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ReCasting Bushings with Polyurethane

Posted: Fri Oct 18, 2019 5:24 pm
by deskinthewoods
https://www.youtube.com/watch?v=2_0BYvTkZ0o

I’m going to give it a try...any thoughts?

ReCasting Bushings with Polyurethane

Posted: Sat Oct 19, 2019 2:20 pm
by Growlerbearnz
Go for it!

I'd use plastic instead of cardboard, or wax/grease the cardboard so it releases cleanly. Did you notice how he very carefully never showed the back side of any of the bushes? I bet they're a mess of ugly stuck-on cardboard. :-)

My only concern would be that they might end up transmitting more drivetrain vibration to the giant tin can that is a Delica shell. Still, new genuine bushes aren't *that* expensive, if it turns out to be a terrible idea you won't be stranded and you can revert to stock easily enough.

ReCasting Bushings with Polyurethane

Posted: Sat Oct 19, 2019 2:56 pm
by deskinthewoods
I’ll be using plastic for sure. I’ve got some of the chopping board stuff. Nothing sticks to it. I’ll try to document the process.

I checked the Shore scale for rubber tires which is 60A and ordered the same polyurethane.

Fun fun fun. Probably get to this next month sometime. Stay tuned...

ReCasting Bushings with Polyurethane

Posted: Tue Dec 31, 2019 11:55 am
by deskinthewoods
Here we go!...

So these are the transmission mount bushings:
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I placed a jack under the transmission to take the weight off the bushings
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and removed them. They came out fairly easily.
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I measured the position of the sleeves as they are not centered in the bushings.
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ReCasting Bushings with Polyurethane

Posted: Tue Dec 31, 2019 12:06 pm
by deskinthewoods
I cut out as much of the old rubber as possible with a utility knife
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and cleaned up the rest with a wire wheel in a drill. The bushings have an outer metal ring around the rubber that can be pressed out of the housing but I left it in in case this all goes south and then I can press out the whole mess. It only took about a half hour to remove the rubber and clean it up.
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I made up a couple of platforms from cutting board plastic (HDPE) as nothing sticks to that stuff. I drilled a hole to hold the metal sleeve, deep enough to have the sleeve centered side to side in the bushing
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I put a bead of silicon around the bushing housing and in the sleeve hole and let that set up for an hour

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ReCasting Bushings with Polyurethane

Posted: Tue Dec 31, 2019 12:10 pm
by deskinthewoods
This is the polyurethane product I used. The 2lb kit I got was $30 Canadian. Loads cheaper than the $400 for OEM parts.
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It's a simple 1:1 ratio to mix and has a 30 minute potlife.
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I leveled up my forms and poured
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Now I wait until tomorrow to see how it all worked out. 16 hours to cure....

ReCasting Bushings with Polyurethane

Posted: Wed Jan 01, 2020 2:44 pm
by deskinthewoods
And...SUCCESS!!!

They came off the form easily with just a bit of silicon to clean out of the sleeve
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The 60A Shore Scale polyurethane seems to have pretty much the same flex as the original rubber so I don't foresee any issues with more vibration.

And reinstalled
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Test drive tomorrow...

ReCasting Bushings with Polyurethane

Posted: Fri Jan 17, 2020 9:14 am
by lrp374
Now that you've had a few days to test them do they 'feel' much different from the units you replaced?

ReCasting Bushings with Polyurethane

Posted: Fri Jan 17, 2020 10:11 am
by deskinthewoods
As they are transmission mounts there isn’t much to feel. However, the clunk i used to hear/feel on acceleration is gone. 👍 :-D

ReCasting Bushings with Polyurethane

Posted: Tue Feb 18, 2020 10:17 am
by deskinthewoods
...and a month and half later, they are holding up beautifully...
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