mtnman82

Quite a few in the threads I read said they let it sit for 2-3 days. I took off the side dams last night late, before things got too hard, so I have a ~3/8" X 2" piece to play with. It was pretty hard this morning, and bounced off the ground nicely, but it broke when trying to fold it back over on itself. This afternoon it is significantly harder - it would take a lot more force to tear it or even fold it back over itself. I'll let you know after 2 & 3 days, which I'm thinking will be fine, but I probably won't get the tranny back in until next weekend anyway (oil & filter change/brakes on 2 other vehicles which have priority and I want to finish up installing injectors/fuel lines/resistors/chip). Here's a close up of how things turned out:

m73m95

How much HP are you guys running with this mount? I know its more solid than the stock mount, but how does it compare to a solid mount?

spoolin51

How hard can you go on the urethane?
I was looking at the 8644k19 ?
thoughts anyone

mtnman82

Like I said, at this point I'm 'only' looking for ~350whp/tq. I think I'm about 300 now (@15~16) psi. I'll let everyone know the difference in stiffness once the tranny is hanging on it, but right now I can't budge it with all my might - and it was easy to move before w/just my hand.

There was some talk of going with the harder (94 hardness) compound in another thread but I don't know if anyone's actually done that. That chunk I have to play with has gotten pretty darn hard, and still bounces off the concrete nicely.

spoolin51

How hard has the mount gotten?
i just ordered the 8644k18 .... Ill let you know how that turns out

mtnman82

The urethane has gotten really hard. It still bounces off the ground, but there's no way you could tear the 3/8" x 1" x 2" scrap piece now. Also, the thinner piece of scrap I have (~1/8" thick) will bend completely over without breaking now. Hopefully I'll be puting the tranny back in this evening, so I can let you know how it feels when it's hanging there. I expect it to be pretty solid, because there's no way to budge the mount by hand now, and I could move it easily before.

APKhaos

When ever this topic comes up there's always a question about, "Can I use a harder urethane?"
It's a free country, and you can use JBWeld if you really want to.
This is the urethane I used. Its rated at 80 Shore hardness, which looked like the best compromise between rigidity and resistance to cracking. It has worked well of several seasons of hard race use in my car.

mtnman82: They call 'em dams for a reason. Leaky dams are badness, but it looks like you mount is deep enough to contain the rubber components of the stock mount, which is goodness.

Good to see some more guys having success with this trick.

mtnman82

Yeah Tony, I really thought I had things sealed up tighter . But yes the urethane did still completely cover the rubber and fill up everything.

So, I wanted to prove to myself I could still turn a wrench in a speedy manner and proceeded to see how far I could get wth installing the tranny over a lunch hour. In about 1:15 I got the tranny back in and mostly everything bolted up - just need to slip & tighten the driveshaft collar (need someone to push the clutch so I can turn driveshaft & line up the bolts in the access holes to tighten), get the shift rod attached at both ends, and re-assemble the shift ****. BUT, in my mad rush I forgot to put the shift rod tube back in AGAIN (forgot when I put the clutch in and was going to install while I had things apart again).

With the tranny hanging by the mount and no axles attached I can't budge the tranny in any direction. Feels VERY solid to me. If I had to do it all over again, I'd still use this 80 hardness urethane. Like I said before, that scrap piece is very tough but still resiliant.