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Deuce and a halves?

Discussion in 'The Garage' started by eldon519, Jun 9, 2002.

  1. eldon519

    eldon519 1/2 ton status

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    How hard is it to swap 2.5 ton Rockwells or GMC axles into a '78 pickup? Would everything be able to handle the increased unsprung weight? How about hooking up the steering? If I went ahead and did it, i'd probably run 44's and the superlow gearing would help for crawling. Which is better also, the Rockwells or the GMCs? Would they be expensive from a junkyard? Thanks to anyone who can answer any of my many questions.
     
  2. mudrunner78

    mudrunner78 1/2 ton status

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    as I am gathering parts for the same swap you mention I can answer some of you questions. the swap is pretty easy just requiring custom u-bolts, shock mounts. Now also keep in mind your break setup, theres either a custom(I think there are also kits) disk brake conversion, or a pinion break setup for offroad only. Steering for me is going to be totally hydraulic, for both ease of use and I plan on 48 firestones. You can pickup rockwells for around 800 dollars a set. I plan on dual steering, hydro. I need to get my other truck done first, then I can work on the hybrid. Hope some of this helps, Jesse
     
  3. Depdog

    Depdog 1/2 ton status Author

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    Go to Pirate4x4 and do a search on their forums, there are TONS of info there. Drop me an email and I will send you the links I have on 2.5 ton axles. The rear chunk is centered but due to the way the gear reduction on the input gears are, the actual input is offset 4" to one side or the other. There are pinion brakes, but they HEAT up quite fast on the road. Chucks trucks in FL sells true hub disk brakes (thats one on each wheel) they will work only with the hubbs flipped out to their 79" width, thats 10" wider than what you are running now. There are quite a few good and bad points to this.

    Drop me an email and I will send you what I have.

    /forums/images/icons/grin.gif
    Depdog
     
  4. eldon519

    eldon519 1/2 ton status

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    So do Rockwells come with drum brakes on the front and rear or just the rear? Also, i've heard mention of oil pan clearance with the rockwells, do you know how much lift you need to have to be able to run them?
     
  5. 70~K5

    70~K5 1/2 ton status

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    The Deuces I drove when in the Army had "Wedge" air brakes vs. the "S cam" air brakes on most big rigs. They were drum f&r. Disc brakes are rare in heavy duty trucks. /forums/images/icons/cool.gif
     
  6. eldon519

    eldon519 1/2 ton status

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    Why is that, I thought disc brakes were generally superior than drums since that's what everyone wants to upgrade their GM-14bolts to? Also, does this mean i'd have to convert my truck's brake system to air brakes as well?
     
  7. Overkill

    Overkill 1/2 ton status

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    I believe that disk's are superior, but they are new technology (sort of) compared to what was available when the deuces were designed. You can stay with your stock braking system since you will not be using the original deuce drums (hopefully). The aftermarket kit will be simple hydraulic like half ton axles have. The 4 wheel disk setup is quite pricey, (around 2k I think) and the pinions can be done for a couple hundred, but it's not legal for street use. Hope some of this helps too, good luck.
     
  8. 70~K5

    70~K5 1/2 ton status

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    There have been disc brakes made for Class 8 trucks but they've never caught on. The one setup I remember came out around '79/ '80 and at every brake pad change it seemed to need new rotors. Where drum brakes do the job for and are cheaper. Cars/ light trucks don't see the use that Class 8 trucks do. A set of drum brakes last me between 50k to 100k miles depending on how many steep hills I run and how much traffic I'm in. A brake drum might last a million miles too. /forums/images/icons/laugh.gif
     
  9. mudrunner78

    mudrunner78 1/2 ton status

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    I am welding on a custom braket that I picked u from a friend that allows the use of willwood 4 piston calipers and a 13 inch rotor. I priced the whole setup will run me right around 900 dollars. Jesse I'll have details later
     
  10. DieselDan

    DieselDan 1/2 ton status

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    70K5 your memory is getting fuzzy. The wedge brakes were on the M939 series 5Tons (they still suck btw). Dueces still run juice brakes (drums) front & rear; even the ESP M35A3.
     
  11. 70~K5

    70~K5 1/2 ton status

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    Maybe but I ETS'd in Aug '77. Could have sworn the '67 series I drove had air, but Iquess it could have been air over hyd. I've driven so many different trucks since I got out some of them are running together in my mind. /forums/images/icons/laugh.gif ps: you ever drive the ones with the exhaust that exits between the right side duals?
     
  12. eldon519

    eldon519 1/2 ton status

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    Would the 2.5 ton GMC axles be worth looking into at all? Would they be more of a direct swap seeing as they're GMC products? What kind of brakes do they have? Also, I just saw in the newest Peterson's 4Wheel and Offroad they mentioned using Marmon-Herrington axles, have you ever heard anything about this? I think they come from dump trucks and the like?
     
  13. Jeff427

    Jeff427 1/2 ton status

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    If you would like to see a truck with GMC axles in it, click on the Mudzilla link in my sig below. The front axle was a direct bolt in, other than the steering. The GMC axles have dual cylinder drum brakes (there are wheel cylinders on the top and bottom of the shoes). If you run GMC axles you have to run the GMC transfercase, because the front axle is reverse rotation (not to be confused with reverse cut). The front driveshaft actually rotates in the opposite direction as the rear. You can eliminate this problem by taking out the front differential and rotating (it is mounted into the axle similarly to a F*rd 9 inch, only MUCH larger) it 180 degrees, but, this will lower the front pinion, and make the front driveshaft angle rather extreme (especially if you have a lot of lift). There are some issues with running the GMC axles, but as you can see from the pics, they can be overcome /forums/images/icons/smile.gif.
     
  14. eldon519

    eldon519 1/2 ton status

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    I actually followed the building of Mudzilla a little bit on Custom Truck Showcase and on CK5 as well. It's big trucks like yours that actually get me considering these somewhat wild ideas(for my budget anyway). I really would like to run 42's with 1 ton axles or maybe step up to 2.5 ton axles with 44's. I can't really go bigger than that cause i can't trailer it but it's not a daily driver so i could deal with the low diff ratio. Rockwells seem a little bit too "custom" for me seeing as there are lots of little mods that you have to add. We want to use the truck as a bulletproof rockcrawler. How did you get the 12" superlift springs to flex so much, I thought a spring that tall would be really stiff? Also, you mentioned having to run a GMC t-case, would a NP205 work without having to rotate the diff? I really like your t-case/tranny combo as well, how much custom work is involved if i were to replace my 350Sb/th400/np205 with a similar drivetrain? Also could you tell me about fitting the rear axle and steering to the truck? I know i've asked about a million questions but huge mud trucks really catch my attention even though that's not exactly what i'm working on. THanks alot.
     
  15. Jeff427

    Jeff427 1/2 ton status

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    You asked for it, Corey;
    Actually our original intent with Mudzilla was to be able to drive it where ever we wanted, but we got such a good deal on the 48" tall tires (free) that our plans changed. The GMC axles that we have in Mudzilla would not be all that bad for a street truck on 44's. It has 6.17 gears.

    You would have to rotate the differential 180 degrees in the housing to run the 205 t-case, and if you run a lot of lift, you will have problems with driveshaft angles in the front.

    The steering was an issue with the amount of lift and the long throw of the steering arm, we could not use the stock steering box. We adapted a steering box and power assist cylinder from a C65 dump truck. The steering arm on this box pushes from front to back, but has very long travel, so there is no problem going from lock to lock.

    We are currently changing the motor, tranny, and adding some kind of gear reduction unit to the back of the tranny. The 350, and Clark 5 speed were never intended to be anything more than something temporary for testing purposes. The motor and tranny combo that is being swapped in is a Caddy 425, with a TH400 behind that. We are also looking at adding a 203 range box with a yoke on the back to drive the divorced GMC case. We want to have low range, and the GMC case does not have it, because the GMC dueces have low range in the tranny.

    We got the 12" Superlift to flex by adding dry graphiting inbetween each leaf, and adding extra long shackles front and rear. The long shackle let the springs move with less restriction, and add more leverage to the end of the spring pack.

    Ok, the rear axle took some work to get it installed, and actually, we are in the process of reworking that as well, because we have had some trouble with it the way it is. The spring pads on the rear axle line up as well, but they don't have conventional spring mounts, because the GMC doesnt have the springs mounted to the axle. They are mounted to the frame. So spring pads have to be fabricated.

    Another thing to keep in mind is, unless you can build your own wheels, you will have to shell out some $$$ for wheels.

    To be honest, there is no "easy" way to 2 1/2 ton something. No matter what 2 1/2 ton axles you choose, there will have to be some fabricating, and some compromises, which is why 2 1/2 ton axles are cheaper than one ton axles. I'm not trying to discourage you, but I don't want to mislead you, and make you think it is easy either /forums/images/icons/smile.gif.
     
  16. 70~K5

    70~K5 1/2 ton status

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    What years did GMC use this setup? Also I looked at M35A2 today and it had hyd brakes. I quess the one I drove in the Army had air over hyd? /forums/images/icons/wink.gif
     
  17. Jeff427

    Jeff427 1/2 ton status

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    I can't tell you the range of years, but the 1951 Deuce that we have has air over hydraulic brakes.
     
  18. eldon519

    eldon519 1/2 ton status

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    Wow, that's an incredible project you've got going, i didn't realize how much ingenuity had to go into it all. I wish i could do something like this but i think i'd be in over my head, i might just have to stick with the Dana 60 and 14 bolt which I can't complain about. 42's will probably do the trick i suppose as well. Someday though, maybe i too will be riding on 2.5 with the big boys. Anyways, thanks for all your help, it's really helped me finalize plans for my project. Good luck with the future Mudzilla mods.
     
  19. 70~K5

    70~K5 1/2 ton status

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    On the 2 1/2 ton M35 series, the one I looked at today had fixed sides, but the ones I drove had drop sides. Anyone know the years for each?
     
  20. rocnwilly

    rocnwilly 1/2 ton status

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    i have a set of front 2.5 ton rockwells from a duce and a half. $850 for the pair of fronts. i may be able to deliver when i travel to Denver, CO in July from Ventura, CA
     

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