Quick Sudden stop, brake pedal seems to slowly return and brakes continue to grab

[terr5178]

If I have to make a sudden stop on my 2003 expedition 5.4 162k, the pedal grabs like normal, the front dives but as I let go of the pedal it slowly returns and brakes slowly release. Other than that the brakes work perfect. The brakes still grab hard when emergency stopping but seem to keep grabbing for a few seconds after I've let go of the pedal.
Any thoughts

 

[Big Brian]

front calipers hanging up maybe?

 

[terr5178]

No, New calipers both sides.. continued braking after the peddle was released was an issue long before I replaced the calipers. The truck stops as well as expected but it's just strange to fell it continue to stop after the brake was released..

 

[99WhiteC5Coupe]

No, New calipers both sides.. continued braking after the peddle was released was an issue long before I replaced the calipers. The truck stops as well as expected but it's just strange to fell it continue to stop after the brake was released..

Are you sure the caliper slides and slide bolts are properly lubricated (front and rear)? You also may have one or more rubber brake line hoses that are collapsing inside and restricting the fluid return when you let off the brake pedal. Are there any metal clamps holding the rubber hoses in place? If so, that is a common location for the internal collapse.

 

[terr5178]

I was thinking the same thing.. Other than replacing all hoses, is there any way to tell which hose is the problem. I know the hoses are relatively cheap but Murphy's law will always make a bolt crack in the caliper or a union nut snap a rigid line.. causing me to loose my mind..

 

[99WhiteC5Coupe]

I was thinking the same thing.. Other than replacing all hoses, is there any way to tell which hose is the problem. I know the hoses are relatively cheap but Murphy's law will always make a bolt crack in the caliper or a union nut snap a rigid line.. causing me to loose my mind..

I'm not aware of any easy method to determine if a hose is collapsing on the inside - other than to examine each hose and see if there is any swelling or abnormal areas. I have seen metal clamps from the factory (which are designed to hold a rubber line in place) rust and deform, causing damage to the rubber hose.

Your concern about something going wrong is well founded. Good luck.

 

[docraymund]

Get the truck on a lift and see if the wheels spin freely. Otherwise, it could be a master cylinder problem.

 

[stamp11127]

I would look at the abs module also. Is the brake fluid dirty?

 

[USMCBuckWild]

The continued braking after releasing the pedal is a classic collapsed/collapsing brake hose symptom. The master has plenty of pressure to force the fluid through the bad hoses to the caliper and force it to clamp, but the "vacuum" that is supposed to draw the fluid back out of the caliper is 1/100th that pressure. I would honestly start hosing down the fittings with some PB blaster or other penetrating oil.

If it is the master, it would be showing more symptoms. If it was the ABS module, it would be making ABS noises. Cycling the ABS when flushing the brake system is essential in ensuring good fluid is in the entire system.

 

[stamp11127]

Usually an abs module failure can give a random clicking noises but other failures in the system may not. One sure sign of abs failure is the ability to lock any of the wheels during hard braking.

 

[waldo]

Most probably you just experienced "Ford emergency brake assist"

Basically under hard stopping the pedal bottoms out but the truck continues to brake. The pedal remains soft for a bit, very strange feeling the first time it happens to you.

 

[brad03]

Thank you for clarifying this everyone. Does anyone know a good source for braided brake lines for the second gen? Thanks

 

[Boose]

This is a design built into the brakes!
This is a fail safe for a panic stop. If you exert a panic stop scenario and your foot were to slide off, the truck will continue to apply the brakes for a set period of time. Nothing is wrong with the truck.

http://www.nytimes.com/2002/10/27/a...n-smooth-transition-still-big-now-better.html

 

[terr5178]

WAldo and boose, are you guys serious? I've never heard of this but sound possible considering cars park and drive themselves these days.

 

[waldo]

Yup very, go out to a parking lot drive about 30mph and slam the brakes, it will scare the hell out of you the first time.

 

[waldo]

Right out of that article:

"The new Expedition has the largest brakes in its class, and along with an antilock feature they incorporate a brake assist feature, which helps to reduce stopping distances by applying the brakes at full force in panic stops. (Testing has found that drivers tend to hesitate when they ought to slam the brake pedal and hold it.) I found the brakes effective, smooth and confidence-inspiring."

 

[terr5178]

I found out about this with a 2 and 5 year old in the back seat at 60 mph as we crested a hill to see brake lights and stopped traffic. I slammed the brakes hard then was able to move out of the lane where I could slow down normally. But I wasn't expecting the weird feeling in the pedal. I assumed something was wrong but couldn't find any bad hoses or lines.

 

[waldo]

No your truck is fine, feature not a fault.

 

[Boose]

I stumbled on this accidentally as well after I had my 05 for about a year. Had to slam on the brakes coming around a blind curve/on ramp. Scared the crap out of me as it made no mechanical sense. Then, low and behold; there it is in the owners manual

 

[PHIL CLACK]

I almost died (via heart attack) the first time this happened, lol.
Always bring an extra pair of clean drawers.

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