Rudder Pedal Mods

[HighWing]

I have had some brake issues with my new Model IV. When it occurs, it is overheating of the right brake and it's occasionally locking up. I first felt it was a faulty parking brake, but it persisted after bypassing the right side of the parking brake.

Then Esser's very thoughtful solution to his height issues got me thinking about the Model IV rudder brake pedal geometry.

My current brake pedals are of the C variety rather than the E pedals on my first Model IV so didn't have the lower arm to help keep off the brakes while taxiing. Examining the geometry of the pedals and where my feet would normally rest, I decided I needed to make some modifications. I cut some notches in the pedal tubing and bent the notch closed and welded it up. Several cuts and welds later, I had a pedal where I could sit normally and not feel the brake arm first. Notice that the two pedals are not symmetrical as it was the right pedal that required the greatest bend to provide the clearance I needed. It was also the right brake that was the troublesome one.

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I then decided to weld in some U shaped tubing to give a bit more feel while in the rudder only foot position. I did some taxi testing and really like the feel. It is a lot like the E pedals, but more positive in the ball of my foot.

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[mr bill]

I have the E type pedals, but could not leave well enough alone. I added 1/8" aluminum tread plate. It feels better.

[Av8r3400]

Lowell, if I may be so bold as to suggest that you should really consider adding some strapping to the welds where the vertical and horizontal tubes meet, as well as the side cable attach points…

My Theory of what the rudder and brake peddles should be:

http://www.avidfoxflyers.com/uploads/monthly_01_2013/post-36-1358478860371.jpg

[HighWing]

Lowell, if I may be so bold...

No problem with being bold. Actually I was in the first few hour of flight on the first IV when the first word of the pedal arm failure came out with the factory's recommended fix. I had a local welder do mine then, and then this time, I did exactly as you have done. The arm at the left on the last picture very faintly shows the strap. My pedal assembly is slightly different than yours where the rudder cable attaches. An arm is welded to the pedal upright. Reinforcement is there too. Thanks

[HighWing]

A follow up on my pedal mod. I had originally used the brake arm's relationship to the vertical connect tube to position the brake pedal when I repositioned the master cylinder attach arm. The thinking was that if the horizontal brake arm on the "C" type pedal was positioned slightly behind the axis of the vertical tube connecting the pedal to the horizontal torque tube I would be able to taxi without constant pressure on the brakes. Then seeing Josh Esser's comment on the Tall Pilot thread, I decided I needed to position myself in the seat and see exactly how my foot angle related to the fixed geometry of the rudder pedal assembly.

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The picture still shows the angle of my foot fairly tight, but far less tight than it needed to be if I had not made the mod.

Personal thanks to Josh for his insightful solution.

[Esser]

Hi Lowell,

Glad I could help but I can't take credit for that myself as John Pitkin originally guided me in that direction. The mods look great.

[jtpitkin06]

My mod was pretty simple and it did not require any welding. I merely moved the mounting of the rudder pedal torque tube brackets aft one inch on the floor. This allowed the entire assembly to rotate forward to change the pedal angle.
There is no change to the cable length, either. You may re-use half of your existing mounting holes. Be sure to check for full rudder with full brake for any binding. You may need to relieve the floor bracket a bit to clear the brake cylinder.

[HighWing]

I appreciate the post, John, and since this was your original idea - Thanks to you for your innovative thinking. On my IV with floor boards in and the firewall wrap in place, moving the pedals would have been days rather than a couple of hours of fitting and welding. Hopefully the factory will see this idea and put it in their manual as a tall man's alternative set-up.

[Jollyrancher]

Hello, on a kf4, the toe brakes bottom out against the firewall. Other then the loss of leg room, is there a problem with shortening the rudder cables? Thanks....

[HighWing]

I don't think there will be a problem. This based on the original design where there was a link consisting of a pair of straps about 4" long on each side with holes drilled about every half inch. This allowed for essentially doing what you suggesting and, i suppose, was an attempt to add an adjustment to finesse the angles and clearences.

[Jollyrancher]

I dont see the strap as you desribe, I do see it however, in the picture below. The plane is an hour from me, wonder if the adjustment could be at the other end of the cable? Thanks

[HighWing]

Going back to the manual, I was surprised to find that it called for the adjustment links to be at the rudder horn. I had placed them at the pedal. I guess they could be at either end. In my manual, the picture of the links in place is very dark and undistinghishable. I did copy the image below of the links.

[mr bill]

I don't like having to crank my toes so far forward to get good brake action. I have turnbuckles on the rudder cables, so I will shorten them and see what happens.