1990 W250

I have replaced everything in the rear brakes in the past two years. I upgraded to 1 ton cylinders and shoes, new drums, new star wheel adjusters.

Brakes always feel great right after I work on it, but then a few months down the road rear passenger side starts squeaking as I approach stop signs. Like the shoe is only making light contact with the drum.
If I hit it hard, that wheel locks. Sometimes skids on gravel with only light foot pressure.
With light foot pressure, I can feel it grab-release-grab, as if the drum isn't round.
I thought the self adjusters weren't working, but if I jack it up and spin the wheel, I can hear the shoe lightly dragging on the high spot with each revolution, so I cant crank the star wheel any further without adding drag.

It did this with the old drums as well.

Sick of taking this apart. Any suggestions?

 

Did you replaced the rubber hose. I have had similar problems with hoses deteriorating and putting pieces of rubber in the lines and cylinders. also the RWAL (Rear Wheel Anti Lock) is a known problem causer on these trucks.
Mine locks then lets completely off then locks.

Yours sounds like the pressure isn't getting through the line So My guess is pinched or damaged hard line, hose or the antilock valve.

 

Yeah is sounds like a check valve type situation. Try pumping the brakes a few times and see if that passenger side brakes drum drags a little more then the drivers side.

If so you should probably replace the rubber line, then remove the metal lines from the wheel cylinder, and junction block, and blow them clear...both directions...with compressed air.

Could also be an E-brake cable not releasing completely. If the e-brake is staying on just a little, then it will engage the brake hardware just a bit so when you apply the brakes with the brake pedal it will grab right away on that side.

 

Sounds like the drums maybe out of round. Most are made in CHINA and poor quality machining. Did you buy bonded shoes or riveted? Make sure lining is not separating from the shoe, also check heal and toe contact on the drum with shoe material (chamfer the edges if heavy contact). If not already done. Back off on the parking brake adjustment then adjust the star wheel until you have slight drag on brakes. Back off on adjustment until wheel spins free. Then adjust the parking brake cable. You can usually tell if drums are out of round when you spin wheel while adjusting the brakes. You can also check on a road test by applying parking brake at slow speed. If drum is out of round you will feel that when vehicle comes to a stop.
Good info here
http://www.autoshop101.com/forms/brake03.pdf

 

Amazing how many of us experienced bad rear brakes on our trucks....


Well, I had the same exact symptoms you have, and this is what I did..

I replaced everything.... except the drums, which I had resurfaced. About a month and a half later, same exact symptoms back. When I took the drums off this time, the surface of the drum had been polished smooth like a mirror. I cleaned it up, scratched the surfaces with sand paper and reassembled. About a month later, I had the same issues all over again...

How'd I fix it ? Replaced everything with Rabestos parts.

Replaced the recently replaced (7 months earlier with Cheap local brake cables) rear e-brake cables that I changed about months prior. The one's I just put in were frozen after just 7 months.. The passenger side (longer of the two) wasn't retracting, and caused the new brakes to heat the drums, causing the symptoms you're talking about. New Raybestos brake cables was step #1, as I knew I didn't want to be doing this all over again...

Next on the list:
This time, I replaced the drums with new, and the shoes again, only this time buying raybestos NEW shoes, and not the cheap ones, and not the most expensive heavy metalic shoes either. They were their middle shoe and riveted, where previously I bought bonded.

This time, I installed the shoes, and barely... I mean barely had the shoe contacting the drum. I drove it around for about a week. Once the shoes set themselves in place, I tightened up the star wheel a bit, but still left the shoes barely touching, as to let the drums freewheel and not overheat. Well that did it. Because the new shoes and new drums never overheated, they didn't warp..although I've found that some of these chinese drums and rotors are warped out of the box.

It's been almost a year, and the rear brakes still work great.

Here's a list of the parts I installed:


You have to modify this cable as you can read in my review of it in the listing.






IMO, the issues you're having are from shiny surfaced / warped drums.


Good luck and post your results when you fix your ride.

 

Im doing rear disc brake swap on my 90 right now I'll let you guys know what I think when i get her on the road