1997 F150 2WD 4.6L

so last night on my way home from up north i drive about 3 miles hit the brakes and the whole truck i mean WHOLE truck starts shaking violently i let off the brakes it stops i hit them again and get slight pedal pulsating. i get on the free way and as we exit for food i hit them at 60 and again VIOLENTLY SHAKING THE WHOLE TRUCK! then i back off them start to down shift my auto trans *it works belive it or not* then i try them again they are fine. i get to my buddys house to drop off his 4X4 now the pedal goes to the floor.

i checked the fluid its fine.

we did just replace the front left cailper but its working fine.

as i left his house the red BRAKE light came on *Ebrake light* and my ABS light *my truck has no ABS and the light has never been on before*

i dont see any puddle's under my truck but now the pedal goes right to the floor and i have about 2" of stop in the pedal please help.

 

https://www.f150online.com/forums/19...ake-issue.html

 

Probably a master cylinder

 

must have two threads... but, i had the same issue of pedal to floor and no leak. Im betting one of the springs in a drum had failed and is allowing your pad to catch and not return causing the shudder. pull your rear drums and check the pads, springs, and cylinder that pushes pads out.

 

you are definitely looking at 2 separate issues, but most likely it is one issue that created a second issue.

the "violent shaking" due to braking could pretty much only be ABS. Warped rotors could cause some shaking and shimmying but I wouldn't call it "violent".

You say you don't have ABS, but in your other thread on this topic someone argues that you do have rear ABS - you need to check/confirm this.

If it is an ABS issue then it could explain the soft pedal issue. Your master cylinder is rather old (assuming its original?) so the seals are probably worn. Then you have some crazy hard ABS applies and it blows a hole in the worn seal. This creates an internal leak in the MC so you have a soft pedal and no fluid on the ground.


If you find you really do not have ABS - then it must be some sort of issue with your custom tuning maybe? Your sig says that you created your own custom tune... Did you screw with your shift points?

 

Thanks all. i am pretty sure i dont have ABS any time on dirt or snow when i slam the brakes all 4 lock up no pulsing in the pedal and my wheels are all locked. so i am pretty sure i dont have ABS.

i have never done rear shoes in the whole time ive owned the truck *got it at 98,000 now has 178,000* so maybe its the rear shoes but where is my brake pressure going? i pump it and nothing happens my RPM doesnt change goes right to the floor. i still have full fluid. yes i did make 2 threads wanted to get all base's coverd.

 

From your pics, it looks like you have an XLT (power mirrors). In that case, I believe you have ABS. Like the others have suggested, check you rear brakes.

 

ok thanks. i have never got the pulsing or anything like ABS ever from my truck. the front has the spindle for ABS and had the rotors but no wires or anything in front.

 

replaced the master cyl. still the same was about to crack the front cailpers to bleed them when i noticed a puddle in the back left my rear brake line where it goes into the rubber line for the rear brakes is leaking.

so i will prob end up running a new line all the way from the master cyl. to the rubbers and im doing my rear brakes today as well because we all know 15 year old wheel cyl's the bleeders are going to break.