Reply To: Shaking at High RPM Running 1955 Evinrude Fleetwin Aquasonic 7.5HP

[fisherman6]

As Fleetwin said, these are both damaged from the shock absorber being expanded. Neither of them appears unusable if cleaned up. The shock absorber from either of these would need to be compressed back to at least close to original size. If you do not weld the seam, it may work for a while, it may for forever if you don’t hit anything with the prop, or it might fail on you 5 minutes into the first run.

I know you said your broke the shock absorber from your original gearcase. While I’m not quite sure how that happened, you have another one now. My suggestion for getting this one back to a usable length is as follows. It may sound like hack work to some, but it will work and I can’t imagine breaking on using this method.

Take a length measurement of the shock absorber first. Open the jaws of a bench vise to allow the stub shaft that drives the pinion gear to slip through but still firmly support that half of the shock absorber. Sit the shock absorber on top of the vise jaws with the stub shaft hanging between the jaws. Using a brass hammer (maybe 2lbs) give the top half a couple good whacks straight down to drive the top half into the bottom half. Take another measurement to see what progress was made by the first try. A few strikes with the hammer is usually enough to get the halves back together. If the piece now measures the correct length stop. If it is still too long try again. If it doesn’t go all the way back to the correct length as it is not wearing against the bottom of the bearing carrier for the drive shaft, that is enough. It just may not work in another motor if it was swapped out later. If you are able to weld it, it can be welded now. That will prevent it from expanding / breaking later. If you are not able to weld it, you can try using it as-is and it may or may not work without issue from that point on. When you got the last one back to 6.75″ I’m sure that was good enough. If it was over 7″ you squeezed over 1/4″ out of it which nearly 100% of that should have been clearance if it came out of your gearcase at the 7″+ dimension.

If you do not have functional vise anymore, a hole large enough for the stub shaft to pass thru in a steel plate will also work. You just need to support the lower half of the shock absorber while you force the top half back into it. You do not want to apply force to the stub shaft that drives the pinion. That part is only designed to take rotational force. Not axial or side loading. It is pinned in place and that kind of force will damage it. I hope this helps.

-Ben

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