Thursday, November 6, 2008

The Better Mousetrap

The past few days have been spent installing the NOS Datsun brake booster on the bike. I had none of the brackets or any other hardware to make it work, so I improvised. I welded up a bracket to bolt to the side of the block in the holes provided by Chevy for the clutch linkage pivot ball. So far, so good. I rigged up an arm that pivots on the foot peg mount and engages the booster push rod. I then ran the clutch cable to the arm. Squeezing the lever pulls the arm and pushes the booster. A short. adjustable push rod goes from the opposite end of the booster to the throwout arm. I ran a vacuum hose to the booster and fired it up. It felt like the cable was welded to the frame. Two finger pull my butt!! Realizing that I may not be pulling enough vacuum, I went on my merry way to the junkyard in search of a vacuum pump. GM used them on a bunch of 4 cylinder stuff in the early 80s. I figured I'd pick up a couple just in case. Yeah, right. We have two large self serve yards nearby and not one lousey early 80s Citation/Sunbird/Cimmaron to be found. Too old for the regular yards and not old enough for the antique/oldies yard. So I went home and stared at it. I thought that something like a Harley mousetrap might be the answer, so I fabbed up this unlikely looking contraption. It pivots on the old swingarm hole. I went to the hardware store and grabbed two of the heaviest springs that they had. One end attaches to the lower end of the mousetrap and the other to a tab welded to the frame just under the seat. The springs are stretched tighter than a bowstring. A link attaches the mousetrap lever to the throwout arm. As it sits, the spring is over center and holds the mousetrap in the engaged position. As I pull the clutch lever, the contraption goes over center in the opposite direction and the tension of the springs assists the vacuum booster. The springs are a bit less powerful than the Belleville spring in the pressure plate, so when I ease off of the lever, the clutch re-engages. It seems to work very well. I still have some fine tuning to do. The hardware store springs look like they're stretched to the limit. I'm going to look for a more powerful spring to replace them. Maybe a hood hinge spring off of a large car or truck.
Of course, all of this didn't go without some hassle. The fuel pump had to be relocated. The On/Off/Reserve lever now pokes through the side cover. It looks better than what I had before. The hidden switch panel that I had, so cleverly, built also got the heave-ho. I need to find a new spot for them. I didn't like the key switch on the side cover because the leather fob rubbed on the paint and left a worn spot. I'll sit on my little thinking stool tomorow and stare at it some more

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