ok, over the last four years ive been building and redesigning.. scrapin building ect ect my 1974 f-250 so much so that its been 4 diff trucks without ever leaving the shop lol and now the current design calls for 52'' military tires and 2.5 ton rockwells, my plan was to just weld in a 4-5'' sub frame around the perches. brace them n what not then build a leaf pack that would give me enough clearance.. simple and effective.. not very adjustable or comfortable on road trips.. then! i was thinkin what about a air bag suspention? with 4 link suspention front and rear.. one that would allow me to run the 52''s then say 44''s on the lowest setting.. maby up to the massive 66'' all aired up.. the only reason im thinkin about this is i just received 4 66*43*25r tires for free and with them standing next to the truck i drool lol and i would love to be able to say yah my street truck is a part time monster truck... pull up to the local muddin partys with them on a trailer push a button the air bags fill up... truck raises get out switch the tires and go.. my question is.. is this possible? or just the over zealous day dreams of a first time builder with eyes bigger then his truck?

p.s does anyone know if the stock master cylinder on the f-250 is big enough to push the drum brakes on the rockwells? 1800 bucks on brakes is a lil expensive lol

 

Will that thing ever fit on a trailer? When giving advice, I say, build the rig for what you want it to do. One rig can't do it all. I think airbags from a semi truck might work. You will have a lot of force from bouncing around off roading. Due to laws you could never drive it on the streets. If you are a frist time builder I would not go this route. Good luck.

 

Anything is possible. How much $$$$$ do you have? Hopefully a lot. If you think $1800 on brakes is expensive, wait till you get the bill for that custom airbag/four link suspension! Not to mention the initial cost of the rockwell axles alone. When you are talking about tires of this size, DO NOT skimp on the brakes!! That my friend is a lot of rotating weight to stop. The F250 power booster will not work, it won't be able to provide enough clamping force. You would need something like a hydroboost setup that runs off of the power steering pump to provide enough force. You will also need a much beefier steering setup (perhaps hydo assist) to steer them tires. Also the frame would probably need to be heavily re-enforced especially around the steering components.

I don't know how much abuse the 2.5T axles are going take from 66" tires, you may be better off with 5 ton axles. I notice they require a 25" wheel. They will cost plenty.

What are you using to power this? Hopefully a +600hp big block (say a 460 punched to a 552). You will need massive amounts of power to move all of the added weight, not to mention, be able to overcome the inertia of those 66" tires. Then you will need a transmission,T-case, and drive shafts that can cope with that amount of power.
If you use 1 ton stuff, it will break like fisher-price plastic. You really need to upgrade everything as whole. Every system within the whole needs to be compatible, or else the weakest part will become cannon fodder.

I not saying it can't be done, but it will cost HUGE $$$$$.
Good luck!!!

 

You should really watch trucks. Stacy is building a old Power Wagon and he is using old Rockwells and big ol tires. Look at my gallery and you can tell I went the other way, but you could get some good places to get parts and some good ideas for your build on the show. Good luck with it!!!


Nolan

 

yah thats the thought that was always in the back of my mind... 2.5 tons being to small for the 66'' tires... in recent news though i have came up with a solution to most of the problems lol... i bought a 65-66 lincoln cont. with suicide doors decent body.. frames beyond shot... so i guess i'll save my tires for that project and im gonna build the f-250 to just run the 52'' michelins.. and btw.. this build up is way cheaper then what i have been saving up n lookin for, for the last year or two i wanted 49'' iroks with dana 60's and ouch that was gona hurt the wallet.. then i found the 52'' michelns witch you can get for $400 a set.. they weigh 400 lbs a peice and would gernade a good d60 not to mention the cost of regearing.. so i started lookin for rockwells and they are half the price of d60's! im pickin up a set in elk river this weekend two rear axles and a front for $800 they already are geared down to 6.72 and will take more abuse then any d60 as for the motor its the last on my list.. my IDEAL pipe dream motor is a powerstroke beefed up to 400hp and 1000 pounds of torqe.. but the only way i see that happening is winning the lottery other wise i was lookin at a 460 pushed to 532 with hopefully 500 hp and 600lb pounds of torqe (i want the power down low and more mid range more then up top max rpm 6500) and run a e4od... but if spring rolls around and im just gettin to the motor. i may get antsy and through in the mild performance rebuilt 460 i have in the back with a c6 thats intended for my bronco.. just been lazy and havn't put it in.. also my idea is to take 2'' square tubing and build sort of a tube frame inside the old frame and box it in make the transmission crossmember out of the tubing the transfercase mount (its still divorced) out of the tubing and then as many cross members as practicle that will clear everything so it would hold up to the heavyer axles heavyer tires and the abuse of the mud pit. ive been told my many mud runners and builders runnin rockwells and tires like these that the stock t-case in my ford will hold up just fine. btw is it a np205 or the dana ** i can't think of the number right now if its the dana can i make a twin stick shifter for it?

 

oh and my plan for the stering was to either look for a stering box in the junk yard from a larger 2-5 ton truck for one that resembles the style in my ford and swap it in or run the hydro assist with a 9'' ram and plumb it off the power stering on my ford now. it looks fairly simple and a company in ohio will drill n tap my steering box for 50-75 bucks. as for brakes the clampin force should be fine its the volume you have to worry about the rockwells have two cylinders in each drum doubleing the amout of fluid needed

 

As for the rockwells, I would convert them over to disc. There is a company ( I forget the name) that will install disc brakes on your rockwell hubs.

It's not just volume that you need, it's also pressure. The two are related to one another, as in when volume increases-pressure drops. You need serious pressure as well as volume to produce the braking force required to stop a 500+ lb tire/wheel combo.

FWIW: A 460 can be taken to about 815 cu. in. Albeit at a huge $$$$. That would make some killer torque in a usuable rpm range.

 

That sounds neat. Can u post some pics of it or create a free gallery for us to drool over it?

 

For an 815ci engine you can expect to spend $40-$50K on and of course it's not done with a stock 460 block and it's not to nice to drive on the street. But hey, with enough $$ anything is possible.

As already mentioned 66's on a 2.5 ton Rockwell won't fly. In addition to the gearing being way off and the axle shafts which would snap when you hit the throttle the knuckles of the 2.5 ton axles cannot handle the 600+ pound rotating weight. FWIW 2.5 ton Rockwell axle shafts are "relatively" weak which is why there are companies making chromoly replacements now. You can ride those 52" tires around on them fine but you can't do it with decent horsepower. You'll snap the inner shafts of those rockwells just as easily as you would a D60. If you plan to build a high torque engine for the truck you'll want to look into upgrading the axle shafts and u-joints. Chromoly shafts up front, with u-joints, will run you about $3000 and you're looking at around $2000 for the rear axle.

There are already LOTS of trucks setup with 4 link and airbags for adjustable ride height, though you'll find most of them are newer trucks. It's not hard to build if you're a fabricator but there's still a great deal of expense in materials alone. You can expect to pay $800-$1000 for the heim joints alone and DOM tubing will run $15-$25 a foot. Multiply that by the length of your links times 8. I'd estimate another $1000 minimum in raw steel for a project like this. So figure $2000 right there and that's not even getting into the cost of the airbags, compressor, etc. That's also assuming that you're building it yourself. If you have to pay someone else to design and build it expect that figure to double at the very least.

You can use a Ford steering box with a crossover steering setup but you'll still need hydro-assist to turn those tires. Hydro assist is inexpensive to setup and easy to do so that's not a problem. It's already been said several times but what the heck, I'll say it again. You DO want the disc brakes on those axles and at the very least you need to look into swaping an F350 booster in to get enough pressure to stop effectively. Even a better option would be hydro-boost.

I don't say all this to rain on your parade, I love BIG trucks and love to see people build unique suspensons etc but it's a huge project and a huge expense. And if you think building something like this is bad wait until you start driving it. I burn $400-$600 a month in gas and I only drive my truck a few days a week.

 

yah i think im gonna have to save the 4 link air bag set up for when ive got more fabrication under my belt... cause anyone can pay someone to build a bad *** truck... i think it shows more decitation when you build it your self then even if its not the best.. its yours and you built it. also it looks like im gonna have to run the discs because thats the only way to have legal brakes with the hubs turned in. oh well just gotta put in some more overtime i guess lol hey maby i'll get a promotion with all this dedication to the job lol.. btw when you say decent horsepower how much are you talkin?? by no means do i need extreme power that would rocket this thing down the quarter mile in 9 seconds but i don't want a doggy slug either like my friend with his suzuki and 38's run by a 4 banger n stock gears.. i guess just enough to let you know your pushin the stupid pedal to far, the company ive been lookin at for brakes is usa 6x6 with there wildwood calipers.. and thats 900 a set bolt on in front and weld on in back, but there is also a few people sayin there is stock rotors out there that will fit and you take the caliper of a gm 1 ton and put it on there with steel plate 3/8'' thick i beleave and you can build your own for a fration of the price.. and yes i know gas is gonna cost me more then the truck lol but thats the price you pay for driving around something like this.. besides it wont be able to be driven all that much since im puting collector plates on it.. (makes it exempt from lift laws in mn.. witch suck by the way 25'' bumper limit.. 6'' lift limit, and a maximum of 38'' tires) either that or im gonna have the gross vehicle weight increased past 10,000 or get a dakota address lol