Okay, I'll try to explain this as well as I can without writing a novel.

I've noticed in the morning that the first time or two I use the brakes they will grab very hard and often lock up one or both of the rear wheels. Today it did this too me again but while driving in traffic and going a little faster. I had been stopped at the gas station, truck shut off, and the brakes locked up on the road when I went to stop for a car turning left. I had to pump the brakes three or four times to get the thing stopped.

A little background on the truck. It's got new rotors, pads, calipers and rubber lines up front. Out back it's got new shoes, drums and wheel cylinders. After installing the hardware I bled everything and pushed the fluid through till I got clean fluid in all four corners. The brakes work great the rest of the time other than the soft pedal which from what I understand is normal on these trucks. The rear abs light has been on since I got the truck, I hadn't been worried about it until the truck started locking up tires.

I'm guessing the abs module has something to do with this? Any ideas on where to start looking would be greatly appreciated.

 

Here's a post on the Abs valve. https://www.ford-trucks.com/forums/7...2-f-250-a.html Your symptom of lockup sounds like a out of round drum. Are those drums new or newly turned? If a drum is to big (out of spec.) the wheel cyl. pushrods can **** at a angle and jam, then the shoes won't retract. Your park brake "push rod" ?(sits under wheel cyl. between shoes) might be installed incorrectly (the spring) and jamming up.

 

that same thing can happen if the brakes are adjusted too loose.

i would suggest pulling the wheels off and taking a look, being sure to adjust them properly as you're there

and yes, a soft pedal is normal. if i really try, i can stop without enough pedal pressure to turn on the brake lights

 

I'll pull a drum this weekend and take a look. The drums were brand new parts store house brand as that was all that was available. I havent used the park brake yet as I have yet to fix the pedal assembly in the cab, it will apply the brakes but it won't hold tension.

I'll give the spring trick from the other thread a try, can't hurt. Any one know if that will make the abs light go out? It would be nice to have a working cruise control

 

Brakes and Traction Control: All Technical Service Bulletins Rear Brakes - Grab When Cold

Article No. 93-4-6

February 17, 1993

BRAKES - REAR - "GRAB" WHEN COLD
LIGHT TRUCK: 1987-93 BRONCO, F-150

ISSUE: The rear brakes may "grab" in the morning and/or after the vehicle sits for a long period of time. This condition may especially occur in cool and damp weather conditions. High humidity increases the friction of the brake linings.
ACTION: Replace the existing rear brake linings with new brake linings that are less sensitive to humidity/temperature conditions. Refer to the following service procedure.
1.Remove the rear brake shoes. Refer to the appropriate model year Service Manual, Section 06-02, for the removal procedure.
2.Install new brake shoe and lining assembly Kit (F3UZ-2200-A). Refer to the appropriate model year Service Manual, Section 06-02, for the installation procedure.
3.Clean the brake assemblies and drums.
4.Adjust the brakes according to the Service Manual.
PART NUMBERPART NAMECLASS
F3UZ-2200-ABrake Shoe And LiningB Assembly Kit

or

Brakes and Traction Control: All Technical Service Bulletins Brakes - Sticking/Binding/Grabbing
Article No. 93-11-7
05/26/93
BRAKES - STICK/BIND/GRAB - FRONT CALIPER PINS CORRODED
LIGHT TRUCK: 1987-90 BRONCO II 1987-92 AEROSTAR, BRONCO, ECONOLINE, F-150-350 SERIES, RANGER 1988-92 F SUPER DUTY 1991-92 EXPLORER
This TSB article is being republished in its entirety to include F Super Duty vehicles.
ISSUE: Sticking, binding or grabbing of the brakes may be caused by brake caliper slide pins that are corroded. The corrosion does not allow the brake caliper assembly to move freely.
ACTION: Install the new improved caliper pins that are corrosion resistant. Refer to the following Service Procedure for service details.
SERVICE PROCEDURE
1.Remove the caliper and pins. Refer to the applicable Light Truck Service Manual for service details.
NOTE: IF PADS ARE DAMAGED OR WORN, PAD REPLACEMENT IS REQUIRED.
2.Clean the upper and lower knuckle pin grooves, upper and lower knuckle inner pad grooves, and the upper and lower caliper pin grooves with a wire brush or portable wire wheel.
WARNING: USE SAFETY GLASSES AND AN AIR RESPIRATOR WHEN CLEANING THE GROOVES.
3.Apply a light coat of lubricant (D7AZ-19590-A) to the upper and lower knuckle inner pad grooves and upper and lower caliper pin grooves.
CAUTION: LUBRICANT SHOULD NOT BE USED ON ROTORS, LININGS OR CALIPER PISTON BOOTS.
4.Re-assemble the caliper using the new pins, (F2TZ-2C150-A) for all vehicles except F Super Duty. Use new pins (F2TZ-2C150-B) for F Super Duty vehicles.
NOTE: NORMAL BRAKE MAINTENANCE REQUIREMENTS LISTED IN THE OWNER MANUAL SHOULD BE PERFORMED EVERY 15,000 MILES.

 

some time ago ford changed from Adjust on release to adjust on application,type adjusters, if you don't have many miles on the new brakes you might experience your symptoms when temp and humidity are changing a lot as in spring.. or leaking slaves. Or cheap brake component's..

 

On drum brakes there often is a primary shoe and a secondary. The shoes are exactly alike with the exception of the pad on one will be shorter than the other. This is the primary shoe and needs to go on the side towards the front of the vehicle. If the shoes are reversed it will cause grabbing/pulling on that wheel.
It is not uncommon for people not familiar with drum brakes to reverse the shoes or put both primaries on one side and both secondaries on the other.
If all four of your shoes have the same size pad on them then this is a non-issue for you.

 

I haven't had time to take it apart and check yet, although the bulliten about the moisture sounds like it may be the culprit. We have had typical pacific northwest weather here lately so it's been quite wet. The shoes were supposed to be premium shoes, but I haven't been too impressed with the quality of the rest of the brake components the parts store sells. (The though of chinesium brake components is a little worrying, especially with some of the logging roads I take my vehicles.)

It appeared that there was only one way to put the shoes in as one had a post and the other holes for the parking brake assembly. I also did one side at a time and everything seemed to match up and function as it should.

Thanks to everyone for all the advice so far, it'll give me something to work on theis weekend.