I've got a 97 F150 and lately when its raining and I first start driving the rear brakes are grabby. In fact I left skid marks in the drive when I lightly applied the brakes! I pulled the drums off and the drums and the shoes looked really good. I havn't done anything to them since I bought the truck 4 years ago. It only does it when it wet outside. Any ideas what the problem may be???? Thanks!

 

Take 120 grit sandpaper and knock the glaze off the shoes and wash them with water after sanding.

 

Ive had the same problem lately. After I stop once, it goes away. The good thing is, it wakes you up leaving for work. Nothing like the threat of going through your windshield in the morning to wake you up!!!

 

depending on the style of drum brakes, they can be self-energizing (without too much technical detail, it has to do with where the pivot point is for the shoes). This is good in that it requires less brake pedal force to achieve the same stopping force. This can be bad in that when the brake pads are damp they can have a higher friction coefficient and then the self-energizing design magnifies this higher friction force and causes the brakes to be "grabby" when damp.

So, basically there is not really a problem with the brakes... it is just a "feature" of the design. Like Torkum suggested, buffing the pads with sandpaper might help for awhile... or just use caution on your first stop after it rains.

 

Thanks guys, I'll have to try the sanding the pads. I definitely don't think has anything to do with the designs since its just kinda started doing it and I've had the truck for about 5 yrs. I thought maybe flushing the fluid but even then if it was contaminated seems like it would do it all the time. Thanks again.....