7.5 and 5.5 OMC lower units

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  • March 18, 2015 at 3:05 am #949
    opposedtwin
    Participant

      US Member

      ok, I know this has been discussed before but it’s a brand new day here at the aomci boards. 😀

      I own 3 of these motors and all 3 have the same problem. the shock absorber mashed and deformed the bearing housing and I know both parts should be replaced and are expensive and are somewhat hard to find so where does all that leave us as far as alternatives go?

      on all 3 motors, the shock absorber has a bluish end from heating up due to the friction I assume. but they are all 6 13/16 long and so should be within spec for a good one. I remember reading 6 3/4 was the correct length. OR would that 1/16 inch do it? what’s the longest you guys have seen them stretch to? I know it’s hard to tell if the shocks are bad, since the spring which breaks is on the inside.

      I have heard welding them is an option. do you remove the pin and the spring inside and then weld it to 6 3/4 exactly? where on the shock absorber would the weld go?

      based on this design flaw, I will probably stay away from them in the future. but in the mean time, how much of a sin is it to run them like they are?

      thoughts?

      scott

      March 18, 2015 at 3:52 am #12226
      Mumbles
      Participant

        All of the good ones I’ve seen measure 6 11/16" and yes, it’s tight in there so 6 13/16" will be too long.

        I use to press them back to size and braze them up but now I’m thinking they expand doing their job when the prop hits a log or something hard so just because they are stretched doesn’t mean the spring is broken. They can be pressed or mounted in a vice and pounded back to size. I’ve done several this way and they are working just fine. 😀

        March 18, 2015 at 8:49 am #12227
        chris-p
        Participant

          I would think making up an insert drive shaft should not be too difficult for a good machinist? Not sure. Then use a modern prop with hub to take any impacts. Just a thought.

          Until that day, I hoard all the good shock absorbers I find!

          March 18, 2015 at 11:00 am #12228
          frankr
          Participant

            US MEMBER PAY BY CHECK

            What Mumbles said. Not all of the ones that are expanded are actually broken. There really isn’t anything keeping them from expanding when they are in the "spin" mode, i.e. dredging up rocks. I’ve pounded them back together with good results when the spring isn’t broken. If you clean out the hole real good and get out in the bright light and look in, you usually can see the broken ends–if it is broken. Depends on where it is broken though, sometimes it is out of view.

            I’ve also used the new prop method. But you have to change the propeller shaft to do that.

            March 18, 2015 at 11:41 am #12230
            david-bartlett
            Participant

              Again what Mumbles said. Get a big vise and squeeze it back to proper length and run it some more. The two that I have squeezed back have stayed that way.

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