I've never been happy with any solution I've seen or tried for bracing the brake master cylinder. There are quite a few solutions that work fine. But as many of you know, I strive for form as much as function. Every time I installed or fabricated a master cylinder brace, I kept feeling like they were too ugly or too hard to install. The last time through this process I finally designed something that I'm really happy with.

My new brace installed in about 10 minutes start to finish. It doesn't require a welder or any other special tools. It's been tested with a 19mm master cylinder, but according to my research, it will work with a 17mm as well. It only work with the steel crossmember. If you've got the aluminum 911 crossmember, you're out of luck (unless there are enough people to warrant R&D). It may require slight modification of the 'belly pan', if you're running one. (EDIT: I was able to install an unmodified belly pan on the prototype car without modification)

Here is the prototype unit. There's not much that will change in the production version. They will get some sort of finish (paint, powdercoat, plating) and the 8mm bolt pictured will be replaced with a section of solid 8mm rod, welded in place. Also, the M6 bolt, with use an allen head for easier installation.

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Sale price will be $60. I'm leaning towards plating them, even though this will add a couple weeks to the build process. I'd like to get an idea of how many people would be interested in these so I can get an initial production run that will cover everyone and still give me stock for 6 months or so.

So who's interested now? And who's interested 'sometime in the future'?

What prevents this from turning downwards under braking? Just the pressure on the cross member?

Seems like this could easily slip downwards?

Sign me up. How is the belly pan modified?

Thanks

David

A cup for the end of the master cylinder (instead of the notched cut) would stop that from happening!

I installed this actual unit in a car this morning and had my employee mash the pedal while I was underneath to watch. Zero movement. I literally couldn't tell when he was on the pedal.

Win... But naturally, I'll want it powdercoated before it goes on my 914

Sure beats the muffler clamp I have wedged in front of my MC. Was a temporary patch and it's been on there for 4 or 5 years now.

I'm leaning towards plating because the brace fits so tight that the additional thickness from the PCing may make it not fit.

i'm in for 2 - perfect timing : )

May need a dented section where the brace sits to actually have the bolts fit.

I'll take one.

When i said "slip downwards" i did not mean the MC inside the brace.

I meant what stops the brace from rotating downwards on the cross member (See red arrow in picture below)?
From the looks of it the only thing preventing this is the pressure you generate between the MC and cross member by turning the bottom bolt.

Since the force from the MC when the brakes are applied is pointing downwards at the tip (See green arrow in picture below), i am wondering if there needs to be something to prevent the brace to rotate, other than friction.




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You drew a perfect force vector. See where your green line intersects the lower 'tooth' of the brace? That's what keeps it from going down. The master cylinder is contacted on three sides. Once the M6 bolt is tightened, the B portion of the brace is firmly clamped against the master cylinder.

The blue arrow is also a contact point.

I honestly can't fathom how it could slip down. You have tension forcing the A-piece firmly against the cross member. You have tension forcing the B-piece firmly against the master cylinder. The lower 'tooth' on the B-piece would have to break off in order to allow any movement, and even then, I'm pretty sure the blue arrow contact wouldn't allow.

Can anyone else understand what Andy's trying to say and help me out? Or can anyone understand what I'm trying to say and set him straight? I'm so

Oh, and I have to keep reiterating that I've seen this installed and under load and there is no movement. In fact, if you were to keep tightening the M6 bolt, you could probably press the MC into the passenger compartment.

Maybe this is the missing piece of info. That M8 bolt (to be replaced with solid M8 rod) goes through both pieces acting as a hinge.

Cool Widget !

Shoot a u-Tube video of it under load for the people in doubt.

I would be interested in seeing what has to be done to the pan to run it.

I like the no welding, no hose clamping installation approach !

With it using that C shaped section to help with the brace, I wouldn't powder coat it.

As much as I like powder coating, it has been a problem in fits like that as it can cause clamping or friction fits like that to spin. It uses the layer of powder as a slip point.

I understand what you're trying to do but this all comes down to the contact point on top (your blue arrow).
If the fit at that point is not perfect and there's any play there between the top wedge and the MC, the whole assembly *can* rotate on the cross member precisely *because* it is hinged at the top.

The centerline of the MC lies below the center line of the cross member, so any force working downwards on the tip of the MC is trying to rotate the whole brace and (with enough force) the top hing would allow it to do so unless the contact at the blue arrow is perfect.

I'm probably over-thinking this (wouldn't be the first time) ...

Nicely done! Great solution for those without welders and fabrication access. Simple and adjustable. Unfortunately it won't work for my Wildwood m/c for my hydraulic clutch. So I'll be welding supports on my crossmember anyway.

Forgive my ignorance, but is this to prevent some known issue with the MC moving under load and reducing braking force, or something else?
Is this noticeable only in race conditions or is this for any car, street or race?

I've never seen this before is all.

McMark has a short video somewhere showing the problem. This affects all cars, not just race cars.

I think that's the issue. When you look at the real restrictions on movement imposed by the MC to body/pedal cluster attachment, and the clearances of what we're talking about there isn't really room for movement.

As Pete suggested, a video solves everything. Andy is correct-- at the sub-millimeter level. If you look closely at the after-video you'll see the front suspension is moving slightly, and while shooting the video I noticed the rear of the pedal cluster is lifting slightly. Bottom line, there is still movement, but more from other parts of the chassis. Further stiffening of the pedal would be more effective in other places, not from this brace.

Again, I'm completely satisfied with the performance of this part.

Before:

https://www.youtube.com/watch?v=TRz387hvFhU

After:

https://www.youtube.com/watch?v=674n722tdwQ

Sign me up for one.
Good job. Mark

Edit: Does the sheetmetal cover still function normally?

Edited the first post. I was able to install the belly pan (sheetmetal cover) on the test car without modification. Some cars may require minor clearancing, but most shouldn't have issue. Just install the small front bolts first.

Put me down for 1 as well, please. Thanks,

-DB

Mark, any chance of transferring road noise into the cabin via the "direct connect" ?

Edit: or destructive vibration to the metal brake lines?

Sign me up! I want one...

I'm in for one. Sooner is better--going to DE's starting in March!

Nice work! I think you made a wedgie.

I saw these at Marks shop on Sunday, nice design and fit.
I'm in for two, white car already has a welded one.

Jeff

Mark was nice enough to fit one of his prototype units to my car the last time I was in there for servicing. Even though it wasn't up to his standards, I can still feel an improvement in pedal stiffness. He mentioned at the time that these improved units were in the works.

I am definitely in for one Mark!

-Jerry

Just a thought....If there is any doubt that this wedge could rotate, you could always put a couple tack welds on the round cross member and that would prevent any rotating. If the bolt was left in, instead of a piece of rod you could dis-assemble the unit for master cylinder service with out breaking the tack welds(I would think you could anyways).

I'm in for one.

Way cool!

Can this be modified for the aluminum crossmember?

Spoke, I think Andy's car has an aluminum member in it. I'll try to remember when I have it up on the lift to take a look at what may work and see if it's feasible.

So have you driven with this installed for events or on the street?
My only worry would be flexing of the chassis when going over a bump and transmitting force backwards through the MC into the footwell now that it's more of a solid piece. If you had a weakened footwell for any reason or repeated pressure there if it would cause the metal to start to fatigue.
Have you thought about bracing the MC bolt area with extra metal or is it unnecessary?

Not trying to discount the design or implementation, I think it's cool! Just worried about forces in the real world driving and going over speed bumps and the like.

How long before these are available?

I am in for one at least.

John

I had a similar setup in my car (not this design) for a long time. Never noticed an issue or oddity. And people have been running this sort of device for years and I've never seen anyone report an issue. As far as reinforcing the MC attachment area, the MC actually bolts to the pedal cluster with the body sheet metal sandwiched in between. So there 's already a pretty solid mounting structure there.


I need to get the raw materials, build all the units, and then send them out for plating. I could have them back in a month, depending on how long the plater takes. I could offer them in raw steel and let the buyer (you) deal with rust prevention on your own.

I'm also in for 1

I'm in for one. Thanks.

Oh hells no!

I used to have one until i saw how they can twist. Went back to the steel one the same day.

See, I'm behind on the times.
Yeah, I'm not a fan of the aluminum member either. I really don't see the benefit.

I believe - and I'm not gonna go dig up Frère's Porsche 911 Story to verify - they appeared right when Porsche was trying to homologate the 911RS Lightweight and every gram mattered.

I'd be in for 1 - if it fit a 911 with a 23mm MC...

Looks like a fine solution.

I would like two one for each my cars at your shop.

The cross-member in my car is aluminum. Should be accessible to you soon-ish if you wanted to mock something up

i want 1

I'll take one.

Well, it's been a couple days since you invented this. Are they ready to ship yet???

How bad do they twist, sounds like I may not want the one in my V8 car?

I'll take one.

I'm interested in one at some point. This looks a lot nicer than other solutions I have seen. What do you expect the price to be after the initial group buy?