Stop here! Let's talk about brakes

obyone

The brake pedal will usually go to the floor at least once when starting a vehicle after a brake job. However, multiple depressing should return the pedal to normal. Have you tried depressing the pedal multiple times?

gods_girl

Yes, I can "pump" the brakes and the pressure (resistance) returns but then after a few moments of driving, the pressure diminishes again. I can create pressure by pumping the brakes. I need to figure out why they are not holding the pressure. I've been working on the van (and test driving it) for 4 days now. I'm at a loss. I don't want to replace unneeded components so I was hoping someone here would know which component might be leading to my loss of pressure. Thanks!

Mr_Shiftright

Have you tried blocking off all the lines to the master with plugs or bolts (be SURE they are the exactly correct pitch of thread), and then bleeding just the master? (you can bleed by loosening the bolts or plugs). If you get the same symptoms with the brake lines disconnected, then you know it's your master. If the pedal stays tight, then you know you have a hydraulic issue outside the master.

I presume you have rear drum brakes? If so, your brake shoes must be properly adjusted or the piston in the brake cylinder will extend too far and cause these problems.

srs_49

When you lose pressure, do you also lose all braking? If the master cylinder is shot, like one of the piston seals is leaking, the pedal will go a lot further down until the 2 pistons come in contact with each other until you start to get braking. The one piston provides braking to the front right and left rear brakes, and the other piston provides braking to the front left and rear right brakes. That way, short of losing the seals on both pistons (a multi-point failure), you still have some braking.

bpeebles

The ABS pump may have air in it... this cannot be "bled" using the pedal and bleeder-nipples. Even "pressure" and "vacuum" bleeding may not get the bubbles out of the ABS pump.

To propery bleed ABS pump, you need a computer-connection to the car to activate the ABS pump. I use my laptop computer connected to my car to perform this function.

I have read that some people have been able to "fake out" the ABS system into activating the ABS pump... thus bleeding the system. Slamming on the brake-pedal while driving on ice is one option. Even hitting the brakes hard while on a dirt road may do it.

wtd44

You just might be wise to take the vehicle to the OEM dealership shop.

Mr_Shiftright

He shouldn't have to bleed the ABS system at all unless the HCU (Hydraulic Control Unit) somehow took in air---the base brake system is usually bled separately for simple jobs like a wheel cylinder, etc.

obyone

She

bolivar

You might have a badly leaking master cylinder, (I do hope your rear drum brakes are not too loosely adjusted and causing you all this grief), but I also think there is air in the ABS pump. And bleeding manually will not get it out.

With all the work you've done, including 2 large jugs of fluid, you probably at least once let the fluid in the MC fall too low and pumped some air into the system and it's now in the ABS pump.

It's time to take it to a shop with the electronic equipment to activate the ABS pump and pump that air out of there.

bluejay7

I am working on my wife's 2003 Pontiac Bonneville brakes. The car was hardly stopping, the rear brakes looked like they never worked, the pads still looked new but they obviously were not engaging and it seemed like only one of the calipers in the front were working, so I replaced all 4 calipers and brake pads and all 4 rubber brake lines. I tried bleeding the brakes for hours and never could get the brake pedal to be firm so I thought the master cylinder was bad and replaced it. SO FRUSTRATING, bled for hours and still no brake pedal, it goes right to the floor. PLEASE SOMEONE HELP!! Anyone have any ideas? Someone in a previous post mentioned something about engaging the ABS, what will that do and how do I do it? Does anyone have any ideas? It seems like a nice car, sure would be nice if it would stop. Someone . . . send help. Thanks for any information.

99accent

If you have ABS type brakes thats it ,take it to a brake place,let them bleed it.

kiawah

As 99accent indicated, you need to take it to a brake shop or the dealer. They have pressure/vacuum assisted bleeders, and certainly the dealer has the service computer that will be necessary to allow purging of the ABS system. Since the ABS is normally controlled by a computer sensing the 4 wheel speeds and braking pressure, the service computer is needed to tell it the ABS to engage when the vehicle isn't moving.

With replacing everything you did, you most certainly would have air in the system.

Your challenge, will be how to get your vehicle to the dealership if you completely have no brakes. Consider a tow truck, or rent a tow dolly if you have access to a tow vehicle for the dolly.

88fan1

I replaced my mastercylinder on my truck, bled the lines and it seemed to do fine. But yesterday my pedal went to the floor and my light came on. I pumped my brakes and everything was fine after that, but the pedal still feels soft. Any suggestions?

kiawah

Since you just filled your master cylinder, you'd know whether you lost fluid or not, right?

If you lost fluid, figure out where it's leaking.

If the brakes are soft, need to re-bleed.

bpeebles

You asked for suggestions....

If you are certain that there are no leaks (the fluid-level is not dropping) then it sounds to me as if your "new" master-cylinder is not right. The light will come on if either of the 2 seperate hydolic-systems lose pressure. The light will "reset" if you can 'pump up' the pressure again.

There is no guarantee that a replacement is any good. My experience with some aftermarket parts is that they are made SOOO cheeep that many of them are bad right out of the box. (Rebuilt alternators are often bad.)

I assume the replacement has a warantee.... although it is a lot of work, I suggest you take it back under warantee and get another one.

88fan1

There are no leaks, bled them 3 times already. A friend told me it could be the check valve box that is located by the mastercylinder. Said the needle vavle could be sticking, that would cause the light to come and soft brakes.

bpeebles

Yes-- but would NOT cause pedal to go to floor. That is either a leak or bad Master-Cylinder....and you have told us there are no leaks.

You have isolated the problem to bad Master-Cylinder. Take the "new" one back under warantee for replacment.

kiawah

Is the master cylinder reservoir, at the fill line where you filled it to after doing the initial repair, or not?

lilengineerboy

I wanted some input on replacement brake pads for a 2005 Subaru Legacy wagon. If I can get some improved performance without sacrificing behavioral characteristics, I would like to.
1. Need to work well cold (and very cold in Michigan)
2. Need to be relatively rotor-friendly (don't want to replace rotors before pads)
3. Good initial bite, fade resistance, and friction performance, reduced stopping distances
4. Relatively quiet
5. No excessive brake dust on wheels...some is okay, car washed about once a week, but if it looks like a car was parked next to a wildfire every 2 days, I will be annoyed.

I don't have a huge problem with the stock pads but I wanted to see what else was out there for the price. The EBC greens and Hawk HPS came to mind, but I am worried the stock pads are better than EBC greens and the HPSs mght not work so well cold. Any thoughts?

philx

Hi, Just some fews questions !
i just changed my brake line because of a lose of pressure (line was almost new but the connector get loose)
but still after changing it i still dont have brake (almost nothing) until i press really hard on the pedal (btw the pedal is tight, not loose)
ALSO
when i press on the pedal i heard a sound like WOUUUSHH (like air coming out of something so i found that probably the brake booster faulty
someone have infos on brake booster and how its works maybe i can repare it myself or at least change it myself
i also found a loose tube connected to 4 others tube coming from my headers to near the brake booster
can any1 help please ?

bpeebles

It is not easy to put into words how a vacuum brake-booster works.... Here is my stab at it.

I assume you know that the brake-booster is essentually a big rubber gasket with the center connected to the hydrilic-pistons in the Master-cylinder.

Under normal conditions, there is vacuum applied to BOTH sides of this brake-booster gasket. The result is NO MOVEMENT because of equilibrium.

As you push on the brake-pedal, you open a valve which allows ambient air-pressure into one side of the brake-booster. Due to the vacuum on the other side, it moves twards the master-cylinder....pushing the hydrolic-pistons with it.

=====

Now that you know how it works... you should realize the first thing you need to do is measure the vacuum applied thru the hose connected to the brake-booster. Make CERTIAN there is good vacuum while engine is idling. Then turn off engine... the vacuum guage should NOT drop. If it does not hold vacuum, then there is a leak somewhere.

Most brake-systems are designed to contain enough 'reserve' vacuum with the engine off so you have about 3 presses of the brake-pedal while still having some power-assist.
After that, the pedal will be hard to push.

One way to "test" the brake-booster is as follows;
1) With engine off, push brake-pedal several times to bleed out all of the reserve vacuum.
2) While holding brake-pedal down, start engine
3) The pedal should 'drop' twards the floor a bit as the vacuum builds and the power-assist kicks in.

I hope this gets you started.

gods_girl

Hi Guys,
Thanks for all you input. I have replaced the MC but am still having issues. I typed out a complete history here for you. Let me know what you think - Thanks! (oh, and sorry I haven't replied in a while - I had to save up money to purchase parts)

Current Problem: My brakes are very soft when van is running. With a little bit of pumping the van stops but not as immediate as I would like it to and the pedal isn’t as hard as it should be.

Current situation (as of this morning after everything below has been done):
1999 Town and Country LX 2whl drive 3.8 w/trac
-With the van in off position, the pedal travels 2 inches before it is hard. Multiple pumps do not change the hardness or travel of the pedal.
-When I hold down the pedal and turn the van on, the pedal sinks to 1inch off the floor.
- With the engine on, I pumped it 30 times and the pedal does not get hard – it continues to travel 1 inch from the floor.
- When I drive the van I have to press down hard for the brakes to stop the van. If I pump it a little (depress pedal two-three inches only) a couple of times, the van seems to stop faster – or in less of a distance.
- While sitting at a stop light, vehicle in gear, with my pedal almost to the floor, I can pump the brake a couple of times to get the pedal to rise to about 3 inches from the floor. The pedal does not sink any further while stopped, running, and in gear.

History of Repair:
Back in January the vans rear wheels were squealing – ex-husband said rear shoes needed replaced. They didn’t need replaced but they were replaced anyway and the drums were cleaned of debris. Van stopped squealing. Braking was normal. Pedal a little squishy but safe. Pedal would travel about 3 inches before grabbing.

March - April: Front pads were metal on metal so I replaced both the pads and the rotors on both front wheels. After the test drive, I didn’t like the stopping distance required to stop the van so thought this might be due to air in the lines (don’t know how it got there but worth a shot). Then I striped the bleeder valve on the passenger rear wheel cylinders.
I replaced it. Then manually bleed all the lines. During the test drive the rear wheel was rubbing a small bit and the pedals sponginess worse than ever. I decided to bleed the brakes again. I bled the brakes then did a test drive, then I bled the brakes again and then another test drive. I did this 5 times total (I followed owners manual sequence). It did not fix the squishy pedal. So I decided work on the slight rubbing issue. I took the drum off and reseated the shoes (rear passenger side only). This did not help. Due to my ignorance, I failed to readjust the star lever. Ex-husband came over and fixed the adjustment bar for me in the process he broke the bleeder screw – no idea how that happened. I could not find any leaking oil coming from any of the lines, MC or the bleeder screws so I let the van sit for 2 weeks on cardboard to see if I had drips (with broken bleeder screw). No drips so I placed paper towels around the front calipers, MC and bleeder screws on the rear for one week. Nothing. I figured I broke the master cylinder during the multiple bleeding attempts. I installed a new (not rebuilt) one. I bench bled it and then bled the lines going into it. Then I replaced the passenger wheel cylinder again. This time, I used a vacuum pump one person bleeding tool to bleed all the lines in sequence according to the owners manual. From the begining, I have consumed 4-32oz bottles of dot 3 fluid – just to make sure. Then I did my test drive last night. The van stops but not very fast and the pedal still does not have enough pressure behind it (see above current conditions)– thus my pumping before stops. I checked for leaks (paper towels overnight) and this morning found no leaks. Fluid level in the MC reservoir has not changed.

Any help or ideas would be much appreciated!
Thanks in Advance,
Tina

shipo

Hey Tina,

Hard to diagnose stuff like this over the internet, but I have two guesses that you might want to check-out.

Scenario 1) A compromised brake hose. To diagnose this, start the engine and have an assistant pump the brake pedal a bunch of times until said pedal feels as firm as he or she can get it. Hold the pedal there while you visually inspect each brake hose between the metal line and the individual brake cylinders. If one (or more) of the hoses has an issue, it/they will be visually larger in diameter than the others. My guess is that you're going to find that one or both of the front hoses has an issue.

Scenario 2) One or both of the rear brake shoe sets is misadjusted and are standing off too far from the inner surface of the drum. To diagnose, crank each star wheel until you cannot (or at least not easily) turn the wheel (assuming of course the wheel is lifted off the pavement), and then back said star wheel off a bit. If scenario is your issue, you'll find that one (or both) of the rear shoe sets will take lots and lots of star wheel adjustments before the wheel is difficult to turn. FWIW, I think this scenario is the less likely of the two.

If both tests prove negative, the next thing I'd try is to have all four wheels lifted off the ground and with the engine off, have your assistant press the brake pedal one time and hold it. Then you go around to each corner and attempt to turn each wheel in turn. My guess is that one of them will be easier to turn than the other three, and that's where you should concentrate your diagnostic efforts.

Keep us posted.

Best regards,
Shipo

gods_girl

Hi Shipo,

Thanks for your help!

I've checked the brake lines again with the method you stated above. With the engine started, no matter how many times I pump the pedal, it does not get any harder (with the van off, after one pump the pedal is really hard and high).Regarding the brake lines, they are all medal except for a few inches near the rear of the van and again in the front by the calipers. They are hard corrigated looking hoses. They did not buldge or look any bigger the the other ones when my assistant held down the pedal.

Regarding #2: I had done this previously when I replaced the one wheel cylinder. I rechecked and tightened/backed it up again just to be sure.

Regarding #3: I do not have the means to lift the van up off all four tires. So we did front then back. They all feel the same.

Update: I changed the other wheel cylinder and bled the lines again. The brakes are better but not where they were a few months ago. Any more suggestions?? Is there a possibility that the front calipers are bad? Thanks in advance!

Tina

shipo

I guess I wasn't specific enough regarding my discussion about the "brake hoses". Said "brake hoses" are the rubberized hoses that run from the end of the metal brake line into the wheel cylinders, and they are typically less than a foot long. It is one (or more than one) of these that I suspect has a problem.

As for how the pedal feels with the engine on versus off, not a terribly relevant comparison. Why? Because your van has what used to be called "Power Brakes" which in turn means that when the engine is on your foot generates a lot more pedal/braking force than with the engine off. That the brake pedal doesn't move all that far when the engine is off isn't terribly surprising, that the pedal moves way too much when the engine is on is worthy of concern.

Another area to hold suspect is the master cylinder; I believe I remember you writing that you've already changed it, however, I have seen rebuilt brake cylinders of pretty sketchy quality on occasion, and if you ultimately become convinced that your braking system is good from the metal lines down to the wheel cylinders, then the primary area left to reconsider is the master cylinder.

Keep us posted.

Best regards,
Shipo

wtd44

Diagnosis from a distance is so difficult. At this point you may want an opinion from a knowledgeable person who can do an on site inspection. Sometimes you can get an opinion for no charge from some brake specialty places.

mtk989

95 civic si
The pedal can easily be depressed to the floor, a very soft pedal. Also the brakes will lock up very easily when its wet and the car will slide some. Before the problem started : new rear assembly, lines, master cylinder, booster were all added and replaced. What could be the problem?

bolivar

Whoever did all that brake work did not get the air out of the system.

kiawah

Who did the brake work? It needs to go back. As bolivar suggested, it doesn't sound like the brake system was bled.

mtk989

The brakes were bled MANY times a different shops. I believe the rear is locking up before the front because the back end slides out. The master cylinder that was installed was from a type r civic.

bolivar

Did they have the electronic shop machine to attache to the car to get the air out of the ABS system?

When air gets into an ABS system, the old manual 'bleeding' approach will not get the air out. The ABS pump has got to be 'turned on' electrically to pump the air out. You can twist the wheel brake bleeder with a helper pumping the brakes forever and you will not get the air out of the ABS pump.

mtk989

They aren't abs

bpeebles

You said ==> "The master cylinder that was installed was from a type r civic."
Perhaps that Master Cylinder is not the correct one for your car. The "Type R" may have different wheel-cylinders on it which your car does not have installed.

Other possibilities,
*)Since you said the REAR is locking up... it is likely that the front brake system has either air bubbles in it or soft hoses.

*)This can also be caused by something not installed correctly on the front brakes which is adding some "slop" into the system. (Any type of 'anti squeel' goop on the back of the pads can cause pedal-squishiness)

*)Also, if the pad guide-pins are not completely clean, the pads may not move freely.

mtk989

I'm getting them checked out asap.

mtk989

The type r civic master cylinder is a popular upgrade for my car and its supposed to increase the braking force.

shipo

"The type r civic master cylinder is a popular upgrade for my car and its supposed to increase the braking force."

I'm thinking the probability of such an "upgrade" doing what it was intended to do is extremely remote. Why? Because the factory master cylinder has more than enough ability to create enough pressure in each of the four wheel cylinders to lock them up; any more force beyond that is completely irrelevant. If you really want to “upgrade” the braking on your car you will need to change not only the master cylinder, but the hardware at each corner.

bpeebles

It may be a "popular upgrade"... but being "popular" has nothing to do with being "good", "useful" or "safe". (Frankly, most of the populus is not very smart and I prefer to decide for myself instead of rely on what others are doing.)

Example: It is also "popular" to add a "K&N" air filter thinking it will increase power. The fact is that it filters WORSE and does nothing to add power. Hence, it promotes engine-wear and costs a lot more than a real air filter.

Hence, I side with the last appender. The hydrolic system is "balanced" in that the amount of fluid displaced by the master cylinder is matched to the wheel-cylinders. Simply swapping out your master-cylinder with something else could cause all kinds of issues like "squishy pedal" and "premature locking up" of the wheels.

At least you did not try installing "high performance" or "Racing" brakepads. Those are only useful when they are fully warmed up on the racetrack. They are actually dangerous if used on a road-going car because you will not have much braking power at all when the pads are cold. (which is most of the time on a roadcar)

If your brakes have enough stopping-power to kick in the ABS, then the weak-link in your stopping-power is your TIRES... not the brake-system!

0patience

The type r civic master cylinder is a popular upgrade for my car and its supposed to increase the braking force.

Odd how all these "upgrades" usually turn out to be problems that later on end up having to be removed.

You'd be surprised at how many of these upgrades I end up having to diagnose and put back to stock, because they end up causing more problems than they are worth.

Unless it was manufactured by a reputable company with a good warranty, then modifications should be left alone.

wtd44

It's always tempting to try home repairs, and with some diligence home repairs can be very sufficient. Now, when it comes to vital subsystems of the motor vehicle, one must moderate the desire for self help when discovering a need for more than just a little help. Let an actual "expert" assure your continuing safety.

0patience

Agreed.
I am one of the biggest self help advocates around, but a person has to know their limitations.
There are certain systems that a person shouldn't be messing with, unless they know what they are doing or have purchased upgrades from a "known reliable" company who specializes in those upgrades.

Replacing brake parts off another vehicle, that it wasn't designed for would be like taking an air bag from another vehicle and retro-ing it to fit. Gonna take a chance on that it will save your life when the need arises?

Changing the master cylinder, changes the pressure to the brakes, which changes the way the calipers apply the braking, which changes the way the ABS reacts and so on and so on. See a pattern here?

Do these people know enough about their braking systems or the computer systems to compensate for the differences? My experience has been that they don't.

wtd44

I truly agree! The danger to the driver and passengers is at stake. :shades:

joelolly

I changed the brakes in my Ford F150 over a month ago. I noticed that on the passenger side, the outter pad had a little pad left on it while the inner pad was completely gone and digging into the roter. I had the roter turned and replaced the pads the way I always do. Yesterday, while driving, I heard a noise and it sounded like the brakes were griding. The steering wheel was shaking and I pulled over to find metal shards on the passenger rim. I had to leave my truck in a parking lot. I'm guessing it could be a bad caliper? If anyone has any suggestions, i would greatly appreciate the feedback. I need to know what this could be so I can get the correct parts and fix it before I get my truck towed.

srs_49

First thing I would look at is the caliper bracket, on the surfaces where the brake pads' ears are supposed to slide. Have to remove the caliper and pads to see this. Make sure those surfaces are rust free and clean, and put a little bit a high temperature brake lubricant on those surves so the pads can slide freely.

While you have things apart, also make sure the caliper pistons can slide in and out freely.

kiawah

You don't say how old the truck is, but what I've found common, is caliper's get corrosion in them.

Brake fluid absorbs moisture, and you need to periodically flush it. If you don't, the moisture and other particles collect out in the caliper, immediately behind the piston. As the brake pad normally wears, the piston pushes further and further out, and the corrosion continues to build behind it. At the time you do a brake job, you need to push the piston back in, to make room for the new thicker pad. When you do that, the piston now begins to bind in the corrosion area and crud.

With the new brakes, when you apply the brakes the high pressure is able to overcome the binding piston, and the brakes get applied. However because the piston is binding, it is not able to 'float' back away from the rotor when you take your foot off the brakes. As a result, the brakes are continually on, and it is typically the inside pad that wears. If you felt the rim, you would find it extremely hot and could burn your hand. You'd also smell the brake material, and see lots of black dust on the rims.

The solution, just replace the calipers, and put a new set of pads on. You may also however, have to replace the rotors, as they could be warped due to the excessive heat. You'd now that, by whether your brake pedal pulsates at lower speed while applying the brakes hard.

Personally, I replace the calipers on every 2nd brake pad replacement. They're so cheap now a days, it's a gigantic savings in time to just replace them and then the new brake job is good for another couple years. You have everything pretty well all apart anyhow when you're doing the brake job, so the incremental time to replace the caliper and flush is minimal.

As you see, going back and repairing them a 2nd time becomes costly in both time and materials.

joelolly

If the rotor is bad, would it hurt to drive it 30 miles from where i have it parked to my house to change the rotor if i put a new caliper on it? Its a 2000 model

shipo

Assuming the caliper is bad then you probably already need a new caliper, new brake pads and a new rotor. So, take it slow and easy and driver'er home.

kiawah

Personally, I wouldn't drive it 30 miles without first looking at it to confirm what has ground up. If it was 5 miles and low speed back roads I'd consider. Not sure I'd be driving 30 miles without knowing exactly what was going on.

You can rent a car dolly pretty easily, just need someone else with a tow ball.

99accent

I had the same problem on2 cars and for whats its worth the darn rubber brake lines going in-to the caliper were collapsed or clogged, after changing both lines they worked fine.

jipster

Is there any test to determine whether brake fluid is good or bad? One shop told me my fluid was bad and held up a litmus strip of paper, saying something about a high acidity level due to a high metal content.

The other shop said "not really" the only way to tell is to look at it. So who's giving me the b.s?

kiawah

I look at the color, it starts out clear, and becomes darker as it picks up contaminants.

Many master cylinders are now opaque plastic, and it becomes easier to see the fluid level as the fluid becomes darker and darker.