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  • Piston pin pinch bolts questions

    Everything is back from the machine shop and I'm getting started putting my 289 back together. I have the shop manual and I have made copies of the series of engine rebuild articles that ran in TW back in the 90's. In the TW articles, he says to have the machine shop install the rods in the pistons. I would like to do it myself but I have some questions. The piston pin pinch bolts are such a critical item I want to make sure I get them right.

    1. Are the piston pin pinch bolts an item that should always be replaced? Mine look OK except for a couple of dings in the screw threads that will probably clean up with a thread chaser.

    2. I removed the pins by putting the nut on the other end of the pin to draw it out. Unfortunately, a couple of the pins were tight enough that this took the threads out of the nut. Does anyone know of a good source for this nut? I think I'll replace them all while I'm at it. It's low-profile and I assume a higher grade than standard. Studebaker part number is G120369.

    3. To be safe, I think I would also like to replace the star (shakeproof) washer. Does anyone know of a source for this washer? Studebaker part number is G138489.

    4. Should I use a little locktite on the threads?

    5. I haven't looked at my new pistons yet but on the old pistons that I'm pulling out, the skirt would be in the way of using my torque wrench. Any ideas on getting these torqued properly?

    Thank you all very much.
    Cliff
    54 Commander Coupe driver
    53 Commander Hardtop project
    SE Washington State

  • #2
    If the threads look weak I'd replace the nuts with the correct stude# nut.
    The damage on the bolts and nuts are usually caused by incorrect installation and removal.
    Due to the machined taper on the pin you cannot use a die to chase the threads, the die will "hang up" on the corner of the taper. Follow the manual on the installation procedure and I'd recommend the loctite. These pinch bolts make me more nervous then anything on the assembly of the stude motor, maybe because I've heard to many horror stories or maybe because I grew up with full floating rods and these pinch pin just make me nervous. by the way stude wasn't the only one to use this style rod.
    Good Luck
    Originally posted by cliffh View Post
    Everything is back from the machine shop and I'm getting started putting my 289 back together. I have the shop manual and I have made copies of the series of engine rebuild articles that ran in TW back in the 90's. In the TW articles, he says to have the machine shop install the rods in the pistons. I would like to do it myself but I have some questions. The piston pin pinch bolts are such a critical item I want to make sure I get them right.

    1. Are the piston pin pinch bolts an item that should always be replaced? Mine look OK except for a couple of dings in the screw threads that will probably clean up with a thread chaser.

    2. I removed the pins by putting the nut on the other end of the pin to draw it out. Unfortunately, a couple of the pins were tight enough that this took the threads out of the nut. Does anyone know of a good source for this nut? I think I'll replace them all while I'm at it. It's low-profile and I assume a higher grade than standard. Studebaker part number is G120369.

    3. To be safe, I think I would also like to replace the star (shakeproof) washer. Does anyone know of a source for this washer? Studebaker part number is G138489.

    4. Should I use a little locktite on the threads?

    5. I haven't looked at my new pistons yet but on the old pistons that I'm pulling out, the skirt would be in the way of using my torque wrench. Any ideas on getting these torqued properly?

    Thank you all very much.
    Cliff

    Russ Shop Foreman \"Rusty Nut Garage\"
    53 2R6 289 5SpdOD (driver)
    57 SH (project)
    60 Lark VIII 2dr sd (driver)

    Comment


    • #3
      I don't believe I have seen the type of bolt you are talking about. Could you post a couple of pictures. Thanks, Neal

      Comment


      • #4
        Cliff,

        I'd just replace them, that's what I did. You have already spent alot of time and money at this point, it'a just good insurance! I got them from Studebakers Northwest in Ferndale, WA. Since you are from WA, you might want to contact Rich, although other vendors have them as well. As far as getting a torque wrench on the nuts, if you pivot the rod towards the skirt, you will be able to expose enough of the nut to get your wrench on it. It may take an extension to allow the ratchet head to clear the skirt on the other side. Use red loc tite.

        Scott

        Comment


        • #5
          Didn't Ted Harbit comment on this assembly. He mentioned that once installed, he would return after a day and rap the side of the rod, close to the pinch bolt. Then he would torque it again and it would move. He supposedly, did this a number of times. It's somewhere in the Archives..
          64 GT Hawk (K7)
          1970 Avanti (R3)

          Comment


          • #6
            You must rap on the pin so that it takes its "set". I used Ted's procedure when I did my engine. Each time I tapped the pin I would be able to torque the bolt a little more. Most every rod took at least three of the torque,tap, torque again procedures, before they were tight enough.
            1962 Champ

            51 Commander 4 door

            Comment


            • #7
              I buy the nuts and outside star washers at my local NAPA dealer. If the threads are bad on the pinch bolts, I would recommend replacing them. The nuts are 3/8ths fine thread and are available at most of the larger parts houses. Tapping the pinch bolt a few times while tightening the nut is a good idea and I do that when I rebuild an engine. I also put a drop of red loktite on the threads because it makes me feel better. I always use new nuts and star washers on the pinch bolts when I assemble an engine. Bud

              Comment


              • #8
                I also used Teds method, and have had no issues (so far). Yes,replace any questionable bolts, nuts,or washers. I went over the torquing procedure per Teds advice until I got no more movement on the pin,nut assembly. Some rods tightened up with 3 tries and others took several more,but I did get them all to tighten to the same torque. Hope this helped, B.V.

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