Trying to figure out why my truck hops at exactly and only 40 mph as one slows down from above that speed at a normal pressure on the pedal.

If the brake rotors were out of round, would I not feel this at all speeds?

If I panic stop, I don't feel the hop.

I will diagnose further tomorrow by using the parking brake to only apply the rear brakes. In the meantime, any ideas would be appreciated.

 

could be something wacko in the abs system.

 

I have the same hop but at 45 mile per hour. smooth braking
at other speeds. Think it is the abs? Does any body know where the abs module is located in the 2000 f-150?
I can read the codes if I can locate its wiring connector. My abs warning light lit up a few times before but went away.

 

Tried slowing down from 50 mph through the dreaded 40 mph about six times yesterday, using only the manual parking brake.

NO hopping. No vibration. No anything.

This is indeed odd. When front rotors are warped, I am used to feeling this in the steering wheel. The steering wheel shows no signs of vibration or oscillation when the hopping occurs.

 

The parking brake is located in the rotor as a drum brake. It wouldn't vibrate if the rotors were warped in the rear. I would have the rear rotors turned and see what happens. Jimmy

 

This truck is a 1997 F150 2WD. It has rear drum brakes. Sorry this wasn't clear from first post.

 

2003 f150 2wd has anyone found an answer for this?
i have changed rotors and pads 3 times emg brake shoe's and cable axle and bearing any more ideas