Super Duty axle swap Questions

Discussion in '6.9L IH & 7.3L IDI Diesels' started by Mammoth73, Aug 24, 2018.

  1. Mammoth73

    Mammoth73 Registered User

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    I've got a 93 F350 cclb 4x4 with the 3.55s.

    260k on the odo and noticed the pinion bearings in the back have play and leaking out the seal and is developing a howl. The front has a bad seal along with choccy milk fluid and metal shavings.
    Found a set of SD axles (tires, wheels, brakes springs and all) for $400 3.73 LS that look to be in great shape off what I believe to be an 04 250 that's been wrecked. (Dude says it's an 04 but also says it's got the 7.3) I'll need to confirm.

    I know there's a million kits out there going for upwards of a grand but they're not in the budget now.

    Ideally I'd like to do the reverse shackles up front and run SD springs without having to shell out big $$$ on kits. Only thing that concerns me is the wider perches and hangers for the SD's and then the centering of the new axle in the wheelwell.

    Other than that I think I could figure the rest by myself but wanted some input from those who've been there and done that.

    As far as the job goes I'm hoping to accomplish better braking, bigger gears, softer ride, better stability in back as well as avoid dumping money into my current ones...Or should I just break down and save up for the kit?

    Pic is of the potential donor truck[​IMG]

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  2. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    Is the donor truck possessed?

    Rear axle bolts right in with stock hangers. I would do it first, then tackle the front, that way you can use the rear to square up the front.

    With the rsk it literally bolts into place onto the obs, without buying the whole swap kit you will need to fab your own sway bars and track bar. With a leaf spring setup these aren’t required but make the suspension work like originally designed from the factory.
     
  3. Mammoth73

    Mammoth73 Registered User

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    Possessed no, cursed maybe. But as long as that curse stays with the frame I'll be alright.

    Just talked to the dude and he said he's pretty sure it's an 04 but he knows the dude did an engine swap. So it's looking like I'll be good there. We're supposed to pull them tomorrow so I'll know for sure then.

    I'l look more into the kits. Any specific brands y'all love or hate?

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  4. u2slow

    u2slow Plan B

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    My buddy bought a Sky Offroad RSK crossmember for his OBS. That's a beefy unit. I believe they make one to adapt the SD housing.

    I'd be a little torn on the idea. You're getting gearing, brakes, and wheels.... but comes at the expense of proper wheel bearings and handy 8x6.5" bolt pattern. 35's will touch the leafs on stock spring pacing, and even easier on the SD spring spacing.

    Hydroboost is another route to beef up the braking. I loved that swap on my '95 F350.
     
  5. Mammoth73

    Mammoth73 Registered User

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    Well it turns out the front was a 50 plus it wasn't really in the budget anyway.

    Think I might just end up rebuilding the front with an auto locker and 3.73s. I've already replaced everything else on it plus then I avoid those unit bearings.

    Never done gearing before but I've always wanted to learn and I've done quite a bit of research and will continue studying. Since it's the front I'm hoping whatever imperfections I'm left with aren't as crucial. I wouldn't mind taking it to a shop but last time my ram 1500 rear open diff was rebuilt it cost over a grand. So I don't wanna know what they'd charge for gears, seals, and a locker

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  6. Mammoth73

    Mammoth73 Registered User

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    I'll probably also do the rsk with SD springs. Makes that part a little easier at least.

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  7. ifrythings

    ifrythings Full Access Member

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    If you really truly want an upgrade in all ways find a 2013 or newer set of axles from an SD, way bigger brakes 14.3” vs 12.56”, big ball joints, 1480 axle joints vs 1410, huge unit bearings, factory selectable locker in the rear, rear disk brakes, coil spring front suspension, tighter turning radius, if you grab the rear springs too they are 10” longer and make for a better ride in the rear, and more that I’m forgetting about.

    If you can get a rolling chassis everything bolts on fairly easy and the only thing you need to buy is a tracbar bracket.

    Personally I wouldn’t waste my time doing an rsk or switching to 99-04 axles after doing everything above it was easy.
     
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  8. clifdawg

    clifdawg Full Access Member

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    Mammoth, in what part of TX are you? I’m in N. Miss and have a set of 3.73 axles from an 06 f250 or 3.55 axles from an 08-10. I also have one suspension setup to go with either sets of axles.

    Most of what is said above can be had in 05+ axle setups. F & R disc, coils up front, etc etc. Let me know if you’re interested.
     
  9. BrassBandit

    BrassBandit Registered User

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    Is there a write up anywhere detailing this? I have a 1993 dually 7.3 that I would like to convert to 4x4 but I love the coil springs in the front and the turning radius i have now and don't want to give it up. this sounds like a step up in every way.

    Ps this is my first post but I've been lurking and learning lol.
     
  10. clifdawg

    clifdawg Full Access Member

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    I’m not sure if there is one here on OB or not, but there are some on other forums. Do some searching around on google and it will point you to some of those threads/writeups.
     
  11. clifdawg

    clifdawg Full Access Member

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    I’ve got a 91 f350 drw that’s getting 06 axles. I’m still a ways out on getting to it, though. Too many projects.
     
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  12. ifrythings

    ifrythings Full Access Member

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    I did mine with 06 axles and if I were to do it again I would use 2013 axles and do what my brother did and get a rolling chassis.

    https://www.oilburners.net/threads/project-crewcab.79692/

    And here’s my brothers

    https://www.ford-trucks.com/forums/1261619-1989-f250-project-8.html go to post 319
     
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  13. BrassBandit

    BrassBandit Registered User

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  14. Mammoth73

    Mammoth73 Registered User

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    I'm a little west of Austin but I got the 01 rear 10.5 with the 3.73s just because the tires on it are worth more than I paid for it.

    Looking into the coil swap, as well as what others have said about them and am seriously considering doing that down the road. Are y'all using kits to put yours in or just fabbing as you go?

    I'll continue to research it but so far what I've gathered is that the rsk will offer better ride quality than the coils until you do the 4 link upgrade. Which as of right now just the kit just topped $3,000 not including the new axle.

    At the moment it looks like I might just try and re gear and seal the front along with the rsk and revisit the coil idea once I get my other truck back on the road.

    I swear I can feel my wallet getting thinner with every new post.



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  15. ifrythings

    ifrythings Full Access Member

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    @Mammoth73 I used the stock spring buckets, radius arm brackets, steering box and tracbar (bent it slightly more), the only thing I had to buy was new shocks as the ones I got with the axle were toast, new tracbar bracket which apparently an 08 stock one will work, new steering stabilizer as the stock one was toast too, new u-bolts for the rear and bolts to put it all together. No welding or fabbing was required, just drilling of rivets and new holes.
     
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