The fulcrum pin orientation question I posted has exposed some
controversy, I'm afraid. Funny how some of these issues seem to
present such an obstable to finding the 'right' answer. I received
an email from one list member who points out that there was a
correction issued in a 1992 Practical Classics magazine where
apparently the magazine admitted that the caption and photo on page
78 of the Practical Classics & Car Restorer Triumph TR6 Restoration
book shows INCORRECT installation of the upper fulcrum pin. A few
other responses had generally supported the instructions from the
book, which recommends that the curved part of the fulcrum pin should
'bulge' toward the engine and prior to the above information, I had
come to the conclusion that my fulcrum pins had been intentionally
reversed at some point in order to gain some negative camber in the
front wheels.
This new information casts doubt now on the whole question
I think
everyone agrees that the part in question is asymmetrical, and as
such the orientation of the fulcrum pin HAS TO affect the camber of
the front wheels. On my TR6 the curve of the fulcrum pin bulges AWAY
from the engine and yet the camber of the front wheels was set (at
last alignment) at around .75 deg negative. In other words, the
orientation of the fulcrum pins on my car has not resulted in a
greater-than-normal amount of negative camber.
Of course, the other variable in this equation is the number of
alignment shims installed under the lower wishbone pivot brackets.
The basic idea is that the greater the number of shims used, the more
NEGATIVE camber will be introduced, since adding shims pushes the
LOWER end of the vertical link AWAY from the longitudinal centerline
of the car. Also, adding more shims behind the FRONT lower wishbone
arm than is used in the rear tends to decrease caster and adding more
shims in the rear than in the front tends to increase caster. All of
this is somewhat theoretical, as I expect that on each individual
chassis the lower wishbone support brackets are welded in SLIGHTLY
different locations. As a result, each car will require different
numbers of shims in different combinations to achieve the same toe,
camber and caster specs.
With all of that out of the way, I've just taken 'inventory' on the
number of shims installed on my car for purposes of comparison. This
is only for the front suspension, mind you. And these numbers may
change in a couple of weeks when my suspension is back together and I
take it in for another alignment.
Right Front: 1 shim
Right Rear: 6 shims
Left Front: 4 shims
Left Rear: 3 shims
This combination was arrived at 12 years ago after I took it to a
front end shop for an alignment after rebuilding the front
suspension. (new bushings, ball joints, etc.) As I recall, this
combination yielded about .75 deg negative camber and I think the guy
was only able to get about 2.5 deg positive caster on both sides.
All of this, of course, with the upper fulcrum pin installed with the
curve pointing AWAY from the engine.
--
Pete Chadwell
1973 TR6
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