I have a 2000 X with a V10 and 108k on it, runs great but one problem I can't diagnose is the brakes are stiff as hell? New pads and rotors but I have to stand on the pedal especially at a downhill stoplight. Any suggestions?
Check for vacuum leak or defective vac brake booster. There use to be a test to check it for leaks. Basically with ingnition off you should have 2 to 3 power assist strokes on the pedal. It is also possible the check valve at the booster inlet is defective. You must be able to hold vacuum with the check valve. Basically you are driving pretty close to manual braking from the way I understand your issue.
vettdvr has it. Your not getting much help from the power assist or the calipers are seized. Do the test he described and report back.
Also you can check for vacuum leaks by spraying WD40 or starting fluid around the booster and hose while the engine is running. If the engine revs up, then you have a leak.
i have the same problem, i just thought it was a heavy truck...i just got it today, but if i needed to stop fast, i dont think i could...what is the power assist strokes on the pedal? id like to try this tomorrow...thanks alot
The brake booster holds a decent amount of vacuum in it's reservoir. The idea with the test to see if the pedal feels the same as you bleed off the vacuum in the booster. Each time you press the brakes, a little vacuum is lost. Usually there is enough vacuum present for 2-3 easy presses of the brake and then the pedal starts to firm up until it's really hard to press.
I just thought this was the nature of teh beast as well. My 03 F250 V8 stops much better and with much less pedal effort. I have suspected something was up but figured maybe its just heavy?
I was gonna go in for some more little warranty work again, I will bring it up when I do and see what they come up with. They will probably tell me my aftermarket powerslot rotors are causing it and try to sell me factory rotors though lol.
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One other test I forgot about. Engine off press the brake 4 to 5 times, then hold the pedal down hard. Start the engine and you should feel the pedal fall away from your foot. If it does not the booster doesn't work. If it does work this does not mean you don't have a leak, but if it doesn't fall away from your foot you know right away the booster is defective.
hey guys...thanks alot. tried the tests and everything seems right?? when i pump up the pedal it gets hard to push, and then when i start the engine it loosens up and is soft again??? dont know whats up, maybe nothing, but i do know the truck doesnt want to stop very easily. any more help would be appreciated. i have a 3 month warranty so if it a warranty issue, id like to get it taken care of. thanks again
Then I would have the calipers pulled and pins greased. Also have the brake fluid flushed. It's probably not covered under warranty, but would isolate some of the mechanical aspects.
If your brake fluid appears green, have it flushed if they want to do it or not. It's saturated fluid that has corroded the copper washer and turned green, not a good thing.
Check for vacuum leak or defective vac brake booster. There use to be a test to check it for leaks. Basically with ingnition off you should have 2 to 3 power assist strokes on the pedal. It is also possible the check valve at the booster inlet is defective. You must be able to hold vacuum with the check valve. Basically you are driving pretty close to manual braking from the way I understand your issue.
Ok I did this test and seemed to do as you called fine, and did the start back up and peddle did fall away, so no what to look for? the vacuum line?
If the booster held enough vacuum for 2-3 presses, then it's sealed up well enough. It sounds like you had pushed the calipers out most of the way, then when the booster got vacuum again it encountered very little resistance in the master cylinder. I don't think this is a problem, but if it is, it points to the master cylinder.
I am having a very similar problem as described in first post. I just this past weekend changed both of my front calipers, flushed out all old brake fluid, bled all four wheels, and replaced all pads with carbon metallic pads from AutoZone. I already have ART rotors that I previously installed a year and a half ago. The stopping performance is now about 90% better but in a panic stop you have to stand hard on the pedal to get the truck to stop in a short distance. I am having a hard time getting the ABS to activate when I stomp on the pedal hard. I have also performed the brake pad bedding procedure that ART rotors recommends. Are there better brake pads that I should be using instead of the carbon metallics that I have installed ?
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