GrimmSpeed Street Transmission Mount - All Subaru 5MT and 6MT


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GrimmSpeed SKU: GRM123041STR

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Lock Down Your Drivetrain for More Predictable Shifting!

OEM chassis mounts are usually designed with the top priority going to low NVH (noise, vibrations, and harshness) and low cost. This means that there is a huge opportunity when you are trying to increase performance. Made to compliment your GrimmSpeed Pitch Stop Mount, our Transmission Mounts will dramatically stiffen up the feel of your drivetrain, allowing for more predictable shifting and greater confidence during spirited driving.

The core of this upgrade is 75A durometer polyurethane bushings, which keep the transmission from moving under high torque without transmitting excessive drivetrain noise and vibration to the chassis.

This part retains OEM fitment for almost all AWD Subaru manual transmission setups. There is a minor difference between the 5 and 6 speed models, but it is an easy fix by using the included 5-Speed Adapter Spacer between the stainless steel bracket and transmission cross member. 

Install is a breeze since we use an OEM-inspired press-fit stud in the stainless steel bracket. This minimizes the risk of misalignment or damaged hardware. Our Transmission Mount will arrive fully assembled and ready to install, and all required mounting hardware is included in the kit.


From the factory, Subaru offers multiple levels of their own transmission mounts, with the softest being the WRX, OEM STI in the middle, and then Group N as their stiffest option. But even the Group N leaves a lot of control left on the table.

With the 75A durometer bushings included on our Transmission Mount, ours are 2 times stiffer than the Group N mounts, which makes them 5 times stiffer than the stock STI mount, and a staggering 16 times stiffer than the stock WRX! That means that the improvement in transmission and drivetrain control will be felt coming from any of the factory options.

Even though this setup is designed to feel right at home on a track-prepped vehicle, there is no need to fear daily driving with it. We have tested a variety of bushing stiffness's and found that these offer the best balance for on-road use, making certain that there is a minimal increase in NVH during normal driving. 


  • Robust 6061 Billet Aluminum and 304 Stainless Steel Construction
  • Red 75A Durometer Bushings for Reduced Transmission Movements and a More Solid Shifter Feel
  • Compatible with both 5-Speed and 6-Speed Manual Subaru Transmissions
  • Kit Includes and Adapter Spacer Required for Proper Geometry with 5-Speed Manual Transmissions


  • 2004-21 Subaru STI (6MT)
  • 2002-14 Subaru WRX (5MT)*
  • 2015-24 Subaru WRX (6MT)*
  • 2004-08 Subaru Forester (5MT)*
  • 2005-09 Subaru Legacy GT (5MT/6MT)*
  • 2005-09 Subaru Outback XT (5MT)*
  • 1993-22 Subaru Impreza (5MT)*

*Not compatible with 4/5 Speed Automatic or CVT Models

The GrimmSpeed Transmission Mount is only compatible with AWD Subaru transmission, meaning they are not compatible with the RWD Aisin AZ6 transmission found in BRZ/FRS/86 models.


Coming Soon