Master cylinder brace: Grimmspeed vs Perrin

[MightyMeeple]

Originally Posted by KelvinBRZ

Nope hahah, same old Prius tires that came stock 30k miles ago

I agree that there is a lot of travel - I wonder if the MC brace will fix that

Not sure the brace helps the travel, but from what I've read definitely firms up the feel. Get some Michelin pilot super sports on your car....instant acceleration/braking/ride quality upgrade!!!!

[Hyper4mance2k]

I made one for my Rx7 for less than $10 at home depot and it added more pedal feel than my stainless braided lines. Oh and it lasted over 10 years, and saw service on 3 first gens. I also made one form my FC and it saw service in both the FC's I have owned. I cant justify spending even $60 for less than $10 in parts.

[V_86]

Sorry to necro this thread, but @GrimmSpeed , if I have an auto and I want to keep the bracket for the AT harness, have others done this? Does it impact the performance of the piece?

[KDad2]

Originally Posted by V_86

Sorry to necro this thread, but @GrimmSpeed , if I have an auto and I want to keep the bracket for the AT harness, have others done this? Does it impact the performance of the piece?

I have the same, but I ditched the bracket. No problems with performance. I believe others just zipped tied the harness. But, I didn't even worry about that. It's fine as is. If you want to get creative, fabricate a new bracket.
http://www.ft86club.com/forums/showthread.php?t=21238

[GrimmSpeed]

Originally Posted by V_86

Sorry to necro this thread, but @GrimmSpeed , if I have an auto and I want to keep the bracket for the AT harness, have others done this? Does it impact the performance of the piece?

Yep, what KDad2 said (thank you very much). Either remove it altogether, ziptie the harness to the master cylinder brace, or fab up your own. It might be possible to modify the existing bracket to bolt on outside the master cylinder brace too.

Chase
Engineering

[V_86]

From the install guide it looks like we DO reinstall the fuel line bracket correct?

[GrimmSpeed]

Originally Posted by V_86

From the install guide it looks like we DO reinstall the fuel line bracket correct?

Correct, and that's why the brace includes the little provision for the locator tab on that bracket.

Nice, right?

Chase
Engineering

[RJasonKlein]

Originally Posted by Norville Rogers

Won't these just transfer forces from the strut mount to the master cylinder?


Something you'd really want to avoid?

That's an intereting question. My understanding is that the strut mounts deflect very little under normal loads, but that the firewall itself deflects much more so due to the driver's leg pressure on the brake pedal under heavy braking. I had assumed the stability of the strut mounts is what actually shores up the master cylinder, but that same stability prevents load from being transferred to the master cylinder in the other direction. Can anyone confirm my hunch?

[GrimmSpeed]

Originally Posted by Norville Rogers

Won't these just transfer forces from the strut mount to the master cylinder?


Something you'd really want to avoid?

Originally Posted by RJasonKlein

That's an intereting question. My understanding is that the strut mounts deflect very little under normal loads, but that the firewall itself deflects much more so due to the driver's leg pressure on the brake pedal under heavy braking. I had assumed the stability of the strut mounts is what actually shores up the master cylinder, but that same stability prevents load from being transferred to the master cylinder in the other direction. Can anyone confirm my hunch?

That really is an interesting question, and the simple answer of course is yes it will. That's just basic physics, every action will have an equal and opposite reaction.

However, how much force is really going into the master cylinder, and where is that force being going?

First, the fore and aft motion of the strut towers is very small, mainly because the strut towers are very strong in this direction. The large round shape of the strut towers makes them inherently strong, but more importantly they have a large anchor point to the frame on both the top and the bottom of the strut tower.. If you think about it, how the strut towers are mounted to the frame in the fore and aft direction is substantially wider than how they are mounted to the frame in the side to side direction. And to further reduce movement in the fore and aft direction they are braced at the top of the strut towers to the top of the firewall near the cowl (nice and sturdy there compared to lower on the firewall).

Now, what kind of forces are really acting on the strut towers at the point where the master cylinder brace is mounted? Well, you've got the springs and shocks reacting to what the wheel is doing mainly. And since there is a certain kingpin inclination to the shock (and caster) there is a component of force that can be resolved into two forces, one that could transfer to the master cylinder through the brace, and one that would be resolved into a completely vertical force up through the strut tower. However, since the angle of the strut towers relative to vertical is pretty small, the majority of the force is not going in the fore and aft direction, so you're looking at a very tiny bit transferring into the master cylinder via the brace.

In fact, you'll most likely see some of the largest forces in the situation where you are braking (forces going into the strut tower towards the master cylinder), and you're stomping on the brakes which is pushing the master cylinder right back into the brace. But once again the anchor point to the frame on the top of the strut tower and on the bottom of the strut tower, as well as the brace to the firewall is taking the majority of this force to the point that the force transferred to the master cylinder from the strut tower should be pretty much negligible.

That's just the super long winded way of saying that the strut towers are very strong in the fore and aft direction. Because RJasonKlein's answer was probably more than adequate. The firewall is very weak compared to the strut towers. And even if there was a substantial load coming through the strut towers and acting on the master cylinder brace the firewall would just deflect to absorb the force just like it does every time you step on the clutch or the brakes (sans MCB).

We have thousands of master cylinder braces out there in the wild across many many different vehicles. Not a single one has ever resulted in a failure of the master cylinder, or strut tower, or firewall. The transferred force is non-destructive even when it is at it's maximum.

Make sense?

Chase
Engineering

[RJasonKlein]

Originally Posted by GrimmSpeed

Make sense?

It sure does, and I can attest firsthand that a master cylinder brace firms up the brake pedal substantially. Thanks for the explanation - it was exactly what I was looking for!

[GrimmSpeed]

Originally Posted by Norville Rogers

So it does transfer vibration and stresses from the suspension system to the brake master cylinder.

But it's OK?

The forces transferred are very very small, so yes. And the amount of vibration transferred is no different than what the entire rest of the car is experiencing as a system, so again, yes.

The majority of forces from the suspension (which is mainly the up and down motion which is the already dampened component of the spring/shock combo) is mainly locally acting upon the frame (the lower rail and along the upper fender). A very very small amount is acting where the master cylinder brace. And the component of vibration is nearly null. It experiences no more vibration than any other component on the firewall.

It isn't as if the Master Cylinder Brace turns the master cylinder into a load bearing component like a strut bar or anything, there are no harmful effects to worry about at all.

Chase
Engineering

[ItsReiko]

Sorry to revive this old thread, but @GrimmSpeed, can you confirm if your brace works on 2017+ model brz's?

I noticed someone on one of your product reviews mention that there is a "change to 2017 model that may require an update to the design where a wire loom bracket on the first hole cannot be re-used with the brace in place."

Just wanted to make sure this would fit before I made the purchase. Anyone who have added this piece to their 2017+ and can chime in would be appreciated.

[Rail]

Originally Posted by ItsReiko

Sorry to revive this old thread, but @GrimmSpeed, can you confirm if your brace works on 2017+ model brz's?

I noticed someone on one of your product reviews mention that there is a "change to 2017 model that may require an update to the design where a wire loom bracket on the first hole cannot be re-used with the brace in place."

Just wanted to make sure this would fit before I made the purchase. Anyone who have added this piece to their 2017+ and can chime in would be appreciated.

I've been running the GS brace on my 2017 for a couple years now with no issues. Very nice piece of kit.

[Contender]

I have this one...works good.

2020 PQY Brake Master Cylinder Brace For Subaru BRZ / Scion FR S / Toyota 86 Black With PQY Logo PQY HBM01BK QY From Guolipanqingyun1, $18.14 | DHgate.Com
https://www.dhgate.com/product/pqy-b...542284855.html