Re: Torque steering 164

[Scott Fisher <sefisher@domain.elided>]

Fred Di Matteo writes: 

> Well, severe torque steer to the left was very annoying especially 
> because I nail the gas pedal almost at every traffic light.  About 
> one week's worth of this nonsense made me get out and check tire
> pressures.   I found 44 in RF and 38 in LF, enough circumference 
> difference to make it torque steer badly.   Reduced the pressure 
> to 31psi on both front tires and torque steer vanished. 

You live in Florida, right?  Maybe your tire shop guys had just come
from working the Daytona 500 and thought they were giving you a little
stagger to come off the high bank faster.   :-)

(Now, THAT is how Alfa could come back to the U.S. -- get the Olive
Garden to sponsor a NASCAR 166, with Michael Andretti driving!  Ah,
well...)

> With front drive cars, both  wheels and tires MUST be equal 
> dimensions.  

True indeed.  (Also true for both tires across a limited-slip axle,
front or rear; having widely unequal tire diameters can wear out a
clutch-type LSD.)

Speaking of tire pressures and their effect on circumference, I thought
I'd relate a winter-driving trick told to me in SCCA driver's school
almost a decade ago.  The second weekend, it rained so hard that they
closed half of Sears Point after a couple of formula cars slid off track
because there was a 6" deep *stream* of water between turns 4 and 5.  So
we did a modified version of the track that weekend.

Since I didn't have purpose-rain tires but only high-performance street
tires, the instructor gave me this tip: Overinflate the tires by 5-10
psi or so.  This will cause the tire to "crown" (that is, the center of
the tire will have a larger circumference than the outer edges). 
Normally this is a bad thing as it reduces the contact patch -- but in
heavy rain, reducing the contact patch effectively increases the amount
of the car's weight pressing down on each tire, which forces the water
out more effectively.  Darned if it didn't work -- while it still felt
like running around a freshly waxed kitchen floor in socks, at least it
didn't feel like the socks were buttered.

I've done the same thing to my Spider this year for the rainy season,
and traction, braking and linear stability are greatly enhanced.  And
forget what the songs all say, *this* year in California (at least in
the northern/central portion), we've been having a TON of rain for the
past month or so.

 -- Scott Fisher
    Sunnyvale, CA

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