Brakes grabing

This your first frieghtliner?
I don't ask to annoy or insult, every freightliner I've ever driven (5) has had seriously touchy brakes. Like, you put the tip of your big toe on it and apply a small amount of force and the ####### would put about 40 pounds on the drums.
When I got out of the freightliners and back into a volvo or an international, I always had to remind myself that the brakes in them weren't squishy, they were designed for normal human beings.

 

Not sure where you were at or what the weather was like when this started happening, but with this cold streak pretty much everywhere's had lately, if it was cold, I'd look to seeing if ya have a bunch of water / gunk in your air system, that stuff will freeze up everywhere and make stuff like this happen.

 

I agree Freightliner gets special valves from Bendix, they do it just to aggravate, buying the same valve if you have a KW especially if you have a CAT in it, they have the other special valves that work properly. You have to wear a special foil cap to get those parts.
If the springs, on the shoes are reused they will grab, if the drums are out of round they will do that, cracked drums, very rarely is it an air problem, never is it the airlines are a different length. You have an application guage on the dash, I have seen pedals that the plunger in the floor, will stick from corrosion and dirt.
Just a thought!

 

The brakes will grab if they get grease or oil on them especially when it gets cooler. What I do to check for a leaking seal is to take a 12 inch plastic wire tie about 1/4 inch wide, bend the tip a little more and if you have dust plates slide it towards the "S" cam, with the kink towards the brake shoes, it will go between the brake blocks on the shoe slide it all the way in. When you pull it out if it has an oily film you have a contaminated brake. If you have one leaking seal and must change one set of shoes change the other side as well, same for the drums if you change one do the other.
Just a thought!

 

I worked on a truck a few weeks ago the guy only changed one side, wow caused his truck to slide in a ditch

 

Plungers sticking was a big issue with the E8 foot valves, but I think they finally stopped using them in the early 2000's. They did have a rash of bad foot valves. They would do very little as you first stepped on the brakes, then come on hard and fast.