<VV> brake bias (F/R and L/R)

[AngryCorvair@aol.com]

Joel asked why we'd want disc brakes for the front when corvairs are  
rear-heavy and therefore need more output from the rears than the fronts.
 
my answer is that we're not buying more output with front discs, we're  
buying a setup that's more stable directionally.   duo-servo drum  brakes are 
sensitive to all kinds of things, and rarely do they engage at the  same time and 
at the same rate.   this leads to cars feeling "darty"  under braking.   discs 
are much less sensitive to environmental /  contaminant concerns, and they 
require no adjustment.
 
in fact, when dimensions are maximized for a particular wheel limitation, a  
duo-servo drum will give greater output than a leading-trailing drum, and much 
 greater output than a single-piston disc, for a given line  pressure.   
that's why front disc kits come with prop valves for the  rear circuit.
 
Ken questions front-skid versus rear-skid brake balance.   the  answer, quite 
simply, is that occupant safety is optimized for straight-on  impacts.   with 
the fronts locked, your vehicle will point in the  direction of travel of the 
CG of the vehicle, and if you hit something at least  you'll hit something 
head-on.
 
oversteer, whether induced by throttle or by brakes, is an unstable  
condition, and sometimes full opposite-lock steering input is not enough to get  
things back in line.
 
i'm on holiday, so i'm taking off my brake engineer hat until monday.
 
patrick aka _AngryCorvair@AOL.com_ (mailto:AngryCorvair@AOL.com)