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

[Mos]

On Wed, 4 Dec 2002, Adam Wade wrote:

> --- Mos <mos at sydney.net> 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.
>
> Actually, that is exactly why the rears are more prone
> to locking than the fronts.  With less loading, they
> have a much lower friction coefficient with the
> roadway.  That coefficient is not linear in proportion
> to load; it is exponential.

Yeah, what I was *trying* to say :) was that when you're happily puddling
along, in a well balanced car, the load on the front and rear is somewhat
equal, but the brakes are more powerful on the front - so a violent pedal
stomp in this situation results in more braking force being applied at the
front, which in turn can lock the front wheels up as the braking force can
exceed the maximal traction force. Once the weight transfers, obviously
there's more tractive force available.

So the co-efficient changes with load?
Obviously the tractive force varies with load (and coefficient) but I
didn't realise the co-efficient itself changes.
In the high school mechanics classes there was never any mention of the
co-efficient of friction changing with load - what materials does this
happen with?

Mos.

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



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