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14 bolt SF-a few questions

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 90K5, Jan 23, 2001.

  1. 90K5

    90K5 1/2 ton status

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    Allright-I want to get a 14 bolt SF rear so I can have the 4.10 gears and more strength. I really don't plan on swapping out the front axle, just regearing it, so i want to keep the 6 lug axleshafts.
    1. What gears come in the 6 lug version of the SFs? I know most of these are Z71s with the towing package, so would that be 3.73 or 4.10?
    2. Would 6 lug axleshafts fit in the 8 lug housing and carrier? Do they have the same spline count?
    3. What problems should I look for when looking at these axles? Most of them aren't that old, but they have probably been used hard. How long will they last?
    4. Should I change any seals when i get it?
    5. Do they come with a gov lock? Either way I will probably put an Eaton or Auburn posi in it.
    6. How much should I expect to pay for one at a junkyard?
    7. Do I need a hybrid u-joint for the driveshaft?
    8. What do i need to do for the brakelines?
    Thanks

    90K5

    See my truck at <A target="_blank" HREF=http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502>http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502</A>

    <P ID="edit"><FONT SIZE=-1>Edited by 90K5 on 01/23/01 02:49 PM (server time).</FONT></P>
     
  2. Corey-88K5

    Corey-88K5 1/2 ton status

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    90K5,

    I'll answer as much as I can.. From what I understand the rearends came with 6 &8 lug's, depending on the year. My rearend is out of a 93 2500 xtd cab. It has 6 lugs. I'm not sure about gears or what not, but I lucked out and got 3.73:1's that match my front axle. I think, ( I can't remmeber and do't have my notes any where around here) the splines were either 32 or 35 on the axles. I also think that the 6 * 8 lug's would be the same for the housing. As far as seals, when I pulled the shafts, I just replaced the seals anyway. They only cost a few dollars each.. Don't know about the Govloc. I'd suggest looking for an open carrier if you are going to put in your own locker. You may have to get a new carrier if you don't. The junk yard I got mine out of said they usually get over $1000 for the axle. But mine had been in a flood area. I got a trick U-joint so I wouldn't have to do any drive shaft work. The 10/12 bolts use a 1330 U-joint. The s/f uses a 1350 Ujoint. The trick U-joint has a 1330 on one cross, and 1350 on the other. The brakes all linked up together. The lines are al the same. Mine mated together great. I did end up putting disc brakes on, but the lines are all teh same size threads.

    Corey
    88K5

    [​IMG]<font color=red>Girls Like Guys In Bow Ties
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  3. ken

    ken 1/2 ton status

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    The shafts are 33 spline, 1 3/8" diameter. The last 6 lug SF 14 bolt I bought was $150. It had 3.42 gears. I didn't have a need for such a light duty axle so i sold it. They are a great axle, just that I'm partial to FF 14 bolt rears. Try to find a 6 lugger, as converting an 8 lugger to 6 lug (new axleshafts) can get pricey. Or perhaps you could have the 8 lugger re-drilled to 6 lug.

    ken
     
  4. 6.2Blazer

    6.2Blazer 1/2 ton status

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    The sf 14's were most common in 3/4 ton trucks starting back in the early to mid 80's and, to the best of my knowledge, are still used today......but most of these were the 8-lug version. The 6-lug version was introduced in the '88 light duty 3/4 ton (2500 series) pickups when they went to the new body style and IFS. I guess there were a few Z-71's with the towing package that offered the 6-lug sf 14 also, I've heard about several people on various boards that have them but have yet to find one on the road around here with that axle. Basically what this means if that you will have to move the spring and shock mounts to get a factory equipped 6-lug 14 to fit in your Blazer.

    Another option that I looked into a while back is converting an 8 lug to 6 lug. New axle shafts are available for about $100/piece, but also I talked with Moser Engineering (they make customer rearends and high strength axle shafts) who said they could simply re-drill the axleshafts and drums for a total cost of under $100. This would allow you get an easy to find and cheaper (at least around here) 8 lug sf 14 bolt that will bolt right up.
     
  5. 90K5

    90K5 1/2 ton status

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    so, correct me if I'm wrong, but what I need to do is find an axle from an old body style truck(before '88) and get new axleshafts. Will axleshafts from a 6-lug version fit in an 8-lug carrier?

    90K5

    See my truck at <A target="_blank" HREF=http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502>http://albums.photopoint.com/j/Albumindex?u=1329584&a=9886502</A>
     

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