Auto Clutch Install on Chevy Sprint 9/2001
Driving in heavy traffic can be tiring after a long day. When I hurt my knee in a Triathlon, the auto clutch sounds like a good idea for the Chevy Sprint. The Toyota would a candidate for it too, but on the other hand, being an off-road vehicle, extra accessories could affect its reliability though.
Searching on Google.com, there was an outfit in Korea that made a kit to convert a manual clutch into an automatic clutch. The web site is: http://www.semiauto.co.kr/YUNJIN/main.htm The contact was: "KIM SUNG KWANG" <hand88@netsgo.com>. Since then, the same web site has came down. They don't have a retailer in the US. The owner was willing to give me a sample unit for $250 + $70 shipping. He was even open to the idea of letting me be a representative for the US market.
The actuator is basically a windshield wiper motor connected to a cable with a pot, and two limit switches.
The circuit board consisted of a relay with delay timer for power, a Motorolla microcontroller, and some power transistors with heat sink for the motor. Various dip switches set the number of cylinder on the engine. It could accomodate 3, 4 and 6 cyl. After some hacking in the car interior, the motor was installed underneath the dash board. The first time, my girlfriend switched the two power supply wires to the unit, and upon power on, the circut board was fried immediately with some smoke and spark. We looked at each other for a moment, and investigated. Another email was sent to Kim in Korea. In his broken english, he asked what happened. From the tone of his email, he seemed fustrated at our Yankee DIY types. Another board was ordered for $150 or so. This time, we double checked the wires, and hooked everyting up. After some adjustments to the unit, it worked.
You press a button on the shift lever to disengage the clutch. Then you can shift into gear, and release the button. As you apply gas, the computer sense the increase in engine rpm, which then gradually release the clutch. There are several speed curve on clutch release base on how high the rpm is increased to upon starting. When everything is adjusted correctly, the unit workes pretty well on level ground. However, if is adjusted for level ground, then on steep hill like in San Francisco, the clutch release curve is too fast for the condition. At a stop light, stepping on the brakes will also automatically actuate the unit to disengage the clutch. In stop and go traffic, the operation is quite automatic.
There is also a potentiometer that you should install on the dashboard or somewhere accesible. That adjust how fast the clutch engage after you press on the gas. Suppose, you could use that to compensate for hilly terrain. It takes some trial and error to set it just the way you normally drive. I just set once and forget.
I have used the unit for 2 years so far. Some things that would be nice to add would be a vacuum sensor to sense the engine load on engagement. That would of course add complication to the controller programming. It would also be nice to have a modification so that the clutch would not disengage in traffic immediately when you touch the brakes. I like to use the brake to modulate the car speed with the engine at idle in traffic. Idealy, the clutch should only disengage when the engine is below 1000 rpm. That way, the clutch can stay engaged while I am timing the traffic..
Isold the Chevy Sprint in summer of 2003. Of course, the auto clutch was taken out before selling the car. The unit worked well at the time that the car was sold. The only issue with the auto clutch was the switch on the shifter. When you press and hold the button on top of the shifter, the clutch should stay disengaged. The switch was wearing out for some reason. It would make intermittent contact. Therefore, the clutch would cycle in and out when you are pressing down and holding the switch. It was more irritating that an issue. The unit was still workable. I learned to hold press the switch in just the righ way so that it make continuous contact. I bought a good quality contact switch, but never got around to it before selling the car. If I were to install this in another car, I would put a good switch on the original shifter knob using a dremel tool to make a cut out on the knob.
Update 11/30/2004
I have forgotten about this web page in geocities until recently when someone emailed me asking questions about it. I have been using AT&T for web site. They gave me the link to my own webpage as well as the auto clutch website :) To my surprise, the company is still in business. In fact, they have added several products to their catalog. Their power clutch looks interesting if it does what I think it does. I though about that same idea also. With some cars, the clutch is heavy especially after a long day of driving. A power clutch like a power brake would make sense. You don't really use feel the engage the clutch anyway. It is usually done by position, so loosing the feel of the clutch with a power clutch would not make any difference.
Update 4/18/2013
Another auto clutch idea: TrollTuner