hi,
i am thinking to buy or to fabricate my own polyurethane motor mounts and i would like your opinions about what durometer to use.
can someone please post his experience or sugestion?

thanks

 

I've used 94A from McMaster and it wasn't nearly as hard as I thought. The durometer rating has different scales. The A scale is all softer than the D scale. So for instance a 70D will be harder than my 94A. So you gotta make sure that you check which scale the compound is on before you buy it. But in my experience 60-74D is usually considered for street use. 80 is "sport" meaning you'll start getting more NVH. If you try using anything over 80 it's just for racing because it's essentially solid

 

We make all of our out of A95 and they are quite firm. A95 is the same as D45. The following chart helps explain just how hard the various durometers are.

 

from my research i found out that most engine builders make mounts of 90A durometer.
but , many guys here in forum used from 60A to 90A.
So i am wondering how hard is the 90A and how soft is the 60A since i do not have experience in these materials and i will order a bar from internet.
here i need your experience.

from the chart i see that the 90A is about the Bowling ball hardness????
is the bowling ball too hard? (almost no elasticity?)

GodSquadMandrake, how was the ride and engine noise with the 94A?
"60-74D is usually considered for street use. 80 is "sport" meaning"
60-74D ?????? that is out of scale. do you mean 60-74A?
thanks

 

The 94A I had was still quite soft. I would say that it was maybe a tad bit stiffer than the Mazdaspeed transmission mounts. No major additional NVH and just a minor improvement in the stiffness. Yes I could hear the transmission and engine through the firewall a little more, and maybe my dashboard and mirror were shaking, but not rattling. I was comparing to a brand new OEM bushing so it wasn't like the comparison where someone takes off an old worn out bushing and puts in poly and "OMG it's magic". Overall I would say that I wanted a stiffer mount and I would've gone for something on the D scale the next time. I've had a car with solid mounts before and it was wonderful to shift through the gears. The downside is just the NVH.

I was using a 2 part poly compound from McMaster Carr. The thing about doing this is that if you don't get the proportions exactly right, it changes the end result. I just mixed the entire two cans together so I think it was correct, but it's possible that results may vary. I didn't let mine cure for the full 36 hours or whatever before driving it so maybe I messed it up. I took the mount out later and looked at the poly and it looked fine to me. It's incredibly stiff stuff and I can barely make a dent with my finger nail. But when the engine torque is applied, yes it moves quite a bit.

Achilles yes maybe I got the scale wrong.

 

The scales aren't linear. So A95 isn't as hard as a bowling ball. It is fairly hard though. One all of the cars we have installed mounts into, there is little if any movement of the engine. Mixing polymers is tricky and strict measurements and temperature controls are needed to get consistent results.

 

thanks guys,
i will try the 90A home made mounts and i will post my results.