G
the vertical element that is the wheel’s axis of
rotation when the kart is turning.
To accentuate the camber change of the
unequal A-arm suspension, I made kingpins
slightly longer than the height difference
between the upper and lower suspension
mount points on the frame.
The kingpin is part of the spindle, a bracket
that holds the axle and other components.
Both kingpin and axle must be made of material sturdy enough to support the kart under
stress. I used steel tubing.
STEERING
For small karts like this, a quick-release
steering wheel hub makes it easier to get
in and out of. Press the button, and the
wheel pops right off.
The steering shaft must be held on in
2 places. I used pillow block bearings bolted
to tabs welded onto bent cross-members
on the frame (Figure F). The steering shaft
disassembles into 2 pieces for easy removal.
At the steering shaft’s forward end, a
Pitman arm angles down perpendicular to
the shaft (Figure G). The arm is a short, flat
metal bar with one or more holes (I used 3)
for bolting to the rest of the steering system
through an adjustable tie rod. Attaching the
swing arm to the inner hole on the Pitman
arm makes the steering system the least
sensitive, while bolting it to the outer hole
makes it the most sensitive.
The swing arm runs to the right, where its
other end attaches in a stack to 2 more tie
Steering shaft Swing arm Spindle
Pitman arm
Spindle
Steering block
Right steering
rod (drag link)
Center
steering rod
Left steering
rod (drag link)
H
rods: the right steering rod (aka steering arm
or drag link), which connects to the right front
wheel spindle; and the center tie-arm, which
connects back across to the left steering
rod, and by extension, the left front spindle
(Figure H).
To make the steering and wheel alignment
adjustable, I tapped all 4 tie rods with right-handed threading on one end and left-handed
threading on the other. This lets you lengthen
or shorten each connection length without
removing the rod from the kart. The rear
wheels also have tie rods, but these are just
for alignment since they don’t steer.
The steering rods connect to the spindle
a few inches behind the kingpin so that while
the kart turns, all 4 wheels angle around
the same point. This geometry, known as
Ackerman steering, minimizes tire slippage
and skidding around curves. (With proper
Ackerman geometry, the steering connection
would be angled in rather than directly behind
the kingpin, but my geometry approximates
this for lower wheel angles, which are the
ones you take at high speeds.)
SPINDLES
The spindles bring your suspension, steering
arms, wheels, and brakes together. They
represent the most precise part of the construction, and are especially involved if you
want to minimize weight like I did.
Since I’m using drum brakes on the rear
and no brakes on the front, my rear spindles
connect the kingpin, axle, drag link arm
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