Scott Fisher I writes \
\Phil Ethier writes>
\>If you find it is too strong, you can soften a bar on the rear of a B
\>by moving the mounts on the trunk panel closer together. Put in enough holes,
\>and you can adjust to your heart's content. Brian Erickson had several sets
\>of holes on his last (hmm, better make that "previous," it doesn't sound so
\>final) B. He found the best distance, so his present chassis only has one set
\>of holes.
\The other way to make a bar adjustable, of course, is to slide the
\end mounts back and forth along the longitudinal links.
Right, Scott, but that is only going to make the bar stiffer, not softer.
By "longitudinal links", Scott means the arms that are part of the sway bar
that reach from the mounts towards some point above the axle. A sway bar
resembles the letter "U". The sides of the "U" are the arms.
The "links" are the short rods which connect the sway bar to the axle. These
are jointed on both ends, to allow for the difference in arcs between the axle
and sway bar end. Joints can be Heim (Rose, for you UK readers) joints or some
sort of flexible rubber or plastic. Various effects can be accomplished by
relocation of these joints.
Moving the joint between the link and the axle outboard increases roll
stiffness. Inboard reduces it. The effect is not usually very pronounced,
it can be hard to do, and exteme angles make the arms move laterally, so this
is not too typical.
Moving the joint between the link and the sway bar down the arm towards the
bottom of the "U" increases the roll stiffness. It is easy to see why. We all
know tight bolts are less easily removed with a shorter wrench. A little means
a lot here. If you move half way up the bar, the stiffness doubles. Double
the stiffness of a bar generally is a major change in chassis tuning.
The problem is that converting a non-adjustable bar to an adjustable one by
this method can only stiffen the bar. On a bar with typical links, they are
attached the end of the arms. You could try extending the arms. Messy.
Luckily, the trunk panel on an MGB is flat and you can easily relocate the
mounts on the bottom of the "U". Normally, you would think that shortening the
bottom of the U would make a stiffer bar. This is true, but it is not exactly
what you are doing here. You are still twisting the entire length of the U.
You are also allowing more of the bottom of the U to bend vertically. This
effectively makes your arm longer.
I have had people tell me this won't work. Wrong. We've demonstrated it. I
have had others tell me that it will work, but the combination of forces will
wreck the bar. Not in this application. Brian has been using the same cheap
non-adjustable bar (I think it is an ADDCO) on two successive MGB bodies for
years of autocrossing. I don't know how many others have done this, but Brian
arrived at it independently, and doesn't mind sharing it.
My Midget bar came from Winner's Circle with heim joints mounted to slider
blocks on the arms, but I found that I wanted a softer range than that. So I
moved the body mounts closer together and had a range of adjustment more
appropriate. I had lots of holes in the car so I could experiment. I found
the best results were just a bit less rear bar than it took to get wheelspin on
corner exits.
I'm going to miss that tune-ability. I can't see a way to tune the front bar
on the Europa, and I'm not sure I want a rear one.
Phil Ethier, THE RIGHT LINE, 672 Orleans Street, Saint Paul, MN 55107-2676
h (612) 224-3105 w (612) 298-5324 phile@pwcs.stpaul.gov
"The workingman's GT-40" - Anthony Colin Bruce Chapman
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