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Posted

Can someone take some detailed pictures of where their brake master cylinder bottom tabs attach to the rudder bars and post for me? I have to weld the tabs on as part of brake conversion and want to make sure I get them placed right so the geometry works out.

Thanks!

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Posted

Can someone take some detailed pictures of where their brake master cylinder bottom tabs attach to the rudder bars and post for me? I have to weld the tabs on as part of brake conversion and want to make sure I get them placed right so the geometry works out.

Thanks!

best pic I have right now is one of the ones I took when I found mine under the tarp....

:BC:

post-2-12682238659806_thumb.jpg

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Posted

Here are pics of my Mk-IV and Avid+, both of which have the tabs located in the same place on the pedal control tube.

post-53-12682395609837_thumb.jpg

post-53-12682396455289_thumb.jpg

I found that rather odd, as there were many 'unofficial' and well documented solutions to improve the braking efficacy by correcting the original poor geometry over the years. One tip published in the Avid Family Flyer or Avid Comm newsletter almost 20 years ago was to attach the top brake cylinder clevis to the pedal tab in a new mounting hole 1" inboard of the original hole. If you look close in the next pic, note how it changes the angle / position of the toe piece towards the pilot. That, along with the 'master cylinder intensifier kit' offered by Matco, apparently worked wonders for most.

post-53-12682397469287_thumb.jpg

But the greatest and most effective mod was to change the location of the brake cylinder lower mounting tabs on the pedal tube. Look at a Kitfox, they figured it out. Steve W sent me a pic of their setup that explains.

post-53-12682398275887_thumb.jpg

Since I have to weld on tabs for the passenger side, I was going to put them in the more forward location and re-position the pilot side tabs too. Someday I will make some new toe pieces as well.

post-53-12682399820421_thumb.jpg

Hope that helps some. Good info in the Tech Support area at www.matcomfg.com including this: MAXIMIZING THE OUTPUT OF YOUR BRAKES - Getting Your Pedal Geometry Right

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Posted

Here are pics of my Mk-IV and Avid+, both of which have the tabs located in the same place on the pedal control tube.

post-53-12682395609837_thumb.jpg

post-53-12682396455289_thumb.jpg

I found that rather odd, as there were many 'unofficial' and well documented solutions to improve the braking efficacy by correcting the original poor geometry over the years. One tip published in the Avid Family Flyer or Avid Comm newsletter almost 20 years ago was to attach the top brake cylinder clevis to the pedal tab in a new mounting hole 1" inboard of the original hole. If you look close in the next pic, note how it changes the angle / position of the toe piece towards the pilot. That, along with the 'master cylinder intensifier kit' offered by Matco, apparently worked wonders for most.

post-53-12682397469287_thumb.jpg

But the greatest and most effective mod was to change the location of the brake cylinder lower mounting tabs on the pedal tube. Look at a Kitfox, they figured it out. Steve W sent me a pic of their setup that explains.

post-53-12682398275887_thumb.jpg

Since I have to weld on tabs for the passenger side, I was going to put them in the more forward location and re-position the pilot side tabs too. Someday I will make some new toe pieces as well.

post-53-12682399820421_thumb.jpg

Hope that helps some. Good info in the Tech Support area at www.matcomfg.com including this: MAXIMIZING THE OUTPUT OF YOUR BRAKES - Getting Your Pedal Geometry Right

You can also just weld a new tab on lower on your existing toe piece and run the threads down lower on the master cylinder shaft. You can cut new threads or have a machine shop do it, as long as you drop the mount point down to give you more leverage. Just lowering the bottom mounting bracket will not give you the increased pedal pressure, but may make it more ergonomic for your feet. You have to lower the pivot point on the top section in order to increase the pressure put on the master. Right now geometry works against you, but by lowering the top attachpoint, you gain leverage and pressure to the caliper.

:BC:

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Posted

Hey guys thanks as always for the pictures. There's a guy that has already done all the trial and error on modding pedals. Here's some pics of the custom ones he built for me. The attach points are much shorter. I'm running the MC-4D Master Cylinder which is only 6.5 inches end to end vs the MC-5 which is 7.7 inches. Here's a shot of the Brake Pedals

IMG_5689.jpg

IMG_5688.jpg

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Posted

Leni - you're right of course, it's not just repositioning the lower attach tabs. If you look at the Kitfox setup, you'll see the toe piece tab is moved lower too. I agree that results in more leverage but, keep in mind, before that change a good number of complaints were because if the rudder pedals and toe pieces were straight up or angled forward with neutral rudder, one's ankles couldn't physically articulate far enough to engage the brakes when the rudder was fully depressed. With the old Avid setup you couldn't simply cant the toe piece back toward the pilot because the big reservoir cylinder hit the pedal crosspiece. Not an issue with remote reservoir, and if you look at the latest Kitfox setup the cylinder bottom is no longer even attached to the pedal control tube, it's now fastened to the floor well ahead of the tube.

Joey - your new toe pieces resolve the top tab problem but I see no reason why you wouldn't want to reposition the bottom tabs farther forward on the pedal control tube if helps cant the toe pieces back slightly to make braking easier or more ergonomic. The toe piece I posted moves the top tab down to correct geometry and also helps prevent inadvertent braking when the toe piece is canted back. Kind of looks like yours does something similar but with less bulky. Please let us know how you like that aspect of their design.

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Posted

the pedals on the right are the ones that Bob modified from the amphib, and the ones on left are from the KF III kit that he has. You can see that the KF mounts are lowered and in a good position to give you some mechanical advantage. I will build a set of pedals like Joey has now if I put my plane back on wheels. I am really liking the design! What did he hit you for a set of those?

:BC:

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Posted

the pedals on the right are the ones that Bob modified from the amphib, and the ones on left are from the KF III kit that he has. You can see that the KF mounts are lowered and in a good position to give you some mechanical advantage. I will build a set of pedals like Joey has now if I put my plane back on wheels. I am really liking the design! What did he hit you for a set of those?

:BC:

Thanks Leni. Mine were built by a guy in Canada named Michael Schuetz. Mike do you care to chime in here? They are really well built. The bushings keep you from having any slop. I guess just having some slop in your pedal can make you lose up to 1/3 of your PSI down the line.

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Posted

Thanks Leni. Mine were built by a guy in Canada named Michael Schuetz. Mike do you care to chime in here? They are really well built. The bushings keep you from having any slop. I guess just having some slop in your pedal can make you lose up to 1/3 of your PSI down the line.

cool! if he has a good price on them, I will save myself the trouble and just get them from him!

:BC:

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cool! if he has a good price on them, I will save myself the trouble and just get them from him!

:BC:

Leni:

You're the one who recommended Joey look into the pedals I designed.I'm thinking you must have have handled the ones I did for Jack King.the whole Idea behind the design was to create something effective and quick to get reinstalled on already up and running planes.Numbers wise the setup has 5.3 leverage ratio in static position and with activation around 3.5.I did a rudder bar/brake pedal mockup on a bench hooked to a pressure gauge and can wrap a 600 psi gauge using single thumb pressure on the top of the pedal.(the Matco troubleshooting page puts 600 psi as a more or less top end base line for there systems)I did bench test the stock avid /mc5 setup and you are hard pressed to make 250 psi with that last 50 creeping into the picture about 5 seconds after you wanted to have the airplane stopped :lmao: I've taken some flak over my pedal ratio claims in the past.larry martin was first to use the mc4 type ram to improve leverage, he went with an mc4 extended to attach right at the top of the pedal, ending up with just under 2.5 pedal ratio under activation. I followed his lead and went with the 6.5 ram trying to target a little more leverage (3.5)then made the necessary structural revisions to the pedals when I realised they were keeping the system from spooling up the nessicary line pressure.(pencils out to a 33% line psi improvement)

larry also had people tell him he was "out to lunch" so to speak in his pedal ratio numbers...What I want to clarify here and now is that the methodology both larry and I used in our calculations , at it's origin , came directly from George Happ the president and r+d head of matco mfg...sooo I think the leverage values I'm quoting are in pretty good standing.

The 2 piece pedals are a bargain but they aren't cheap so to speak. I'm guessing I had 200 hrs of brain sweat into the design before they ever became an in hand working product.The best stick welder I know told me I couldn't build this 2 piece pedal design because the machining tolerances were too tight and the welding would seize everything in a lump...end result proved him wrong. What I'm charging ends up being an hourly rate less than $20, so it is a bargain but the work is a real time eater.

Mike

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Posted

Mike thank you for the info and welcome to the forum. Lots less bickering over here than on the Yahoo listing.

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Posted

Leni:

You're the one who reccomended Joey look into the pedals I designed.I'm thinking you must have have handled the ones I did for Jack King.the whole Idea behind the design was to create something effective and quick to get reinstalled on already up and running planes.Numbers wise the setup has 5.3 leverage ratio in static position and with activation around 3.5.I did a rudder bar/brake pedal mockup on a bench hooked to a pressure guage and can wrap a 600 psi guage using single thumb pressure on the top of the pedal.(the Matco troubleshooting page puts 600 psi as a more or less top end base line for there systems)I did bench test the stock avid /mc5 setup and you are hard pressed to make 250 psi with that last 50 creeping into the picture about 5 seconds after you wanted to have the airplane stopped :lmao: I've taken some flak over my pedal rato claims in the past.larry martin was first to use the mc4 type ram to improve leverage, he went with an mc4 extended to attach right at the top of the pedal, ending up with just under 2.5 pedal ratio under activation. I followed his lead and went with the 6.5 ram trying to target a little more leverage (3.5)then made the nessicary structural revisions to the pedals when I realised they were keeping the system from spooling up the nessicary line pressure.(pencils out to a 33% line psi inprovement)

larry also had people tell him he was "out to lunch" so to speak in his pedal ratio numbers...What I want to clarify here and now is that the methodology both larry and I used in our calculations , at it's origin , came directly from George Happ the president and r+d head of matco mfg...sooo I think the leverage values I'm quoting are in pretty good standing.

The 2 piece pedals are a bargain but they aren't cheap so to speak. I'm guessing I had 200 hrs of brain sweat into the design before they ever became an in hand working product.The best stick welder I know told me I couldn't build this 2 piece pedal design because the machining tolerances were too tight and the welding would sieze everything in a lump...end result proved him wrong. What I'm charging ends up being an hourly rate less than $20, so it is a bargan but the work is a real time eater.

Mike

Hey Mike

Thanks for the info, and yes, your right, I did have my grubby little dick skinners on Jacks pedals.... hmm... that almost sounds real bad don't it. I meant his brake pedals that you built :lol:

If I go back on wheels I will get a set from you. Looks like I could save you some time if I send in my old ones and have you modify them :dunno: At any rate, I am deffinately into more braking power as mine just suck for what I want to do!

:BC:

Mike thank you for the info and welcome to the forum. Lots less bickering over here than on the Yahoo listing.

Yeah, and if we get to bickering (sometimes alot of fun) we can call a jackass a jackass :lmao: It is a hell ov a lot easier to find info on this type of forum versus the yahoo groups style.. but it is hard to convince guys that have been "loyal" to the group to change.

:BC:

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Posted (edited)

Here are pics of my Mk-IV and Avid+, both of which have the tabs located in the same place on the pedal control tube.

 

post-53-12682395609837_thumb.jpg

 

post-53-12682396455289_thumb.jpg

 

I found that rather odd, as there were many 'unofficial' and well documented solutions to improve the braking efficacy by correcting the original poor geometry over the years. One tip published in the Avid Family Flyer or Avid Comm newsletter almost 20 years ago was to attach the top brake cylinder clevis to the pedal tab in a new mounting hole 1" inboard of the original hole. If you look close in the next pic, note how it changes the angle / position of the toe piece towards the pilot. That, along with the 'master cylinder intensifier kit' offered by Matco, apparently worked wonders for most.

 

post-53-12682397469287_thumb.jpg

 

But the greatest and most effective mod was to change the location of the brake cylinder lower mounting tabs on the pedal tube. Look at a Kitfox, they figured it out. Steve W sent me a pic of their setup that explains.

 

post-53-12682398275887_thumb.jpg

 

Since I have to weld on tabs for the passenger side, I was going to put them in the more forward location and re-position the pilot side tabs too. Someday I will make some new toe pieces as well.

 

post-53-12682399820421_thumb.jpg

 

Hope that helps some. Good info in the Tech Support area at www.matcomfg.com including this: MAXIMIZING THE OUTPUT OF YOUR BRAKES - Getting Your Pedal Geometry Right

 

 

 

Regarding the matco link above, the most revealing yet sorta hidden,and not readily known thing I can show to yaall about pedal ratio appears in diagram 3, the illustration on the right side, there is some writing that says PERP DIST TO MC CENTERLINE. Which unabrevated reads perpindicular distance to master cylinder center line, basically means the shortest distance from the pivot point formed between the brake pedal and rudder pedal to a line running directly down the center of the brake cylinder.So with a mc-4 type brake cylinder bolted to the stock avid rudder bar attachment point, you can make that distance .5 of an inch.(the cylinder shaft is 3/8 dia and the rudder bar is 5/8 so half of each added together is 1/2 in)Divide that number into the pedal height of 2.65 and the resulting start pedal ratio is 5.3 to 1.With activation, the shorter the mc-4 cylinder you use the closer it stays to the pivot point, and the more leverage you maintain. The 6.5 inch length is the off the shelf optimum. 6.0 is possible but then the clevis hits the back of the rudder bar first and start leverage cuts back to 4.7 to 1, with activation ends up being a pedal ratio only .08 higher than the 6.5 delivers.(basically an undetectable amount) :news:

 

Mike

Edited by saskavid
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Posted

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IMG_0001.JPG

IMG_0002.JPG

IMG_0007.JPG

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Posted

Well the trick is to get the activation shaft of the master cylinder as close to the back of the rudder pedal as you can to get max leverage potential. You have a bit of room there to work with. You can tip or cant the tops of the brake pedals a bit further towards the pilot if you are comfortable with how that works for you physically or you can cut the tabs mounting tabs off the brake pedals and weld new ones on where they need to be, put the tops of the brake pedals where you personally like them to make everything work to your personal preference and get the most leverage you can. One thing to try and avoid in any mod is getting a condition known as an over center where the master cylinder actually starts to rotate back towards the redder pedal as opposed to away, where the system then has potential to act like a vise grip and lock itself up. 

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