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Dana 60 going in...eventually

Discussion in '6.9L IH & 7.3L IDI Diesels' started by david85, Nov 7, 2019.

  1. david85

    david85 Full Access Member

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    I have no idea how long it will take to get this done. Don't expect a speedy conclusion on this thread.

    Some of you may remember I've been mulling over a 4wd conversion of my truck for just about as long as I've had it. Even with LSD on the back, it's utterly hopeless in the snow, mud or... wet grass. As much as I wanted to make a TTB setup work, I came to my senses and bought an F350 parts truck a couple weeks ago. The donor truck is a 1996, so it is a balljoint front end but I don't expect to break things any time soon. I only run stock tires and don't plan to wheel this truck.

    It also means that my era of cruising with 3.08 gears will eventually come to an end. The Dana60 is 3.55 gears, so the original 4.10s that came with my truck won't work either. But, as it so happens I do have another 1986 donor truck that should have a 3.55 sterling rear end.

    So in theory, I have everything I need in order to install an OEM spec, leaf spring front end. This swap has been done many times before, so I'm hoping to get some opinions from others.

    After pulling the axle and springs, it seems clear where the weak link is. The front shackles have a very small upper bushing that's about half the size of the leaf spring bushing directly below. It is of course trashed. I also looked at a 1999 superduty recently and noticed they have rear shackles from factory. They also have fullsize bushings on top and bottom. I know there are aftermarket RSK kits for the 80-96 trucks but those all come with a built in lift, which I don't want. As it is, the truck will be 3" taller.

    My first question is, how much of a difference in ride does the RSK make for a truck that was already equipped with monobeam front end? I'm trying to imagine how much of a difference I can expect if going from Twin I-Beam 2wd to a stock 1996 style monobeam.

    It looks like the 1st gen superduty has a solid mount bushing that could be adapted for a rear shackle setup fairly cleanly. I'm just trying to figure out if it's worth the trouble. Looking at photos online, it may interfere with the front cab mount.

    IMG_3459.jpg

    IMG_3460.jpg

    Superduty front bushing.jpg
     
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  2. compressionignitionrules

    compressionignitionrules Full Access Member

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    Well I did this conversion once but it was on a 1983 F150 4wd:idiot: in my offroading days .
    the odd little front shackle was engineered to work withthe TTB leaf front suspension to aid with articulation in 1980, then in 85 the dana60 front came back in the F350s. Ford unfortunately used the same parts until 1997............... yup it sucks.
    if you want to save some cash, a set of F250 TTB leafs will work with a reverse shackle swap kit and will only lift your truck an inch instead of 3 inches. the shackle reversal improves ride and also helps with the wander. don't fear the ball joints in that axle unless they start to seize up. they are huge, and much easier to align than a kingpin 60.

    just remember , your twin I beam deisel F250 is a pretty nice riding truck, you will not like the stiffened ride of a leaf spring front end truck RSK or not. be prepared for a change.
     
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  3. franklin2

    franklin2 Full Access Member

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    I have driven a factory 1994 f350, and it does ride better than my 89 ttb with lift springs on it. If you want to go completely factory with your conversion, I think you will be ok.

    It does look like Ford just stuck the dana 60 in there, in place of the ttb. The theory is when the frontend leaf hits a bump and flattens out, the spring grows in length. This means the front tire not only goes up, but moves forward also, since the shackle was left up front. They say the ride is better if the shackle is in the rear, so the front tire moves up and toward the rear when it hits a bump.

    But like I said, even with it's problems, the factory setup for the dana 60 rides good enough for me.
     
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  4. mblaney

    mblaney Full Access Member

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    I switched my TTB to a D60 (link in signature). I listed a bunch of part numbers and other info you may be interested in.
     
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  5. Garbage_Mechan

    Garbage_Mechan Garbage Mechanic

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    There is a way to do it with Super-Duty front leafs, maintain a lower ride height and have a good ride. No reversed shackle, but have to weld in your own shackle tubes in the frame. It was posted on Pirate 4x4 forum.
     
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  6. Garbage_Mechan

    Garbage_Mechan Garbage Mechanic

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    I have been studying this for years because I don’t want a lot of lift. The Super Duty through the frame rear shackles won’t work, the frame width is different. There were never any factory 4x4 80-97 trucks or FSuperDuty with rear shackles.
     
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  7. david85

    david85 Full Access Member

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    Thanks for the feedback everyone.

    I did some more reading on the subject and it looks like the reverse arch springs won't really benefit from RSK setups because the length actually tends to shrink as the axle travels up. That means the axle also travels aft as it goes up. I didn't take good photos when the springs were in the F350 donor, but there was a slight negative arch. And since the donor was a 460, I can't imagine my truck having a smaller arch after all is said and done. I may even have to get new springs but I'll hold off on that for the time being.

    Maybe I'll just get a polyurethane bushing kit and try that for a while since the front shackle is easy to access. I even wonder if using a rear leaf spring shackle on the front end could fix the problem of not having enough bushing material. The 2wd frame would have enough width inside the channel to accommodate the wider bushing. I'd have to make a custom boxed section, but that wouldn't be a big deal.
     
  8. franklin2

    franklin2 Full Access Member

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    You have got the theory now. But I think Ford's priority was snowplowing and other work duties on the f350, not necessarily ride quality. But like I said, they do not ride that bad. Nothing like mine, those lift springs are stiff.
     
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  9. david85

    david85 Full Access Member

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    Yeah I'm not expecting it to ride like my F150. In my opinion, the Twin I beam worked best on the half ton trucks and rangers. Even my twin I beam on F250 was quite stiff. If it gets a little worse, so be it. I still spend most of my time on pavement anyway.
     
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  10. Garbage_Mechan

    Garbage_Mechan Garbage Mechanic

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    You hit on one of the ideas I had before I decided to go SD springs....weld a full width tube through the frame at the front to elementary the factory “A” shackle I made up some tubes that take the same poly bushings as the spring eye. Now they can be purchased from Rough Stuff.
     
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  11. Garbage_Mechan

    Garbage_Mechan Garbage Mechanic

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    I also totally agree on the physics of negative arch springs. Front mounted shackles may not hurt ride quality.
     
    Last edited: Nov 8, 2019
  12. u2slow

    u2slow Plan B

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    IMO, the shackle location doesn't matter much when the leaf spring is so very close to flat. The length change of the spring through it's what? 2" suspension travel? ... is almost nonexistent. What that unstable front shackle does is makes a trac-bar necessary, and its small bushing pounds out fast.

    I promise you, OE monobeam springs will ride better than any TTB leafs. They are especially stiff because thats what they need to be for the twisting and cantilever loading of the TTB.

    I did find this thread about using 99-04 leafs, but you're on your own for the photobucket pics...
    https://www.pirate4x4.com/forum/ford/2286946-99-04-superduty-leafs-obs-without-rsk.html
     
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  13. david85

    david85 Full Access Member

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    Yeah, I can only imagine the type of forces involved on that tiny little bushing up front when using TTB leaf springs. Even the donor truck, the bushings were metal on metal thrashed. It's taken me a while but I think I can finally grasp why so many hate that leaf sprung TTB front end setup. The fact that Ford made it so easy to bring back the Dana 60 after only 5 years leads me to believe that even they didn't have complete confidence in the design. If they had simply used a beafed up coil sprung setup with similar geometry to the F150s, it could have been a winner...But anyway, we're talking about arguments between engineers that must have been raging nearly 50 years ago.

    The more I think about it, I'm leaning toward that stock setup but with poly bushings. If nothing else, the front shackle and its bushings are easy to get to.

    BTW, do any of you know what the stock spring rate is on the F350 monobeam springs?
     
  14. u2slow

    u2slow Plan B

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    Rockauto lists monobeam as 2200#. The TTB springs are listed 3486-4100#.
     
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