garrett376

After installing WEVO engine mounts, I wanted to stiffen the transmission mount. There are stiffer C2 tranny mounts available, but nothing for the C4. Well, with a little epoxy, you can turn the existing C4 mount into a much stiffer mount.

The original mount has openings in the rubber bushing to permit movement of the rubber in various directions - most heavily reinforced to support the fore-aft movement based on the alignment of the rubber supports. Using plastic methylmethacrylate epoxy resin, I filled the gaps in the bushing. Now the bushing movement is permitted only by compression of the rubber itself, versus the rubber moving through the spaces in the bushing.

There are only 3 bolts on the bracket, and 1 bolt on the bushing itself to remove the bushing support. In order to get it loose, the transmission cross-member 6 bolts also need to be removed. Those are on at 34 ft-lbs - not too tight so they're easy to remove. Just support the tranny with a jack and it's easy to get it all off and back on.

The epoxy needs 4 hours to set, so I have not driven the car yet, but it will hopefully add to the driveline stiffness. Looks good to me

KirkF

Cool idea.

Is that like regular 2 part 5 minute style epoxy?

Looks good to me. I can't see why it wouldnt work, unless the mount shifts around so much it pops the epoxy out.

How are the Wevo mounts holding up? I was planning on ordering a set next week.

Kirk

springer3

Great idea. RTV comes in various hardness grades, and perhaps can be used to tune the bushing for a little more compliance. You may feel a bit more high-frequency with solid epoxy around the rubber spider.

Your rubber is cracked on two of the spokes, so you salvaged a failed part if you are pleased with the result.

garrett376

Hi Kirk - yes, it's called "Plastic Weld" 5-minute plastic epoxy that I got from the auto parts store for about $4 per dual-syringe. I used 2 syringes to get it all filled up. The stuff is supposed to bond to the rubber, so I think those pieces popping out would be a small risk... but I'll keep you posted!!! The WEVO's are working perfectly - I need to put on a stock exhaust so I can tell how much of a difference they make on engine noise inside the car. Right now the exhaust/intake is so loud I can't tell if any of that noise is due to the mounts!

Springer - yep, I figured this was a good way to salvage my cracked mount since a new one is definitely more than $8, and I may have gained some signifcant drive-line ridigity this way.

ttAmerica RoadsterAWD

Hey Garrett. Thank you so much for hosting a get-together BBQ. Celina and I had a great time. Good to connect avatars with faces and even better to share a beer and talk shop!

Great Idea. Thinking outside the box.... I like that.

Jaime

Oddjob

Is that type of epoxy hard/rigid, like a JB weld, or does it retain some plasticity when cured (ie: is it brittle, or still somewhat flexible/pliable)?

garrett376

Hard/rigid - but any plastic has some flexibility; although I wouldn't say it's brittle.

frankvan

So it's been 4 yrs - any updates on this experiment?
Looking at going the Wevo engine mount route, and wondering about the other end of the member...

ChaseN

I've used window weld to achieve the same on BMW shifter support bushings. Works great.

Chase