Or when the driver lifts off the gas in a vehicle with rear-driven wheels.
This is functionally equivalent to activating the rear brakes only; in
slippery condictions, this is virtually begging for trouble.
Which is also why most road cars' handling is set up for understeer.
How do you know that? Are all the parts exactly the same, except they
insert an ABS pump in the hydraulics? Is this comment even meaningful,
since now most (all?) Hondas include ABS as standard?
I looked at the parts catalog for older Hondas and at least in some
cases the master cylinders and proportioning valves are different
depending on whether you got ABS or not. For instance a 1996 Honda
Civic 2Dr EX without ABS used Proportioning Valve P/N 46210-S04-962
(see http://tinyurl.com/ygprxny , line 4). A 1996 Honda Civic 2Dr EX
with ABS got Proportioning Valve P/N 46210-S04-852 (see
http://tinyurl.com/yf9ms3f , line 4).
It can be advantage to use the ABS to handle the brake balance. ABS
can adapt to the vehicle load and provide maximum braking force for
all four wheels (please note you could just use rear wheel only ABS to
provide the enhanced proportioning function). If you depend solely on
proportioning valves and/or brake size to handle the chore, it is
likely your rear brakes aren't doing all they could if you vehicle is
loaded to the max. This is probably not a big deal in most passenger
cars, and when it is some non-ABS vehicles compensate for the lack of
ABS by adding a rear proportioning valve (a dump valve of sorts). This
valve has an activating link tied to the rear suspension. Under severe
braking the rear end of a lightly loaded vehicle will raise up more
than the same vehicle when heavily loaded. The mechanically activated
proportioning valve takes advantage of this difference. When the rear
of the lightly loaded vehicle raises up under braking the link between
the suspension and the valve will activate the valve and limit rear
brake application to prevent rear wheel lock up. It is not as
effective as ABS, but it does allow the rear brakes to be larger to
handle heavy loads while reducing the chance of rear wheel lock-up
when the vehicle is lightly loaded. If you are interested in seeing
what one looks like see:
On 3/2/10 11:34 AM, in article hmji79$p5$ email@example.com, "C.
Four ABS equipped Hondas/Acuras & the FSM for each is how I know. What
Hondas do you have experience with?
Note I am only commenting on the ABS. The VSA (vehicle stability assist)
adds a level of complication to it and since the two are integrated on the
newer Hondas, I suspect the overall effect of disabling it will be like
stepping back 20 years (I still remember how the '86 Aerostar would lose it
in the back if you just looked at it funny. That was one scary vehicle if
the road was the least bit slippery).
Interesting you should pick out a '96 for the discussion as I owned a '96
Odyssey and my daughter had a '95 Integra that used the same system. ABS in
'96 Hondas is a passive system that did not routinely regulate anything
until and unless a wheel sensor asked for it. It certainly did not
participate in routine proportioning of the rear brakes. The part
differences you found relate to the way the ABS system was spliced into the
The ABS that Honda used in '96 was so problematic and expensive to repair
that I suspect it no longer works in most of them that are still on the
road. It failed in my '96 Odyssey and in my daughter's '95 Integra within a
few months of warranty expiration and the $1500+ repair cost meant that it
stayed that way. There was (is - the Odyssey is still on the road) no
difference in braking feel or performance in either of those cars vs.
anything else I ever drove. Certainly no tendency for the rear brakes to
lock up on either one of them.
1997 Civic. I still have the shop manual but the car is gone.
Did you actually try to lock the brakes? The difference would only
become apparent under severe braking. The ABS doesn't provide
proportioning in the same manner as a proportioning valve. It handles
it by relieving pressure to the rear brakes when rear brake slip is
detected. Traditioanl proportioning valves operate differently. Except
for the type with a mechanical control like I showed in one of my
prior posts, they just provided a fixed split between the front and
rear brakes. I wonder how the ABS and fixed proportioning valve
Since the ABS system still includes a proportioning valve, it seems
that Honda soes not depend on the ABS operation to provide
proportioning. Others do.
On 3/2/10 2:08 PM, in article hmjr8f$vu4$ firstname.lastname@example.org, "C.
Absolutely. As the ABS was showing signs of failing, that was one of the
TSBs relating to that vintage ABS - exercise the ABS and sometimes it would
clear and start to work again.
Once the ABS stopped working altogether no amount of exercise would make it
start working again. Neither car ever locked the rears first, always front
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