This was 2nd times when I backup my car out of driveway (there is about 10-15 degree slope on my driveway). The situation was I was on the reverse and put my feet on the brake and backing up my car. Suddenly I felt no brake in my car. I have to release it and press brake again in order to stop the car, otherwise car will slide all the way down. Is anybody know what is wrong on my car? It is normal when i back up on the flat road. I never have had this experience before, especially the driveway I use everyday.

 

Does the brake pedal go to the floor?

 

Sorry, I did not get it. You mean can I press brake pedal all the way?

 

I'm not understanding your scenario.
So, I'll ask a few questions to help me better understand whats going on.

When you have your foot on the brake pedal, does the pedal move all the way to the floor?
kinda feels like a loss of pressure.

 

My scenario is just opposite. My brake pedal feel stiff, I can not press further and car is going down. I have to release brake pedal and press it again to stop the car.

 

but only in reverse?

 

Yes, and only apply to slope, not flat road.

 

check your brake fluid.
I wonder if the slope is causing the brake fluid to slosh to one side!?

 

Thanks. will check tonight.

 

cant be sloshing to one side, as its pressurized, or bled to let all the air out.

 

I wonder if rather than being because of the slope or even the reversing it's because it's been sitting in freezing temps overnight. Looking at the avatar, looks like snow...

could the piston in the calipers be frozen in place until he applies enough pressure or they warm up? or the fluid just loses it's liquidity in cold climates?

 

^i'm leaning towards the temps of the fluid not being warm enough......!?!?
just throwing ideas out.

 

Well, another thing that comes to mind is if you continually press the brake peddle before starting the car. At that time, you have no vacuum assist on your brakes so you would have to assert more force at the peddle for equivalent braking pressure at the caliper. If this is the case, I would start the car first, give it a second or so for the brake booster to get some vacuum then press the brake peddle.

 

when a car is off, and you pump the brakes, the brake pedal gets stiff.
again, just thinking out loud.

 

do you start your car with the foot on the brake before the car is started?

 

BOTH of these is what I was thinking. I know when I first started driving i used to press the brake and hold it before I started the car and once the car started you'd slowly feel it sink down. I don't do it as much nowadays though, or maybe im just so used to it that I don't think about it. Kinda dangerous if you have to let up on the brake and get back on it.

 

My first car was an old Ford that required the brake pedal to be pressed for the ignition switch to unlock. Ever since then, whenever I drive an AT I just put my foot down on the brake out of muscle memory. I've never noticed anything funky with my brakes and my driveway is on a grade as well. I don't think sheer slope is the culprit here nor is holding the brake while you turn your car on.

 

I was leaning more towards that it may be the slope. Well im hoping it is an nothin wrong with the OPs brakes. Went back an re-read.

EDIT: Forget to add, you have to push the brake pedal anyway to start cars with keyless ignition anyway. I've also been in cars where you can shift them out of park w/out even using the brake OR a key in the ignition.

 

This was old picture. My car is sitting in garage.

But, I think you maybe right about pressure things. Yesterday I did try to start the car and press brake pedal few times before put in the reverse. I felt exactly same thing, my brake pedal became stiff after first few press, than if you keep press it, it will become normal. I think that was how it happened when I start the car, put into the reverse and drive right away. so it just happen I put in the reverse first. It should be the same when I put in the drive.

How come the brake penal will feel stiff when the car already started. It normally happen you press brake pedal when car is off.

 

maybe or maybe not. I can not recall. I will try tonight to see is any different. Dose our car require to do this or just safety things?

 

I would like to try this tonight, because I think this might be a blame.

But Is this normal to wait few seconds before moving the car after start the car?

 

if you're on a slant, i hope you're using your e-brake too...