How to Lengthen Heater Control Cables

[dnewman9]

Due to my dash reconfiguration and DOHC conversion I found my self a few inches short on 2 of my three heater controls. Based on this I decided to replace them with longer units.

On an early Bronco there are only two types of cables;

1. Push - Pull Only (Defrost and Temperature Control)
2. Push - Pull - Twist (Fan/Heat Control)

The first operate a baffle for defrost and the baffle for temperature control , The second control the fan speed by twist and the coolant valve in the engine compartment.

I replaced both types as follows.
I first measured the length of cable I needed and the appropriate throw required to actuate my setup. I then went to Ray's Auto Air & Heat http://www.rayeveritt.com/HeaterCables/HeaterCables.html
and ordered 2 cables in the LS (loop one end, Straight the other) configuration with my required throw. You are better measuring longer on the throw as you can shorten the cable to your requirements. If you order too short you have to shorten the cable cover to meet your needs.

The factory cables are constructed two ways to accomodate the push pull and twist functions.
The first type the control rod is drilled down the center and the cable is crimped to the rod, the cable sheath is then slid into the control housing and crimped to it.

The second type the rod is drilled down the center, and a second hole twice the size of the cable is drilled perpendicular to the rod. The cable is then slid into the the control rod and a punch is used to create a flat spot in the cable. This allows the control rod to turn around the axis of the cable yet push and pull. Without this you could not turn the fan control without breaking the cable or at a minimum having the fan control snap back when you did turn it. Once again the sheath is crimped to the housing.

To modify them I simply used my pipe cutter to cut the housing just past the crimped part. I then used a small cutoff wheel to remove the cable from the control rod. I used a small drill bit the same size as the cable and re-drilled a new hole in the control rod.
Here is where I had problems,

1. Solder will not hold the cable into the rod.
2. Welding a cable with a wire feed welder with a cable size roughly 75% of the cable you are welding will quickly burn through your cable even on the lowest settings.
3. JB weld alone will not hold the cable.

You will need to mar the cable with plyers or as I did after a failure in #2 I ended up with a small ball on the end of the cable. I then slid this into the drilled hole, with some JB weld for safety and crimped it down with my vise. I then used a hand file to make sure the rod was round and would slide in and out of the control. I then slid the cable sheath into the housing, crimped it with a pliers and added JB weld for safety. Make sure you have the cable sheath on the cable as you are putting this together as you will not be able to slide it on after the rod is in the housing.

The second cable (Push - Pull -Twist, I simply recreated the factory cable. A punch from ACE helped me peen the cable flat and a quick crimp and JB weld keep the sheath to the housing. If you do not want to buy to punches, you can take the flat end of a drill bit. I took my time peening it flat and it worked fine, (read many soft blows of a regular hammer rather than one or two hard blows with your sledge)

I took a bunch of pictures however I can not for the life of me find the pictures I took of the reassembly.

LMK if you have any questions.
Dennis

 

[dnewman9]

BTW, you could use the re-assembly process for Push - Pull - Twist for both cable styles if you are not comfortable with the holding power of a crimp and JB weld. Alternatively you may be able to braze the cable into the rod, I was more worried about heating the control rod up too much and having the plastic nob melt off.
Dennis

 

[msweb]

Good write up, thanks but I still have a couple of questions just to make sure I understand and do it correctly the first time.

After securing the cable to the control rod and sliding the sheath into the control housing, how did you keep the JB weld from getting onto the cable and locking everything up?

With the sheath in the control housing, how much of a crimp will the housing take before the sheath binds on the cable?

For the push-pull-twist, are you peening the cable to prevent it from coming back out yet allow the control rod to rotate around it?

I'll need to lengthen all three cables due to where I'm relocating them. Fortunately, I have an extra cable that happens to be the longer of the two in-cab cables and it should give me the additional length for the defrost/floor baffle. Coming up with another cable that controls the temperature control and using it for the baffle may save a step for anyone else undertaking this task.

 

[dnewman9]

Good write up, thanks but I still have a couple of questions just to make sure I understand and do it correctly the first time.

After securing the cable to the control rod and sliding the sheath into the control housing, how did you keep the JB weld from getting onto the cable and locking everything up?


I did this over a couple days, JB welded the rod into the cable, then once dry cable cover into the housing. I also used a small hand file to make sure it was all free moving. Frankly the more I think about it, its probably better to use the second process on all cables. Had I not created a small ball when my mig burned my cable I would have tried something different. The factory setup just has a hell of a crimp.

With the sheath in the control housing, how much of a crimp will the housing take before the sheath binds on the cable?

Thats pretty hard to describe. The control housings are pretty soft steel. A pliers works good, a channel lock or vise would easily distort it. With a good working cable and baffle you do not need much crimp to hold it though.

For the push-pull-twist, are you peening the cable to prevent it from coming back out yet allow the control rod to rotate around it?

Yes exactly the flat part in the cable is to large to pull through the hole you drilled. You absolutely need a drill bit the same diameter as your cable. though to make sure it stays in.

I'll need to lengthen all three cables due to where I'm relocating them. Fortunately, I have an extra cable that happens to be the longer of the two in-cab cables and it should give me the additional length for the defrost/floor baffle. Coming up with another cable that controls the temperature control and using it for the baffle may save a step for anyone else undertaking this task.

The cables are so cheap, its worth it to me making new, they all work great, and with my rebuilt heater box the whole system is like new. Good luck with yours!