Stuck brake

[Prairie Dog]

Just got back from a 30 minute run at speeds of 50-60 mph. Something didn't reel right during the drive... When I parked and got out I could just slightly smell brakes ~ not like riding them down a long hill with a load but i could definitely smell them. Both back ones were hot and popping & snapping. I'm thinking the parking brake stuck on just enough that the light didn't show on the dash.

So what have I done? Does the parking brake use the main shoes or does it have a separate inner set? How much damage did I do?

 

[jelag]

The parking brake uses the main shoes unless you have rear disc brakes than there is a second set of e-brake shoes in addition to the rear pads... If your where it can freeze, its not uncommon for the brake cable to freeze with moisture in the inner cable... in the winter here in Spokane we don't use the parking brake for fear of it freezing... on the larger trucks we carry a rubber snubber for putting under the tire if necessary... But the truck is left in gear, or P as the case might be... .

If you can smell the brake shoes and it was that way for more than 10 minutes or so, there is the chance that you've cooked the resin out of the brake shoe, in which case they are now scrap... once the resin is damaged they will eventually fall apart... the resin both bonds some shoes to the steel and a different resin holds the raw materials in the brake shoe or brake pad chemical mix.

I'm not speaking of a bonding resin that holds the shoe to the backing plate but I'm speaking of both the bonding resin and the resin that holds the fabric together in the brake lining its self... In both cases the resins will start to fail at exposure to temperatures above 500*F and will de-bond from the steel shoe if they are bonded shoes above the 600*F range based on the quality of the bonding resin used...

Most disc brake pads start to fail in the 750*F ranged, again based on the quality of the bonding resin... When I ran the shop, we only used a high end bonding resin, something with a failure above 650*F when correctly applied and cured in a bonding oven... .

One thing to remember that a inexpensive bonding resin is under $150 a 5 gallon bucket and a good resin is closer to $325 and has to be stored under refrigeration to maintain its life... We purchased it as a 5 gal container but a large production shop would get it by the barrel... .

Hope this answers your question... if you have others post them and I'll try and help. .

 

[Prairie Dog]

Thanks Jim, thats very interesting. I did a little checking with my manual (1st I had to find it. . ) and I do indeed have Disc's with the separate drum PB brake shoes. I guess I'll just have to wait until I can hook up the trailer in the spring and see if the PB still holds. Until then, I'm going to have to figure out why the brakes were slightly engaged but the indicator light wasn't on.

 

[jelag]

If you have rear disc brakes and you've got a stuck piston(rear), something you might not feel when you brake and you've exceeded the temperature of the resin... you'd see surface cracks in the pad... . with the wheel off, you should be able to look into the caliper and see the edges of the pad... any cracks evident mean issues that need attention... or if you have the time it would be great to pull and examine the rear pads...

You can live without a parking brake... but a problem with the pads on the rear can damage a rotor... I just wrote a long post about me feelings on this on another thread...

You've had some bad weather there... . but can we assume that you've not had freezing weather to freeze the parking brake..... and if you have only smelled one side... that's the side I'd take apart first... .

Also remember that the rear brakes only do about 25-35% of the normal braking when you come to a normal stop... . so if the rears were bad and the piston is no longer stuck all you'd do is add 35% or so to your stopping distance on a panic stop...

Hope this helps...

 

[Prairie Dog]

I'm fairly sure it was the parking brake because both rear brakes were hot and it seem to be emanating from where the shoes are instead of from the caliper. The temps hear were in the 50 when it happened and it hadn't froze in several days.
Why I didn't think to get out my laser thermometer and shoot the brake components is a mystery to me. I always have good idea's too late!

 

[rbattelle]

in the winter here in Spokane we don't use the parking brake for fear of it freezing...

There's an undeniable logic about this, but I don't do it because I fear if I didn't use the parking brake all winter, the first time I tried to use it in spring it would snap or hang up.



Is that an unreasonable fear?



My truck sits parked many days at a time with the parking brake on in winter. So far, it hasn't stuck on me. (Watch, tomorrow morning it will. ).



-Ryan

 

[jelag]

Ryan...

I've not had a problem not using the brake and its always there when I need it... . In the last 15 years, must be 10 trucks between the Fords and now the Rams... and maybe 2 million miles over these years with these trucks... . we've never pressed the e-brake pedal and not have it work...

I can say we've had to adjust the rear shoes on some of the trucks as the self adjusters wouldn't keep up... . they just didn't get backed up enough to do their job...

 

[RobertHiltz]

Jim's advice is right on. Park brake cable freeze up is common here in Northern Minnesota. Have had a few vehicles that the hood latch release cable did freeze too. Most people here only use the park brake when checking auto transmissions that need to be checked in neutral.

 

[rbattelle]

I've not had a problem not using the brake and its always there when I need it... .

Good enough for me. I think I'll change my behavior.



(BTW, it worked fine for me this morning. Phew!)



-Ryan

 

[Blakers]

I've never had a parking brake cable freeze from ice, but many times from rust. Usually it's on the automatics. My theory has always been to use the parking brake a lot and it will always work. Don't use it and it will rust up.

As far as them seizing up, there are some linkages behind the backing plates that get rusty and make them stick. If that is your case, you may be able to lubricate them with oil and work the levers back and forth until they are free. May solve your problem and you may not have to pull the rotors until you have to work on the regular brakes later.

~Blake~