60/40 bias was dialed into the static configuration of cars past because - in low traction (wet road) environments, that 40 was all it could handle before lock up risk was increased (and even on dry road hard brake while cornering can have the rear end swap with the front if back brakes get applied too hard). On dry roads that left the vehicle with less stopping force than the dry road could handle - but still more than wet road, and still within reasonable stopping distance. An engineering tradeoff. That "unused" back brake was simply wasted - or more precisely returned a longer life span in the linings.
With the computer the tradeoff becomes unnecessary (except in system failure - see below) - the brakes can be used at maximum, independent of each other - front rear AND left right biased - at all road conditions. This causes the wear to be greater in the rear - compared to a static biased non ABS system! This does NOT make the rears the predominate brakes. Weight will always transfer fwd in braking and the rear end will thus always LOOSE weight and can never be the predominate brake (the harder you brake the more weight comes off the rear the lower the traction available). What this means is a wet stop can be 60/40 while a dry stop is 51/49 Or even better than 50/50 - depending on how hard you are asking the brakes to work.
Further with computers traction control can be made to use the brakes (and the JK does this) - and applies one or both rear even when on the gas - if slippage or slide is detected by the wheel speed monitors and Gyro.. This also adds to wear - comparative to a non TC system - and again its simply using brake potential that would be left on the table if it was simply a 60/40 non ABS, non TC! Does not make rears predominate!
There is still a 60/40 mechanical bias in the brakes. That's the "failsafe" so that if TC and ABS do fail leaving you suddenly with only hydraulics brakes - you wont have an end swap when braking under a corner. The abs and tc system merely "equalize and maximize" the brake force at the tire contact by a strategy of bleedoff and individual wheel PSI increases.
J Wm Bishop EA, ASADE
The wagon should, of course, be as light as possible, but strength should not be sacrificed to lightness, for on any but the regularly traveled roads, the wagon will get many a
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