Throttle quadrant cables

[Davepar]

This is a long story, but hopefully it helps out someone else. I've wasted a fair amount of time and money trying to get custom control cables for my throttle quadrant:


To back up a little bit, I've taken the advice of others to heart and have decided to not cover any large holes in the firewall with aluminum, e.g. the cabin heat box, control cable pass-thrus, etc. EPM.AV makes a nice replacement for Van's cabin heat box that's all stainless steel, and I purchased these firewall eyeballs for the control cables:


Back to the throttle quadrant, other builders suggested that the quadrant cables can be ordered the same length as the standard knob type cables. This depends on where you mount the quadrant, but did hold true for my case.


I ordered one Vans 48" quadrant cable to test this. That cable is not a custom length, so I figured I could return it if it didn't work. The length was fine, but the diameter of the cable was much larger than the knob type cables, about .35" vs .25". Vans quadrant cable:


The steel eyeballs I already purchased and installed can be drilled out according to their instructions, but the cable is so large that there would be nothing left of the inner sleeve that is supposed to hold the cable in place.

This started me on a long journey of trying to get custom control cables from Spruce. Their cables are .25" in diameter, which works well for the steel firewall eyeballs. However (and this was a 3 month long, $150 lesson), their A-1550 cables do not have the same throw as Vans cables. This puts the bulkhead mounting nuts at a position that will not work with Vans FWF set up. Vans cable is top, Spruce bottom:


In order to make them work, I'd have to order some super-custom cables from Spruce that ended up being $139 each. No thanks.

So now I'm back to Vans quadrant cables, using aluminum firewall eyeballs (a.k.a. 1" flame throwers), and somehow covering over the mounting holes for the steel eyeballs.

The funny part of this whole thing is that Pete James down under warned me about this whole problem. In among all the other advice he's sent me along the way, he mentioned the problem with Vans cables and the steel firewall eyeballs (#4 in this message). I just forgot about it along the way.

The lesson learned is that customizations will cost time and money. If you want to fly your project sooner, build it per plans.

[sf3543]

I installed a custom set up in my RV8, similar to what you are trying to do.
For the eyeball, I used the ones that VAN's and others sell that has the removeable ball in the center. Since it is a split ball that is held in place by a separate nut, as long as the cable fits through the entire opening, you can install the eyeball halves over the cable easily.
For the cable, I went to a local brake and clutch shop and they made up cables for me. They did same day service and charged about $30 each. You tell them what throw you want..they had two or three to choose from. Using the custom quadrant and the Bendix IO servo system and an MP governor. Everything is working fine after 40 hours. When measuring for the custom cable, I used a piece of plastic tubing and measured end to end..make sure you have the knob to the maximum throw and also the other end at the maximum throw, or you could get a cable too short or too long. The only difference in the cables is that they are black. A friend of mine did the same thing and they have been fine for the last 5 years.

[N941WR]

Dave,

Keep these coming! I'm right behind you in ordering the cables.