I did want to reply regarding the e-brake comment, but the thread got locked:

You absolutely DO NOT want to use the rear wheels as the sole braking wheels in normal braking and CERTAINLY not in an emergency situation. The reason is that as a car slows down, weight bias is shiftwed to the front (even more pronounced in FWD cars) and the front wheels are typically responsible for 80% of the stopping ability of your car.

You are much better off using the "middle pedal" regardless whether or not you have vacuum assist, leave your hands on the steering wheel, and focus your efforts on steering.

Use the ebrake and you'll end up with 2 very narrow, long strips of black on the road and a bunch of twisted metal.

 

Yup. I think the point was that the argument was that you had it available if you needed it in an emergency and not that it should be your sole way of braking. Of course it is less efficient and the best thing to do would be to push hard on the pedal.

I hope there is no debate on this and we all agree.

 

I guess I'm the guilty one who brought up the e-brake thing....Oops....

Anyway, my point was that I still have brake pressure after a reboot, and that if for any reason I chose unwisely and rebooted in a place where "uh-oh, I need to stop" and I have LOST brake pressure, then I could use the E-Brake to stop "in an emergency in which my regular brakes would not work" and that is still a valid option.

Regardless of how the car reacts, spins, whatever - when you are in an EMERGENCY situation and your REGULAR brakes are not stopping the car, the e-brake is there to be used for that. Hence the name, emergency brake.

 

Hi All:

___It isn’t the E-Brake issue so much as it is where you would lose all vacuum brake assist. If you FAS from 60, you aren’t going to lose your brakes to 0 under most circumstances. You will know when that time comes … Even if you were to hit the binders 7 - 10 times hard, you will be traveling at 10 mph or less and the E-Brake would be fine from that speed. IIRC, I lost vacuum assist in the Insight during an AS! It was a long slow decline from LeMont road to Cass Ave on I-55 just south of Chicago in and amongst a normal afternoon traffic nightmare. I entered an AS after a slight acceleration at its normal 19 mph and declining speed. Some coasting, a little brake, coasting, a little brake, coasting, a little brake etc. and I lost assist while still traveling ~ 8 mph. I used the E-Brake for the next ¼ mile while still coasting in a 2 - 8 mph range while still in AS and there wasn’t a problem in the least. I was not about to start the car in a crawling traffic jam at < 9 mph so I could regain vacuum because at those speeds, I could stop by pulling a Fred Flintstone maneuver if I had to The E-Brake worked spectacularly from that slow a speed and would in all circumstances.

___E-Brake from 60 mph? That one would be dicey and I would definitely feather that bad boy in so as to not simply lock up the rears and end up a flaming piece of spinning twisted metal

___Good Luck

___Wayne R. Gerdes
___Waynegerdes@earthlink.net

 

In an emergency situation you are better off dumping to a lower gear and engine brake then ever yanking the ebrake in a panic. If you can slow down the car with the ebrake sure, but it not designed for a high speed panic situation. your brakes have built in backups, so this case will most like never happen.

 

One thing about this is that we have vacuume assisted brakes.
The real-deal 100% actual, real brakes are still all there, but only require additional effort.
The real brakes have not failed: there is no reason to use an emergency backup.

I've owned several 60's era autos with no power assisted braking at all.
While I missed the assist, they never failed because it was missing one.

In my case 1-2 stops no problem.
If I go longer than that I keep the Left foot at the ready in case that extra effort is required.
No safety issue, especially rolling at 30-35MPH.

 

I agree with hot_georgia 100%, when you lose the vacuum, you don't lose the ability for the car to stop by pressing the brake pedal. Heck, my parent's old VW rabbit that I used to sneak out before I had my license didn't have any assist either.

I personally haven't run out of vacuum yet, and here's why; If I need to brake, 90% of the time I simply "restart" the car by finding an appropriate gear, pop the clutch and use the regen braking (remember, you don't burn fuel when regenerative braking!). If I have the opportunity to keep coasting, I simply turn the car back off. If I need to add additional brake input, the vacuum is fully built back up.

Manual braking (non power assist) is analagous to rebooting the car and "waiting" for the electric power steering to kick back in if you are on a curve. Those of you that do that know exactly what I am talking about. Its fun to do this in mid-turn

 

Ok, I will admit to using the e-brake during an auto-stop to avoid the loss of brake pressure from causing an engine restart. I never do this above 15 mph, and I use it in stop-and-go conditions only, and typically on mild downhill grades when it is most useful.

I also never rely on the main brake's mechanical backup (by allowing brake pressure to drop during an FAS) because it takes a lot of leg strength (which means I admit to trying it enough times to decide it was a stupid thing to do).

If you haven't tried it yet then find a safe spot at say around 15 mph, and lightly pump the brake pedal with the engine off, the brake pressure will fade after a few pumps, and you can see just how much leg strength you need to get the car to stop. If you don't want to do this then take my word for it, it takes a lot of leg strength to stop the car. My take is you would never want to rely on that pitiful backup in a panic stop situation.

Cruising at freeway speeds during an FAS without brake pressure would be playing Russian Roulette in my opinion. Sooner or later you would lose.

That is probably a good safety tip, if you touch the brake pedal at all during an FAS, it is time to turn the key and start the engine for a few seconds to restore that brake pressure.

I have experimented with it and takes only a second or two of the engine running to fully restore brake pressure. And only a few pumps of the brake pedal (two or three) will fully lose brake pressure.

I live on a hill and used to coast out my driveway and start the engine at the bottom of the hill when I first needed brake pressure. I have rethought that little stupidity as a result of this thread and promise to start the engine at the beginning and FAS to the bottom with full brake pressure. :-)

Technical details: It is the act of the brake pedal moving in that uses up pressure, holding the pedal with a constant pressure does not lose brake pressure (other than what you used to get there in the first place). So you can come to a full stop safely on stored pressure but be careful to engage the brake pedal and hold it relatively constant, the key is never go up, only down, there is even enough stored pressure for a single full panic stop. So if you want to play Russian Roulette, at least now you know how it works.

I think what we have here is a feature request for hybrids, just like the A/C compressor can work without the main engine on the 2006 HCH, it would be a nice if the brakes could too. :-) Then we could FAS to our hearts content and not have to worry about brake pressure.

Since it is a safety issue it might even be a bit of a priority for car manufacturers, of course we would have to publically admit to doing foolish things like cruising down the freeway at 60+ mph with the engine (and hence the power brake pump) off. Personally I think this is a good argument against FAS at freeway speeds, or any speed over about 20 mph. Which is probably why Honda doesn't auto-stop over that speed anyway.

I remain a fan of FAS when sitting at a stoplight with a cold engine however. :-)

 

I think this post pretty much covers the topic perfectly. I'm going to rename it and close it.