Van's calls for using two separate bolts to attach the brake pedal to the rudder bar (not sure what else to call it - it's a pedal, but not really - step on the white bar for the rudder, move up to the actual pedals for brakes). There have been quite a few reports of issues with that setup though. The pedals are slightly tapered from bottom to the top, which means they don't really sit parallel to the welded tabs on the rudder bars. With two separate bolts, the pivot on each side is not in the same plane, so some people have had issues with the brakes binding. There are two solutions that I've found for this - use one long bolt instead of two to keep the pivot point where it needs to be, and add some springs to the brake cylinders to beef up their internal springs for greater power for returning the brakes to neutral.
Bolts that are this long are ridiculously expensive, so instead I decided to go with a 3/16" rod cut to length and threaded/drilled on each end for castle nuts and cotter pins. I started with a piece of stainless rod, but drilling a 5/64" hole in it for cotter pins was easier said than done. Because there really isn't much stress on this part, I decided to switch over to brass instead. It was much easier to work with. The difference between this setup and the two bolts approach was immediately apparent. The single rod decreased the friction of the pedals quite a bit.
The next addition may or may not be necessary given how the pedals feel on the rods. In anticipation of the issue with bolts, I had already jumped on McMaster Carr and bought springs, some plastic collars and some aluminum shaft collars with set screws. The brake cylinders already have return springs in them, but people say they often don't have quite enough power to completely release the brakes back to neutral. The idea is to add an additional spring to boost that. The last thing I want is a stuck brake on landing. I don't really know if all of this will be needed, but it's super easy to remove if not.
There is still one thing to do to set the cylinders up: The bottom portion has to be drilled to the attach plate on the pedals. The gotcha is that the geometry of the rudder bars is not the same since one bar sits behind the other. So I need to line the part of the bars up that you press on, then decide how much back angle I want on the pedals before I drill the holes for the brakes. Too little angle and it's super easy to accidentally press the brakes while only wanting rudder. Too much angle and it's hard to slide up to the brakes when you need them. I'll do a little more research to see what others have done before I drill.
