Thread: Bias Ply T & F!
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Old 10-28-2016, 09:32 AM   #4
CapriRacer
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Re: Bias Ply T & F!

Quote:
Originally Posted by RidingOnRailz View Post
Ok. #2. was based on my readings that,
given the same vehicle, putting bias-ply
tires on a car with alignment specs for
radials resulted in a white-knuckle driving
experience. The writer stated that on his
car at least, radials needed very little toe in,
but the bias plies needed at least 1/6" toe
in to achieve the same feel.
There is quite a bit of variation between tires and what you described sounds like you are dealing with some of the extremes. And while it is true that radials are generally more sensitive to toe-in, this property can be changed with some simple changes in tire construction, so it is highly dependent on what 2 tires are being compared.

Quote:
Originally Posted by RidingOnRailz View Post
#3. Do you know which caster is which?
Negative = axis leaning forward(toward front
of vehicle), and Positive = axis leaning
backward. For the last 40 years, at least,
the vast majority of vehicles have called for
POSITIVE caster(from half a degree up to
seven degrees depending upon purpose
of vehicle). For reasons I never quite
understood, a lot of cars from 1960s and
earlier speced negative 1-2 deg caster,
and they were from the bias ply era.
Oops! I always get that backwards. Yes, it is positive caster that adds stability. I, too, have wondered why some vehicles spec'd negative caster - but I also noticed that they changed to positive caster before they changed to radials. If there was such a fundamental difference between bias and radials (and there are!), why wasn't this a change made EXACTLY when the changeover took place? I suspect it has more to do with how sloppy the suspensions were (maybe I should use the term imprecise here!) I know it was somewhere in the 1960's when Calspan started measuring the forces on tires and maybe that influenced the car makers and their suspension settings - instead of going by the feel of a test driver.
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