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[Roadsters] Help! mechanical genius needed,

To: <tomet9@sbcglobal.net>, <datsun-roadsters@autox.team.net>
Subject: [Roadsters] Help! mechanical genius needed,
From: "Fergus OFarrell" <fergus06@socal.rr.com>
Date: Fri, 14 Sep 2007 20:27:58 -0700
Tom,
perplexed you are, but not too far off.

It is time to get a bit more geometric on this challenge.
We need to get a 15-25# fish scale, and see how much force the stock vertical
linkage arm is pulling on the carb cable linkage (Keith Williams, got any
ballpark quantitative number on this?)

Without this, we get a pc of PVC pipe and some cheap poly rope and some small
weights (arm curl dumbbells or ankle weights) and make set-up where the PVC
pipe is our new 'belllcrank', as close as possible to the same height and
perpendicular to the cable outage, the poly rope is the cable extension, and
we weight the end of the rope until the pedal feels "neutral". Then we know
std pedal force needed to overcome cable friction.

Now do the same for your new set-up, in the opposite direction, finding the
force needed to actuate the throttle set-up you have. (when running, which
seem to be the challenge)
Then work the geometry, (free-body diagram) measure the radii of the
bell-crank(s), (partial pulley curves) , lever arms in the system, and work
out what we need.  Then go looking in junkyards (and possibly motorcycle
junkyards for the cable linkage that made that carb set-up work at only wrist
torque) for parts, and maybe Summit and other folks.

Anyone, am I way off base?  Beuller?

Phergus O'PhysicsPhun, 69 2000, HB, CA
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