Electric Crawler Gears
Bypassing a Clutch Safety Switch Short Cuts
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By: Randy Burleson - 11/2000

You've heard of the Electric Slide, right? You know, that group dance at a wedding reception, generally played right before everyone dashes for the exit as the DJ spins up the Chicken Dance? Well, the Electric Crawl is a whole heckuvalot more fun, and you'll never have to pay blackmail to avoid a 'friend' selling the tape to America's Funniest Home Videos.

Photo by Randy Burleson
Starting on a steep hill with a clutch bypass means three-footing the clutch, brake, and gas.


Why?

Three-footing the clutch, brake, and gas on a steep hill is difficult, especially when your buddy parked his freshly painted rig two millimeters behind you. Sometimes you want to start your rig in gear, without losing any position on the obstacle. Sometimes it is convenience, but other times it is darn near necessary for safety. With the clutch safety switch bypassed, turning the key spins the starter -- and holding the key turned to the start position keeps the engine slowly turning until it fires and the vehicle idles off (all without stomping on any of the pedals).

4-wheelers with low gears want to be able to start in low gear -- as noted before, sometimes safety almost requires it -- but it also may be their lowest gear. Think about it... many starters have an additional set of reduction gears built into them, and electric motors develop their peak torque regardless of RPM. If the starter motor can turn against the load of the vehicle, the truck will move up the obstacle. This is pretty rough on the starter, and lengthy use of the starter as the sole means of motivation for the rig will dramatically reduce the life of your starter.

Why Not?

The manufacturers put a safety switch on stick shift vehicles to prevent people from mistakenly starting their vehicle while in gear, and having the car jerk forward. If anyone else drives the rig, and they are used to that manufacturer-enforced security blanket, they may turn the key without depressing the clutch. With enough motor and gears, that may mean explaining to the insurance company why the rig drove over the car parallel parked just ahead of it.

Graphic by: Randy Burleson
Stock ignition systems generally have a clutch interrupt switch between the keyed ignition switch and the starter.


How? The Easy Way.

Bypassing the switch is easy enough. Getting under the dash to find the switch is the hardest part. Most manufacturers use an interrupt switch in the starter trigger circuit. Depressing the clutch pedal pushes a plunger switch that closes this starter trigger circuit. Locate that switch and disable it: tape the switch closed, cut the wires and splice them together, or just use an appropriately-sized jumper to bridge the switch's connector. To test it, put the vehicle in neutral, with the parking brake on, and turn the key without putting the clutch in. Turning the key should trigger the starter every time, regardless of the position of the clutch pedal. Be careful to use the clutch pedal when you start it in the garage, though... otherwise the vehicle will lurch foward, and may keep going right through the garage wall!

Graphic by: Randy Burleson
A simple jumper (shown here in red) is enough to bridge the clutch bypass circuit.
Graphic by: Randy Burleson
Jumping the clutch bypass circuit with a switched subcircuit allows easy toggling between switched and bypassed states.


How? The Better Way.

If anyone else drives the vehicle, a safer way is to use a two-position switch that disables the clutch safety switch on demand. Better still, using a three-position switch provides an additional switch stop for security purposes. Leave the switch in this third position, and the starter won't engage at all. Check the schematics for details.

Graphic by: Randy Burleson
Jumping the clutch bypass circuit with a three-way switch is even better. Switching to the first position (red) bypasses the clutch at all times. Switching to the second (middle) position provides a security setting; the bypass circuit is open and the starter will not fire. Switching to the third position (green) reinstates the stock clutch bypass.


The Downside

This trick only works with stick-shift vehicles. Automatic vehicles have no clutch pedals.

This can be pretty rough on the starter, and lengthy use of the starter as the sole means of motivation for the rig will dramatically reduce the life of your starter. Use this electric crawl gear with discretion, or buy stock in a starter remanufacturing shop.


Related Links:
    Interactive Questions & Answers on this article can be found in the ORN TrailTalk forums
  • Heavier Flywheel: Running a heavier flywheel helps keep crawling at low engine speeds.
  • Jeep Tech Electrical: Discusses vehicle electronics including batteries, starters, ignitions, wiring, lighting, computers, gauges, and more.


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