[Diy_efi] OT: ABS retrofit into older car...

[Mos]

On Wed, 4 Dec 2002, Scott F. Williams wrote:

> Mos. wrote:
> > I would've thought the front brakes are more prone to locking up first
> > upon a heavy stomp, as they have more braking power to start with, and the
> > front wheels are unloaded relative to when the car is actually slowing
> > down rapidly.
>
> Shocking the tire contact patches by stomping on the brake pedal extremely
> abruptly makes it possible to lock up the front tires first -easily so in
> slippery conditions. However, under most circumstances the rear tires are
> the unloaded ones during rapid decelleration. The weight transfers to the
> front which dives towards the ground. Front grip is often *increased* in
> this scenario. Meanwhile, the weight comes off the rear end which lifts
> skyward. Traction is reduced and the rear tires tend to lock first.

I understand the weight shift - what I was describing was the initial
shock, before the weight transfer - not continued heavy deceleration - I
guess I worded it poorly.

> "Proper" bias necessitates mechanically setting the front brakes to perform
> the majority of the braking force given the inevitable weight transfer. With
> many environmental and mechanical variables considered, this bias is set to
> create the desired (not necessarily best) stopping and handling performance.
> This is a subjective matter often decided more by lawyers and accountants
> than driving enthusiasts.

Oh great.... :)

> Meanwhile, optimal braking is never achieved by violently stomping on the
> brakes. A smooth modulation of force is best -even when ABS is there to bale
> one out electronically.

Agree completely - however it appears most ppl tend to stomp violently
during an emergency braking situation.

Mos.

-- 
84 AE86, 90 ST185GrpA, 91 MX83Gr, Sydney, Oz.



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