mtbackpacker

I have a 1997, F 150 4.6L, 4 wheel drive. When coming to a slow rolling stop, the brakes shudder, but only right before the vehicle comes to a complete stop. It does not shudder until my speed has dropped to about less than 5 mph. If I have to brake harder and more sudden, there is no shudder. It is not the vibration that comes from warped rotors. It never occurs when braking to reduce my speed, but only just before I come to a complete stop. The brake pads and shoes have plenty of life left on them. I replaced the rear speed sensor on the transaxil with no change. ABS light is on. I bled and flushed the brake fluid. When I apply the emergency brake just slightly (not enough to drag) there is no shudder. ABS problem? Any idea?
Joe

pilotdan

I have a 1995, F150 short-cab, 4X4 with the same issue. When I apply the brakes lightly, the rear brakes begin to vibrate (shudder). If I apply harder pressure, it appears to diminish. I turned the rear drums and put in new shoes and kits. It improved slightly, but soon returned at the same amplitude.

My suspicion is the ABS is somehow affecting the rear brakes. My next step is to look for a pressure valve along the rear brake line and see if I can disable it or unplug it (if it's electrically controlled).

Here's what I have found so far on all the forums, regarding this issue:

From FordF150.net and F150Forum.com: possibilities for braking vibration in the rear.

1) loose u-joint - vibration caused by tension release or reverse torque while braking.

2) Emergency brake sticking? Probably only true for 4-wheel disc brakes.

3) ABS interaction

4) Try applying the emergency brake. If no vibration, it's in the hydraulic system, possibly ABS to the rears.

5) Does this truck have Traction Control? Turn it off or disable it for a test.

6) Out of round wheel? Try rotation, front-to-back.

Let me know if you find something new. I'll post back when I discover the answer. I'm a systematic troubleshooter from way back. I will find this.

- Dan

pilotdan

I have a 1995, F150 short-cab, 4X4 with the same issue. When I apply the brakes lightly, the rear brakes begin to vibrate (shudder). If I apply harder pressure, it appears to diminish. I turned the rear drums and put in new shoes and kits. It improved slightly, but soon returned at the same amplitude.

My suspicion is the ABS is somehow affecting the rear brakes. My next step is to look for a pressure valve along the rear brake line and see if I can disable it or unplug it (if it's electrically controlled).

Here's what I have found so far on all the forums, regarding this issue:

From FordF150.net and F150Forum.com: possibilities for braking vibration in the rear.

1) loose u-joint - vibration caused by tension release or reverse torque while braking.

2) Emergency brake sticking? Probably only true for 4-wheel disc brakes.

3) ABS interaction

4) Try applying the emergency brake. If no vibration, it's in the hydraulic system, possibly ABS to the rears.

5) Does this truck have Traction Control? Turn it off or disable it for a test.

6) Out of round wheel? Try rotation, front-to-back.

Let me know if you find something new. I'll post back when I discover the answer. I'm a systematic troubleshooter from way back. I will find this.

- Dan

pickupsrule

97 F150 with the exact same problem.
I was wondering about it.
It probably is something in the ABS.
Since so many trucks have the problem, and it is not unsafe, and the brakes on my truck work great otherwise, I will declare it normal, and not worry about it.
Good posts, thanks guys.

Kaz Jr

You just answered your own question. Get the codes pulled, and ill bet theyre the abs sensors for the front.

Kaz Jr

You just answered your own question. Get the codes pulled, and ill bet theyre the abs sensors for the front.

Javi_F-150

I got a 97 and have the same problem...it's normal.

TRD-Toy

Are you guys sure it isn't unwanted abs activation. Have seen a lot of trucks with this problem. Always under 10 mph. Typically caused by a speed sensor to tone ring gap too excessive. If it is unwanted activation, you would need a scan tool to pinpoint the speed sensor that is dropping out at low speeds. Abs light can be on and the abs can still work, typically not but there are always exceptions.

90turbo1

my 1998 4x4 5.4 does the same thing, i chased a low soft pedal for years and changed everything I could think of, master cyl, pads, rotors, drums and shoes, (used brand new hardware kit and cleaned and lubed evertyhing) well my soft low pedal went away but after that I got a strange problem jsut like that, driving through city at some stop lights truck would stop normally, but then others the rear brakes would lock up and the truck would shake violently. removed rear drums and found that my NAPA drums were two different designs on the inside the right rear was not machined as wide as the other so the metal on the shoes was contacting the drum and catching.. there was a groove in the new drum and on the metal of the side of the shoe.

changed the drums again and it was better, now i get a shake (feels like warped disks, but its not) some times, other times it stops smooth as silk. Dont know what it could be, I have no codes in the abs system at all.

cbc24

tierod play? lol pitman arm usually does it