At 10:18 am 2/5/97 -0800, you wrote:
>
>>I saw a message a few weeks back suggesting there was a fix for
>>the Ackerman angle steering problem. It mentioned new linkages?
>>Is this true, does something exist?
>
>>I didn't see any reply. I also assumed this is some mythical fix,
>>otherwise nearly everyone would have corrected the problem.
>***** NOTES from Jay Laifman (JLAIFMAN @ PNM) at 2/5/97 10:14a
>I don't recall the post. But, I will note that in The Book of Norman
>(page 81) there is some discussion about Doane Spencer flipping the
>front rotors which allegedly eliminated the problem. Personally, I
>do not understand what was done from the description. Any more
>details out there?
Tiger,
I spent many hours on my computer using Wolfrum Mathematica,
and under my Tiger trying to find a way to solve the problem.
All the attempts at adding some sort of idle arm either did not solve
the problem because the "linear" motion changed to tangents of curves.
and just changed the problem.
I am presently "attempting" another fix that has fixed arms attached
to the ends of the rack. The fixed arms are lined up with the end
of the steering arm on the spindle. This took MAJOR surgery on
the cross member. I still have a problem in that the arms are off-
set from the rack (toward the back of the Tiger) and they seem to
cause a rotational force on the rack. I may have to add a cross rod
in front of the rack. With the rod supported in a linear bearing and
the rod attached to the arms. This modification does allow almost correct
Ackerman. The "almost" conserns the fact that The steering arms
are too short. Can't make them any longer or they hit the inside of
the wheel. By the way the proper angle for the steering arms is such
that if you project a line from the steering arm ball joint hole, through
the steering axis on both sides, you will intersect the center of the rear end.
This does not determine the length of the arms, just the angles. It is
very hard to measure because the steering axis is hard to determine.
I assume someone will try to explain that reverse Ackerman
is good for high performance cars, because of the slip angles
during hard cornering increase on the outside tire. The Tiger starts
with about correct Ackerman until you turn the tire more than about
15 degrees then it reverses. Excellent for scrubbing off speed and tires
when making a tight corner. I would prefer to have the Ackerman
angles start and end correct. I can turn the wheel more to account for
slip angles.
The real solution is to move the motor back several inches, and
remount the rack directly in line with the steering arms. Just because the
firewall is in the way .......etc.
Jim Barrett Tiger II 351C and others.
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