Polyurethane engine mounts advice!
 

Making polyurethane mounts to replace the one I sheered the bolt off in the other day. Got my old RX8 motor mounts, cut the bottoms off and drilled the holes to release all the oil. Sanded and repainted them. Just need polyurethane to fill them with.
However in the USA people generally use 80a, 80a being the hardness rating. However here in the UK we use different measurements and I can't figure out what unit of measurement the Americans are using so I can get the equivalent here. I'm finding 2 part urethane on ebay fine, but its all in mPa.
Can anyone advise me on what I need to use? Thanks.
https://cimg7.ibsrv.net/gimg/www.rx8...f76b026f82.jpg

According to google 80a durometer is about 3.5mPa. 80A durometer seems pretty stiff, but the RX8 has totally different mount design than I have experience with so maybe it is fine.

Seems a bit off to me. This is the stuff i'm looking at.
https://cimg8.ibsrv.net/gimg/www.rx8...bdcb055695.png
Nothing makes sense lol!

Hardness is what you want to look at. Shore D = Durometer which is what the a in 80a means. So that stuff is 70-75a.

That sounds fine to me. 80a is quite stiff. 75 is stiffer than rubber. I just ordered it! Thanks for the help

Some urethanes have a cure time of up to 2 weeks. Be sure to let your mounts cure completely, before installing them. Also be sure it is a high temp formulation. Some have a max working temp of 135F. 180F is fairly common, and 225F is available.

I used 60A, when I filled mine and found it to be plenty stiff.

Here are some typical specs:
https://www.mcmaster.com/#urethane-c...ounds/=1e82640

Here is a good discussion of relative hardness (scroll down):
https://www.mcmaster.com/#about-rubb...dness/=1e827cm

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Done! That polyurethane sure does get hot. It set up hard in around 5 minutes. It says that its fully set in 30-40 mins. But I'm not installing them for a few days anyway. I'd prob leave them 24 hours.
​​​https://cimg8.ibsrv.net/gimg/www.rx8...054824e412.jpgtg

Looks like you did a good job. Let us know how they feel in the car and if they transmit a lot of vibration.

I just did this myself! I used 60 hardness and feel just a little more vibration but nothing crazy. These updated mounts plus new poly diff mounts got the 8 shifting to perfection.
https://cimg1.ibsrv.net/gimg/www.rx8...fb0432511d.jpg
https://cimg3.ibsrv.net/gimg/www.rx8...280fb8bc83.jpg
https://cimg4.ibsrv.net/gimg/www.rx8...fc913b603e.jpg
https://cimg6.ibsrv.net/gimg/www.rx8...4e7a2cd60b.jpg

Are you getting a lot of resonance or vibration with the solid engine mounts?