Darrell, a.k.a. TR250Driver (though I don't know what a TR250 has in common
with a Spitfire or GT6 other than the engine) wrote:
> What role do the front springs play?
It strikes me that there may be a question of terminology.
When some people talk about sag they are speaking of the body roll, i.e. the
lean, toward the driver's side due to the driver's weight. Since the frame
doesn't twist, the front and rear must roll the same amount, but people tend to
notice it only from the rear because that's the end you watch for extended
periods of time when you're following someone. At least on the swing-spring
cars and to a lesser extent on all the other Spitfire-bassed cars, most of the
roll stiffness is in the front. So the rollbar and the balance between the
front springs are the main determinants of roll. The rear of the car simply
leans left or right according to what the front dictates. The driver's side
spring would have a spacer to compensate for the driver's weight, to produce a
level (laterally) car when only the driver's seat was occupied, or when the
passenger's side was occupied by someone who might typically be much lighter.
(I'm trying hard to avoid any gender imbalance here, probably!
n!
ot succeeding. :-)
Other people speaking of sag might be referring to the nose-up attitude, i.e.
pitch up, that happens when the back end drops. Unlike your TR250 the
Spitfire-based cars have a single transverse leaf spring, so when it (singular)
weakens or if the axles are lengthened or the back bumper gains weight, the
entire back end sags regardless of the roll.
--
Jim Muller
who driver the Spitfire to work today after a year of being without it
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