773 (1950) version crank pin replacement

I’ve never tried to replace a crank pin on the early 773 steel drivers. If the crank pin is pressed on with the same force as the wheel is pressed on the axle, that crank pin would probably be pressed in with the same force that turns coal into diamonds. As long as the rod bolt wasn’t cross threaded, thus reverting to nature’s loctite ….ie; seized, you’d be surprised how they can be backed out. My suggestion, put a tiny dot of penetrating oil in the hole, get a sharp tiny pick tool, and start picking in the direction that backs out the broken fastener…..if she gets to wiggling, you’re practically home free, you just need to work it in the direction that threads out……I’ve fixed a gazzillion broken fasteners, and as long as it wasn’t cross threaded, the load is off the broken bolt, and should back out pretty easily……

Pat

Thank you for the suggestion. I'll give that a try and see what happens. I'll let you know.

Thanks,

Joe

@pajoek posted:

Thank you for the suggestion. I'll give that a try and see what happens. I'll let you know.

Thanks,

Joe

Don’t mangle it, …if you can’t get it, send the frame to me for servicing. I can get it out, and leave the crank pin perfect. ….

Pat

I usually try a reverse twist drill for those.  I have some tiny enough to drill into the small threads of the rod bolts.  Of course, if that doesn't work I sent it to Pat.

Hello again,

I tried removing it with a pick but no luck. It is either cross threaded or in too tight. I drilled it out using a small hand drill and can see part of the screw around the edge of the crank pin. I did this before I saw your post about sending it to you. Still no luck getting it out. I can feel threads in certain areas but can’t get it to release. If I knew the size of the threads I would try tapping it out or chasing new threads. I put it aside for now and might pick at it again tomorrow. I did find pictures of the wheels and the hole for the crank pin goes completely through the wheel. I also found replacement pins on eBay. This tells me it is not part of the wheel but is probably pressed in. If I can’t remove the old screw I might try pulling the crank pin out and replacing it. Thank you for your advice and suggestions.

Joe

Someone might have put a dab of Loctite on the rod hex bolt before it was installed.

I've never personally replaced a crank pin.  I know they are splined and press straight in.  My guess would be that they are designed to be pressed in, perhaps with a bench vise or arbor press, BEFORE the wheel is installed on the axle.

Maybe Pat or someone else on here with more experience can coach you about pressing in the pin, while leaving the wheel in place on the train.  As you might know, if you pull the wheel to install the pin, you'll have to press it back on "in quarter," synchronized with the other five driving wheels.  Quite a can of worms!

I would avoid pulling wheels and crank pins at all costs. The fasteners used by Lionel in the prewar/postwar era are not of any hard grade material. Out of hundreds of broken off rod bolts I’ve retrieved, I’ve only ever had to drill out a handful. The crank pin however, is surprisingly harder than the fastener. Using the proper bit for the thread, ( I wanna say it’s 3-48 ) I’d drill it out on center and just re-tap the crank pin. For a PSA, you guys should never ever use loctite on a rod bolt. You’re asking for trouble!!……if you have a habitual offender that backs out a rod bolt in motion, you have another problem,….the hardware used in our world isn’t even grade two!!!!….

Pat

Thanks for your input Ted. I appreciate all the information I’m getting

Joe

Thanks Pat,

Do you have any idea what size tap this would take? Maybe someone else on this forum can help me out with the right size tap. I want to avoid pulling the wheel if at all possible. I don’t have any experience with the crank pin. I’m so thankful for this forum. It’s full of useful information and experience and it helps those of us without the knowledge or experience. Thanks to everyone.

Joe

@pajoek posted:

Thanks Pat,

Do you have any idea what size tap this would take? Maybe someone else on this forum can help me out with the right size tap. I want to avoid pulling the wheel if at all possible. I don’t have any experience with the crank pin. I’m so thankful for this forum. It’s full of useful information and experience and it helps those of us without the knowledge or experience. Thanks to everyone.

Joe

The thread is 3-48. You’ll need a #47 drill bit to pass through the crank pin. Fashioning a jig of some sort, and doing the procedure on at least a drill press will yield better results than winging it with a drill. Sneak up on the procedure. Use quality HSS bits, and cutting oil of some sorts, …thin motor oil works in a pinch. Keep running the drill head in and out to clear chips, the closer to the bottom you get, the sneakier you gotta get to avoid the dreaded snag at the end that snaps the bit off in the bore. Orient your driver so the crank pin is at the 6 o’clock position so the drill doesn’t poke the chassis.

Pat

Thanks a lot Ted, I appreciate the information. If I can’t get it to work its way out then that’s the route I’ll take. At least now I know the right size bit and tap to use. You’ve been very helpful to me.

Joe