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4 links, torque links, and the missing link (long)

To: "Land Speed List" <land-speed@autox.team.net>
Subject: 4 links, torque links, and the missing link (long)
From: "Bill & Dee Bennett" <benettw@earthlink.net>
Date: Sun, 17 Jun 2001 22:17:45 -0400
Here is something that has perked my interest for months. The ability to get
traction at Bonneville seems to be one the keys at making a good run. The
idea of using a four link system seems to be fairly common. To me this would
be fine as long as you were constantly accelerating. The force is there to
make this type of suspension work. The four link system has a variety of
adjustments that can be complicated in obtaining the proper setup. By
changing instant center position anti-squat can be changed to control front
end lift and how hard the tires are hit. Once you reach the top of each gear
G forces start decreasing, the forces available for traction are now lower.
It seems the 4 links just doesn't allow for 100% use of the motor having to
leave something on the table for traction.
    Now Keith has mentioned the use of a 3 link or torque link type
suspension. This is one I am more familiar with having hung around the dirt
circle tracks for years. It can be just as complicated as the 4 link to
setup. The 3rd link attachment point can be one of the most important as it
not only controls acceleration, but also braking. The front of the 3rd link
is decoupled from the frame by a spring loaded slider or rubber doughnut to
prevent wheel hop during braking. Even with one less bar to adjust you are
still trying to achieve they same goal. To arrive at the proper instant
center point without creating to much front end lift while creating enough
rear end down force to gain traction.
    Let me throw one out to the list that I haven't seen, but no doubt that
someone smarter than me has tried. Why not replace to top 3rd link with a
wishbone common to four link systems. The wishbone would have a longer than
normal center piece and coupled to the frame similar to a 3 link. The rear
attachments would be vertically inline with the lower arm attachment points.
This would allow doing away with the diagonal link or panhard bar. Also you
would have the ability to preload the right and left sides separately.
Granted the gains maybe no more then the 4 link or torque link, and the
setup a real bear. Overall size may be too much for some vehicles. Has
anyone ever seen a setup similar to this and does it work?

My take on the whole thing is that until someone rewrites the laws of
physics it will always be a struggle to balance out creating  rear wheel
down force without creating lift.

Bill

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