Disabling ABS

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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.
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Tegger

The Unofficial Honda/Acura FAQ
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On 3/2/10 8:53 AM, in article hmj8pe$t8g$ snipped-for-privacy@news.eternal-september.org, "C.

Wrong. On a Honda, you get exactly what you would have without ABS.

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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:
http://www.taurusclub.com/forum/uploads/monthly_05_2009/post-11154-1241200861_thumb.jpg
.
Ed
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On 3/2/10 11:34 AM, in article hmji79$p5$ snipped-for-privacy@news.eternal-september.org, "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 main brakes.
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.

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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 interact.
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.
Ed
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On 3/2/10 2:08 PM, in article hmjr8f$vu4$ snipped-for-privacy@news.eternal-september.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 first.

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