--- "George P." <spitdriver78@yahoo.com> wrote:
>
> 1. Brakes - Tandem master cylinder operating front
> and rear brakes independently. I thought I read
> (granted this was a long time ago) that the dual
> circuits operated on diagonals - LR/RF on one
> circuit, and RR/LF on the other. Supposedly for
> more stability under braking if one circuit is lost.
> Yes/no?
Diagonal circuits are better in loss of pressure in
one circuit, but it's also more expensive to produce
since it requires two proportioning valves.
"Expensive" doesn't go with "Spitfire," hence both
fronts on one and both rears on the other as Joe
pointed out.
> 2. Chassis data - many measurements have "(2 up
> condition)" after them. What does that mean?
Interpret "2 up" as "2 aboard." Most obvious would be
changes in overall height, rear camber, and
acceleration specs.
> 3. Gearbox - what does the "overall" ratio tell us?
> I figured out that the overall is the gear ratio
> multiplied by the final drive ratio, but I still
> don't understand what that's telling me...
In the good ol' days, all transmissions had a 1:1 top
gear, so the final drive ratio was equal to the
overall ratio - knowing the final drive was good
enough to compare two cars. Once internal overdrives
(e.g., most 5-speeds) and external overdrives (e.g.,
Spitfire) became available, though, the overall ration
was NOT 1.0 x the final ratio. You had to know the
final drive ratio AND the top gear ratio to calculate
revs/mile or cruising revs at various speeds. Rather
than do the math for each case, the overall ratio
became a more important spec for comparison purposes.
For example (made up), a car with a .8 top (5th) gear
and a 5:1 rear end would cruise at the same rpm as a
car with a 1:1 top gear and a 4:1 rear end because
they each have an overall ratio of 4:1. And before
someone says "no car has a 5:1 rear end," the '66 Alfa
Romeo Giulia TI I owned had a 5.12:1 rear end (with a
5-speed).
M D "Doc" Nugent
Renton, WA (USA)
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