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DIY Polyurethane mounts bushings options

8683 Views 7 Replies 4 Participants Last post by  Lumberg
Hey guys, I was researching polyurethane options and I thought I'd share what I found.

  1. 3M Window Weld
    • Medium findability (not avail. at my local parts store)
    • Price: ~$11
    • Hardness--60A
    • Lots of examples of use
    • Cure time >= 24hr
    • Thick applications don't cure well
  2. Caulk type application from Home Depot/Lowe's
    • Easy to find
    • Price: ~$5
    • Hardness unknown
    • One example of use
    • Cure time >= 24hr
    • Thick applications don't cure well
  3. Professional 2-part mixture
    • Hardest to find, many examples out there
    • Price, high--ex. $40-$65 / lb
    • Hardness varies, have found 87A and 97A
    • No examples of use, but recommended as best choice.
    • Cure time = 6-12 hr (functional)
    • Thick applications cure fine

Since I own my own business, I checked out Grainger and signed up for an account. I purchased a product called Flexane, which, unlike the other products, is specifically designed for creating/repairing worn/torn rubber parts. Here are some links to the mfr. website:

I went with the putty because a) I figured it'd be easier to work with and b) it's the softer of the two (87A vs. 97A), and people have reported good results with the even softer Windo Weld (60A).

It was $42 out the door for 1 lb, and it comes with a smaller curing compound bottle, a larger main can, and a short wooden stirrer.

I know it's higher priced than the Windo Weld, but I think it's got enough advantages to be worth it. Quicker cure time, higher hardness and durability, and not dependent on external environment to cure (the other kinds, being one part, need to be exposed to humidity and/or be able to evaporate their solvents to harden).

Note that the mfr says you can put the stuff into light duty in 6-12 hours, but that the full cure time is 7 days. But I am pretty sure that letting it dry overnight in your house and driving gently for a week would lead to a great outcome.

Also of interest is another product called Flex-Add Flexibilizer, which can be added to Flexthane to customize the hardness to durometers below 80A--all the way down to 43A (OEN rubber is ~50A).

You can also purchase a curing accelerator, which is pretty cool, as it allows faster curing and curing down to 32F.

I need to do my rear mount, which is going to be a bear, but I think I'll try it in my dogbone first (it's not broken, I will just fill in the holes) to get familiar with it.

Please add your comments/suggestions/etc.
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I think the more expensive kit will work best, and trying it on your dogbone mount will be a good feeler for how tough it is. :thumbup:
I'm still waiting on some junkyard motor mounts so I can start experimenting.

Thanks for the comment.

Part # 8644K11
80 shore polyurethane resin kit. 20 bucks.
I just did the deed. Note my Camrys are dead so I did it on my 2002 Suzuki Esteem (also called Baleno).

There are three motor/trans mounts. Pretty much corresponding to a Camry's.

There is a middle crossmember from the lower rad support to the subframe to which are affixed the front and rear motor mounts. All four are round.

I did three mounts with the Flexane and it sets quick. It says that the 'pot life' is 20 minutes but it's more like five.

One of my motor mounts was cracked, the others were fine but I filled in the spaces with the putty.

My arms and hands are tired as hell from working it, it says to mix it vigorously for two minutes then transfer to another container and mix for another two minutes. By the end of four minutes it was about done. On the first mount I kind of dripped it in but on the next to I had to try to stuff it into the gaps.

Anyway the good news is it will probably cure much quicker than advertised (overnight to become rubbery--more like 5 mins), 70-95% done in 24 hours, and done in 7 days (or 24 hours @ 150F). They are sitting in my oven at 170F (lowest setting). After I clean up a bit more I am going to turn off the oven and take a nap. Within a few hours I'll reinstall the mounts. I'll try to hold off on 'spirited driving' for a few days but that will be tough!
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I will be interested in the outcome. Did you just press as much of the putty into the cracks and crevices or did you apply it differently?

The primary effect or outcome is that the idle shakes the steering wheel like the dickens up to about 1200-1500 RPM in drive gears. It goes away in neutral/park.

While driving, I feel much more in tune with what the engine and trans are doing--more in touch with the road, too. I can tell exactly when the trans is up or downshifting at all times now (for example if you are accelerating hard and then all of a sudden lift off--as you're coasting the trans will upshift again if it's not already it top gear).

Overall I am happy for solo driving but "shudder" at the prospect of carrying passengers. haha get it?
I will be interested in the outcome. Did you just press as much of the putty into the cracks and crevices or did you apply it differently?

On the one that was broken, I made sure to put it in the tear in the rubber as well as packing it in. On the others I just packed it in as best as I could as it was already stiffening.

I imagine that there's an air bubble or two, but the effect is more or less the same as a solid disc of polyurethane.
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