s14kev

We all know the rubber in 944 is a little worse for wear after 25 years. It’s not unusual to be able to swing the transmission a few inches left and right just with hand pressure it the stock transmission mount being the culprit. An unstable transmission will lead to bad shift feel at the least and to broken CV joints at the worst.

Solid transmission mounts are hardcore. Too hard core for a pansy like me. Numerous vendors (Lindsey, 9products etc) make semi solid versions but at considerable cost.

Tony Kelly posted his version a while ago which has been christened the ‘Kelly mount’.

https://rennlist.com/forums/5509238-post4.html

The ‘Kelly mount’ looks to solve the problem cheaply but I didn’t like the idea of permanently bonding the mount to the transmission cross member.

I just wanted to pack the mount with liquid urethane. First I started off with a standard mount. I had the mount and all hardware zinc dichromate plated first.

s14kev

Assemble the mount with the stock hardware.

s14kev

Tape up the mount with masking tape. I would recommend erring on the side of using a crap ton of tape as the urethane is pretty liquid and will leak through relatively easily.

s14kev

Once taped up, pick up some liquid urethane (I used a 1 pound pack of 80A hardness). Half a pound should fill a typical mount. Mix it up and fill the mount with it.

s14kev

Once set remove the masking tape and you have a budget version of a semi solid mount.

teamcrossworks

I love stuff like this!

Please update when installed and how it holds up after some time.

Thank you.

Nice job.

CurtP

How much of the factory rubber did you remove prior to using the urethane? I removed a lot - including the entire bottom portion that fits down into the recess of the crossmember. I used a spare crossmember to mould mine similar to what most people do, but I sprayed the whole thing down with mould release because I didn't want it permanently bonded to the crossmember either. When I bolted the mount in the crossmember, I added a washer between the mount and the crossmember. After it cured, I removed the washers. This allowed me to give a little bit of pretension on the mount when bolted in. Here's my finished project:

86 951 Driver

I just filled my mount with Windshield urethane. Seems to have done the job pretty well.

s14kev

I left the rubber alone. It's really just 2 half inch strips of rubber that hold the central portion to the frame of the mount. Filling it with urethane sets the rubber in a solid block of urethane with very little motion possible. Rubber bonds/vulcanizes to metal much better than urethane so I would consider it the failsafe. The urethane peels off metal pretty easy so if too much rubber is removed, I would be worried that the central metal post would come loose.

3M window weld works too. I've used 3M window weld before in other cars but this should be much firmer as it is hard to get every nook and cranny filled with window weld. The mounts I have window welded all seem to have some degree of air pockets depending on how complex the mount is. Plus the result is much neater and more factory looking with the liquid urethane.

andys-944

nice work

MB968

Can you purchase that brand of urethane in a lower durometer. I assume the 80A refers to it being 80 durometer on the A scale. I'd prefer something a lot softer, like 60-65 A scale.

CurtP

Yes, it's available in different durometers. I've been thinking about doing another one using a softer compound. It's available through McMaster Carr.

reno808

very nice wish all write ups were like this

MB968

Thanks for the info on where to purchase. I've used a 65 A durometer version of the 3M window urethane in the past. But, as said you do end up with some air voids even if you fill from the bottom and vent diagonally on the top.

When you installed the 90 durometer mount how much additional vibration/noise comes through. I use my car mostly as a DD and for touring the countryside around Portland, Or. So, I wouldn't mind a small amount of additional vibration/noise, but not much more. What kind of change do we get with solid transaxle mounts?

s14kev

I did this write up about a year ago. Mount has been holding up great. You can see pics of it here after having been in use for about a year:

https://rennlist.com/forums/924-931-...ggestions.html

I did not notice any increase in vibration/noise but then again my car is so damn noisy anyway (solid suspension mounts, coilovers) that I may not be the best judge. I would recommend the 80A hardness. I see no reason to drop down to 65 urethane.