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Need "How To" for 14 bolt gear set up

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Eric M., Oct 19, 2002.

  1. Eric M.

    Eric M. 1/2 ton status

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    Need \"How To\" for 14 bolt gear set up

    I'm swapping a used locker and gears out of a damaged 14 bolt FF into a good housing and need to know how to do it. I know I need to have the same pinion depth and will need pinion shims to accomplish this. I'm also aware to match the backlash form the original set up to the new. I'm sure there is more, but can't find it. I've done a search and came up with the technical artical from Tanner 4x4. It left out a lot of detail and suggested that professionals do the job. I've also gone through a shop manual and a Chiltons Guide with no luck. Any ideas?

    Thanks,

    Eric M.
     
  2. sapper

    sapper 1/2 ton status GMOTM Winner

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  3. Eric M.

    Eric M. 1/2 ton status

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    Re: Need \"How To\" for 14 bolt gear set up

    Yeah, that's the one I saw. It left out a lot of detail if you wanted to do it yourself. I'm wondering if Steve didn't want to tackle it, maybe I shouldn't. has anyone done this thenselves? Is it that difficult?

    Thanks,

    Eric M.
     
  4. 8_YOUR_H2

    8_YOUR_H2 1/2 ton status

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    Re: Need \"How To\" for 14 bolt gear set up

    There is one fact that I dug up you will not hear much about. The pinion bearing preload has to be set with the pinion seal out. The chilton truck and van repair manual 1971-1978 goes into detail on how to correctly set the pre load.
     
  5. Eric M.

    Eric M. 1/2 ton status

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    Re: Need \"How To\" for 14 bolt gear set up

    Thanks. I went searching through my Chiltons when I came across the 87 GMC Repair Manual ... I was looking in the Service Manual! I'm gonna read through it tonight, but I think all the info. I need is in there.

    Eric M.
     
  6. Leadfoot

    Leadfoot 1/2 ton status Premium Member

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    Re: Need \"How To\" for 14 bolt gear set up

    Setting up any ring and pinion can be a [sarcasm]fun[/sarcasm] experience, but of all the GM axles I have worked on the 14FF is probably the easiest due to the "external" pinion support (six bolts on front of diff) and the "screw adjusters" for the carrier bearings (no shims needed). This allows you to shim the pinion in and out without unpressing and repressing bearings, and allows you to set carrier backlash and preload without unpressing and repressing bearings.

    VERY quick overview:

    A. Remove Pinion nut and yoke (easiest to do with tires on the ground for resistance). Unbolt pinion support housing (six bolts) and set shims aside (or measure thickness for intitial reference).

    B. Unbolt axle shafts and remove (tires can remain on if you do not have center caps, another reason it is easier with the 14FF).

    C. Remove diff cover. Mark screw adjusters with punch (for intial reference). Undo bolts that hold the wire "locks" on the screw adjusters. Loosen both carrier bearing caps. Loosen both screw adjusters an equal amount (not necessary but MY preferred method). Remove carrier bearing caps MAKING SURE TO MARK LEFT AND RIGHT, TOP AND BOTTOM as it is very important to put them back on the correct side and correct orientation. Slide carrier out (may need persuasion).

    D. Clean inspect spider assy/locker/LSD for proper operation and any excessive wear replace/upgrade if needed. Cleans housing and assemblies well (I recommend brake cleaner). I recommend replacing all pinion bearings and carrier bearings, but you may reuse (make sure to follow specs for used bearings if you do). You will need a press (or you might try gear pullers, but usually wreck the bearings, not a problem if you are using new) to remove the bearings from the carrier (a little tricky as you will need something to get between the bearing and carrier as you press). The 14FF has 3 pinion bearings. Two located in the pinion housing (only press one way and should be intuitive) and one located if the diff housing. I use a bearing/seal driver to remove it (presses out toward front of diff when removing).

    E. Install new bearings (lightly oiled), races, and pinion (no crush sleeve at this time) into pinion housing, and install yoke and nut with NO seal and GENTLY tighten to remove "play", but still allow you to turn pinion. Install shims (starting with originals or original thickness) onto pinion housing and bolt to the differential housing.

    F. Remove old ring gear and install new ring gear (assuming no carrier break was encountered or "thick" gears are used). Install carrier into housing, with races on the bearings (and lightly oiled). Install caps loosely, tighten down adjusters evenly to about the original settings (may or may not be possible, but try to keep them even). Tighten caps and check for ease of rotation. If it will not rotate semi freely something is bound or overtight (inspection is needed).

    G. Set backlash to spec and check pattern with compound. Compare to pictures that are available on the net (and have been posted on this site) as to what is and is not acceptable for a pattern. Adjust as needed by loosening caps, adjusters, removing pinion support, adding/subtracting shims, putting everything back together, setting backlash, checking pattern, and repeating until you are satisfied it is perfect/acceptable (See a recent post).

    H. Once you are satisified with the pattern remove the carrier (counting turns of adjusters). Remove pinion yoke, nut, and front bearing, install crush sleeve, and well lubed pinion yoke seal. Reinstall pinion yoke and nut and begin to tighten. Crush sleeve slowly (VERY tough to do at first until it starts to crush). Check frequently with a rolling resistance torque wrench (not the kind you torque head bolts with ***also not available at most parts store that I could find***) until spec is reached.

    I. Reinstall carrier and tighten down to previous setting and double check backlash and pattern. Adjust if necessary. Install wire locks, diff gasket and cover, fill with good quality lube, and follow break in procedures given with gears.


    J. Crack a beer (or soda) and pat yourself on the back after a LONG DAY of work.

    As you noticed I did not say anything about carrier bearing preload. It is hard to check, and with talking with Randy's ring and pinion, he said to tighten it down has much as I could, as he had not seen a 14FF carrier bearing wear out from over tightening, but HAS seen them fail because of too much slop.

    DISCLAIMER: I have not done this in a while, so I may have forgotten a step or two, or switched something. This is to be used as a guide to give someone an idea of what they are up against. As always, follow instructions given with your ring and pinion set. If you buy from a reputatable shop, they usually have a tech line to call if you have any questions or need to know proper procedures. I recommend Randy's but there are others (just do a search).
     
  7. Eric M.

    Eric M. 1/2 ton status

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    Re: Need \"How To\" for 14 bolt gear set up

    Thanks. It's good to hear from someone who has tried it and says it's not something that shold be left to a shop. I'm gonna print this up and hold onto it.
    Eric M.
     

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