Re: Roll Centers and CG

[Nizam Zambri <nizam@domain.elided>]

Well well.  Thanks for the input so far, Michael, Paul, George, et. al.

The opinions (some based on practical observation) gathered so far 
largely favors leaving the roll centers at, or close to, stock.  While 
this is a reasonable enough direction, I still find it hard to believe 
that for a track-duty car, a more neutral behavior cannot be induced 
from lowering the roll center and CG.

I understand that a good understanding of what goes on with the chassis 
is key to making any changes.  As my 75 slowly makes its way from a 
street/track vehicle to a completely track vehicle, I've come to 
appreciate the amount of engineering that has already gone into the 75's 
chassis, even though the basic design is over 20 years old (since the 
Alfettas)!  Perhaps I'm foolish in thinking I could better the career 
engineers at Alfa Romeo, Spa. but on the other hand, their design also 
includes a range of adjustability which one could exploit to the 
extremes they desired.

Larry Jr. at APE thought that lowering the rear roll center of the 75's 
chassis would not be very beneficial, preferring instead to lowering the 
front roll center where the endemic consumer-focus-understeer exists.  
To this end, he has made us both a set of drop spindles which I shall 
get to try very soon at the next track outing.

Since I'm making this change without changing the spring rates or damper 
rates, (also keeping the camber, caster and toe settings the same, along 
with the ride height), I can hopefully see if there are any advantages 
at all to this approach.

Keep it tuned to this station.

Nizam
88 75 3.0V6
94 164 Super 3.0V6 24v
97 155V6

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