First let me thank all who have replied to my post requesting steering
dimensions. While I did not get the info requested, I did get some ancilliary
data.
But, I still need the data: What is the distance from a line drawn between the
lower ball joints to the centerline of the mounted rack & pinion and what is
the distance between the rack's ball sockets?
I need the data because I am too lazy to drag my Tiger out of storage and
measure myself and it is a heck of a lot easier with the crossmember on the
bench. Now why do I want this info? I have owned my Cat for 31 years and in
all of that time I have never seen an analysis of the Tigers steering problem.
I have seen many fixes come and go and they all seem to be trial and error. I
want to understand the problem first and then to solve the problem as best it
can be solved analytically. I will post this analysis as I go along. I am also
buildin an ET Bracket racer from a rust bucket SV Alpine. So I have all of the
basic components to implement the fix and to report on the effort, again as I
go along. I may even have to build a new crossmember to fix it!
Now, I have preliminarily made the first step in the analysis: that is to
determine the correct ackerman angles for our cars. This is pretty simple trig
based on the following conditions: 1) the correct steering arm angle for
proper ackerman is that it must lie on a line drawn from the center of the car
at the rear axle centerline through the lower ball joint. With wheelbase
dimensions of 86 inches and distance between the ball joints, the correct
steering angle arm is 14.667 degrees, splayed to the outside. Given this then
the following is easily found:
Inside Wheel turn Angle Outside Wheel Turn Angle
5 degrees 4.78 degrees
10 " 9.17 "
15 " 13.22 "
20 " 17.00 "
25 " 20.55 "
30 " 23.91 "
This basic analysis is predicated on Dave Morgan's Chassis builder book.
As soon as I get more info, I'll do more and let you all know how it is
progressing...
Thanks,
Larry Mayfield
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