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

Page 1 of 2  
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?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
micky wrote:

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



Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

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.)

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.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I would check the brake fluid level in the master cylinder first. If that seems to be OK, then I agree with Terry that bleeding any air out of the brake lines and cylinders should correct the problem.
--
nestork


Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 10/29/2014 10:56 AM, nestork wrote:

Ditto and I'd do it ASAP!
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 10/29/14, 10:27 AM, micky wrote:

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.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
micky posted for all of us...

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

Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
I've had that happen with a couple of vehicles after I changed the brake shoes or pads and didn't bleed their cylinders. Bleeding always stopped the pedal from sinking.
After I bleed brakes, I close all the bleeder screws and pump the pedal hard a few times. Then I open each screw, and usually no fluid comes out right away, indicating there was still some air inside.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Thu, 30 Oct 2014 01:25:39 -0700 (PDT), snipped-for-privacy@my-deja.com wrote:

Badly adjusted brakes will have a low pedal on first push, and come up and be firm on second. Poorly bled brakes will come up a bit on each succuessive push but will never be "firm"
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Thursday, October 30, 2014 5:50:57 PM UTC-4, snipped-for-privacy@snyder.on.ca wrote:

Adjusted? I haven't owned a car with brake shoes in my lifetime. I doubt Micky's import has shoes. And never seen a disc brake that you could adjust.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 10/31/14, 8:25 AM, trader_4 wrote:

Have four-wheel disks taken over? Well call me Rip Van Winkle! How do you guys go parking without rolling into the lake?
The 1949 Chrysler Crown Imperial had four-wheel disks, but owners hated them. The 1950 Crosley Hot Shot had them. Owners paid to have them changed to drums.
The 1962 Studebaker Avanti established the standard of disks on the front and drums on the rear.
If Micky has no drums, I believe brake mechanics could still be the problem. Typically, runout is specified at less than .05mm.
If it's greater, and the cause is uneven transfer from the pads, resulting in uneven disk thickness, the driver will feel pedal pulsing.
If that's not the case, and the measurement varies once per revolution, the problem could be contamination between the disk and the hub face.
Otherwise, it could be a warped disk, which can happen putting lug nuts on.
If a disk wiggles ever so slightly as the car runs down the road, the caliper will wiggle. I can't speak from experience, but I imagine this wiggling could open the caliper ever so slightly, causing a long push the first time the brake pedal is pushed.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On Friday, October 31, 2014 4:10:22 PM UTC-4, J Burns wrote:

We're talking about Micky and the service brake, not parking brakes.

Never said brake mechanics couldn't be the involved. The issue was that Clare brought in "adjustment". Disc brakes don't have an adjustment. And I'll bet Micky's brakes on that care are disc.

I would agree that sounds possible. But it would seem it would have to be quite a bit of wiggle to result in the pedal going half-way to the floor.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

If you bleed them, bleed the nearest one to the master cylinder first and then the next nearest, etc.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

What kind of vehicle are we talking about? Was it ever stated? Both of my cars still have drum rear brakes, with self adjusters which by their very design have a tendancy to fail to adjust the brakes - particularly on cars with automatic transmissions where the driver seldom if ever uses the parking brake - which adjusts the brakes when it is applied.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 10/31/14, 9:18 PM, snipped-for-privacy@snyder.on.ca wrote:

I wondered, too. Found it (September 30): "I hit a curb with my car and broke in half the right half-axle, broke a big chunk out of the RF rim and a piece the size of a tea-cup saucer from the tire too, cracked my lower suspension arm, and severed the right ball joint (2000 Toyota Solara, only has a lower ball joint. I'm not sure how many cars this story covers. "
That car seems to have disks all around. After gazing into my crystal ball, I'll vote for runout. It could come from damage to the disk or hub, or it could be a little rust from all the time it sat disassembled.
http://www.motorsforum.com/tech/disc-brake-rotor-runout-46368-.htm
It may take thousands of miles of wear before the pedal starts to pulse. Micky may have caught it quickly enough to fix it without buying parts... if it's rust or dirt.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

Well, runout on a disc WILL cause the problem if it pushes the pistons back - effectively "backing off the adjustment"
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
On 11/1/14, 11:32 AM, snipped-for-privacy@snyder.on.ca wrote:

I've been too optimistic. How could the hub transmit enough force to break an axle, crack a suspension arm, and sever a ball joint, without being damaged? Hub runout should show that a new hub and bearing is needed. An optimist could hope the disk is OK.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
micky wrote:

that is indeed, the text-book symptom of a bad master cylinder.
GW
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
wrote:

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.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Supposedly these are one of the few things that Sears sells that are still worth it... apparently the same as S-K, Blue Point etc.
http://www.sears.com/craftsman-hose-pinch-pliers-set-of-3/p-00947218000P?sid=IDx01192011x000001&kpid947218000&kispla947218000P&kpid947218000&mktRedirect=y
Or, the plastic ones from Harbor Freight work fine.
Lots of guys just use flat jaw vice grips but I don't like doing that.
nate
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Related Threads

    HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.