[DeTomaso] Clutch setup
MikeLDrew at aol.com
MikeLDrew at aol.com
Mon Nov 14 15:42:48 EST 2011
In a message dated 11/14/11 11 41 0, oldwheel at shaw.ca writes:
> When I look at the drawings there is a pivot lever which goes between the
> control arm attached to the foot pedal and the Clutch MC.
>
> Mine did not have it when I took it apart. What is it for? Limit travel?
> Limit push rod angle? Does everyone use this? I am questioning it's need.
>
>>>That's the clutch effort reduction kit. One of the knocks against the
Pantera early on was excessive clutch effort. To combat that, the linkage
was redesigned to incorporate some monkey-motion to increase the mechanical
advantage of the pedal over the master cylinder.
The TSBs state that this went into production on all cars built on and
after September 1st, 1972. My August '72 car came to me with this kit
installed, although since it had a former lady owner some time in its past, I don't
know if it was built that way from the factory, or retrofitted.
TSB #6, article No. 49 details the work necessary to install the kit on an
earlier car. The kit came complete with a new clutch cross shaft, but that
isn't necessary for the capable do-it-yourselfer.
Here's a drawing of the kit:
http://www.panterasbywilkinson.com/images/final_catalog/gif/ill08b.gif
Note the depicted angle of the arm which drops down from the shaft #1 to
engage the linkage. On early cars, that arm hangs just about pointed
straight down towards the ground, when the foot is off the pedal; it then moves
forward as the pedal is depressed to depress the plunger in the master
cylinder. On a car with the effort reduction kit, as seen in this drawing, that
arm points towards the rear of the car at about a 45-degree angle, and swings
through an arc as it rotates the monkey-motion linkage which in turn
actuates the master cylinder.
The only difference in the two shafts (I have held both in my hands
side-by-side) is the location of the hole drilled in the opposite end, where a big
roll pin connects the shaft with the pedal. That pin secures the shaft to
the pedal, and its location dictates the orientation of the arm at the other
end. By simply re-drilling this hole 45 degrees out from the original,
early-style location, you can achieve the desired result of changing the arm's
orientation.
The kit is available from some of the vendors, either with or without a new
shaft. It costs a small fortune:
With the shaft, $400:
http://www.panterapartsusa.com/cgi-bin/detail.cgi?prod_id=04028A
Without the shaft, $207:
http://www.panterapartsusa.com/cgi-bin/detail.cgi?prod_id=04028B
(Pay no attention to the images; Steve's website is a bit goofed up, and
sometimes his images are 'off' by one part number).
I've been told that the effort reduction kit results in a non-linear curve,
with decreasing pedal effort as the pedal gets closer to the bottom of its
travel. I've never noticed this; if it's true, the decrease in effort is
probably fairly slight. However, there is a noticeable difference in pedal
effort overall, between those cars equipped with this setup and those
without.
The Ultimate Solution would probably be to install this linkage in
conjunction with a diaphragm (Centerforce-style) clutch. Even with my three-finger
clutch, my pedal effort is not unreasonable. Early cars with stiff
clutches and no effort reduction kit can be rather brutal.
Mike
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