99 IH 4700 Driveshaft / Axle Placement questions

[Xplorer99]

hey again guys, i have 2 questions and would like some input on axle placement. just bought a use 20ft flat/dump bed for my truck. the truck was originally a 254wb with a double frame most of the way back. last owner move it up to a 218wb. im a little concerned with axle placement since the bed itself is much heavier than a regular flatbed, and its only a 26k truck. with the 218wb the bed will be about 15ft in front of the axle / 5ft behind the axle. the original mounting holes are all still there so it would be rather easy to move the axle back to the stock 254wb. then the bed would be about 18ft / 2ft. wondering which way would give me the best weight distribution.

now with moving the axle back to the 254wb, what would be the easiest way to do that? there are 3 driveshafts, with front being 41" the second is only 12" and the last being 46 3/4" im guessing they just shortened the middle one. so im gussing i could just get a 48" for the middle and be good to go.. i was looking at used ones for around 150 bucks. im not sure what kind it is. i see different styles listed such as 1510, 1610, 1660, the stickers are still on my driveshafts but i cant really figure anything out from them haha its got a spicer 6+1 ES 066-7b and the N175 rear axle...

any thoughts and info is much appreciated

 

[BobWolf]

You should be fine returning it to stock besides it might have a nicer ride. Make sure youhave a shop that specializes in this type of work do the job or you will have a total nightmare. Also, they will recomend a bettter placement than stock depending on what you plan to use the truck for.

Bob Wolf.

 

[Xplorer99]

what would be a better way to go? the 218wb that its at now, or would 254 be better? as far as how much weight i can put on it? i kinda thought that rear axle would max out alot faster at 218. ive never really thought this much about load placement before since i always ran a 53' spread axle flatbed with 45k loads... this litttle guy really has me thinking alot more about axle and load placement. maybe im over thinking this a little bit. just trying to get everyhting set up the best way possible before i put this on the road.

thanks again

 

[zorry]

Do you know what you'll be hauling ?
Do you know the weight ?
Do you know the weight of the chassis and body ?
Do you know the axle ratings ?

 

[Xplorer99]

general friegh from where i work. as stated its a DUMP bed....so with removable side. gravel andfirewood - which is my concern.
weight of what?
26k truck. there are all speced pretty much the same. 8k front 17.5k rear.
c/c weighs just under 10k (that was factory its now a little shorter. so probably 9-9.5k)
body is a DUMP flatbed. most 20-24ft flat beds are 3-4k im guessing this bed is more around 5-6

 

[zorry]

My guess is the shorter wb is going to work. You're going to get heavy on the steer and with only two feet behind the axle,if lengthened, you won't be able to transfer the wt to the rear axle.

 

[zorry]

A shop capable of doing the install will know just by looking at it.
That's what they do.
Go to a specialist. Get it right the first time.
Too much liability to have some tire changers mount it for you.

 

[Xplorer99]

ah good point. i was more concerned with over loading the drive axle with the short WB... but then again the front axle would also be an issue with the longer WB. thanks for the input... ill have to get hit a scale with it before i change the WB. loading freight would be much of an issue. but like i said my main concern is ill have removable sides for it so i can haul gravel and firewood. cant really adjust anything hauling that lol... thanks again!

 

[jt1980a]

I had one of these trucks years ago. It was a FL-70 with a 24' dumping bed. I had used a few before I bought this truck as a Cab and Chassis. I used it to mainly haul building materials and steel. I cant remember what the wheel base or Cab to axle was off my head but I do remember that I had the Pivot point on the dumping flatbed set exactly 48" from the end of the flatbed. The center of the drive axle was then located exactly 48" from the pivot point (8' from end of flatbed to center of drive wheel). I was concerned at first, constantly second guessing my decisions and thinking I may have gone too long. I can honestly tell you that there wasn't a day that I regretted any of the specs. The length and locations of the vitals were perfect. I could get the back of the flatbed to touch the ground (of course it would depend on the location of your hoist and its capacities). In this position the flatbed was probably on a 80 degree angle, so anything that wasn't still strapped down, was coming off!
When it came to weight distribution? I had a 12,000 lb front axle and 21,000 lb rear axle so it was a little different but still usually only had 8-10K on the front axle at most and the rear was usually around 20K when loaded. Just thought I'd throw that out there for you to think about. I know it can be a pain when you dump something and the bands break apart. With the way my truck was set up you never had to worry about restacking a pile of plywood because the bands broke.