14-Bolt Disc Brake Upgrade

Discussion in 'Lifted & Offroad Suspension' started by Crawdaddy, Mar 7, 2010.

  1. Crawdaddy

    Crawdaddy All hail the Mad King!! Staff Member 5+ Years 1000 Posts Platinum Contributor

    Well, for a while I've been wanting to upgrade the drivetrain on my Suburban to 3/4 or 1 ton strength, and my puny 10-bolt with 3.08s just wasn't going to do the job. So, I set out in the local junkyard to find a suitable 14-bolt axle. Well, I found a 14-bolt and a set of 1-ton leaf springs in a 1999 Chevy Silverado 1-ton 4x4. I got it for $88 including a $10 core charge. Only took around 2.5 hours to remove with having the wrong tools; however, it probably took me another hour to get the junkyard guys out with a forklift to drag the axle up to the front... it only weighs in the neighborhood of 300 pounds! :gasp: I've been researching the ever-famous disc brake conversion on it. However, it seems like I hit a roadblock. It appears that I have a second-design 14-bolt that includes a different hub that allows for the drum to be removed separate from the hub. Is there a disc brake conversion kit that will allow me to convert to discs without switching to the first-design hubs? If not, where would be a good place to source the first-design hubs? Obviously the local junkyard doesn't have them because I would have picked up an older-model axle if there was one available. Also, anything else I should know about these axles? I am pretty sure I'm going to have to relocate the spring perches because both sets on the axle seem to be in the wrong spot. I'm hoping Tim can help me here.

    And now for some pics of my newest project :party: :


    And the leafs I got. These things are frigging heavy too!

    Thanks for any help guys!
  2. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    Thats a good deal for that axle.
    Are the leaf eye to eye measurements gonna fit your truck or will you need to do some mods?
    The pads should be in the right place, this axle is a lot larger than you presently have things look out of place until you start mounting it up.
    You need to check pinion angle on both axles, theres a slight difference between the two, you might need to split the difference by relocating the pads a slight bit.
    I'd try without relocating first, if you use CV's on the driveshaft they'll be able to handle the angle.
    Spicer just came out with a U-joint the acts as an adapter for this particular swap. If you go that route though you may need to adjust the pinion angle, but I think it'll be cheaper than having a new driveshaft with CV's made.
    The driveshaft length will be ok if you have a slip joint on the rear D/S.
    Brakes are a different story, I like the disc conversion but every kit I've seen is expensive.
    This axle has larger braking surface than the one your removing, the drums wont be as fancy but they still offer an increase in braking. All lines and cables should hook up easily, might need a new bracket for the E-brake cable.
    Before you mount it up check those axle seals, GM full floaters are known for leaking.
    Do yourself a favor and pop the leafsprings apart and clean between each leaf, if you can find some a small teflon pad between each spring would be a good idea too, those things get squeeky.
    Last edited: Mar 7, 2010
  3. Crawdaddy

    Crawdaddy All hail the Mad King!! Staff Member 5+ Years 1000 Posts Platinum Contributor

    For the leaf measurements, I have no idea if there's going to fit. I think there's only 2 lengths for GM leafs, 52" and 56". So, I should have a 50/50 chance of them being the right length. I did a quick measurement of the distance between the leaf pads, but I was about to go out to eat and was wearing nice clothes. The measurement appeared to be 44". Also, if I remember correctly, the existing 2 sets of leaf pads on the axle measure 42" and 46" inches apart or something. In other words, right in between, though I need to get under the truck and remeasure exactly.

    I currently know nothing about pinion angles, so I need to figure that one out. As for the driveshaft, it's a single straight-shaft with no slip-yoke. I figured I was going to have to locate a trick u-joint to hook it up, I just don't know what series to what series the u-joint have to go between.

    It seems that most disc brake conversions for 14-bolts cost around $300 for all the parts including discs, calipers, brackets, etc. However, as the hard-core wheeler and fab king, you should know better. I figured the stock drums on the axle would be significantly better than the ones I have now, but I figured I'd get it done while I had it out. E-brakes are going to have to be worked out, especially since I cut the ones on the axle I pulled.

    I was also planning on completely rebuilding the axles, including seals, bearings, and the like. one of the drums has either gear oil or brake fluid all over it. Still gotta figure out where it came from, I've only had the axle a couple days now. I'm also going to wire wheel it and slap a few coats of paint on it to clean it up.

    I wasn't planning on taking the leaf packs apart, but if you think it's best, I shall. That'll give me a chance to sand and paint them.

    I'm hoping to go back to the junkyard next weekend and pull a leaf spring front end, 700R4/xfercase, and what I think is a straight Dana 44 to put under the front end of the suburban. The only question is whether I'll get to go back next weekend and whether someone will have yanked them before I get there. Hopefully I can! That would be so awesome.

    Thanks for the help Tim!
  4. tbplus10

    tbplus10 Epic Member Staff Member 5+ Years 5000 Posts Platinum Contributor

    GM has some early 90's leafs that are in the 60" range too, but those dont look that long and I think the 60's were used on 1/2ton 2wd only.
    You wont be able to measure the D/S length accurately until you get the axle located.
    Look on Spicers website for the U-joint I mentioned, it's a greasable joint and if I remember it has a greater range for steeper pinion angles.
    Check the price again on the disc conversions, ya gotta read the fine print to find out that many of them only include the brackets and lines, you supply the calipers, this is what runs the price up cause most times the calipers are either some hard to find model or you cant find a cheap enough core for the parts store.
    Good idea to rebuild, shouldnt be expensive or hard mostly a seal change and look for odd wear patterns.
    Yea I'd look the leaf packs over real good for cracks, the truck was in the yard and you dont know how hard it was worked over to get there. Spring packs have a habit of getting squeeky with a tiny bit of rust or dirt between the leaves.
    The last pack I rebuilt I couldnt find teflon sheets to use between the leafs so I found a binder that had a thin teflon cover for like $275 at Walmart, it now resides between the leaf packs of my 91 Yota.
    Check the drop on that 44 before you buy it, 44's come in center, right, and left drops, you need to make sure what side drop you need.
  5. Crawdaddy

    Crawdaddy All hail the Mad King!! Staff Member 5+ Years 1000 Posts Platinum Contributor

    Ugh on the leafs. My Suburban is a 91 1/2ton 2wd. I'll have to check on that. I do know the Eldorado calipers can be costly since they're now rareish. I was planning on going with 3/4 ton calipers, though e-brakes would probably be good to have on a street truck.

    All the parts I was planning on pulling next time are on an 88 Suburban, so the D44 axle on it should have the right drop I should hope. The transmission, xfer case, front leafs and hangers, D44 straight axle, and front driveshaft would also be coming out the same suburban. I'd also pull the rear driveshaft but it's badly bent. I will have some fab work do do for the leaf hangers because the 91 was the first year that GM used IFS. Might be able to use a hanger like this: http://www.sky-manufacturing.com/new/detaproduct.php?id=64 . Then of course I would need to convert it to 8-lug to match the 14-bolt, but that shouldn't be hard, the Bronco people convert their D44s to GM 8-lug all the time.

    I dunno, we shall see on all this...

    BLUBURBAN Rockstar


    DAREDEVIL Rockstar 4 Years 1000 Posts

    thanks !!!!!!!!!! Very cool!

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