Brakes Low Brake Pedal After Service - Need Advice

[Dennis M Wilson]

I recently took my 2002 Mustang GT (approx. 92,500 miles) to a local (sort of - it's clear across town) repair shop to have the following parts (which I purchased separately; on my own) installed and service performed:


(2) new Timken front wheel bearing/hub assemblies (with, of course, new Ford hub retaining nuts)

(2) new Hawk drilled and slotted front disc brake rotors

(1) new set of Hawk Sector 27 front disc brake pads

(2) rebuilt Power Stop front disc brake calipers (w/new mounting brackets)

(2) new Hawk drilled and slotted rear disc brake rotors

(1) new set of Hawk Sector 27 rear disc brake pads

(2) rebuilt Power Stop rear disc brake calipers (w/new mounting brackets)

(4) new Russell braided stainless-steel flexible brake hoses

Entire hydraulic system flushed & refilled (with Motul 600 brake fluid), and bled

Engine oil & filter change (I supplied six quarts of Royal Purple oil and a Royal Purple filter)

My primary reason for replacing all these parts was not only to upgrade my braking system, but also to cure an annoying vibration in my steering wheel/front end under moderate to heavy braking (caused, I'm sure, by my front disc brake rotors being warped or out of round).

I would normally do all this kind of work myself, but my job as a tractor-trailer driver gives me very little time at home, and I also have nowhere to work on my car at my apartment complex. Anyway, the shop I took it to has the word Mustang in its name, so I figured that meant they specialized in Mustangs, and would know what they were doing. The owner confirmed they specialized in Mustang repairs when I called him on the phone to confirm that he'd be willing to install my parts that I'd supply him, and he gave me what I thought was a reasonable estimate for labor. So, I decided to take it to his shop. When I arrived there, his lot was full of Mustangs - all years; all types. I was feeling good about this.

Until I went to pick my car up - the FIRST time, that is!) I paid the bill, and he handed me my keys. I got in my car; started the engine, and put my foot on the brake pedal so I could shift out of "PARK" - the pedal was extremely soft, and went almost completely to the floor (it felt like a brake pedal feels after you've replaced your front disc brake pads, and you push the pedal down once or twice to "seat" the pads, because you had to push the caliper piston back into its bore).

I shut the engine off; went back inside, and told him something wasn't right. He came outside; got in my car; pushed the pedal down a few times, and agreed it didn't feel right. He said if I wanted to leave it there, he'd try bleeding the brakes again. I said O.K., and had my wife take us back home.

When I called him a few days later, he said even after gravity bleeding the brakes, the pedal was the same way. He also flushed the entire hydraulic system a second time, replacing the Motul 600 fluid he had previously put in there, replacing it with fresh, regular DOT 3 brake fluid (I guess he felt the Motul 600 might have something to do with the soft pedal). That hadn't helped, either. I expressed concern that air had gotten trapped in the ABS pump, and I asked him if he had the correct scan tool needed to bleed that unit; he seemed unfamiliar with what I was talking about, but said he'd look into it.

A few days later, he called to say they were taking my car to their "sister" shop, Fiesta Lincoln, in Mesa (I live in Phoenix, AZ). He said they had the correct scan tool and adapters needed to bleed the ABS pump and brake hydraulic system on my car. I said, "Cool!"

He called me last week, to say they had my car back, and that they had good news - the brake pedal was now firm, and it was firm near the top of its travel.

Except, that's NOT how it is.

I picked the car up Monday, and while the brake pedal IS firmer than it was the first time, it still doesn't feel right. Before I had this work done to my car, it had the firmest brake pedal of any car I've ever driven (which is something I really like). Now, I'd say the pedal is only about 40-50% of its previous firmness (although, the car does stop just fine). If I'm stopped at a light or something, and I apply moderate pressure to the brake pedal, it still travels almost all the way to the floor. Frustrated that my car had been there for nearly four weeks (that's because I had been on the road for most of that time, and couldn't pick it up) and it still wasn't right, I just took it home (I didn't want that place touching my Mustang again ; I think their area of expertise is in classic Mustangs, from the '60's and '70's, and they're not so familiar with late-model Mustangs).

I also have noticed my parking brake system operates differently than before. Prior to this brake work, I could only pull the parking brake lever up about two or three clicks, and it was tight. Now, the lever goes up at least 7 or 8 clicks, and if I put the trans lever in "DRIVE" and apply light throttle pressure, the car moves forward.

So, does anyone have any thoughts on what's wrong with my brakes? With the firm pedal I had before, there's no reason, with the quality parts I had installed (especially the braided stainless-steel flexible brake hoses!), that my pedal should now be LESS firm.

I know there's really no adjustment you can make to the emergency brake cables, but could it be possible they aren't hooked up properly to the calipers (is it even possible to hook them up incorrectly)? Can there be something wrong with one or both of my rear calipers? I know when you replace worn pads in these rear calipers, you have to turn the piston in order to retract it into its bore - is it possible to retract them too far into the bore, so they don't push the pads tight against the rotor during braking? Is it possible my master cylinder just coincidentally went bad at the same time I had this work done?

Any thoughts/input anyone has on all this would be greatly appreciated. Because I don't have the time or place to work on my car myself, I'm now going to have to take it somewhere else, and pay someone else MORE money, to diagnose what's wrong with it.

Thanks,

Dennis

 

[trinity_gt]

The pedal sinking to the floor when at a stoplight ("If I'm stopped at a light or something, and I apply moderate pressure to the brake pedal, it still travels almost all the way to the floor.") suggests a problem in the master cylinder, especially if releasing the brake pedal restores pedal height and initial firmness (even if it starts sinking soon afterwards.)

Master cylinder seals can be damaged during bleeding if the pedal is allowed to travel all the way to the floor during the bleeding process. The seals on the piston may be damaged as they move over what may be rough surfaces in the bore previously unreached/unused and possibly now even lightly corroded due to water that's collected in the fluid over the years.

The MC could be leaking internally (i.e. within the cylinder itself); it may also be leaking externally (have a look up under the dash and see if you can see any evidence of fluid where the pushrod enters the MC...)

 

[Dennis M Wilson]

The pedal sinking to the floor when at a stoplight ("If I'm stopped at a light or something, and I apply moderate pressure to the brake pedal, it still travels almost all the way to the floor.") suggests a problem in the master cylinder, especially if releasing the brake pedal restores pedal height and initial firmness (even if it starts sinking soon afterwards.)

Master cylinder seals can be damaged during bleeding if the pedal is allowed to travel all the way to the floor during the bleeding process. The seals on the piston may be damaged as they move over what may be rough surfaces in the bore previously unreached/unused and possibly now even lightly corroded due to water that's collected in the fluid over the years.

The MC could be leaking internally (i.e. within the cylinder itself); it may also be leaking externally (have a look up under the dash and see if you can see any evidence of fluid where the pushrod enters the MC...)

Yeah, I've had the same exact thoughts that they might have damaged my master cylinder while bleeding the brakes. When I go back home again, I'll have to check for evidence of internal leakage, like you suggested. I do know it's currently got plenty of fluid in it - in fact, it's slightly overfilled. The level of brake fluid in the master cylinder comes up to the bottom of the filler neck, and that's probably 1/4 to 1/3 of an inch above the full mark.

What about my parking brake? Why is it so much more "loose" than before I had this work done? Is there a way to make it ticket tighter, so the handle doesn't pull up so many clicks, and it holds the wheels/rotors tighter?

Dennis

 

[squeak93]

MY theory is that since your rear parking brake has to be pulled up considerably further (with new pads/parts at that) that they still have not properly bled the abs module. I am betting the rear does not have full fluid pressure to it and is not doing much good (indicated by the parking brake issue).

I'd keep after the shop until it's right.

 

[Sluggie24]

First off you don't gravity bleed a brake system to get the air out. That is just to get the fluid through new parts to make the bleeding easier. If they tried gravity bleeding to get a firmer pedal then they don't know what they're doing. Proper bleeding is either don't with one of the various pressure/vacuum bleeding tools or with one person pumping the pedal and one working the bleeder valves.

Secondly there should never have been the possibility of air in the abs unit unles they put it there by being ignorant. When you flush a brake system you never let the master cyl go empty so you don't introduce air into the system. That is first year knowledge stuff.

There is likely air in the brake system. It needs to be fully bled by people who know what they're doing to ensure all air is gone. After that is done, if the pedal still slowly sinks at a stop, there is a bypass in the master cyl and it needs to be replaced, bench bled, and then the whole system bled again.

The parking brake issue could possibly be caused by air in the rear calipers. It could also be caused by the fact that they only hooked up one cable to one caliper. Look under the car to verify they hooked up both cables. Since that shop obviously doesn't know how to bleed brakes, it's likely they didn't know that you need to release the auto ratcheting system on the parking brake handle to reattach the cables to new calipers. They might have gotten one on and found they didn't have enough slack to get the second on and said "good enough".