50 Pilothouse One Ton Brake Issue

[mmcdowel]

I'll tear into this wheel this coming weekend, but wanted to ask some advice first.

The first couple of times I hit the brake after the truck has set all night the driver's side tire wants to lock up.  After a couple of stops it works perfectly.  I have all my books and will use them to hopefully find the issue, but wondered if anyone knew of a common issue that might cause that?  Thanks!

[Young Ed]

Typically that is from brake fluid contamination on the shoes. 

[JBNeal]

What I learned about brakes that lock up is that the problem is with the brakes that aren't locking up:  if brake pressure is equal at all 4 corners, then the brakes that are not locking up are either not engaging...this is either from shoe contamination, or from wheel cylinders not applying pressure, likely from pistons being stuck, or from a leaky wheel cylinder that is letting fluid seep around the piston onto the shoes.  I had a problem with the latter due to pitted cylinder bores, and ultimately had those wheel cylinders sleeved... 20 yrs later, and those rebuilt brakes still hold pressure without locking up

[jeffsunzeri]

Return spring may also be whacked out on the offending wheel.

[mmcdowel]

Excellent!  Thanks!  I'll advise what I find when I get in there next weekend.

 

[MBF]

My 49 1 ton does the same thing.  I've got new shoes, cyls, seals, and lines on it, and had the drum cut.   I've had the hub off several times to see what is going on.  There is nothing leaking and nothing visibly wrong that I can see..  It would lock up the left front in the first stop after it sits in the garage a few days.  So now when  I back it out of the garage I drag the brake for a wheel rotation or 2 and its fine.   I'm anxious to see what you find.  

[mmcdowel]

I certainly will advise.  I believe the brakes are all new-ish and the fluid looks clean so I'm hoping just an adjustment, bad return spring or something simple,.  Generally never works out that way though!