1998 Ford F150 - 4x4 Hot Drum Brakes

[onetonf350]

1998 F 150 4x4 rear brakes get hot but they are not adjusted too tight.

Parking brake cables apply and release as they should. adjusters are not installed backwards or on the wrong sides. new shoes twice. wheel cylinders and return spring kit are new and everything releases properly. I put this truck up on blocks with all the brakes cold, Drums are loosely adjusted, bolt the wheels on and when you turn the tires by hand everything feels normal. So far so good! Turn the engine on... Put in gear... let run at idle speed for a few minutes... shut every thing off. Now drums are getting warm. You can even drive this truck down the road with out using the brakes and drums will get hot.

Drums are not warped. I put black sharpie pen marks on shoes and drums to check contact area, and although its not perfect, its fair and even. I cannot explain how the brakes are applying by themselves. This truck did not have this problem before we did the brakes. Customer has been driving for several days and it seams to be getting worse. Right during snow tire season comeback.

My techs and are frustrated...any ideas?

[Cory]

I see Ford released a bulletin on this, May not be exactly your symptom but might help lead you in the right direction. Bulletin number 99-25-5

[steven kiser]

I've run into similar issues with Fords. Let me start by saying that the issue may have been already there and because of shoe wear wasn't really noticeable. Since this only effects the rears it pretty much eliminates any hydraulic issue. So it must be in the mechanical end or e/brake.

I would remove the e/brake front cable from the rest and drive it. If this resolves the issue look at where the mounting bracket for the cable attaches to the frame. If this is an automatic adjusting e/brake cable (it has the automatic spring tensioning pedal) the mount may have been moved to give it a stronger e/brake pedal. It was a fix used to strengthen the pedal. If it has been moved it may have been moved to far.


If this doesn't resolve the issue make sure the e/brake arm passes the cut out on the shoe or at least meets it. This is the arm that attaches to the cable. If not and it's applying any pressure to the cross bar this may be your issue. I've had to grind a few to make them fit. I've also seen incorrect wheel cylinders causing this issue. If i remember correctly there are a few different bore sizes used for different shoes. Some manufacturers have made one to fit all.


I just love issues like this (at other shops) fortunately, i've pretty much have seen them all in my years. mostly by experience. Another overlooked issue may be a backing plate that has a notch in it from the shoe vibrating around. The new shoe will line up fine and all is well until the brake is applied. The new shoe may get caught in the notch and not return all the way. A bent backing plate can cause the overheating. A bonded shoe replacing a riveted one may be an issue. Did you machine the new drum? I've removed more than i want to admit to to ease friction.

An important thing to remember is that this issue may have been pre existing but the shoe wear was enough so it wasn't noticeable. If this is a crew cab there may be enough sag in it that the e/brake cable may stretch. A rotted body mount will cause the e/brake to drag a bit. Good luck.........

[jbadenoch]

Marbe the outside edge of the shoe is touching the lip on the inside of drum. Drums on by hand not feeling drag but tighten wheels on pushes the drum tight to hub? I didn't see where you machined drums. Even with machining I've seen the cut not deep enough and get a similar issue. Just stabbing here. Good luck

[fortknoxx]

Is it just 1 side getting warm?

Check the diff fluid.

[onetonf350]

Still working on this one.
So it's definitively not the drum machining issue. But yes I've seen that happen before. Steve, I did later disconnect the cables completely and it still got hot. I decided to replace the rear rubber hose just to make sure there was not a check valve type situation going on. That did nothing to change things either. Im starting to think that one front brake is running a bit hotter than it should as well. I'm a afraid to drive this truck to far the way it is because I just replaced all the shoes, wheel cylinders, spring kit and both E brake cables again and do not want to overheat them. I used motorcraft shoes and genuine ford cables. Do you think this could be a hydraulic problem with the combination valve or master cylinder. I've never had a comb valve cause too much presure. Seams like the valve is centered correctly because the light is not on and the brake pedal feels normal. Master cylinders usually cause the front brakes to get hot, not the rears. I'm ordering a valve and installing that Wednesday. Master cylinder is next if nothing else works.
I did get from the customer that he felt like the brakes were not stopping as well as he would have expected it to when he was towing a small trailer down a hill for a short distance prior to us touching the brakes two weeks ago, but I don't know if that is realavent.
I thought I was onto something with the brake cables because they did feel semi stiff when they were removed,
but no.
Then I thought I was onto something with the Carquest shoes. They are welded completely differently than the motorcraft ones and the the shoes could not return to the anchor pin completely. So I thought that was going to be it but no.
I'm convinced everything on the back brakes mechanically is perfect (all new parts again). The drums (which are new now also) spin just perfectly and adjusters are even and click as they should.

[onetonf350]

I truly hate this truck and can't wait to stop test driving this turd. Canopy, lighted mud flaps, running boards, every old man option money can buy.

[steven kiser]

What i would do is with it on a lift with all wheels off the ground (in 4w drive) throw it in drive step on the brakes and release. If rear brakes are dragging crack a bleeder and see if it has any pressure and the wheel spins freely after that. It's something that will most likely need to be done more than a few times. I've run across booster rods that have a wear glitch in them that rear their ugly heads after i've bled the system.. I like to depress the pedal all the way when i bleed the system. I even do this once during a pressure bleed.

I've run into issues where (on this vintage especially) someone has either messed with the rod going to the booster or the rod that goes to the master cylinder trying to "strengthen" the brake pedal. Personally i've never seen a prop valve do this but i've seen improper brake line installation do this. I've had more than one or two where compression unions were used and the line was crushed causing slow release of the wheel cylinder.

Another thing i've run across on Fords is when adjusting the rear brakes i make sure there is slack in the e/brake and before i put the rear drums on make sure the e/brake arm is level with the rear shoe rib and returns after i pull on the cable and release it. After i've satisfied myself that it's fine i install the drum, adjust the brakes. This can be a bit deceiving because the top of the shoe will drag if the adjustment screw is to close, when the bottom is close it kicks out the top. I've seen some where the tech thought it was adjusted where is was anything but.

You mentioned that this truck has all the bells and whistles. On a long shot were oversized wheels installed on this truck within the last year or two. I use this time frame because if it's so, the worn in brakes, may have been able to take the axle flex where newly installed shoes will not. The minor amount of flex could possibly be causing the drag. This wouldn't be detectable with the vehicle on the lift. Happy hunting........

[Jeff @ Able Auto]

A long shot here but is the rear diff and axle bearings tight? Wondering if a little excessive bearing play could be letting the axle sag or walk in & out? Just a thought.