521 brakes "clunk" and stick

[domn8tr]

When hitting my brakes they work but sometimes go "clunk" and then work better. It sounds like its coming from the left but theres no pull when it happens. Also they dont always retract right away. Intuition tells me its the master check valve as I changed the shoes and springs. Slaves werent leaking and I greased the adjuster shims. Should I replace the master? 

[datzenmike]

Front? Check the tension rod bushings. The tension rod forms the third side of a triangle with the frame and the lower control arm being the other two. Without it, when the brakes are applied (or hitting a curb) the wheel wants to stop while the truck keeps moving forward.

 

 

[domn8tr]

Thanks Mike! The upper outer rubber bushing on the control arm is shot so thats probably the clunk but why would that make the brakes grab more. and not releasing I figured was a check ball issue but just saw a post about adjusting for freeplay on the M/C pushrod. P.S. check my post in electrical on dizzy and matchbox Thanks

 

 

[datzenmike]

You may have 2 or more separate problems.

 

The rod adjustment is for when replacing something. If yours was working the rod length isn't going to change by itself.

[banzai510(hainz)]

Only way is to pop the drum check and then when open adjust the shoes and put the drum back on. I ajust it also while it open by turing the star wheel.

 

add jack screw holes if non are there and anti sieze the mating plate(rear drums)

[bilzbobaggins]

Ive got the similar problem on my 521.  Hit the brakes and the left front clunks(randomly).  When it does, it pulls to the left and I get a bit more travel in the pedal.  Cant wait to get it to the shop and look at it.  Been hell at work.

[datzenmike]

Sounds exactly like the adjuster is  not sliding properly on the backing plate or one of the shoes. It's usual to lift and spin the wheel while adjusting the shoes. If the adjuster is sticking only one shoe is actually rubbing and appears to be right. When you step on the brake the adjuster snaps loose and centers itself.