Brake pedal goes half-way to the floor, only the first time

Brake pedal goes half-way to the floor, only the first time.



Finally driving my car again after it was laid up for 2 months.

I don't think it was like this 3 months ago.

When I first press the brake pedal, it goes half-way, but certainly not
all the way, to the floor, and at t hat point it stops the car very
well. If I press the pedal again within 2 or 3 minutes, it moves very
little before it's stopping the car.

If I wait maybe 15?? minutes, it's like the first sentence in the
previous paragraph.

What's the problem?

Bad master cylinder?

micky wrote:
> Brake pedal goes half-way to the floor, only the first time.
>
>
>
> Finally driving my car again after it was laid up for 2 months.
>
> I don't think it was like this 3 months ago.
>
> When I first press the brake pedal, it goes half-way, but certainly
> not all the way, to the floor, and at t hat point it stops the car
> very well. If I press the pedal again within 2 or 3 minutes, it
> moves very little before it's stopping the car.
>
> If I wait maybe 15?? minutes, it's like the first sentence in the
> previous paragraph.
>
> What's the problem?
>
> Bad master cylinder?

If you disconnected the caliper while you were working on the front end
the system probably needs bleeding - even if you didn't it probably does .
Some cars require bleeding both front and rear systems to maintain balance
in the valving system . Your repair manual should have the procedure .

--
Snag

On Wed, 29 Oct 2014 09:48:47 -0500, "Terry Coombs" >
wrote:

>micky wrote:
>> Brake pedal goes half-way to the floor, only the first time.
>>
>>
>>
>> Finally driving my car again after it was laid up for 2 months.
>>
>> I don't think it was like this 3 months ago.
>>
>> When I first press the brake pedal, it goes half-way, but certainly
>> not all the way, to the floor, and at t hat point it stops the car
>> very well. If I press the pedal again within 2 or 3 minutes, it
>> moves very little before it's stopping the car.
>>
>> If I wait maybe 15?? minutes, it's like the first sentence in the
>> previous paragraph.
>>
>> What's the problem?
>>
>> Bad master cylinder?
>
> If you disconnected the caliper while you were working on the front end
>the system probably needs bleeding

No, I didn't. (For others planning to do this: At first I did what I
usually do, I hung the caliper from other parts using a bent wire
hanger, but later I had a loop of fairly heavy stranded electrical wire
and that worked better.)

>- even if you didn't it probably does .
>Some cars require bleeding both front and rear systems to maintain balance
>in the valving system . Your repair manual should have the procedure .

Is the symptom I have really caused by needing bleeding? I had spongy
brakes once after doing something to the brakes, and every time I pushed
the pedal it was the same, spongy, like stepping on a sponge. Now
it's never spongy. When the pedal is going down the first time, there
is almost no resistance (only what comes from the spring) until there is
normal resistance.

On 10/29/14, 10:27 AM, micky wrote:
> Brake pedal goes half-way to the floor, only the first time.
>
>
>
> Finally driving my car again after it was laid up for 2 months.
>
> I don't think it was like this 3 months ago.
>
> When I first press the brake pedal, it goes half-way, but certainly not
> all the way, to the floor, and at t hat point it stops the car very
> well. If I press the pedal again within 2 or 3 minutes, it moves very
> little before it's stopping the car.
>
> If I wait maybe 15?? minutes, it's like the first sentence in the
> previous paragraph.
>
> What's the problem?
>
> Bad master cylinder?
>

I'm foggy, but I think it could be a brake opening up mechanically, more
than normal, as you drive, gradually pushing fluid back into the master
cylinder.

If you have drums in the rear, one or both may need adjustment.
Sometimes pulling up the slack with the parking brake will act as a
temporary adjustment. If a rotor is warped, it could move the caliper
back and forth as you drive, gradually opening it.

micky posted for all of us...


>
> Brake pedal goes half-way to the floor, only the first time.
>
>
>
> Finally driving my car again after it was laid up for 2 months.
>
> I don't think it was like this 3 months ago.
>
> When I first press the brake pedal, it goes half-way, but certainly not
> all the way, to the floor, and at t hat point it stops the car very
> well. If I press the pedal again within 2 or 3 minutes, it moves very
> little before it's stopping the car.
>
> If I wait maybe 15?? minutes, it's like the first sentence in the
> previous paragraph.
>
> What's the problem?
>
> Bad master cylinder?

Is this the same car you did the suspension work on? If so you may have
introduced air into the system through cracks in the hose or bulging.
The first step is to top off the master cylinder then bleed the brakes
properly, per manufacturers instructions. If that doesn't work it is
probably the master cylinder, diagnose and repair per manufacturers
instructions. If it has power brakes it may be the booster but IDK your set
up. I have a faulty memory on this subject.

--
Tekkie

On Wednesday, October 29, 2014 1:05:11 PM UTC-4, J Burns wrote:
> On 10/29/14, 10:27 AM, micky wrote:
> > Brake pedal goes half-way to the floor, only the first time.
> >
> >
> >
> > Finally driving my car again after it was laid up for 2 months.
> >
> > I don't think it was like this 3 months ago.
> >
> > When I first press the brake pedal, it goes half-way, but certainly not
> > all the way, to the floor, and at t hat point it stops the car very
> > well. If I press the pedal again within 2 or 3 minutes, it moves very
> > little before it's stopping the car.
> >
> > If I wait maybe 15?? minutes, it's like the first sentence in the
> > previous paragraph.
> >
> > What's the problem?
> >
> > Bad master cylinder?
> >
>
> I'm foggy, but I think it could be a brake opening up mechanically, more
> than normal, as you drive, gradually pushing fluid back into the master
> cylinder.
>
> If you have drums in the rear, one or both may need adjustment.
> Sometimes pulling up the slack with the parking brake will act as a
> temporary adjustment. If a rotor is warped, it could move the caliper
> back and forth as you drive, gradually opening it.

Good point, bad wheel bearing on a wheel with disc brakes?

However, I'd think that would have shown up on pre-alignment inspection

nate

micky wrote:
> Brake pedal goes half-way to the floor, only the first time.
> ......
> What's the problem?
>
> Bad master cylinder?
>

that is indeed, the text-book symptom of a bad master cylinder.

GW

On Sat, 01 Nov 2014 11:04:59 -1000, Geoff Welsh >
wrote:

>micky wrote:
>> Brake pedal goes half-way to the floor, only the first time.
>> ......
>> What's the problem?
>>
>> Bad master cylinder?
>>
>
>that is indeed, the text-book symptom of a bad master cylinder.
>
>GW
Given the recent history of the vehicle -IE- it's damage history, I'd
be looking at the brake on the damaged axle first. Clamp off the brake
flex hose to that wheel. Is the pedal highand firm? If not, look
elsewhere. If so, you know where to look. Brake hose clamps are
available at Harbor frioeght and many auto parts/tool suppliers at
reasonable cost. Some are little screw clamps, others are a vice-grips
with round rod jaws. Make your own by brazing a 1/4 inch long 1/4 or
5/16" diameter steerl rods to a 6 or 8 inch cheap vice grips.

On Sat, 01 Nov 2014 11:04:59 -1000, Geoff Welsh >
wrote:

>micky wrote:
>> Brake pedal goes half-way to the floor, only the first time.
>> ......
>> What's the problem?
>>
>> Bad master cylinder?
>>
>
>that is indeed, the text-book symptom of a bad master cylinder.
>
>GW

You ruled out a leaking wheel brake cylinder, leaking caliper, brake
line or connections?
--
"Trust me, I'm from the government. I'm here to help."