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

[Mos]

A guy in Qld, Australia, retrofitted almost everything (literally) from a
Japanese JZX81 Toyota Chaser into a RA23 Celica (late 70s), including the
ABS.
He used struts off a Holden Commodore I believe (IE not Chaser
struts/brakes).
The car was fully engineered, even without a "complete braking system out
of another car"... So either the engineer didn't notice, didn't care, or
it was "ok"...

I've been toying with the idea myself, and have two sets of ABS systems
but haven't gotten around to doing it...

Mos.

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

On Thu, 5 Dec 2002, Bevan Weiss wrote:

> The sizing and power of brakes is of little effect, It's pretty easy to get
> a tire to lock up, it only really depends on the characteristices of the
> tire (ie pressure, profile, size, surface area, compound etc).  It's trying
> to keep the tire from locking up that's the hard part.  I thought that this
> conversation started with ABS, which simply modulates the pressure to the
> brake cylinder to keep the tire from locking up (by measuring the speed of
> the tire).  Trying to retrofit this into a older car is a legal
> impossibility in all countries that I know of (apart from maybe some third
> world ones...).  The problem is that ABS systems require very serious
> testing and certification before they are allowed to be used on a road going
> car, most of this testing is quite destructive and very expensive, hence
> only worth while for a large production.  Putting an production line ABS
> system into a new car (ie one it hasn't already been tested for) will
> require this same expensive testing.  Which is not worth it at all.
>
> PS: I'm not sure of the exact method used by the manufacturers for their ABS
> systems but would imagine it's some kind of bang-bang controller, ie it
> allows full brake pressure until the tires almost lock up, then bleeds the
> pressure off and repeats the process.  I get this from the pulsing feeling
> when heavily decelerating in most ABS fitted cars.


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