I have a 4900 dumper I want to convert to a hook lift bc the truck I currently only used in the winter to spread salt n plow. I am going to go with the ampliroll 120 My truck is currently 86"CA need to stretch to 120" CA. For the stretch is it better to add on to the rear of the existing frame only having one weld and remounting the spring hangers or cutting the current frame and adding to the middle having 2 welds. It is a double frame I know to stager the cuts. And I'm aware about the driveshaft work including adding a carrier bearing. I have done a bit of research and think the best way would be less welds but I think the 2 welds would be easier. I read pros n cons of each. PLEASE ONLY COMMENT IF YOU HAVE KNOWLEDGE ON THE SUBJECT
We have an International 4900 with the same Ampliroll hoist and the rear duals are all the way to the rear of the truck. I dont think i have ever seen a single axle truck that didnt have this set up. I would call Ampliroll and ask, they are pretty easy to get answers from.
Like you say, there are pros and cons to each. One thing I have done before is to get a piece of an identical frame out of a junk yard, cut the existing frame near the rear axle, cut the junkyard frame near the cab, and weld them together. One weld, no remounting of suspension. I would look at where a hooklift puts stress on the frame, (I'm passing familiar with trucks, but, I know nothing about hooklifts). The other thing to consider is: is the frame heat treated? It should have warning stickers on it if it is. It won't stop you, but it will complicate things a little. The only thing I would consider putting in the middle of the frame is a used piece of an identical frame. I would be too afraid of the uneven stresses, otherwise. If I couldn't use two frames like my first suggestion, I believe I would go with adding a piece to the tail.Measuring and drilling those holes will be extra work, but it's not much considering the cost of failure. Don't forget such things as how to shape your fishplates so you have no welds straight across, staggering all seams, not just on each rail, proper preheat and weld procedures, proper rods, etc., particularly if your frame is heat treated. Good luck, Mitch
not sure if this is the correct way but me and my buddy shortened and stretched a couple frames for a couple wrecker builds of his and we have cut behind the cab and stretched it from the middle and used a piece of identical frame rail and sandwiched it and bolted it and both his truck are still on the road working today. i did make make the cuts at a 45* and spent a good amount of time cleaning and beveling to get a good sound weld. then the piece of frame rail we cut one lip off and bolted it with some grade 8 bolts. reason we did it before the axle is because it seemed to make more sense to us because of the time saved not having to drill 700 holes for the suspension.
Mitch Did u use the existing rear? I'm tring to picture how you didn't have to remount the rear did you not have to slide the axle back on ur build? Frame is not heat treated It was suggested to have a new pc of metal bent into rail matching the existing frame rather than use a "tired" pc. I would think that a used pc would be the way to go but he said a new PC made isn't that much more for what u get. Also anybody have pix of fishplates they made up? I read on a trucker forum to cut frame as follows: 1/3 of the way down cut frame straight vertical then for the next 1/3 down cut it at an / on one side and \ on the other side the. The last 1/3 straight vert cut. Then for the doubled part just a vert weld staggered from the main frame welds
We had a few old trucks lengthened for installation of larger log loaders over the years. I looked at the 74 International that I am still using. The shop cut the frame a foot or so behind the cab and added in the six foot piece of new frame material that had been bent to match shape and thickness. They cut half way down, then cut horizontal as you say for about 8" and then finished the cut to the bottom of the frame. Then they added a half inch by 10" piece of plate stock about 8 ft 6 inches long across the lengthened area of the frame bolting it to the outside of the frame. This is bolted on with 5/8 bolts with 2 bolts every 12". This old truck gets pounded pretty hard, rocking and twisting with the loader on it while working, and has held up well. My top frame flange did crack right away on the drivers side by the cab cut. It cracked in about an inch. I ground it out and re welded it about three times and it kept cracking that 1" or so. Finally left it alone and it has never cracked any further. There also is additional crossmembers installed at the lengthened area. I think this is the most critical part to add strength.