What this is: A cheap and functional option for most street/daily/autoX engine-mount needs (I’d wager track needs too but some prefer feeling the rpms with their spleen). This involves using the eFocus RMM, and filling the OEM PMM and TMM with 60 duro Forsch urethane from McMasterCarr. I do not believe anyone has documented urethane filling the OEM TMM, and certainly not the OEM PMM, which is odd given our platforms age, but I guess the ingrained coolaid of buying one of the 5 aftermarket options is pretty strong. Then again, we’ll see how this holds up after 10-20k miles. Don’t imagine the TMM would be worse than the CS insert, the PMM is the big question mark. What it costs: Around $80 for a stock ms3 - you buy the EFOCUS RMM and bolt, 60 Duro urethane from McMasterCarr, and some ductape. 1) eFOCUS RMM: ~$25 shipped aftermarket version (02/07/2022 - $18.50): www.amazon.com/dp/B00W3SFJO4 You will need to get a bolt that fits the RMM’s thread, I had taps available so I re-tapped it for m12x1.25, and bought a juicy stainless 80mm long bolt for like $10 (titanium versions are now like $15 if you really wanna be that guy). 2) 60Duro Urethane, 1lb kit: ~$40 shipped: https://www.mcmaster.com/8644k24 3) Ductape What you’ll need to do: Realize that the urethane takes at least 3-5 days to completely cure (7 per the manual) in 77F temps. I know people put them in after 48hrs, but I’d do it right and let it cure for at least 3-5 days, and longer if it’s a cold curing location. This means being able to park your car for 3-5 days while the PMM and TMM are out curing, or buy them new, to fill with the urethane, and swap em over in about an hour when done. Step 1) Get the RMM, figure out the whole sideways bolt situation and install it. It’s not getting filled with anything and I have had one last about 100K miles without deterioration - they are solid rubber, aluminum body, seem to last a very long time. They restrict movement and don’t add NVH. The vertical bolt holding it into the subframe is the stock one, re-used. The sideways one will have to be obtained separately. I believe it’s 75-80mm long, but I can’t remember the thread of the eFocus mount, so someone can comment or figure it out when you have the mount. Step 2) Get the TMM and PMM ready – If new, just clean with rubbing alcohol, if using old ones, clean them well and then clean with rubbing alcohol, as the urethane needs to stick to all kinds of inner rubber/metal surfaces of the mounts. Take the bottom square rubber/plastic piece out of the TMM, it’s taking up precious urethane space. Step 3) Tape off the mounts as follows: a) Tape the back of the PMM (the side that faces the fender is the back) - you will be filling that mount by putting it down on that taped side and pouring urethane into the side that faces the engine. b) Tape the top of the TMM, and ensure you tape up the bolt/guiding pin holes and the bottom has tape to wall off the square space of those holes. You will be filling that mount by putting it down on the tapes side (technically the top) and pouring the urethane into the bottom of the mount, and it will flow down to the top side in addition to filling out the parts you see filled with the Cork Sport TMM insert (See their site for good pix). c) Ensure the tape job is good or your urethane will leak out and go to waste. Extra layers of tape on top of tape seams cannot hurt. Step 4) Ensure the mounts are laying horizontally and fill them with urethane. The 1lb urethane kit allows for both mounts to be filled and even some of the hollow portions of the PMM be filled, as you’ll see. Step 5) Wait 5 days. If you effed up taping, the urethane will have partially flowed out of the poorly taped seams and you may need to buy another kit to fill it up more. This will unfortunately waste most of the new kit, unless you have a buddy who needs just one mount or a small dildo mold filled. The leakage (phrasing!) will usually stop after 5-8 hrs, after that you can see if you need to order more. After 5 days take off the tape and mold inserts. Step 6) Re-install the mounts and enjoy vibeless, practically movement-free engine mounting solution for the cost of less than a single ebay RMM. Pics attached roughly in the sequence described above. Your gf may leave after car no longer vibes. Deal with it. Hairy palmer. Tips: 1) Install the PMM first, as it’s the easiest one (unless your fasteners are super rusty). 2) When installing the TMM, if you happen to have to install the transmission mounted bracket (say if you had aftermarket mounts and are swapping in all OEM parts), do NOT forget to put the transmission cable back into its bracket, before reinstalling the battery tray. Shifting will suck until you fix that. Which involves taking the battery back out, and omfg the feels of fail are just not worth it. Asking for a friend. 3) This urethane has been tested on rats, guinea pigs, and rabbits. Amaze. 4) 02/07/2022 - 25K mile update - Mounts still holding up well. Next update @ 50k.
I recall 1 or 2 people trying this years ago on MSF, but they didnt last. Probably because as you pointed out, the cure time is quite long. It would be interesting to see how these work for you.
One other thing affecting the durometer mix is the temp operating range. I just looked and the Forsch mix I got max is like 170F. Engine bays see close to that and it may affect longevity. There are other duro mixes that can be had with better temp ranges. Time will tell.
