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  1. #1
    retro jet's Avatar
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    951 Counterbalance shaft rebuild

    I think I need a bigger press. I have an arbor press that is pretty stout, but my couple hundred pounds hanging off the handle doesn't seem to want to budge the weight and bearing off the 951 CB shaft. Are you folks using gear pullers? A hydraulic press? Who rebuilds them?

    Thanks,


  2. #2
    big john's Avatar
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    you can buy them exchange or find a bigger press, mayb a little heat on the counter balance to help get it off ??

  3. #3
    retro jet's Avatar
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    I have new bearings and seals ready to go, so I would prefer to rebuild it rather than exchange. I also want to be running at the end of the month.

    So the press that I used was a 1.5 ton 32:1 arbor, I found a 2 ton 35:1 arbor that I will try. Problem with any arbor press is that I can press the bearing and weight off through the base, but need to rig a support for the end of the shaft to press the bearing and weight back on. I figured I would heat the new bearing and weight before installing but am afraid the force will be too much for the support I was going to rig. That is a little engineering project on it's own. A hydraulic press would solve that. Trying to track one down, I know where 3 used to be...

    About the CB shaft I have... the gear, bearings and seals all seem perfect. I have no idea how many hours on it, but it was kept on a lake for 8 years so it could be a couple/ few hundred. Would you risk using it?

  4. #4
    You aren't going to budge it with an arbor press. You will need at least a 10 ton press, or even 20 ton to do the job. It takes a 50 ton press to do the crankshafts. You will also not be able to heat the bearing enough to do the job without destroying it.

    And just a consideration, these things are dangerous to press if you do not have the right fixtures or experience. Having a heavy gear or shaft fly across the shop at 100 MPH is not a fun thing if you are in the path of it. It always scares me when these things let go with a bang even if they stay in place.

  5. #5
    retro jet's Avatar
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    Thanks Dood, that helps my course of action. I will get a rebuilt CB ordered and in the mail ASAP. I have a second 951 to build up and will look more at rebuilding the CB for that. I would hate to show up at a friend of a friends to use a press and have to kludge up some fixturing in a hurry. Maybe a 20 ton HF press in my shop future.

  6. #6
    canuck's Avatar
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    If you have a good hydraulic press it's easy I just did a 951 shaft and it took about 20 minutes. I bought two replacement bearings from a local industrial supply place and two new seals. I could not find a part number for the seals so I got the ones off a 787 counterbalance shaft as they are the same size, part number 420 930 392. Total cost for parts was about $50.00. Make sure to mark the end of the shaft and weight before taking apart so you can line them up on reassembly.

    I was going to buy an SBT rebuild but because I am an international customer they wanted my core shipped to them before they would ship me the rebuilt one and I did not want to wait that long.

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  8. #7
    retro jet's Avatar
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    I just got around to this. Using a buddy's older Harbor Freight 20 ton. I got the first side done easily. The second side galled badly with about 3/16 to go. At this point I decided to keep going. The shaft bent .012" as measured next to the gear with the bearings supported in V blocks. I took it apart to save the seals and bearings. Here is the galled weight and shaft.

    The manual suggests anti-seize and heating in oil warmed to 167F for the bearings. Nothing about the weights. The bearings were a looser fit and moved easily. The shaft has a lead in to help align the mark you make on the end.

    Heating the weight at a minimum seems required. Anti-seize on weight would help install, but would it hold?
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by retro jet; 10-07-2014 at 07:52 PM. Reason: clarity

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