Low brake pedal

[Matt In Detroit]

My car only has 30k on it, the car stops well and did not pull but the pedal seemed a bit low, like the brakes dont catch untill half way down with the pedal. I figured i would give the brakes a freshening and put on all new pads and get the rotors surfaced. I also flushed all the old fluid out, I feel pretty good about not getting any air in the system. Got it all completed and it feels exactly the same. All the pads i removed looked real good and the rotors cleaned up nicely. So whats next? master cyl? anything im missing? Im thinking of re-bleeding it all again to be sure about that.. I see in an old post someone mentioned braking on a gravel road to cycle the abs pump in case there was air in it?

Any thoughts?

[Blackened300a]

Im having the same issue. I changed the fluid, all new brakes, bled them numerous times, a new master and the pedal still sucks. I have some SS lines I plan to install soon. I hear that helps the pedal feel.

[ctrlraven]

Do you have SS brake lines? Those can help increase the feel of the pedal.

Mine are the same way you are describing yours. I have SS brake lines, new OEM pads/rotors/calipers up front and new pads in the rear.

How does one test the master cylinder to see if it's working 100% proper?

[martyo]

Replace the master cylinder.

Rebleed brakes.

***The master cylinders on our cars suck***

[ctrlraven]

Go with OEM or is there a good aftermarket company to get one from?

[martyo]

Go with OEM or is there a good aftermarket company to get one from?

I believe that the one I used was made by Wagner. I bought it from O'Reilly's.

Make sure that you get the right one (traction control cars need a different one than a non-traction control car).

[ctrlraven]

Thanks for the info Marty!

[MMarauder03]

I believe that the one I used was made by Wagner. I bought it from O'Reilly's.

Make sure that you get the right one (traction control cars need a different one than a non-traction control car).

Good to know, thanks.

[RR|Suki]

I have SS lines etc. and my pedal is the same way too. I even convinced myself that I had air in the line after the line lock install. . . then I remembered :rolleyes:

[martyo]

One other thing, I think these are "core" parts, so save the one you pull out because you will need to return it for the core charge (like 20 bucks).

[ctrlraven]

Are people just replacing the master cylinder and/or the brake booster also?

[martyo]

Are people just replacing the master cylinder and/or the brake booster also?

I did just the master.

Another thing is to thoroughly flush the fluid because when the master cylinder goes bad teh fluid gets contamintaed.

[Matt In Detroit]

Thanks guys. The one thing i do notice is the pedal is low on the first hit but if you do a second hit right away on the pedal its up where you would want it to be. I will look into getting a new master cyl. and doing another bleed of the system. So is there anything about cycling that ABS pump?

[Blackened300a]

Thanks guys. The one thing i do notice is the pedal is low on the first hit but if you do a second hit right away on the pedal its up where you would want it to be. I will look into getting a new master cyl. and doing another bleed of the system. So is there anything about cycling that ABS pump?

Check for vacuum leaks. I noticed I would have strong brakes after a second pump due to my intake manifold being a little loose.

[Rocknee]

I have an 04 MM and does the same. Also have trail blazer that when at stop light I can push the pedal to the floor and pump again and it is tight. Brake man said that is normal for ABS.

[fastblackmerc]

I have an 04 MM and does the same. Also have trail blazer that when at stop light I can push the pedal to the floor and pump again and it is tight. Brake man said that is normal for ABS.

That is NOT normal for ABS brakes. Sounds like you have air in the system, a defective master cylinder, booster or a combination of all three.

[tbone]

I THOUGHT the brakes on the MM were inherently bad. But after I overhauled my brakes with slotted/drilled rotors and ceramic pads, stock calipers, I feel that they are absolutlely perfect. Best brakes I've ever had in a car. And I've owned lots of them.

[Rocknee]

Air or master cylinder were my thoughts.

[2vmodular]

one common failure method on these master cylinders is for the aluminum piston bore to get some scratches on the side. unfortunetly, you can't see this damage unless you remove the master cylinder from the car and disassemble it.

in the field, the only common master cylinder tests are to look for poor pedal feel or external leaks around the rear cup seals into the booster.

you can purchase a new master cylinder for around $100. if you suspect yours is worn, then replace it. it's not too bad a job as long as the bleeder valves on the calipers turn freely.


How does one test the master cylinder to see if it's working 100% proper?

[2vmodular]

those braided stainless steel lines might be the cause of your problems.

inside the woven braids is a telfon hose. this generally works good for a car that's only driven on the track.

but it's not something i'd want installed on a street driven car. debris gets wedged in between the metal braides and telfon hose then starts wearing holes in the teflon causing brake fluid leaks. there's a reason that the big oem's like ford don't use stainless steel braided brake hoses on production cars.


I have SS lines etc. and my pedal is the same way too. I even convinced myself that I had air in the line after the line lock install. . . then I remembered

[fastblackmerc]

those braided stainless steel lines might be the cause of your problems.

inside the woven braids is a telfon hose. this generally works good for a car that's only driven on the track.

but it's not something i'd want installed on a street driven car. debris gets wedged in between the metal braides and telfon hose then starts wearing holes in the teflon causing brake fluid leaks. there's a reason that the big oem's like ford don't use stainless steel braided brake hoses on production cars.

I've had my SS brake hoses on for many many many street driven miles. No leaks.

The SS lines increase the pedal feel tremendously.

The reason "big OEM's" don't use SS brake lines is COST!

[Spectragod]

I have an 04 MM and does the same. Also have trail blazer that when at stop light I can push the pedal to the floor and pump again and it is tight. Brake man said that is normal for ABS.

Not normal, your "brake Man" should go back to school. You most likely have a master cylinder that is leaking internally.

[2vmodular]

big oems like ford manufacture millions of cars per year. to notice any statistical significant failure trends, you need data from a large fleet of cars. not just one or two.


I've had my SS brake hoses on for many many many street driven miles. No leaks.

braided stainless flex hoses can indeed provide a little better pedal feel than the oem rubber ones.

but many people are happy with the pedal feel that they get from the stock style rubber hoses too.

the rubber flex hoses are wear items that are commonly overlooked on cars too. many mechanics will only replace them if they can see visible bubbles in the hose exterior wall or the hoses are torn open and leaking fluid. but the hoses were probably providing poor pedal feel long before those symptoms appeared. if you hunt around a little, you can purchase a complete set of stock style rubber hoses for <$150. replacing the hoses is good preventative maintenance on a car that's several years old and also a good time to flush your brake fluid too.

things like brake flex hoses wear gradually over time, so you're unlikely to notice changes in brake pedal feel driving the car day to day. but the difference when you replace your old wornout flex hoses with the new flex hoses can be night and day.


The SS lines increase the pedal feel tremendously.

no, the big oem's won't run the SS hoses on street driven cars for SAFETY reasons.

yes, cost is a concern for car manufacturers. but even on the really expensive collector cars that the oem's aren't pinching pennies on, you won't find braided stainless brake hoses factory installed.


The reason "big OEM's" don't use SS brake lines is COST!

[2vmodular]

for those of you wondering what it means when a master cylinder is bypassing internally, here are links to pictures of disassembled master cylinders to help you visualize.

this is the master cylinder used in the 2003 marauders:

http://www.p71interceptor.com/brakesystem/hydraulic/disassembly/mastercylinder/2004/

and the master cylinder used in the 2004 marauders:

http://www.p71interceptor.com/brakesystem/hydraulic/disassembly/mastercylinder/2004marauder/

http://www.p71interceptor.com/brakesystem/hydraulic/disassembly/mastercylinder/2004marauder/PICT3909-vi.jpg

[2vmodular]

fastblackmerc, here's a link to a wiki on braided stainless steel brake hoses:

http://www.nsxprime.com/wiki/Brake_Lines

yes, this is a honda website. but SS brake flex hoses for acura vehicles are constructed the same as the ones for ford vehicles.

[steve fox]

I have the same condition with 3 CV SP and 1 MM all 03 and 04. The only solution I have found is to install a new MAster cylinder. I buy the NAPA part new not rebuilt. They have a LT warranty. I have done this on two cars so far with 100% success. Interestingly my other 04MM with 15k miles has rock hard brakes. All the rest have 40K or more miles with soft pedal. It may be the original MC have limited lifespan.

[2vmodular]

the napa master cylinders are raybestos stuff.

you can also order master cylinders from www.rockauto.com (http://www.rockauto.com)

the cardone select, centric premium, and motorcraft are 100% new.

do be warned that i had problems with the dorman master cylinders. one of the ports on them came was tapped for a 3/8-24 metric bubble flare even though the brake pipe port was a M10x1 fitting. the anticorrosive zinc coating dorman used in the piston bore was really soft and developed scratches when i stroked the piston a handful of times with a wooden dowel too.

[2vmodular]

i'm wondering if ford changed the aluminum anodizing process they used for the master cylinder piston bores in the later cars. maybe the metal is a little softer and wears more quickly.

[steve fox]

I have replaced the MC on 2 of my 5 CV SP /MM with 100% success when all else as you have described failed to take up the slack in the brake pedal. 2 more new NAPA (LIfetime warranty less than $130 each) MC sit on the bench awaiting some shop time. The fifth car, a 04 MM DTR has only 15k miles and the brakes are rock hard. Maybe the factory MC just have short life.

[steve fox]

sorry thought my previous post got lost in the ozone

[ctrlraven]

I guess I will be adding a new MC to my list of things to replace.

[2vmodular]

do you still have around the old defective master cylinders that you removed?

if you do, could you disassemble them and take a look inside at the condition of the piston bore? do you see any scratches inside? are there any visible defects on the cup seals? how dirty was the brake fluid that drained out of the master cylinders?


I have replaced the MC on 2 of my 5 CV SP /MM with 100% success when all else as you have described failed to take up the slack in the brake pedal. 2 more new NAPA (LIfetime warranty less than $130 each) MC sit on the bench awaiting some shop time. The fifth car, a 04 MM DTR has only 15k miles and the brakes are rock hard. Maybe the factory MC just have short life.

[Colt]

At work I drive 2008 to 2010 CVPI's. The brakes are great. My 2004 MM not so much.

I have thought about booster and Master Cycl swap from a CVPI on my MM.

Anyone know if the current 2007+ CVPI's use the same front and rear brakes as the MM?

The CVPI's are great, where my MM brakes seem to have some creep/spongy feel vs a tight feed back.

[2vmodular]

the 2007+ cvpi's use the same brake calipers and flex hoses as the 2003-2004 marauders.

the 2003+ crownvic power brake booster does have a feature in it called mechanical panic assist. basically if you press the brake pedal really fast, you get a lot of extra vacuum assist so that the antilock brakes are sure to engage. the 2003-2004 mercury marauders do not have this feature and use a 2001-2002 civilian crownvic power brake booster instead.

for your situation, you might try replacing just the master cylinder and seeing if your concerns resolve.


At work I drive 2008 to 2010 CVPI's. The brakes are great. My 2004 MM not so much.

I have thought about booster and Master Cycl swap from a CVPI on my MM.

Anyone know if the current 2007+ CVPI's use the same front and rear brakes as the MM?

The CVPI's are great, where my MM brakes seem to have some creep/spongy feel vs a tight feed back.

[2vmodular]

if you do need a power brake booster, tell the parts person that you have a 2001 crown victoria police interceptor. these have a little different air valve calibration inside than the 2001-2002 civilian crownvic boosters that were used in the 2003-2004 marauders.

you cannot use a 2003+ crownvic power brake booster in a 2003-2004 marauder without swapping out the pedal box. the brake booster pedal rod is wrong and your brake pedal will be way too far off the floor.

if you want to swap out pedal boxes, read this first:

http://www.p71interceptor.com/powerpedals/

your 2003-2004 marauder uses the same pedal box and booster that i pulled out of that 2001 grand marquis. and that 1998 crownvic power brake booster has the same pedal rod as the 2003+ crownvic boosters.