Bypassing an ABS system

We bought our 1993 Caprice Classic 8 years ago at state auction. It was
formally a police car and the only thing wrong with it at the time was
an ABS light that was on. This I was told was probably caused by a bad
wheel sensor but we never addressed it and really never missed the ABS.
In fact I prefered not to have it working anyway. We have always
maintained the brakes and they have always been fine otherwise on the
car.
The other day my son had to make a panic stop to avoid an idiot that
pulled out in front of him. The car did stop almost completely and then
he lost both brake systems. We got the car home and found that the
quarter inch main line to the rear wheels had ruptured due to rust. A
three sixteenth inch line from the ABS unit to the right front wheel
had sprung a leak as well. They both went at the same time apparently.
The master cylinder has a 1/4 inch line which comes out the bottom
front section. There is a 3/16 inch line which comes out of the bottom
rear section. Both resevoirs are shaped differently but appear to hold
the same amount of fluid so it is difficult to determine if one is
smaller than the other. The proportioning valve is mounted under the
master cylinder. These two lines from the master cylinder go in a
straight configuration into the two connections on the top of the
valve. The switch of course is in the top center of the valve. There
are two lines coming out of the bottom of the valve. They are1/4 inch
in front and 3/16 inch in the rear. They both go to the ABS unit.
Coming out of the ABS unit is a 3/16 inch line to each front wheel
caliper and a 1/4 inch line to the drum brakes at the back wheels for a
total of five lines. Although only one line is leaking they are all
rotten. These lines to the ABS unit were obviously installed before the
steering column and most likely the upper control arm were put in. Two
of them also have coils on both the ABS and the valve side which will
be practically impossible to fashion as well.
Now I would like to address some questions to the group:
a. What is the purpose of these "coils" ? There is no chance of
movement on either end of these lines so I can't really understand
this.
b. It would appear that since there is a 1/4 inch line running to the
back wheels and then they tee over the differential that the front
section of the master cylinder, (1/4 inch line ) feeds the rear wheels
and the rear section of the master cylinder, (3/16 inch line) feeds the
front wheels) both through the ABS unit of course? Is this correct?
c. If b. above is correct and since I don't need the ABS is there any
harm in directly connecting the 1/4 inch line from the rear wheels
directly to the front of the valve and then coming out of the rear of
the valve in 3/16 inch line to a tee which then feeds both front
calipers? To otherwise restore the ABS plumbing, something which I
neither need or want seems unnecessary.
I realise that a professional mechanic would never do this to a
customers car and I would not ask that of one either. However there
once was a time when there was no such thing as ABS so if you need to,
speaking in a purely hypothetical sense, will this modification be OK?
Thanks in advance for answers to my questions and your opinions. Lenny.

> wrote in message
oups.com...
> We bought our 1993 Caprice Classic 8 years ago at state auction. It
was
> formally a police car and the only thing wrong with it at the time was
> an ABS light that was on.
> Now I would like to address some questions to the group:
> a. What is the purpose of these "coils" ? There is no chance of
> movement on either end of these lines so I can't really understand
> this.

Actually there is quite a bit of flex in those coils which is why they
exist. Chassis flex and the rubber mounts for the body plus firewall
motion when you step on the brakes hard.

> b. It would appear that since there is a 1/4 inch line running to the
> back wheels and then they tee over the differential that the front
> section of the master cylinder, (1/4 inch line ) feeds the rear wheels
> and the rear section of the master cylinder, (3/16 inch line) feeds
the
> front wheels) both through the ABS unit of course? Is this correct?

Yep the master cylinder is designed as a split system to prevent loss of
brakes on both ends in the event one end fails. Of course if the steel
lines fail then it is possible to lose brakes on both ends.

> c. If b. above is correct and since I don't need the ABS is there any
> harm in directly connecting the 1/4 inch line from the rear wheels
> directly to the front of the valve and then coming out of the rear of
> the valve in 3/16 inch line to a tee which then feeds both front
> calipers? To otherwise restore the ABS plumbing, something which I
> neither need or want seems unnecessary.

Yes this is possible to do BUT check your insurance paperwork very well
first. If they have your vehicle listed as having ABS and you remove it
they can refuse to pay in the event of a collision. Make sure first.

> I realise that a professional mechanic would never do this to a
> customers car and I would not ask that of one either. However there
> once was a time when there was no such thing as ABS so if you need to,
> speaking in a purely hypothetical sense, will this modification be OK?
> Thanks in advance for answers to my questions and your opinions.
Lenny.
>



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Steve
I wanted to let you know how things worked out. I completed the repair,
bypassing the ABS as we had discussed and I road tested the car. When
performing normal stops as well as hard stops the brakes seem to work
just fine. The ABS light that was constantly on since day one is still
on and although the brakes have been bled and there is a good pedal we
now have a constant "brake" light also. Does the brake light circuit
run through the ABS unit (which now just sits there empty), as well as
the proportioning valve? The light is really no big deal if it stays on
but I can't account for it otherwise. Thanks, Lenny.