OMC vs HF flywheel puller

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This topic contains 87 replies, has 24 voices, and was last updated by  johnyrude200 2 years, 5 months ago.

Viewing 15 posts - 61 through 75 (of 88 total)
  • fisherman6
    fisherman6
    US Member - 1 Year
    Replies: 1653
    Topics: 37
    #41272

    Not to stray from the topic, but I love that Golden Jubilee Big Twin! That’s a nice one Wedgie.
    -Ben

    OldJohnnyRude on YouTube

    Mumbles
    Mumbles
    Canada Member - 2 Years
    Replies: 3797
    Topics: 367
    #41281

    Is there such a thing as a puller ever being too good? 😮


    Attachments:


    wetwillie

    Replies: 91
    Topics: 15
    #41296

    Thanks, Mumbles, for spoiling my breakfast. 🙁


    amuller
    US Member - 2 Years
    Replies: 788
    Topics: 125
    #41300

    I’m not so clear on the advantage of the shoulder bolts over ordinary grade 8 hardware. The weakest point in tension will still be at the threads, and a stiffer bolt would seem to concentrate any bending there, perhaps making the stresses more unequal…..

    Alan


    wetwillie

    Replies: 91
    Topics: 15
    #41301

    I share your opinion re: advantage of shoulder bolts for the same reason.
    BTW, here’s a closeup of how I have my flywheel supported by straps. PLEASE don’t tell me the bolts around the perimeter have to be removed.


    jerry-ahrens
    US Member - 1 Year
    Replies: 1011
    Topics: 70
    #41302

    I would remove the thin hardware store washers and only use the thick OMC washers from the kit. The thin washers are to soft and it looks to me like they are getting smashed. From the picture it looks like the puller is digging into the flywheel nut? I can’t tell for sure. That puller will work better with the original shoulder bolts and the original thick washers from the kit. That’s an important part of the kit required to make it perform so well.


    richardg
    US Member - 1 Year
    Replies: 41
    Topics: 4
    #41303

    The OMC Puller has a nice flat on the center bolt where it contacts the crankshaft that is less likely to spread the crank shaft threads the way the pointy section of the harmonic balancer puller does.

    I still try to use a thin nut on the top of the crankshaft to prevent damaging the threads when pulling a flywheel since I have found a relatively large number of crank shafts with the first few threads distorted out.

    When I find a crank distorted that way I have some high end dies that are split so you can expand them a bit, usually get them threaded on anyway, the once threaded down a ways, return the die to the proper size, then back the die up to cut down the distorted top section of the threads.


    wetwillie

    Replies: 91
    Topics: 15
    #41308

    Well, I’m glad no one has told me the perimeter bolts have to be removed. That’s a relief.
    Although its tough to see in the pic, there is a slight gap between the nut and the puller. I considered putting a suitable washer on top of the nut and having the puller push against the nut vs the crankshaft end. My rationale being it would increase the surface area between the puller bolt and the crank and reduce the likelihood of damaging the end of the crank. I still may depending upon responses to the idea.
    As for the thin washers. I put them on to increase the contact area between the bolt heads and the OMC washers which have a pretty large ID vs the underside of the bolt heads. That was the case even with the original shoulder bolts. If they’re getting smashed, its not very much.


    amuller
    US Member - 2 Years
    Replies: 788
    Topics: 125
    #41309

    I believe those perimeter bolts hold the ring gear on and are irrelevant to pulling the wheel off the crank.

    Washers are a problem. I usually use a stack of grade 8 washers of decreasing size, but making up some pads out of bar stock would likely be better.

    I’m right now trying to take off a flywheel that has hammer marks around the hub, suggesting it was pounded ONTO the crank. Not a good sign….

    Wico/Chrysler flywheels frequently have dimples or cast-in holes but they aren’t threaded. Easy enough to drill them on a drill press, but not a very nice job when the wheel is mounted and the mag parts are waiting underneath. Does anybody see a problem with drilling them through, as opposed to drilling and tapping blind holes (assuming the wheel is loose, of course)?


    vintin
    US Member - 1 Year
    Replies: 547
    Topics: 16
    #41310

    quote WetWillie:

    Well, I’m glad no one has told me the perimeter bolts have to be removed. That’s a relief.
    Although its tough to see in the pic, there is a slight gap between the nut and the puller. I considered putting a suitable washer on top of the nut and having the puller push against the nut vs the crankshaft end. My rationale being it would increase the surface area between the puller bolt and the crank and reduce the likelihood of damaging the end of the crank. I still may depending upon responses to the idea.
    As for the thin washers. I put them on to increase the contact area between the bolt heads and the OMC washers which have a pretty large ID vs the underside of the bolt heads. That was the case even with the original shoulder bolts. If they’re getting smashed, its not very much.

    I wouldn’t do it. I believe you may put the threads on the crankshaft at risk.

    fisherman6
    fisherman6
    US Member - 1 Year
    Replies: 1653
    Topics: 37
    #41311

    The biggest advantage of the shoulder screws over the grade 8 hex heads is the shoulder screws square themselves to the surface when the shoulder is tightened firmly against the top of the flywheel. The distance between the shoulder and the head is also a held dimension on shoulder screws. That means when everything is tight it takes as much error out of the setup being square as possible with the least amount of effort.

    Pulling any of the screws at an angle concentrates the load on one side of one of the threaded portions of the screws. That is want causes them to break.

    Heavy hard washers are intended to support heavy loads without distorting. The thickness of them is a lot more consistent than your typical grade 8 hardware store washer too. The biggest problem with them is they just are not heavy of hard enough. They may work OK most of the time, but with as much force as this operation is requiring the heavy hard washers would be a much better option. I hope this helps explain the advantage of the shoulder screws in the puller.
    -Ben

    OldJohnnyRude on YouTube


    wetwillie

    Replies: 91
    Topics: 15
    #41314

    Okay Dan, you talked me out of the washer atop the flywheel nut idea. 😉
    I understand and agree with everything you wrote, Ben. However, FWIW, I believe that the stress applied to a shoulder bolt is concentrated at the shoulder where there’s a change in diameter. What makes that change worse is that its a step and not a radius. The only downside IMHO is that its more likely to break there than elsewhere. When the OMC shoulder bolt broke, it did so at that location, just below the flywheel surface. The other bolt snapped slightly above the surface making extraction a lot easier.
    Tomorrow, I’ll get some heavy hard washers and swap them for the thin washers I have on top of the OMC washers. I’m also giving serious thought to buying some hardened bolts IF I can find any.
    This morning, I tried again. This time, I heated the area around the interface too hot to touch. I then cooled the nut down till it was literally frosted. That’s as close to the crankshaft as I could get because of the nut. I figured it would draw the heat out of the crank end. I then gave it several good whacks with a 3 lb hammer. GOOD whacks!
    It’s STILL on there! 🙁


    49hiawatha

    Replies: 267
    Topics: 25
    #41316

    I hate to be a Debbie Downer but how much do you "love" that motor?


    wetwillie

    Replies: 91
    Topics: 15
    #41320

    Well, "Debbie", at what point do I have nothing to lose and really lay in to that puller bolt?

    fisherman6
    fisherman6
    US Member - 1 Year
    Replies: 1653
    Topics: 37
    #41330

    Here is a photo of the shoulder of a shoulder screw. I will not argue the fact that the shoulder IS the weak spot of a shoulder screw. The step DOES however have a radius inside. That radius is a lot bigger than the one at the root of the threads. The shoulder screws do need to be firmly seated against the top of the flywheel or the shoulder becomes a lever and WORSENS the condition.

    Ultimately it is up to you what you use and how you do it. I’m just trying to do my best to clarify the reason for the shoulder screws. All that said, I probably would have beat the dogsnot outta the thing by now after hitting the center bolt with an impact. I probably would have broken something by now more than once. I’m not saying that’s right, but I know me. 😯
    -Ben

    OldJohnnyRude on YouTube

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