Traction bars

From: Bob Tom (tigers@bserv.com)
Date: Sat Dec 12 1998 - 10:12:40 EST


Leaf springs tend to bend under big power. As power is applied,
the front of the housing rotates upward. The rearend is bolted
to the leaf springs and when the housing rotates, it bends the
leaf front into an S shape and pulls the tire off the ground.
The spring snaps back violently but power is still being applied
so it happens over and over again, causing the tires to bounce up
and down...i.e. wheelhop.

The primary purpose of a rudimentary traction device is to keep
the spring from wrapping up and to keep the tires on the ground,
although some devices serve other purposes as well.

Spring clamps, slapper bars (traction bars), Southside bars, Cal-trac
bars, pinion snubbers and ladder bars are some of the common type
of inexpensive traction aids that can be used in launching.

Traction (slapper) bars slap up against the bottom of the leaf spring.
Most slapper bar designs replace the stock lower mounting pad. As
the housing rotates, so does the bar, which contacts the front portion
of the leaf spring and keeps the rearend from rotating further and
the spring from becoming S-shaped.

Thinking of a leaf spring as two separate entities may help. The
spring's front half locates the housing in the chassis; the rear half
is responsible for most of the "spring" function. The front half
wraps up under power, pulling the tire off the ground. The stiffer
the spring's front half is, the more resistant it is to wrapping up.

One of the keys to the 'legendary' Chrysler Super Stock leaf springs
is that the the front half is shorter and stiffer than normal, and
is designed to preclude the use of any type of traction device whatsoever.

Hope this is useful knowledge in their search for better traction.

Bob



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