying it .
This is what I was thinking (I think my math is right, it's beer o'clock) for an 11' body allowing 10" behind the cab and a 12" overhang. Means you'd be cutting 14" or so off the end of the chassis and moving it ahead 14". I still think an 11' box is big for a single axle tho and you'd be better going 10' but I understand your train of thought also.

 

[Hay Dude]

Excellent, thanks. I forgot about the 10” behind the cab needed for clearance
A longer, higher bed is preferable for the times I’m carrying lighter bulky materials like wood chips or mushroom soil.
I believe the axle ratings Rear 30K and front 16K should ensure the truck has the strength, brakes, tires for holding the load.
I won’t be filling the box with 14 tons of rocks, well maybe once in a while lol
Sounds like an 11’ would be my favorite or 10’ a more realistic alternative

What I now need to do is figure if 96” C/A is ok for a 10 or 11?

Then there’s also the 3rd option of reinforcing the last 3-4’ and staying with 12 lol

 

[mrmikey]

What I now need to do is figure if 96” C/A is ok for a 10 or 11?

NP.
What I've got drawn (CA of 94") I figured for an 11' body, shorten the dimensions up by 12"and you'd be ok for a 10'. There's places you can cheat a bit too, the overhang and the clearance behind the cab. On the last item, make sure you leave enough room for the cylinder cradle, it's a b**ch when you have to work sideways with one hand.

Excellent, thanks. I forgot about the 10” behind the cab needed for clearance

Been there, done that, kinda sucks big time when you go to mount the body. End up getting called all kinds of not nice names and that's by me not to mention the guys working with me.

Then there’s also the 3rd option of reinforcing the last 3-4’ and staying with 12 lol

Ever been called stubborn? (meant with the utmost respect) LOL

 

[4570Man]

I have a 14ft bed on 12-6’ of frame. I don’t particularly like how much it sticks off. It makes it hard to pull a trailer and not cut into it. The axel center is 9ft from the cab.

 

[Rustyiron]

Mrmikey in your experience in the business did you ever "put together" a s/a medium dump for a smaller, mostly owner-oporator operation that had widely varied duties where one day he's running light mulch or dry topsoil and needs the volume, and a couple of days later needs 6-8 tons of stone or sand?
Typically he's going know his truck and load it according to the material (weight) and doesn't want to see a big fine or damage his equipment.
Which of the recommendations on the chart would be the one(s) to "bend" or would it be a combination of this.
Your knowledge and experience have been a great help imho for/to this thread and for anyone following it.

 

[mrmikey]

Mrmikey in your experience in the business did you ever "put together" a s/a medium dump for a smaller, mostly owner-oporator operation that had widely varied duties where one day he's running light mulch or dry topsoil and needs the volume, and a couple of days later needs 6-8 tons of stone or sand

No, 'fraid not. I worked in the welding shop of a provincial DOT mechanical facility for 25± years then went to pencil pushing for 5±, same facility. At first the trucks were pretty much a 50/50 blend of single axle and tandems, in later years they went to tandems exclusively as they were more versatile for the cost. The trucks were used for salt and/or sand spreading in the winter and shouldering or ditching in the summer with the occasional road washout and asphalt repair thrown in. Saying that, the majority of the product has close to the same density/weight not like cotton balls and lead .
They changed to using spreader inserts in the winter which were more rearward mounted so we had to change the positioning of the bodies to find the best compromise of seasonal use as far as weight distribution was concerned. Then you had to take account of the weight of the plow and wing gear which was biased to the right. Add into that mix the weight of brine carried for pre-wet.
All of this while not going over the maximum GVWR as well as the front and rear GAWR

Typically he's going know his truck and load it according to the material (weight) and doesn't want to see a big fine or damage his equipment

You are 100% correct. But that is a situation where he breaks it he has to pay for the repairs, it's out of his pocket. I'll say no more on the subject except the common saying was a machine gets greased twice in it's life time....first and last. I gave up complaining at the end...it made no difference.

Which of the recommendations on the chart would be the one(s) to "bend" or would it be a combination of this.

As for which specs to 'bend'. I can't really answer that, the only true way is to scale the truck with a load of whatever the most common product would be carried and move the body to get the best load specs which I've done.... and it's a pia. Only salvation in my case once you did it, you didn't have to do it again as the trucks were close to identical. Now days there's software that once you have the body weight, axle weights and dimensions it'll do the figurin' for you.
Moving one affects others. Lengthen the overhang, the rear axle gets heavier and the front lightens up. Same situation, you could load the body front heavy and it may even out to a certain extent.

Your knowledge and experience have been a great help imho for/to this thread and for anyone following it.

Thank you, I appreciate the compliment.

 

[aczlan]

As for which specs to 'bend'. I can't really answer that, the only true way is to scale the truck with a load of whatever the most common product would be carried and move the body to get the best load specs which I've done.... and it's a pia. Only salvation in my case once you did it, you didn't have to do it again as the trucks were close to identical. Now days there's software that once you have the body weight, axle weights and dimensions it'll do the figurin' for you.
Moving one affects others. Lengthen the overhang, the rear axle gets heavier and the front lightens up. Same situation, you could load the body front heavy and it may even out to a certain extent

Beamboy should be able to handle that, @Hay Dude if you have current weights per axle, the current wheelbase, the amounts you want to try shortening it by and an approximate weight of a box I can probably get close on there.

Aaron Z

 

[Hay Dude]

I have a 14ft bed on 12-6’ of frame. I don’t particularly like how much it sticks off. It makes it hard to pull a trailer and not cut into it. The axel center is 9ft from the cab. View attachment 785811

Are you sure thats only 18” of overhang? Looks like 2-3’ of overhang

 

[Hay Dude]

I don’t have current weight per axle (if you mean unloaded with body installed).
The rear is a 30,000lb rear
The front is a 16,000lb front
The GVWR is 41,780
Wheelbase is listed as 465cm or 183”.

My previous truck was very similar, but only 33,000GVWR with a 12K front and 21K rear. Only frame reinforcement was an overlay “L” from the back of the cab to the rear. Empty it was 17,000lbs. It had a high wall 12’ dump box. I loaded it with 10 tons gravel a few times. I know it was overloaded, but it handled the load pretty easily.

This truck is built much heavier, so if I’m only looking at a 11’ box (maybe 12’) I don’t expect to be overloaded. I mean the rear axle alone is rated 9,000lbs heavier. The front axle is rated 4,000lbs heavier. The frame is doubled the entire length. The spring packs are much bigger.

I’m more concerned about the frame being modified and repaired properly and the axle being moved forward to the correct position.

 

[4570Man]

Are you sure thats only 18” of overhang? Looks like 2-3’ of overhang

It’s 2ft of overhang because the inside of the bed is 14’ which makes the outside a little more plus the couple inch gap between the cab.

 

[Hay Dude]

It’s 2ft of overhang because the inside of the bed is 14’ which makes the outside a little more plus the couple inch gap between the cab.

OK that’s more like it.
I won’t have 2’ of overhang, probably more like 18”.
I just talked to a guy who runs a lot of state salt trucks and he said that should be fine for an 11’ body, but I think 12’ might not happen.
The 10” spacing from the cab and 18” off a 12’ frame means frame now has 10’-2” of usable frame. 11’ bed would have about 12” of overhang. 12’ bed would leave about 24” of overhang. I don’t know how much it’ll affect towing.

I don’t see many 11’ dump bodies for sale. 10’ much more common.

 

[Hay Dude]

A few update pics. Truck frame is now sandblasted, primed & painted. It looks better, but reminds me of a kid with bad acne. The scars are still there.

We cleaned all the rust jacking out we could reach. You’ll also notice we removed the exhaust stack. I found some 5” exhaust pipe and we are going to try to fab-up an exhaust pipe. The stack is still good, but the bottom where water collects was toast.

I paid $18/foot for exhaust pipe and $24 for a 5” coupler. Not cheap.

Anyway, things are progressing, but slowly.
Still looking for high sided 10-11’ bed, then we will know how to handle the end of the frame and moving the axle.

 

[mrmikey]

The scars are still there.

Not scars...character .

I found some 5” exhaust pipe and we are going to try to fab-up an exhaust pipe. The stack is still good, but the bottom where water collects was toast.

What about just going with a turn down? If you can get away from a vertical stack it my prevent problems with a cab shield depending on the type and style of body you find.
You're lucky, there's no DPF or SCR to worry about. The newer trucks I was working on had $15-20K of exhaust crap behind the cab and enough structure to support a car bridge holding it up. Not only that, since it was an engineered system you couldn't move a thing from factory...nothing.

You get the frame flanges flattened down some? They don't look as angled up as they were.

......then we will know how to handle the end of the frame and moving the axle

Gonna have to watch your drive line angles too

 

[civilian]

Not knowing any better, could Hay Dude cut front off a 10ft box and extend it to 11ft? What would that entail? I have no experience with dump trucks other than buying gravel and having it dumped and sometimes tailgate spread. Jon