Grimmspeed MCB BRZ FRS header

GrimmSpeed master cylinder brace review for Subaru BRZ and Scion FR-S


A master cylinder brace (MCB) is one of cheapest and noticeable modifications you can install on your car. But what is it and how exactly does it work?

Basically, a MCB prevents the firewall from flexing and moving the master cylinder under hard braking. The master cylinder is responsible for changing your foot pressure into hydraulic pressure used to activate your brakes. Here’s an animated gif showing how a master cylinder brace works.

GSBrace gif
Photo credit: Grimmspeed

If you drive like a normal person in every day traffic, you won’t benefit from a brace. However, if you drive hard on the track or on backroads, I would definitely recommend getting one.

Today, I’ll be reviewing the GrimmSpeed master cylinder brace for the Subaru BRZ and Scion FR-S.

Build Quality and Installation

GrimmSpeed’s brace comes with several different parts in the box. You have a red anodized aluminum “force distribution cap,” the brace, and various other hardware. While not as simple as Perrin’s MCB, it’s not overly complex either.

To make the installation easier, you can remove the driver-side strut tower bar but I didn’t find it was necessary. If you do remove it, just be sure to toque it back down to 12 foot-pounds.

Before brace

Mount the brace to the car first with a 10mm wrench. Then grab the tensioner rod and make sure allen key is facing down. From the top, thread in one of the two nuts and place the red cap on top of the rod. Use a 5mm allen key to hold the tensioner rod in place while tightening the nut closest to the driver with a 15mm wrench. To set the proper pre-load on the brace, do a full turn of the nut once the red cap is in place. Lastly, tighten down the second nut (15mm) which faces the front of the car.

There’s no need to use a torque wrench for installation since the loads on the brace are relatively small. Just use your judgment and don’t over tighten.

For a more visual installation guide, check out GrimmSpeed’s excellent video below.

In Use

I haven’t taken my car to the track or done any auto-cross yet but I do drive the local backroads frequently. The brakes on the BRZ are very good stock and provide a lot of feedback. Still, if you’re on the brakes hard, it can be difficult to judge how much force you can apply before triggering the anti-lock braking system (ABS).

GS MCB top view

With the GrimmSpeed brace installed, braking is firmed up under hard braking and I now have a better sense of when ABS will trigger. It’s much easier to modulate the brake pedal to get exactly the amount of braking force I want.

In ever day street driving, you’ll forget the brace is there. You won’t be able to feel it.


GS MCB installed

For about $100, the GrimmSpeed master cylinder brace is a no-brainer if you want to improve the braking feel of your Subaru BRZ or Scion FR-S. There are other braces out there and they will all provide identical performance. I like the GrimmSpeed brace because it adds a little bit of flair with its red cap and logo cutout.

Plus, Grimmspeed does tons of research and development before releasing a product. They constantly engage the FT86club community before releasing a product.

I’ll be purchasing and reviewing more GrimmSpeed parts in the future so stay tuned.


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