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Replacing differential split pin with a better roll pin

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  • Replacing differential split pin with a better roll pin

    I saw one of the facebook posts about welding in the diff pin, and also over on saturnfans one of the refugees was asking about part numbers for the improved pin. I've documented this over on the other site but who knows if it will go away or not.

    First, Hunt4Steve is the real source - read his blog here:
    https://sites.google.com/site/hunt4s...n/transmission

    Here is the pin you need:
    https://www.mcmaster.com/95755a331

    It is 3/16" nominal diameter and 1.5" long.

    I'll document what I did different than Hunt4Steve. Mainly I did not take the differential bearings off. After transmission teardown, I drove out my pin. It was not broken.
    not broke.jpg

    Here the shaft is removed. I drilled this up using a V block in my drill press, with the fancy bit Hunt4Steve mentions.
    carrier.jpg

    I wrapped up the bearings really good to keep the chips out.
    bearing wrap 1.jpg

    I stacked up some scrap to keep the assembly off the bottom bearing. I didn't want it moving while I drilled it.
    blocks.jpg

    I jammed a paper towel in the middle of the diff to keep chips from migrating that way.
    paper towel trick.jpg

    Here the diff is clamped down to the blocks. For the carrier I used a commercial HSS long 3/16" drill bit from Lowe's Depot or somewhere. The soft cast iron drills easily. The fancy drill bit was too short with the bearing in the way.
    clamped.jpg

    Here are the chips.
    chips.jpg

    I pushed the paper towel through and cleared them to the outside of the differential.
    cleared chips.jpg

    Here my then-15 year old is gently pounding in the new pin. It took some effort to get in.
    hammer time.jpg

    We did this back in 2017 at 204,062 miles. As I write this we are close to 222,000 miles.


    Attached Files
    Last edited by Waiex191; 01-25-2020, 02:36 PM.
    '99 SL2, 5SP bought new
    Rebuilt at 204,067 September 2017
    Engine, subframe, diff pin mod, brake lines, headliner, alternator, and so on!
    '98 SC2, 5SP bought 2018

  • #2
    Just ordered the roll pin and drill bit! Thanks for the step by step, will use this when I do my diff pin this feburary.

    Comment


    • #3
      I really think this is better than welding. The pin sees no load normally, just whatever friction the spider gears have. The stock design has a little slop, so the shaft can hammer at the pin. With no slop, there is no hammering, and it should never break. Welding a thin steel pin to cast iron seems iffy to me. I can't remember if the housing or the shaft is a loose fit. If the shaft fit to the pin is loose, it can still hammer. If the housing is loose, maybe welding would take the slop out but a tight fit of the pin should be better.

      Good luck! I will do this again for my '98 before I replace the transmission.
      '99 SL2, 5SP bought new
      Rebuilt at 204,067 September 2017
      Engine, subframe, diff pin mod, brake lines, headliner, alternator, and so on!
      '98 SC2, 5SP bought 2018

      Comment


      • #4
        I always thought people were welding in the split pin. Never made sense to me. Now I see they are welding in the shaft like this:
        https://forum.sixthsphere.com/forum/...ential-welding

        I still like the larger roll pin I'm using but it makes more sense now.
        '99 SL2, 5SP bought new
        Rebuilt at 204,067 September 2017
        Engine, subframe, diff pin mod, brake lines, headliner, alternator, and so on!
        '98 SC2, 5SP bought 2018

        Comment

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