problem with the explorer

[Deamers87ford]

hey guys my dad and me are trying to fix this problem but we stumped.
the explorer while under braking the petal shakes and makes grinding noises. We think it may be the brake booster but we not sure. Any ideas?

 

[martin]

bad rotors and or drums.

 

[Beanmachine7000]

bad rotors and or drums.

+1... sounds like they're warped...

 

[dogboy]

Is this under hard braking, or just light-normal braking, or what?

If this happens under hard braking, it is most likely your ABS working. What you described, is almost exactly what both of the ABS cars I've driven, do. The pedal is smooth under most braking, but as soon as you hit the pedal hard, and the ABS starts to work, the pedal kinda chatters and feels weird, and makes kind of a grinding noise. The noise, on both the cars I've driven, sounds like it comes from the master cylinder/ booster. I don't know if that;s actually where it comes from, but that's where it sounds like.
To me, that's what your "problem" sounds like.

 

[Beanmachine7000]

Is this under hard braking, or just light-normal braking, or what?

If this happens under hard braking, it is most likely your ABS working. What you described, is almost exactly what both of the ABS cars I've driven, do. The pedal is smooth under most braking, but as soon as you hit the pedal hard, and the ABS starts to work, the pedal kinda chatters and feels weird, and makes kind of a grinding noise. The noise, on both the cars I've driven, sounds like it comes from the master cylinder/ booster. I don't know if that;s actually where it comes from, but that's where it sounds like.
To me, that's what your "problem" sounds like.

I semi-agree... On some cars I've driven with ABS (my parents' Grand Am) the pedal grinds under ABS application... Some though, like my Camaro (4WABS) and every single RBV I've driven (all RABS only) never had ABS "chatter"... It's always been a smooth stop, even under full "lock up" (pedal to the floor from 60mph)... On my Camaro it just smoothly comes to a stop very quickly... In the RBV's the fronts would lock up but never the rear and never had anything like what the Grand Am feels like...