Jeep Hand Throttle
Despite their being an abundance of write ups on how to make your own hand throttle, I was asked if I would do one. Being unemployed at the moment gives me ample opportunity to do some of these quick and easy mods. First the list of what you will need:
Derailleur (SP?) thumb shifter for a bicycle. The reason for the derailleur shifter is that it doesn't click as it gets shifted. It will allow you to smoothly move up and down allowing for a finer adjustment of the throttle while holding the throttle at wherever you leave the shifter. I picked up a Shimano that also has a tension adjustment. Cost was $5.
6+ ft of bicycle brake cable w/ sheathing. This is going to go from your shifter to your throttle. I ended up with about 5 ft. and while that is enough, 6 ft or more would have been better. The sheathed cable cost me $8.
Adjustment screw/bolt and nut. I am not sure what the heck this thing is called. But it is that hollow bolt that the bike brake line goes threw that has a jam nut on it that can be used to adjust the tension on the brakes. It cost me $0.25.
Wire ferrule to crimp on the end of the cable at the throttle. [Monster Garage] Freebie...Zip...Zero...Nada [/Monster Garage]
Ring terminal connector to attach cable to throttle. Another hefty expense at $0.40
The first thing I did was check to make sure my cable length was going to work. To do this I pulled the plug in the firewall just above and right of the gas pedal. Once I ascertained that I had enough length, I drilled a small hole in the plug just big enough to force the cable through it. I drilled once size smaller than the cable and then used soapy water as a lubricant to slide it through.
Pic of cable going through the firewall from the cab:
Pic of cable coming into the engine compartment from the cab:
After getting the cable routed through the cab, I attached the derailleur shifter to my TJ gear shift. The TJ gear shift is significantly not as thick as a bicycle handle bar. To remedy this I used black electrical tape and ran round and round the TJ gear shift until I had the desired thickness. I then tightened down the bicycle derailleur shifter to the TJ gear shift.
Pic of derailleur shifter attached to TJ gear shift:
I then measured to see how much exposed cable I would need to make it from the bracket to the left of the throttle to the throttle itself. I added 2 inches to my measurement to allow some leeway. I then stripped back that amount of sheathing from the bicycle brake cable. For me it ended up being about 6 or 7 inches. I then grabbed a center punch and made an indentation a little above and centered over the throttle and cruise control cables on the bracket left of the throttle. I then drilled a hole there to fit the brake adjuster piece. I put that brake adjuster in the hole and put the jam nut behind the bracket with some loctite and tightened up. I then fed my brake cable through the adjuster as pictured below.
The brake adjuster is the silver looking thing on the top middle of the bracket.
I then checked to see how long my exposed wire needed be with the wire ferrule on the end in relation to the throttle. I removed the cruise control cable, put the ring terminal connector on the bicycle brake cable and slipped it over the throttle. I then cut the exposed wire to size, took the ring terminal connector off the throttle and crimped the wire ferrule on. (see the update at the end of this write up)
You will notice in this pic the cable is allowed to move in and out of the ring terminal connector. This allows for slack in the bicycle brake cable when using cruise control or the gas pedal without binding due to slack in the hand throttle line.
I then slipped the ring terminal connector back over the throttle and reconnected the cruise control cable.
I then tested everything to make sure that there was no binding. As expected, when using the gas pedal the hand throttle did not bind and when using the hand throttle the gas pedal didn't bind. I then took it for a cruise control test and sure enough that works as well. I then spent about 45 minutes tooling around the neighborhood using nothing but the hand throttle up to speeds of 55MPH and had no problems.
Some post installation notes:
Make sure you get 6+ feet of cable. I may end up redoing this because I would prefer to have more cable to work with in the engine compartment for routing purposes. Also, the wire ferrule that I got from the bike shop is ok, but since it is a crimp on (and not much to crimp for that matter) I expect that to be the weak spot in my whole setup. If you can find one that screws on, that would be the way to go.
Now as to why I did this. I did this because I hate it when I go over an obstacle or bump on the trail and the Jeep starts violently surging because I can't keep my foot steady on the pedal. I also did this so I would have better control over the Jeep. I can now operate the clutch, brake, and throttle simultaneously. It would require three legs to do this right and my third leg isn't long enough or strong enough. And finally, I can use it to rev and hold the engine at higher RPMs for battery charging and winching applications. So far I think it is a great mod. Especially since my total out of pocket costs are under $15. RE wants $30 + shipping for their hand throttle kit.
The hand throttle worked relatively well. However, there is a potential for binding. I fixed this a couple days ago.
The problem I ran into was that the wire ferrule would get hung up on the cruise control when I used the cruise control. After looking through a few other write ups I saw where one guy had used ball chain and decided to try this. I picked up about 1 ft of ball chain ($0.59) and a ball chain connector (I don't know what they are called. $0.13). I also replaced the shorter 4 1/2 ft cable with a 7ft cable so I could do a better job routing it and moved the hand throttle on to the shifter knob.
I cut about 6" of shielding off of the cable and ran it like I normally would have but didn't connect it to the throttle. I then pulled the hand throttle all the way back and marked the cable where it met the shielding to see how much was needed by the hand throttle (for me it was about 2"). I then cut the cable about 1" below that 2" mark leaving about 3" of exposed cable when the hand throttle has no tension. I then opened a ring terminal connector where the cable would normally pass through and crimped one end of the ball chain to it.
I then put the ring terminal with the crimped ball chain on the throttle and held the ball chain up to the hand throttle cable and cut it so there was a 1/2" or so beyond the end of the cable. I then slid the ball chain connector over the hand throttle cable and then crimped a wire ferrule on the end to hold the connector on.
What this effectively did was allow me to use the cruise control and the ball chain would slacken with no binding. So far it has worked great and I have had no binding. I am not sure yet of the durability of the ball chain connector, but other than that I feel pretty confident about this.