Ever have one of those late night moments where you wake up with a start and realize something important?

I was thinking about the brake thread from yesterday and I found myself wondering if anyone has tried the ABS system during an FAS. I haven't had a chance to try it yet. I called Honda this morning about it and they were not helpful.

My concern is if there enough stored pressure to allow the ABS to operate to a complete stop from freeway speeds without draining all the pressure. If the ABS rapidly drains the pressure (as I suspect) then it transforms from a safety-enhancing device into a device that guarantees you will be relying on the mechanical brake backup in a panic stop when the motor is off.

I read a lot of ABS technical articles on the web this morning but was unable to find a definitive answer to the question. I could determine that ABS systems generally work by draining pressure in spurts, simulating pumping the brake but able to do it for each tire individually. Unfortunately pumping the brake pedal is the worst possible thing you can do when trying to come to a stop relying on stored pressure.

Some of the ABS systems I read about use an electric motor to maintain brake pressure (a good thing that could avoid this potential problem), but the HCH clearly does not maintain brake pressure with the ICE off.
I apologize for bringing this up again, but lives (or hopefully just insurance premiums) are at stake so please bear with me. Once the problem is fully understood then I will happily let it rest.

thanks,
Kurt

 

Lakedude had a first hand experience with that situation.

Look here:

https://www.greenhybrid.com/discuss/...ead.php?t=2954

 

Excellent! That answers the question from 20 mph, and confirms that ABS kicks in when the ICE is off, but does not answer the question if there is enough stored pressure to ride the ABS down to a stop from 60 mph.

It sounds encouraging however.

 

My 05 Accord does well in panic stop with FAS. And had plenty of vacume to get the job done. Also tested with no vacume assist and it all worked out fine. There is alittle bit of resetance when the pedal is first massed on then it goes right on down and brakes hard.Tested it on old hwy 75. But if you use the brakes lightly as I did this morning coasting up to traffic compressing at a light in FAS I did run out of vacume assist. Its wasnt a problem for me.

Men,, be men and press on that brake pedal dont whussy out! If you cant stop a Civic without power brakes and drive thru a problem. You may need to go see a doctor... lmao

 

Hi Psyshack:

___You definitely have a way of saying things the way you see them … I was LMAO on that one

___Good Luck

___Wayne R. Gerdes
___Waynegerdes@earthlink.net

 

You guys must live in some flat areas, there are some hills where I live that you cannot slow down the car without assist. On my road bike (not motorcycle, the kind you pedal) I can get up to 55mph with the help of gravity alone. Try doing an FAS and then a panic stop in that situation.

 

Hi Livvie:

___Because of fuel cut during regen, if you can maintain your speed because of a relatively steep slope, there should be no reason for a FAS. I would never FAS down a slope where I would be accelerating well above the limits while coasting w/ ICE off. In my own area (flatlands of Illinois) FAS’ always comes about w/ a gradual bleed off of speed except for the rare D-FAS’ when they are available and I am always bleeding off speed very quickly because of an incline after the decline running through the bowl.

___All said and done, you do not just perform a FAS anywhere. Caution before action is always the best policy.

___Good Luck

___Wayne R. Gerdes
___Waynegerdes@earthlink.net

 

Somehow this whole topic reminds me of a thread over at Edmunds.
I mentioned that in some instances, on vacant roads, in the middle of the night, on a gently graded downhill I'll switch it to N and just roll, letting it idle.
(Didn't even bring up FAS)

Wow! What a mistake that was.
Even a moderator jumped in and compared it to an experience he had when he rode his brakes all the way down a steep mountainside. When he was suprised by an unexpected light on the bottom and it was red, he "Careened through the red light uncontrolled because of his overheatd brakes" then said "Hey, it's your life not mine"

It was the last time I ever posted FE tips there.

Which brake pressure are you referring to?
Yes, the brake vaccume assist is limited but the important hydraulic (Which acutally stops the car) remains uneffected.

 

Wayne, that makes sense.

My point is that braking a civic without assist in many cases is beyond the average person's strength. This applies mainly to those doing FAS. I agree that an FAS should only be done in places where it is "safe". But commons sense seems to be missing in a lot of people these days.

 

I've only had the ABS kick in one time during a FAS so please keep in mind the sample size before making you own choices. I have run the vacuum assist out a few times and nearly put my car thru the back of the garage. I've been learning how much assist the vacuum can put out before running out, in fact last night I rode the brakes for a long while without running out of assist. I'm still not exactly sure what depletes the vacuum and what does not but it seems like you run out quick if you make brake applications and let off each time. Riding the brake in the same spot without letting off does not seem to use much vacuum.

BTW I don't know how the ABS would work if you had run out of vacuum. Also all this info only applies to my car which is a 2005 HCH. I assume the other Civics would be similar. I think doing a FAS on a older car with a vacuum leak would be dangerous.