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Installing the wrist pin pinch bolt

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  • Installing the wrist pin pinch bolt

    After several interruptions, I am finally getting back to assembling the 289 that I started last spring. I am assembling the rods to the pistons and I want to be sure the wrist pin bolt won't ever come loose.

    I asked this question last spring and I also researched all the other threads I could find and I plan to use the Ted Harbit tap and torque method. Some other suggestions were to also use red loctite. With loctite, I would have maybe 20 minutes to do the tap & torque before it set up. Some of the descriptions of the tap and torque method suggested doing it again after the parts sat overnight. Obviously, this wouldn't work with the red loctite.

    What exact method do you use?

    Red loctite or not?

    The shop manual specifies 20 to 25 ft/lbs torque. If you use loctite, do you back off on the torque a bit since loctite may act as a thread lubricant?

    54 Commander Coupe driver
    53 Commander Hardtop project
    SE Washington State

  • #2
    I use Ted's method, with new stock-style lock washers.

    Suggest you consider using the blue loctite instead of the red. The next person that has to disassemble that engine will thank you!
    Winston-Salem, NC
    Visit The Studebaker Skytop Registry website at:


    • #3
      Tap and torque.....then use Green Locktite (wicking type) afterwards.
      Bez Auto Alchemy

      "Don't believe every internet quote" Abe Lincoln


      • #4
        Your eyes are the the key here

        Working time with Loc Tite may be up to an hour from my experience. Never mind that as being the key to doing it right. It is your eyes, and personal 'feel' of what you are doing that matters.

        Carefully snug up all of the bolts, use your eyes and feel to be sure the bolt is properly lined up and draws into the hole.. These can feel tight, but if the bolt shoulder/wedge portion is not square to the hole, you will be repeating the procedure soon enough. Some use a tiny inspection mirror, double check the work, be sure the bolts are drawn tight into the holes.


        • #5
          Thanks to all of you for the great info. I had never heard of green Loctite so I did some research. It appears to have about the same hold as red loctite but is thin enough to be applied after assembly. Both have a maximum service temp of 300 degrees and need to be heated to 482 degrees for removal. I'm not sure how hot it gets up under the piston. It could be too hot for the loctite to do much good.

          I plan to tap and torque and make sure the wedge on the bolt is square to the notch in the pin and that the bolts all pull in about the same amount. Then when I'm satisfied with that, I'll add some green loctite for insurance.

          Thanks again,
          54 Commander Coupe driver
          53 Commander Hardtop project
          SE Washington State


          • #6
            I believe there is still more than one "green" loctite.
            The wicking stuff is 290. My favorite, for all kinds of things.
            "Sleeve" retainer is 640. High strength, and higher temp range.
            Harley motorcycle crankshafts used to use tapered joints between the "flywheels" ( crank halves ) mainshafts and crankpin, pulled together by tightening nuts between 100 and up to 400 lb-ft depending on year. The cranks have to be "trued" to get both main shafts concentric during and after assembly. In the later years Harley was recommending a drop of thick and green slow curing, high temp loctite be applied to each taper. I think it might have been Loctite 635


            • #7
              I didn't use loctite, though I think it is good insurance. I noticed you said the manual specifies 20 - 25 ft./lbs., but I am wondering if it is inch pounds. I'm on vacation, not accessible to Teds notes, but as fragile as the pins are, it seems to me the torque was 20 - 25 inch pounds. Maybe I'm wrong, but be safe and verify the spec. B.V.


              • #8
                Please remember that this is a 3/8 inch BOLT! There is no way it is going to be torqued in INCH pounds.
                Second Generation Stude Driver,
                Proud '54 Starliner Owner
                SDC Member Since 1967


                • #9
                  Also, all torque values are for clean, blemish-free threads, which have been lubricated, so the lubricating value of the loctite would not be much of a factor in reducing required torque. In areas where it can be measured, fastener stretch is a far better indication of clamping force. It eliminates differences in thread fit and lubrication.
                  Often in error, never in doubt

                  ____1966 Avanti II RQA 0088_______________1963 Avanti R2 63R3152____________