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Truck Length Modification


Cdfarabaugh

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I'm utilizing my student labor to resurrect a '92 4700 IH for my cousin to install a 14' steel dump body.  Southern truck with no rust, but she's been beat.  

DTA360, air brakes and 5x2, will be a nice little truck after we give the brake system a going over.   

There is only 136" of frame behind the cab now.  Will need 162".  So looking at adding a little over 2 feet andmoving the axle back.  

 I'm figuring on staggering the seam on the added on portion with the outer double frame sleeve extended back and an inner portion added inside the main rail for strength at the splice.  Correct me if my figuring is wrong.  

What I'm most unsure about is what is the max length allowed between carrier bearings on the driveline?  I'm hoping to get away with just one carrier bearing, but I have heard anywhere from 5-7' being the maximum.  5' is gonna be dang close, 7' will be no problem. The slip joint on the rear shaft is roached so it needs redone anyways. 

Gotta love 2023 where resurrecting old stuff is no longer a hobby and the only way you can put a decent truck together for under 20k......

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Definitely stagger the spliced places . I would make them similar to this quick sketch. I'd make one point back and one front on both sides 

IMG_20231122_204020055.jpg

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4 minutes ago, bitty said:

Definitely stagger the spliced places . I would make them similar to this quick sketch. I'd make one point back and one front on both sides 

IMG_20231122_204020055.jpg

I hear so many methods for the splice cut, but always figured as long as it's not straight up and down.  I like your method though! 

Do you weld the joint with 7018 or go with a higher strength rod?  

 

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3 minutes ago, Cdfarabaugh said:

I hear so many methods for the splice cut, but always figured as long as it's not straight up and down.  I like your method though! 

Do you weld the joint with 7018 or go with a higher strength rod?  

 

I’ve known people to run a straight joint successfully. I’ve also been driving a truck where such a joint let go! I’ve seen professionals use a stair step type joint and that seems like a good idea. Definitely use a fresh piece of frame to double (or triple) it and use more than four bolts per side.

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I have lengthen/shorten quite a few trucks. I have used the Z cut, half round cut and angle cut. most of the time i just use a angle cut of at least 30*. I always bevel the outside of the cut and leave about 1/8' flat land. I leave around 3/32 gap and weld from the inside first, then go to the outside and grind back to the inside weld and weld it out. I use 7018 or Hobart self shielded wire XLR8 when the frame is 3/8" or thicker. I then cut a oval fishplate that is at least 3" longer than the cut as for example if you cut a 10" frame on a 45* the fishplate needs to be 16" long. 

I personally think the half round cut is the strongest. I have straight cut a few also.

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44 minutes ago, Cdfarabaugh said:

I hear so many methods for the splice cut, but always figured as long as it's not straight up and down.  I like your method though! 

Do you weld the joint with 7018 or go with a higher strength rod?  

 

7018 is what I used but it's been years . I'm told if correct heat settings and procedures are used E70S mig is just as strong although part of me doesn't believe that 

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40 minutes ago, brewcrew said:

I’ve known people to run a straight joint successfully. I’ve also been driving a truck where such a joint let go! I’ve seen professionals use a stair step type joint and that seems like a good idea. Definitely use a fresh piece of frame to double (or triple) it and use more than four bolts per side.

My suggestion when it comes to bolts is use a tapered reamer to drill the holes to the exact size. I have only done some RD model double frame Macks and they use bolts for the cross members and Trunion that are slightly bigger body .....I think they call them body bound bolts . Think the 5/8" bolt has an 11/16" shank . When used with the tapered reamer they are tight in the hole as in bump in with a mini sledge while tightening the nut with an impact 

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9 minutes ago, bitty said:

7018 is what I used but it's been years . I'm told if correct heat settings and procedures are used E70S mig is just as strong although part of me doesn't believe that 

I think if conditions were perfect 70S6 would work. But I never have perfect conditions. Dual Shield would be good also.

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Have you considered changing the pivot point of the dump body? This is a 14’ body that pivots at about 11’ looks a little different, but the truck is super maneuverable, the body dumps easier because it is somewhat counterbalanced. Has worked well for us.

IMG_2963.jpeg

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6 minutes ago, vtfireman85 said:

Have you considered changing the pivot point of the dump body? This is a 14’ body that pivots at about 11’ looks a little different, but the truck is super maneuverable, the body dumps easier because it is somewhat counterbalanced. Has worked well for us.

IMG_2963.jpeg

The long overhang also makes it easier to unload if you have to use a makeshift dock like a ditch or a bank because of the overhang. They are also easier to load vehicles on since raising the bed lowers the back end. Having driven trucks with overhang and almost no overhang, I prefer the ones like you pictured

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If hauling ANYTHING heavy (grain dumped out a chute) or gravel you don't want to move pivot point forward. Grain chute would be on the auger before you get it all to slide back. Gravel will lift front tires off before load comes off. 

Light material it will work, possibly be ok dumping logs out of a dump but I'd caution against it for some uses . 

I should add we have an 18 ft dump that's 10 ft to the center of the tandems on an 80 Mack RD truck. It works because the Mack is very heavy in the motor compartment. Running grain out of a chute you can notice the front end does get a little light compared to normal. I think we added three foot of frame behind the tires and then the tail hinge is 18 in from the back

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To answer your driveline question, I have used this document that Spicer publishes.  It’s pretty thorough on the subject of driveshaft design and specifications.  
 

https://www.dana.com.au/pdfs/service-manuals/J3311-1-DSSP Spicer Driveshaft Installation Manual.pdf

 

On the topic of how to splice frames - everyone seems to have an opinion on that subject that’s a little bit different than the next dude’s.  On newer higher tensile frames I would worry about the metallurgy as much as the actual joint construction.  

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I wouldn't change the pivot point. My dump belonged to a paving company and even though the pivot is all the way to the rear it still has had straps installed to control/bring the body down on a part dump as would be done while paving walks, etc. I actually had to use them once when patching pot holes in the gravel portion of my drive. I can see a real problem if the pivot was forward.

VT is using it to an advantage in that application when hauling equipment.

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8 hours ago, Sask466 said:

To answer your driveline question, I have used this document that Spicer publishes.  It’s pretty thorough on the subject of driveshaft design and specifications.  
 

https://www.dana.com.au/pdfs/service-manuals/J3311-1-DSSP Spicer Driveshaft Installation Manual.pdf

 

On the topic of how to splice frames - everyone seems to have an opinion on that subject that’s a little bit different than the next dude’s.  On newer higher tensile frames I would worry about the metallurgy as much as the actual joint construction.  

With the right filler metal I don't worry about the so called higher tensile frames. All frames have to flex. If they were high tensile they would crack. I have done many winch and silage trucks which take the most abuse possible. 

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10 hours ago, vtfireman85 said:

Have you considered changing the pivot point of the dump body? This is a 14’ body that pivots at about 11’ looks a little different, but the truck is super maneuverable, the body dumps easier because it is somewhat counterbalanced. Has worked well for us.

IMG_2963.jpeg

Our own 14 foot single axle dum is set up like this and it's annoying as the bed height comes down when dumping, eventually only about 2 feet off the ground at full up.  I'm not sure why they were built like this, but a lot of farm trucks around were.  

This design also eliminates the possibility of having a hitch receiver 

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I guess the 2nd question to elaborate on is how long should the inner reinforcement piece of frame be covering the splice?  The outer will be a double frame so its going the whole way to the rear.  

One challenge is going to be the cost and finding an outfit to get this stuff fabricated.  Back in 2015 I double framed my service truck from the rear of the cab to the back due to rust jacking (but didn't lenghten)  and had an outfit PG Adams make them.  I think with truck freight it was $675.  I'll bet it would be double that now  😞 

there's places capable of making that stuff here but they usually just blow walk ins for stuff like this off.  

 

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I use Harbor Steel to make frame pieces. I am working on a silage truck now when I have time and extended it 6ft. 7in. It has a .45 thick frame and they do a good job. I only add fish plates to the outside of a single frame, double or triple I will do inside and outside. I never aim to do a double or triple again, too old.

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1 hour ago, Cdfarabaugh said:

I guess the 2nd question to elaborate on is how long should the inner reinforcement piece of frame be covering the splice?  The outer will be a double frame so its going the whole way to the rear.  

One challenge is going to be the cost and finding an outfit to get this stuff fabricated.  Back in 2015 I double framed my service truck from the rear of the cab to the back due to rust jacking (but didn't lenghten)  and had an outfit PG Adams make them.  I think with truck freight it was $675.  I'll bet it would be double that now  😞 

there's places capable of making that stuff here but they usually just blow walk ins for stuff like this off.  

 

On our double frame Mack RD we lengthened we didn't plate it at all. Just spliced it at the angles and staggered the splices . We did that in 1994 and it's never had any issues with the frame 

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15 hours ago, Finney said:

I have lengthen/shorten quite a few trucks. I have used the Z cut, half round cut and angle cut. most of the time i just use a angle cut of at least 30*. I always bevel the outside of the cut and leave about 1/8' flat land. I leave around 3/32 gap and weld from the inside first, then go to the outside and grind back to the inside weld and weld it out. I use 7018 or Hobart self shielded wire XLR8 when the frame is 3/8" or thicker. I then cut a oval fishplate that is at least 3" longer than the cut as for example if you cut a 10" frame on a 45* the fishplate needs to be 16" long. 

I personally think the half round cut is the strongest. I have straight cut a few also.

I’ve probably done 25 or 30 of them using the same procedure with the angle cut. I have rarely fishplated them, but have taken special attention to try to bridge the joint with the cross member brackets. Have either used 7018 or 8018. No failures that I know of, and I know some of the trucks were not treated nicely. 

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2 hours ago, bitty said:

On our double frame Mack RD we lengthened we didn't plate it at all. Just spliced it at the angles and staggered the splices . We did that in 1994 and it's never had any issues with the frame 

...as a matter of mild interest, bitty,  ....when working on the "R" model chassis...and welding around   rear pivots etc. always  used  ''Hi Ten   Seven ''    rods.....as advised by the Mack dealership ...(Australia  / New Zealand ...)

Excellent rods...but for the prior ''heads up '' from Mack , I would have used 7018  ...and I am sure that would  have been totally satisfactory.......

Incidentally   the Mack  chassis , using 16 foot bodies flexed a lot....and still flexed after in excess of 15, 000  hours of Forestry off high way work...Never cracked

Mike

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2 hours ago, bitty said:

On our double frame Mack RD we lengthened we didn't plate it at all. Just spliced it at the angles and staggered the splices . We did that in 1994 and it's never had any issues with the frame 

A consideration I ponder in regards to the doubling the frame at the splice is that it creates a short very rigid section of frame. I may be wrong but would like to see the frame able to flex evenly from front to back. Personal opinion would be to use an upside down L shaped piece over the outside. I have used this method a couple times on longer stretches. Used a piece of used frame by cutting off the bottom flange 

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