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10blt vs 12blt

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by 88K5Jimmy, Dec 19, 2001.

  1. 88K5Jimmy

    88K5Jimmy 1/2 ton status

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    I was wondering what, if any, are the structural differences between a 10 and 12 bolt? Also, how about stock axle strengths and how many splines are found on 12 bolts. I already know about 10 bolts, but just need the spline count on a 12 bolt. What are some good brands for axle upgrades?
    Thanks!
     
  2. mudhog

    mudhog THEGAME Staff Member Super Moderator

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    12 bolts are NOT much stronger than a 10bolt if you are thinking of going from a 10 bolt to a 12bolt in my opinion it is not worth the time i would (and did) go with a 14ff if you are thinking of upgrading or if you want to stay with 6lug go with a 14sf again this is just my opinion[​IMG]

    wheeling videoshttp://community.webshots.com/user/ssmith6333
     
  3. DesertDueler

    DesertDueler 1/2 ton status

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    12 bolts are stronger, but like said before 14 FF are the strongest. 12 bolts are 30 spline. I run a 12 bolt in my Jimmy with no problems yet. And my old 10 bolt held up untill the last time I atempted to climb a 75 foot hill thats 70 degree incline. The spider gears shattered and I went rolling back down the hill. As for having 10 bolts and 12 bolts hold up is service them regularly and take it easy on the skinny pedal. Wheel hopping is what kills them. Wheel hopping can even kill a 14 FF after a while.

    86Jimmy 4"&35"MTRs,87 burb 4"&33"MT,69Firebird w/525 hp,and 70GTO live in PHX,AZ<a target="_blank" href=http://www.geocities.com/modifierperformance>My vehicles</a>
     
  4. sinchphoto

    sinchphoto 1/2 ton status

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    IS THERE 14B SF 6 LUG OUT THERE? OR HOW CAN ONE BE MADE?
     
  5. 55Willy

    55Willy 3/4 ton status

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    14 SF are around, I believe they are in the 88 to 91 trucks

    <font color=red>Life is like a mud hole:</font color=red><font color=blue>
    When the S#!T gets deep, you have to keep moving and friends can always pull you out</font color=blue>
    55 Willy's
     
  6. CaptCrunch

    CaptCrunch 1/2 ton status

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    Well I think you have to take a hard look at some things for this decision... Look at how you wheel&gt; Mud? rocks? Trails? Daily driver? Obviously you loose a lot of ground clearence w/ a 14B. Also rock crawling is somewhat harder on the rear axle compared to other wheeling. Do you plan to run a locker? A locker will put more stress on the rear. Also what tire do you plan to run? What motor are you going to run? Gears? Anything over 35's is pretty borderline for 1/2 ton axles, but they can live quite well for some. Also if you move to some whicked gears the size of the pinion gear will be getting kinda thin in a 1/2 ton. Also the more power you have the more likely you will break a 1/2 ton axle.

    Now you can beef up the 12B with aftermarket axle shafts or a Warn FF kit but for the money you could swap to a 14B. Also you can reinforce the R&amp;P a bit and keep them from deflecting with a reinforcing diff cover or a steal cap and arp studs. Keep in mind if you go to a 14B out back you will need to get 8 lugs wheels and probably get the 8 lug conversion parts for up front so you can run on spare tire. Also if you want 15" tires you will need to grind the calipers and have to run a steel wheel. Otherwise you will need a 16" wheel. So basically in a nuit shell there ya go [​IMG] [​IMG]

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://coloradok5.com/gallery/captcrunch>http://coloradok5.com/gallery/captcrunch</a>
     
  7. 6.2Blazer

    6.2Blazer 1/2 ton status

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    The 12-bolts use a 30-spline, 1.31" diameter shaft. The earlier 10-bolts used a 28-spline, 1.28" shaft, however the 10-bolts were upgraded to the 30-spline, 1.31" shafts around '88 or so which gives them the shaft axle shaft strength as the 12. However, the 12-bolt still has a small strength advantage when it comes to the differential and gears.

    The 14 bolt SF is very, very common but the vast majority were 8-lug versions. An 8-lug version can be changed to 6-lug relatively easy by either re-drilling the bolt pattern on the axle flanges and brake drums, or by buying new 6-lug parts.
     
  8. ChevyCaGal

    ChevyCaGal 3/4 ton status

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    Look around 6 lug 14b sf are out there... I got one! It'd be easier to buy one then redrill one if you ask me... they do cost more then 14b ff... so crunch some numbers and see if it's worth it to you to go this way and what you want to do with it. For now the numbers worked for me with buying this axle. I can resell it for a good price if I choose too. Then can go one ton if I really get into rocks which I am thinking I might. If not then no biggie what I got will work fine!

    &lt;&gt;&lt;<a target="_blank" href=http://www.chevycagal.homestead.com/steph.html>Steph's Webpage</a>&gt;&lt;&gt;
    Suck Fumes Ford Boy
    I keep trying to lose weight, but it always finds me!
     
  9. 6.2Blazer

    6.2Blazer 1/2 ton status

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    Since the 6-lug 14SF was only found in the newer trucks with IFS, don't the spring pads and shock mounts need moved? A place like Moser Engineering can plug and re-drill the bolt pattern on the axles and drums for under $100. Also, at least around here, the 8-lug versions are very common (used on almost every 3/4 ton pickup and Suburban since early '80's).
     
  10. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

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    If you want lots of ground clearance...and the beefier 30/1.31 spline/inch axels, just find some guy that has installed the Warn full-floater kit in his 10 and is about to swap in a new ff14b...

    =)

    Jason


    See the on-going build up of my '85 Jimmy! http://community.webshots.com/user/jekbrown
     
  11. CaptCrunch

    CaptCrunch 1/2 ton status

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    From the research I have done... the 14BSF deal is tricky. The 8 lugs may or may not be able to be changed to 6 lug. Some swap the shafts no problem, but others aren't the same size as the IFS 6 lug axles. I would personally like to find an IFS one and just move the perches but they are spendy. The older 8 lug versions will bolt right in but the axle change over is kinda a mystery so I would get prices on plug and tapping the shafts you have and cost for custom done axle shafts before you buy in case the crap hits the fan (like usually happens [​IMG])

    -Mikey
    1987 Chevy K5 Blazer- 350 TBI
    <a target="_blank" href=http://coloradok5.com/gallery/captcrunch>http://coloradok5.com/gallery/captcrunch</a>
     
  12. 6.2Blazer

    6.2Blazer 1/2 ton status

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    It really isn't rocket science to re-drill a bolt pattern on the 14 SF. I researched this option a couple of years ago and was quoted less than $100 by Moser Engineering (www.moserengineering.com) to have this done, in fact I checked and they still list those same prices on the webpage. I would also think that most good machine shops could do this also.
     

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