VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1937-1945 Throttle & chock cable repair

Since I have my '39 Chevy out and about, I think I need to do some minor repairs. My throttle and choke cables are a little short. In fact the throttle cable is too short to reach. I found some spare cables that are longer, but have the wrong color knob. I'd like to repair the cables rather than replace them. Looks like the inner wire and outer coil are just crimped to the control. Has anyone tried to lengthen the inner wire or lengthen the outer coil by replacing them?
Mike

A longer wire can be attached to the knob pull assembly but it's difficult and odds are it won't be successful. The knob pull assembly (knob & shank that the knob is fastened to) is crimped on to the the wire. If you're VERY careful and the gods smile on you it's possible to relax the crimp enough to remove the short wire and replace it with a longer one. Then recrimp the end. You'll see that the end of the wire where it enters the pull is flattened a tad to help keep the wire from being pulled out of the knob assembly. Be aware that it's VERY easy for this whole thing to fail. I was lucky in only having a partial failure. The crimp split on mine (choke cable) but not totally. I was able to get enough of the new wire into the pull assembly AND get the wire & pull assembly back in to the housing that the choke cable works normally. The housing is holding the whole thing together. If I ever try to remove the pull/wire from the housing it'll fall apart. Another option is to buy an aftermarket cable and put an aftermarket replacement knob on it.

Is the cable housing long enough that you can just cut some of it off to give the wire length you need?

I think that have just experienced what you are talking about. The outer coil was easy to remove. The control is split and by gently seperating it a little, the coil can be screwed out. The outer coil is slightly smaller than a new choke cable that I got at the hardware store. About 0.015" smaller. The new coil will screw into the control and with some gentle hammering the new coil is in place. The wire, as you say is more difficult. I used a narrow hacksaw blade and cut into the control just down to the wire. The wire became loose, but as I pulled on the wire the knob you talked about cracked the control shaft. This shaft must be some softer pot metal. The old wire is also smaller than the new wire, by about 0.010". I think that I can make a new shaft from some soft steel stock and crimp the new wire in place. I have to experiment with removing the control knob. I thought that if I heat it, it may come off. Have you had any experience with removing the control knob?
Thanks Mike

No, both are too short.

Mike

No but I believe it was likely cast (molded?) onto the shaft. I don't believe it's possible to remove it without destroying it. You can get replacement knobs. Good Luck

Mike,

I've repaired two of these throttle cables where the wire was too short--probably having broken off from continued tightening of the set screw at the throttle cable stop.

For the replacement cable, I bought a small spool of .041" music wire (spring steel wire) from McMaster-Carr. Then I cut off the old wire at the end of the pull rod where it is crimped in place. I then filed the end of the pull rod flush.

I have a small lathe and was able to chuck the pull rod with the jaws on the rod, and the knob clearing the inner bore of the chuck, so I didn't need to remove the knob from the pull rod. With the pull rod in the chuck, I first used a small center drill to locate the center of the pull rod and provide a starting point for a drill. Then I drilled a hole about 1/2" deep using a .050" or so drill. This can be tricky as a .050 drill is pretty small and prone to break. This center drilling and drilling could be done with a hand drill as well. Just procede carefully so as not to break the drill.

Next I measured and cut the new wire to the desired length, then polished about 1" of one end of the wire using 400 wet or dry paper to prep the wire for soldering. I then tinned the end of the replacement wire with flux and solder using a soldering gun. I also tinned the hole I had drilled in the pull rod. Use the end of the new wire to shove the flux into the hole and coat the hole thoroughly. Because of it's larger size, the pull rod requires more heat to solder, so I used a propane torch. Once both parts are tinned, I just put them together, heated them gently with the torch and added a little solder to fill the hole around the new wire. Done.

This operation has worked fine on my 37 pickup and my 36 Pontiac coupe, and I use the hand throttles a lot for warming up the engines, charging the battery, or other miscellaneous purposes.

Mark