Brake pedal mods

[BryceKat 125]

Stock Avid/matco geometry brakes Suck! I'm guessing the hole for the cylinder attach point on the pedal was drilled at the factory. On my pedals, the attach point is 2 inches from the pivot point and the brake pedal dimension is 2.5 inches. That's poor geometry according to Matco.  I need the 2 inches to be 1 inch on the cylinder attach point http://ultralightnews.com/features/images/matco/matco-4.jpg

It appears there is room to redrill my pedal, which I'm going to. 

Has anyone done this before-just redrilling for the attach point?  What where your results?  Thanks,  Bryce

[efil 01 74]

if you drill closer to the pedal, the break cylnder will hurt the pedal, on mine it is already almost touching; may be you can expend the toe, or displace matco attachements

[marksires 484]

I made new pedals for mine, and changed to the shortest Matco cylinders I could get, I think they were 'G' cylinders.  My plane is in another state right now (still moving), when I get it next month I'll take pictures of the new pedals and post them.  BTW, don't waste your money on the 'intensifier kit' from Matco.  I tried that first.  It made a small improvement, but not enough to be worth the time, effort, and money it required.  With the stock pedals and MC-5 cylinders, I could barely hold 3500 rpm, now I can hold it for a full power runup, although it does start to creep if I take too long doing it.

Mark

 

[thebriman 69]

I rebuilt my pedals twice. With double puck matco brakes and mc4 masters, 3.87 to one was too much brake.  My second iteration was about 2.87 to 1 and it is perfect. I had to move the master cylinder attach point on the pedal cross tube and connect the pedal to the top of the master cylinder shaft with a through hole and a AN3 bolt rather than the clevis supplied by matco.  I have enough brakes to easily hold a full power run.

[EDMO 1078]

I rebuilt my pedals twice. With double puck matco brakes and mc4 masters, 3.87 to one was too much brake.  My second iteration was about 2.87 to 1 and it is perfect. I had to move the master cylinder attach point on the pedal cross tube and connect the pedal to the top of the master cylinder shaft with a through hole and a AN3 bolt rather than the clevis supplied by matco.  I have enough brakes to easily hold a full power run.

I would like to see some photos and dimensions of the cross tube attach points and pedal attach that works.   I have heard all kinds of stories on fixing the brakes, but cant seem to imagine exactly what works.

My KF1 & 2 had plain metal for all the control cross tubes, the 1 was homemade tubes - The 3 has all chrome controls, pedal and sticks - Was that a factory made assembly?

EDMO

[thebriman 69]

I'll take pictures and post soon.

[KFfan 151]

Perhaps helpful?

Click on Ed's avitar

Edited 15 Oct 2015 by KFfan

[dholly 718]

Bryce - go for it! There was a 'Builder's Tip', sanctioned and approved by Avid factory way back when and detailed in one of the early newsletters, to drill another hole in the master cylinder to brake pedal mounting tab closer to the pedal. Just be aware of the clearance needs between cylinder piston and rudder/brake pedal cross tube at full rudder deflection.

[EDMO 1078]

Perhaps helpful?

Click on Ed's avitar

Not on the Avatar - Click on Topic for all the stuff written in 2012 - At my age, I cant remember past yesterday - Thanks for the reminder. 

EDMO

 

[allonsye 85]

Bryce - go for it! There was a 'Builder's Tip', sanctioned and approved by Avid factory way back when and detailed in one of the early newsletters, to drill another hole in the master cylinder to brake pedal mounting tab closer to the pedal. Just be aware of the clearance needs between cylinder piston and rudder/brake pedal cross tube at full rudder deflection.

I did this IAW with that newsletter -- in the stuff Joey posted a year ago or so and it works but you've got to watch the clearances.  I have the MC1.  I've got decent and manageable braking authority now w/out throwing more money and time into a major mod.

[Bandit 286]

These are my pedals from Brett. They work better than the old style. No need to have brakes that you can lock up.

[EDMO 1078]

Looks like if you had MC-4 cylinders you would have less problems with clearance, since they don't have the big top on them.   I also wondered about that lower fitting hitting the other tube if you don't make the lower attach ears long enough.

Thanks for the photos,

EDMO

Edited 16 Oct 2015 by EDMO

[Bandit 286]

No problems with clearance.

[EDMO 1078]

No problems with clearance.

Bandit,

I wasn't talking about yours, but others have warned about clearance when reworking MC attachments.  MC4s, long or short, are slimmer.

EdMO

[BryceKat 125]

Mark,

thanks for the pic!  Bryce

[allonsye 85]

I did this IAW with that newsletter -- in the stuff Joey posted a year ago or so and it works but you've got to watch the clearances.  I have the MC1.  I've got decent and manageable braking authority now w/out throwing more money and time into a major mod.

For the record, I meant the MC1's, is what I have -- the skinny ones.

[EDMO 1078]

For the record, I meant the MC1's, is what I have -- the skinny ones.

I think I had the MC1s once, and thought they looked sort of like the ones posted by Bandit, only Black with Yellow sticker on them.  I didn't know that any MC1s were "skinny"

The ones Bandit posted above could be MC5's - they had the large top reservoir like the MC1s.  Those are the only two Matco cylinders that I know of with the larger top end, but there could have been some other models built that way.

EdMO

Edited 17 Oct 2015 by EDMO

[marksires 484]

Those look like the MC5's I took off my Avid.  What I did was remove the existing pedals, and made new ones.  I used flat 4130 that I cut with a tab for the cylinder attachment, then bent them into a 'U' shape.  That put the tab at the bottom of the pedal where it is supposed to be. Then I drilled the hole for the through tube to connect it to the same place the old pedals went.  It was simple, doesn't rely on my welding 'skillz' to keep the tab attached, and didn't weigh anymore than the old ones did.  I used washers and cotter pins to keep the through tube in place.  I had to use the shortest cylinders Matco had - MC4-G or MC4-H, and install an external reservoir.

Mark

 

[allonsye 85]

I think I had the MC1s once, and thought they looked sort of like the ones posted by Bandit, only Black with Yellow sticker on them.  I didn't know that any MC1s were "skinny"

The ones Bandit posted above could be MC5's - they had the large top reservoir like the MC1s.  Those are the only two Matco cylinders that I know of with the larger top end, but there could have been some other models built that way.

EdMO

Dag nabit........ I don't remember what the hell they are.  I'd better take a look next time out.  Whatever they are.  Their like me - skinny and they work really well.

[allonsye 85]

I checked today. The "skinnys" are MC1's.

[EDMO 1078]

I checked today. The "skinnys" are MC1's.

Can you post a photo sometime - I just got another set of MC-1s and they have the top larger than the body.  Never saw a set of "skinny 1's".  I've got a set of skinny 3's, and several sets of skinny 4's, and some skinny Grove and Clevelands.

EDMO

 

Edited 21 Oct 2015 by EDMO

[allonsye 85]

Hmmm.......I'm going by the overhaul kit pkg label in my bin of parts.  I'll look and scan next time I'm at the hanger.

[marksires 484]

A long time ago I promised to post a picture of my brake pedal modifications.  I finally got the picture taken, so here it is.  I didn't trust my welding skills, so the frame was cut from flat piece of 4130, then bent to shape.  the cross pieces are welded, but even there I positioned them so the weld isn't taking the force, just holding the pieces in position so they can push on each other.  I used the shortest cylinders Matco makes, MC4H I think, and put a remote reservoir on the firewall.

Mark