9.9hp/15hp - Upper Thrust Mount - Rubber Durometer?

[JohnnyGuy]

Hi All,

I am in the process of creating some 3D printed moulds to pour some new polyurethane bushings to replace the worn out rubber ones for these upper motor mounts (P/N 386033 --> 436469).

I'm wondering if any of you might have a guesstimate as to what durometer the original rubber mounts might have been.

I think I've got it down to either Shore 60a or 40a.
40a is compared to a rubber pencil eraser.
60a is compared to the tread of a rubber tire.

I'm looking to order the material to do this project and I just thought I'd check here for opinions before I place the order.

Thanks in advance.
JG

 

[Bosunsmate]

Id go 50 if that was an option! sorry

 

[JohnnyGuy]

Id go 50 if that was an option! sorry

:lol: No doubt that would happen! haha
Thanks!

 

[JohnnyGuy]

I just thought I would provide an update on this.

I created some 3D printed molds and poured the Shore50a Polyurethane and it turned out quite well, initially...

My first attempt when I de-molded, the inside shaft was not adhered to the poly bushing that I had poured.
I had sanded down the shaft after removing the rubber from the original bushing from it, but I had handled it alot prior to pouring so I thought I'd clean in acetone before attempting round 2.

Round 2 was better, but upon installation of the bushings into the exhaust housing and pushing the housing back and forth to examine how they were working, the inside shafts of the bushing came unadhered from the poly. At this point I decided to look for a pre-manufactured, press-in poly bushing.

Upon looking for a bushing with similar dimensions, one of the closest I could find via the internet was a sway bar link bushing for a 2004-2006 Pontiac GTO (Whiteline W23034 - $25CAD from my local autoparts supplier).
I was able to get these bushings pressed into the mount with a vise. The inside shaft provided with the kit has a slightly large O.D. and I.D. and is slightly longer than the original shaft. Since I work with a millwrighting company through work, I had them make me up two new aluminum shafts to match the length and I.D. of the original and the O.D. of the shaft that came with the kit. The PU was pretty tough to cut with a utility knife so I used my oscillating tool to trim away the extra length of the bushing.

The end result of the mount with the bushing pressed in is as per the photos; its not "pretty" but I hope to never have to see them again.

I will likely install them this weekend, at which point I'll try to remember to provide an update following installation and then again following operation of the motor, in hopes that this may help someone in the future.

I'm really hoping these work as they should last the lifetime of the motor, not like the OEM ones that are disintegrated on most of these older 9.9/15's.

Any thoughts, comments/recommendations are appreciated.

Cheers,
JG

 

[flyingscott]

Go to leeroys ramblings he tells you how to make them.

 

[JohnnyGuy]

Go to leeroys ramblings he tells you how to make them.

That he does.
However I wanted to use PU for its chemical resistance, since the issue seems to be with the vulcanized rubber used in the original mounts.

It deteriorates due to the exposure to the exhaust (gas/oil, etc).

 

[Dizz]

I think they look great
sorry haven’ Posted in many years
all the great old motors will do this in time
mine failed on my 91 electric start Evinrude 15 four years ago on a trip away from home
after some research with price of mounts and concerned I’d have issues with getting gaskets I did LeRoys Red neck repair
works great but I did add some rubber insulators in my version
i also a redneck repair on gummy throttle grip with monster shrink tube.Lastly my kill switch went bad and a simple toggle switch fixed thaty motor has kill switch halfway up handle
Good luck!