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Axle Questions Specs U-joints and more...

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by merc359, Jun 22, 2005.

  1. merc359

    merc359 1/2 ton status

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    Ok,

    I am relatively new to building 4x4 drivelines as I am used to muscle-car applications, so all the changes I am making to the transfer-case, axles, etc, is for the first time. I'm hoping someone can provide me some information on various yokes and strengths and what not.

    I have a 1978 shortbox chevy pickup 1/2 ton 4x4 with a brand new 350 engine, spanking new TH-350 transmission, and a just-rebuilt NP-205 transfer-case, Danna 44 front axle and Corporate 12 bolt rear axle. Ultimately I would like to upgrade both axles, but more on that later....

    First, The transfer-case I have has a 1310 fixed front output and a 1350 fixed rear output yoke. Naturally, as a 1/2 ton, the driveshafts will have to be reworked as it was all set up for 1310 yokes all the way back and forth on front and back.

    My questions are these:
    1. Where does one buy new yokes for the rear axle input?
    2. My front driveshaft has a CV in it (if that is what it is with the 2 u-joints and large knuckle) given that the rest of the front drive-shaft was set up with 1310 joints, if I upgrade to 1350 on the front (if possible) is there a comparable upgrade to the CV unit or is it strong enough regardless? What about clearance (within the CV) due to the larger cap size of the u-joint?
    3. Any information about the Dana 44 and corporate 12 bolt axles? I have had absolutely no experience with either of these. I don't do a lot of heavy axle wrenching off-roading, but I do like to do long-range off road exploring where making-it-out is the top priority. That is why I am trying to upgrade a lot of this stuff.
    4. I hear a lot of talk about the 14FF axle - I imagine it is the best stock-built axle one can buy - if I upgrade these axles, what should I step up to to "build the beef" keeping in mind that I hate doing jobs twice. I want it done right the first time.
    5. Lastly, is changing the yokes as easy as that single large nut on the shaft or is there a press-on fitting of anything else there?

    Any input or answers will be hugely appreciated.

    Rowan (Merc359)
     
  2. mouse

    mouse 1/2 ton status

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    1. Check vendors board here. I.e. North West and High Angle Driveline sell these.
    2. Yes, possible, but if you need it depends on HP, axle ratio, locker use, and tire size. HAD (High Angle Driveline) make these sorts of shafts.
    3. If you don't plan on running lockers, the 1/2 ton stuff should do fine up to 33 or 35 inch tires. Depends also on how hard you are on the skinny pedal...
    4. 14 BFF is the cheapest way to upgrade the rear to almost undestructible status. The axles, large ring gear, etc make them very durable. They are also easy to find at boneyards, making them relatively cheap (unlike Dana 60's for the front) - $100 to $300 seem like common prices. I stole my eight lug D44 and 14 BFF from my K20 pickup, put the 1/2 ton stuff on it and then sold it.
    5. Changing yoke on the rear depends on what axle. 12 bolt should be done by a shop (unless you're experienced). 14BFF should use a new crush washer, and is easier to change (but the 14BFF already uses a 1350 joint...I upgraded to 1410).
     
  3. merc359

    merc359 1/2 ton status

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    Thanks for that info. With respect to the 12-bolt being changed by a shop, why is that? Do I have to tear the whole thing down to do it? If so, into the shop it goes.
     
  4. mouse

    mouse 1/2 ton status

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    IMO, the 12 bolt should be changed by a shop, because the pinion carrier is not removable like on the 14BFF. For the 14 bolt you can remove the pinion carrier and change the crush sleave and use the old measurements in order to keep proper pinion preload setting when reassembling - plus, its easy to bring the old pinion carrier with the yoke still installed to a shop to have it changed. Maybe someone else can give you more info on how to change the pinion yoke for a 12 bolt?...
     
  5. merc359

    merc359 1/2 ton status

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    Further Axle Question

    Ahh that doesn't sound like I have the expertise to handle that on the 12-bolt. I think I may just run a conversion u-joint until I upgrade the rear-end. That way I'll have the 1350 yokes from transfer-case back and when I upgrade it will all fall into place.

    I know others have asked this question, but I was not satisfied with the answers:

    Is there a way to properly identify the 14BFF diff from the outside without pulling the cover? And if I DO have to pull the cover, what in God's name am I looking for other than ensuring appropriate ring gear size (which I can confirm from the outside anyways based on bolt pattern). Sorry...rookie question.....

    Rowan (Merc359)
     
  6. mouse

    mouse 1/2 ton status

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    They are easy to identify. Of course 14 bolts on the cover. They come stock in 3/4 ton and 1 ton trucks. The axles on the full floater (strongest) have 6 bolts on the ends of the axles, outside the drums.

    See this article at Pirate:
    http://www.pirate4x4.com/tech/billavista/14b_bible/index.html

    Enjoy!
     

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