I have got a 1998 F150 with drum brakes that stick and will not release properly, so far i have put on new shoes, drums, master cylinder, and a new abs valve and nothing seems to help at all, I have hit a brick wall on this vehicle, i have reinspected the rear shoes over a dozen times, and have found nothing that would cause this issue. im at wits end with this vehicle.

also i would like to add that this problem did not arise untill vehicle was in a accedent. There is no visable damage to baking system

 

its very hard to say without more info and pictures.

Do they constantly rub?
or do they just stick after applying?
Was the rear end hit in the accident?

How familiar are you with brakes?
Did you adjust the brakes when you replaced the pads? When you put them on, you should be able to freely spin the drum about the brakes.

Have you tried unhooking the parking brake and seeing if they still stick? Do you use the parking brake?

Its really hard to diagnose an issue like this without seeing the brakes. If you can't find the issue, I'd take it to a dealer or other shop.

 

the vehicle was hit in the front, also i am master certified and i work at a dealer, so i am working on this stuff all the time, all brake parts have been replaced including all brake lines all the way up to the master cylinder. that is why i am so stumped, no one else in the shop can seem to figure this out, and im loosing my *** on this thing

i also doubled and tripled check adjusters, shoes drums and wheel cylinders, the backing plates have no groves from wear, brakes are adjusted, e-brake cable has been completely removed, the rear brakes seem to grabe all the time.

any other ideas????

 

man, I am having the same problem with my 99 F150 supercab XLT.
I have not replaced anything because my problem comes in waves.

It seems that when it is cold or when the brakes have not been used.
After they heat up they seem to work just fine.

I would like to figure out how to adjust the rear brakes...
Just in case that is the issue...
Have you found any resolve since you posted?

any tips or advise?

 

there is an a tsb out for your problem, and i have seen that before, what happends in your case is the rear shoes will get sticky when moister buils up in the shoes causing them to stick for the first few brake applications, if you have never replaced the shoes i would recommed replaceing them and turning the drums or putting new ones on. however i have seen in rare cases were the abs valve can also cause the condition, The bad thing is its a $200 valve and is only available at the dealer.

If you dont have any popping sounds and the brakes apply smothly when they working properly you should be able to get away with a rear brake service, also just double check your abs valve and make sure there is no massive amount of currosion or rust.

 

How about the rubber flex line that goes from the frame to the rear end?Could be the problem,I had the same thing happen at my shop,could not figure it out for the life of me,but in the same token,this truck was never crashed.Could be worth checking.

 

its got new rubber lines, i have seen that before were they flex and collapse causing brake grab

 

Ok,ummm,the only other things I could think of,are the linings bonded good to the shoe,are the rivets or bonded to the the shoes,were the shoes saturated with any fluids before and just cleaned up,are the lines crossed at the master cyl,or at the proportioning valve,is the proportioning valve good,it sounds like maybe a line crossed,because you may be getting too much pressure to the rear,and not enough to the front.How about the drums,did they mic out good,still well within specs.Were the drums put on the side they came off of before.Maybe lube up the contact points where the shoe rubs against the backing plate.I am sure you allready replaced the hardware on the shoes.I am sure the shoes are put on right,meaning the longer shoe on the rear.I have seen some weird stuff happen causing something like this.Things that you would not think could cause it,is the culprit probably.Keep me up-dated on this,i am curious about this,as it kinda has me stumped too now.Been doing brakes since 1981,this is a good one here.

 

Okay, im gonna throw something out there.
From what i read, this problem started to occur after the vehicle was in an accident. I would check to see if a metal Brake line was pinched, causing pressure to go through the line when the brakes are applied. When brakes are released, the pressure remains constant and cannot return as easy due to the pinched brake line.

 

the shoes are bonded and new drums pads are mounted right and backing plate is lubed,, the lines have two diff size fitting at the master cylinder and at the the absvalve so there no way to cross them. I'm almost woundering if the fire wall didnt get bent, making the alighment betweem the brake pedal and the mater cylinder off not allowing the piston to travel back all the way. its the only other thing i can think of. but i have no idea how i can check for this.

Also the only damage to the body from the acccedent was the bumber, it wasnt that hard of a hit, it didnt even bend the brakets to the bumber, so i just dont know it just doesnt make since to me.

the vehicle has all new lines from front to rear, put them on myslef, nothing was pitched or is pintched

 

Maybe they were standing on the brakes so hard when they hit whatever it was,that something got bent.That is the only thing left,you have replaced every component there is on it.Maybe check the rod off the pedal,and look around under the dash and see if you can see anything visible.

 

My guess would be that the pressure is not releasing back at the master cylinder(as has been alluded to). Been thinking a few minutes how to best check this. I would start the truck and pump the brakes a few times, shut the truck off and get out and loosen the line at the master cylinder that goes to the rear brakes. If you have pressure there, that would confirm the theory. Saw this thread and couldn't help throw my two cents in.

 

already tried the test and pressure did bleed back and so i did replace the master cylinder, still no change, the brakes just seem to be slow to release, the only thing that hasn't been replaced is the brake booster, thats what im going to replace first thing monday when i get back to the shop, and if that doesnt then i should know if its the fire wall thats bent(maybe) the guy that owns the vehicke is a bigger guy and i guess it would be possible to bend the shaft in the brake booster

 

There is a possibility that the owner tried to mod his booster to "improve pedal feel". There is a guy on this forum that claims this is the holy grail of mods to perform. If this guy did that, he could have cranked out the booster output rod too far. Then when the master cylinder went bad and you swapped it you could have gotten one with a shorter dead stroke. So with his modded booster you are now trapping pressure.
... just a theory...

It is possible to measure the booster output rod depth, but you need a special tool. The proper way to measure it is with vacuum applied (engine running) but you need to make sure your measurement tool will seal off the vacuum... I'm not sure what Ford uses.

You should be able to tell with a visual inspection if anything is bent on the pedal bracket.

If you don't have the means to measure the booster output rod depth, it will probably be easier & cheaper to just replace the booster.