I’ve been monkeying with old Bavarian cars for about ten years now. In that time, I’ve been able to test a lot of the tried-and-true “upgrades” folks seem to perform to these cars. When the 328 received its s52 swap 3 years ago, I saw how dinky the stock transmission mounts were. The s52 is by no means a stop light drag motor, but 240 horses and torque will eventually take a toll on the rubber drivetrain mounts.
For years on end, the street friendly transmission mount upgrade was to use e21 mounts with metal enforcer cups. The philosophy behind the e21 mounts is that they’re denser rubber less prone to deflection, as opposed to the flexible hourglass shape of the stock mounts. Throw in the stereotypical transmission leak and the stock mounts get extra soggy, and much like Reese Bobby, they don’t do too much in the way of being supportive.
When I first installed the e21 transmission mounts three years ago, I thought they were overkill for my needs. Nonetheless, I installed them and felt the improved throttle response, but within a couple of days, I didn’t appreciate the metallic vibration caused by the enforcer cups. Having my deep socket 13mm still handy, I pulled the transmission brace off once more and removed the metal cups from the transmission mounts. Bingo, my problem was solved. I had no NVH issues and stiffer mounts…or so I thought.
A few days ago, I had the 328 up on jack stands to give everything a routine checkup. At nearly 270k miles on the chassis, it’s always a good idea to keep up on maintenance, because the last thing I’d want is to be stranded somewhere between King City and Paso Robles in triple digit summer heat (Better pack the Coppertone!). When I pointed the flashlight on the transmission, I was disappointed to see my “heavy duty” transmission mounts look more like mushrooms on a leftover pizza. To be fair, this is a classic case of user error. If I had left the enforcer cups on the mounts, they wouldn’t have deformed like they did, but ruined in less than three years? Ouch!
Knowing this needed to be addressed, I took a gamble and went with Rogue Engineering’s upgraded rubber transmission mounts. At a little under 60 bucks, there’s probably better ways to spend money, but Rogue’s claim is that their rubber transmission mounts are as beefy as they come for a street car. They’re a direct replacement for the stock mounts, so they swap right in with a few minutes of work. Since I had to enlarge the holes in my old transmission brace, I purchased a new stock e36 M3 transmission brace. This way I could have the new mounts installed on the brace and swap everything as a unit. With the car up on jack stands, a 13mm wrench and rachet with a deep socket was all I needed for this procedure.
Way Too Easy
Once I had the old brace and mounts removed, I was a bit astonished to see how trashed the e21 mounts were. There were lots of cracks in the rubber, and the mounts appeared to have collapsed by 1/8 inch. I felt it was a good thing that I changed the mounts when I did, as I was probably running on borrowed time. With the old mounts off the car, in went the new brace with the Rogue Engineering mounts installed. All the nuts and bolts were tightened up, then the car was back on the ground.
Starting up the car, I didn’t notice any additional vibrations, so that was a positive in itself. The mounts needed to settle into their new home, so I took it easy for the first ten minutes before hopping on the freeway. Once it was time to give the car some stick, I could feel the transmission didn’t rotate as much, ensuring a more planted driveline. The by-product of this being that gear changes felt noticeably tighter. Who knew that mushy transmission mounts could cause so much shifter slop?
Overall, I’m happy with my purchase. It was a relatively simple job, but it made enough of an improvement to justify the time and cost. That’s not to say the e21 mounts are a poor choice, but you definitely need the enforcer cups to prolong their service life, and they’re not that cheap as in years past. The Rogue units by contrast are more of a purpose built solution to BMW’s notoriously soft transmission mounts.
Products like the Rogue Engineering trans mounts are part of the fun of owning an older car. With a multitude of specialty manufacturers, you can upgrade and improve these cars all you want. Of course there’s always the debate of whether to keep things original, but I’m pretty sure a 21 year old 328is with over ten times the Earth’s circumference on the odometer isn’t going to be winning the Pebble Beach Concours any time soon. But I certainly wouldn’t mind a parking spot on one of those perfectly manicured fairways. Fore!
Want to try a set of upgraded transmission mounts? Here is where you can get them: