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> Brake Master Cylinder Brace, finally something I'm happy with
McMark
post Jan 21 2013, 01:14 PM
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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'?
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SirAndy
post Jan 21 2013, 01:32 PM
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What prevents this from turning downwards under braking? Just the pressure on the cross member?

Seems like this could easily slip downwards?
(IMG:style_emoticons/default/idea.gif)
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Harpo
post Jan 21 2013, 01:35 PM
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Sign me up. How is the belly pan modified?

Thanks

David
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billh1963
post Jan 21 2013, 01:51 PM
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QUOTE(SirAndy @ Jan 21 2013, 02:32 PM) *

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

Seems like this could easily slip downwards?
(IMG:style_emoticons/default/idea.gif)


A cup for the end of the master cylinder (instead of the notched cut) would stop that from happening! (IMG:style_emoticons/default/biggrin.gif)
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McMark
post Jan 21 2013, 02:06 PM
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QUOTE(SirAndy @ Jan 21 2013, 11:32 AM) *

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

Seems like this could easily slip downwards?
(IMG:style_emoticons/default/idea.gif)

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.


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ConeDodger
post Jan 21 2013, 02:09 PM
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Win... But naturally, I'll want it powdercoated before it goes on my 914 (IMG:style_emoticons/default/blink.gif)
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914GT
post Jan 21 2013, 02:12 PM
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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.
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McMark
post Jan 21 2013, 02:21 PM
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QUOTE
But naturally, I'll want it powdercoated before it goes on my 914

I'm leaning towards plating because the brace fits so tight that the additional thickness from the PCing may make it not fit.
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jimkelly
post Jan 21 2013, 02:41 PM
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i'm in for 2 - perfect timing : )
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McMark
post Jan 21 2013, 02:48 PM
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QUOTE(Harpo @ Jan 21 2013, 11:35 AM) *

Sign me up. How is the belly pan modified?

May need a dented section where the brace sits to actually have the bolts fit.
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monkeyboy
post Jan 21 2013, 03:29 PM
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I'll take one.
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SirAndy
post Jan 21 2013, 03:33 PM
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QUOTE(McMark @ Jan 21 2013, 12:06 PM) *
QUOTE(SirAndy @ Jan 21 2013, 11:32 AM) *
What prevents this from turning downwards under braking? Just the pressure on the cross member?

Seems like this could easily slip downwards?
(IMG:style_emoticons/default/idea.gif)

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.

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.

(IMG:style_emoticons/default/popcorn[1].gif)


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McMark
post Jan 21 2013, 04:10 PM
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(IMG:style_emoticons/default/laugh.gif) 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 (IMG:style_emoticons/default/confused24.gif)

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.


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McMark
post Jan 21 2013, 04:13 PM
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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.


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pete000
post Jan 21 2013, 04:34 PM
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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 !

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monkeyboy
post Jan 21 2013, 04:37 PM
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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.
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SirAndy
post Jan 21 2013, 04:43 PM
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QUOTE(McMark @ Jan 21 2013, 02:10 PM) *
Or can anyone understand what I'm trying to say and set him straight? I'm so (IMG:style_emoticons/default/confused24.gif)

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) ...
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914dave
post Jan 21 2013, 04:45 PM
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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.
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IanS
post Jan 21 2013, 04:56 PM
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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.
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SirAndy
post Jan 21 2013, 05:11 PM
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QUOTE(IanS @ Jan 21 2013, 02:56 PM) *
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.
(IMG:style_emoticons/default/driving.gif)
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