What is a transmission mount?
The transmission mounts in a BMW are a common part that is frequently overlooked. They are required to do many things in the vehicle, yet are not quite suitable for those who actually drive their BMWs.
The transmission mount is designed to do the following:
- Help stabilize the transmission under vehicle load allowing the shifter to engage into gear properly
- Isolate vibration from the drivetrain to the chassis
Under engine load, the transmission can wiggle left and right slightly. This wiggle gets worse when the car is being driven in turns. This unwanted movement may potentially causing the driver to miss shift, a costly error which will always be considered driver error.
Solutions to a Potential Problem
With this unwanted movement, what are your choices as a consumer? There are some BMW factory mounts that can improve this situation. However, they don't fit all cars and only offer minimal benefits. There are race-type mounts which can stabilize the transmission so much, you can feel every last vibration. There are even other aftermarket mounts designed with reinforcements to make mounts even more stiff. You could probably even find someplace that offers solid aluminum mounts, for the diehards.
When we sought to have our own transmission mounts produced, we wanted them to be compliant for street use. We wanted to ensure that there were no compromises in performance, no extras to buy, just a mount engineered to do what we want without needless add-ons.
What we have is a transmission mount made from Neoprene rubber, with a completely different shape than the factory mount. The hourglass shape of the factory mount is not the best for stabilizing the transmission. By changing the shape to the cylindrical shape of the Rogue Engineering mount, it reduces deflection significantly.
We have designed this mounts to minimize unwanted transmission movement while maintaining vibration dampening characteristics. No additional adapters, mounts, cups, or braces are required for our mounts. To eliminate even MORE movement from the transmission, you must go to the root of the issue, the factory motor mounts. Unfortunately, BMW Motorsport motor mounts (if available), can cost over $500 or more.
There are companies out there pushing their solutions to unwanted transmission movement which are no suitable to street driven cars. Sure, solid aluminum or Delrin mounts product a nice, solid feel, but at the expense of tremendous NVH. In a racecar, this kind of noise and vibration is commonplace. However, in a street car, this is not acceptable.
Using external "cups" or bushings with "bolt-through" designs are excuses for poor design, over zealous claims, or just a way of promoting a gimmick. Being realistic about the amount of play at the transmission that can be minimized is important. Thinking these small bushings can eliminate it all together is unrealistic.
Rogue Engineering Transmission Mount, cut in half showing no bolts going through the mount.
A Simple, Affordable, Complete Package
The Rogue Engineering Transmission Mounts are sold as a pair, and come with Grade 8 Zinc plated hardware. Unlike other aftermarket mounts, the mounting plate and studs of our mounts have been Cadmium plated to prevent corrosion.
Currently, the transmission mounts fit the following vehicles:
- All E34
- All E36 including M3
- All E46 including E46 M3
- All Z3s include M Roadster/M Coupe
- All Z8s
- All E39 including M5s
- All Z4s
Application Note: Transmission mounts are NOT required or necessary for vehicles equipped with automatic or SMG transmissions.