Throttle Control Cable – 2 hrs

Monday Dec 24, 2012

It’s Christmas Eve so I did not a lot of time on the project today but I did do some preliminary work on the throttle cable routing. First I went by the hardware store and bought a 17/64 cobalt drill bit so I could enlarge the holes in the eyeballs for the throttle cable which is .265 diameter. Then I drilled out the eyeball, installed the cable and began messing around with the routing while trying to figure out where to mount a bracket to tie down the control cable just before the servo. There are many variables to play with including the amount of thread engaged with the spherical rod end, the location and angle of the bracket, and the hole in the servo control arm selected. Initially I was using the outer hole in the control arm but I found that the extra motion was causing the cable to come up short at the instrument panel bracket. I think this cable is just barely long enough. I moved the spherical bearing to the inner hole in the control arm and adjusted the nominal angle of the arm so that the cable is perpendicular to it at the mid point of the throttle stroke. You can see that in the two pictures below. The first is at full throttle and the second is at idle. Note the angle of the control arm relative to the control cable. They are perpendicular half way in between these two positions.

I also adjusted the tie down bracket to get the most clearance I could between it and the engine mount tube. There is about 1/2 inch clearance in this configuration. I think that is enough to allow for engine motion on the mounts. But before I drill this and lock it in I will sleep on it. Sometimes things I forgot come back to me when I give them time to season a little.