Braking Me

[Burbdually73]

Recently picked up an 81 swb 2wd c10 Silverado I been trying to buy for almost a decade. Drove it home after a lumber stop at Home Depot about 25 miles through town and 70 on the freeway. Brake light was on but never seemed like there was any issues or felt unsafe. Get it home and notice the front res(rear brakes) on the MC was dry so I filled er up and pumped the hell out of the brakes…light went away.

Didn’t drive it and parked it for a few weeks while I got the interior cleaned, repaired and presentable.

Drove it, rear brakes lock up at any speed and any amount of pedal pressure, feels like right side. Pulled the drums and had a leaky wheel cylinder on the right side. Replaced both, adjusted drums and bled. Didn’t bleed well, intermittent pressure for quite a while. Drove it…still locking up rear.

Decided to bench bleed the MC since I have a kit. A ton of air in the MC but still having issues bleeding out back. Drove it…still locking up.

Thinking I may have ruined seals in the MC or they were already dried out from being without fluid…I installed a new MC, bench bled and went to bleeding, this time I have a centering tool for the PV. Still not bleeding properly. Original MC was the alum/plastic combo, got the same one.

Pulled off the proportioning valve and torr it apart, rear side with the large fitting is full of rust. On to a new PV2 proportioning valve and blew out the rear rubber and 2 hard lines with air. Everything bled good.

Drove it…STILL locking up. No brake light on.



Sorry for the long winded post…but I need some help. What can I look for? Neighbor car builder says to check for a pinched hard line or collapsed rubber line at axle.

Could there be an issue up front and sending all fluid to rear now? Assuming I only had front brakes the first day I drove it home and they worked well enough to not worry.

 

[Strick]

Sounds like a thorough repair. Can you back off the shoe adjustment a click or few or have you already tried this?

HS

 

[Burbdually73]

Sounds like a thorough repair. Can you back off the shoe adjustment a click or few or have you already tried this?

HS

I may do that. I tightened till they would drag then backed off till they didn’t. But they locked up before any of this work was done or that adjustment. I have had the wheels and tires off so many times I’m going crazy.

 

[Ricko1966]

Did you replace the shoes? Do you have the long shoe in the rear position and the short shoe in the front position? Is the combination valve you bought for a disc drum vehicle?

 

[Burbdually73]

Did you replace the shoes? Do you have the long shoe in the rear position and the short shoe in the front position? Is the combination valve you bought for a disc drum vehicle?

Did not replace shoes.

Yes, Big shoe on back.

Yes, PV2 is the disc/drum valve.

 

[Ricko1966]

I'd be looking at my front brakes do a panic stop in sand or gravel,will the fronts lock?

 

[Burbdually73]

I'd be looking at my front brakes do a panic stop in sand or gravel,will the fronts lock?

That’s the plan tomorrow. And get whatever picture folks may need to help me out

 

[Burbdually73]

Couple pictures of what I’m working with. Forgot to mention I have hydraulic trailer brakes. I removed them from the MC partway through the day thinking it was tripping the PV, that’s the line with a red cap in the picture

 

[Burbdually73]

Backed my adjusters WAYYY down in the back just to try it. No longer locks up but does feel like it’s all front brakes now. I may do a couple turns at a time and see if I can find a happy spot

What is the correct procedure for adjusting rear brakes?

My boat trailer has 1 ‘plunger’ per wheel cylinder compared to this truck having 2 per. On my boat…I tighten till they drag and back off till they don’t..never had an issue there or brakes locking up. Maybe it’s because it’s a single plunger?

 

[Ricko1966]

Backed my adjusters WAYYY down in the back just to try it. No longer locks up but does feel like it’s all front brakes now. I may do a couple turns at a time and see if I can find a happy spot

What is the correct procedure for adjusting rear brakes?

My boat trailer has 1 ‘plunger’ per wheel cylinder compared to this truck having 2 per. On my boat…I tighten till they drag and back off till they don’t..never had an issue there or brakes locking up. Maybe it’s because it’s a single plunger?

You adjust up until you can't turn the drums,then back off until you can without significant drag. Baking the adjustment way off is a crutch,and the self adjusters are going to be put the shoes back eventually.. What is the production date on this truck. And I'd still inspect my front brakes.

 

[Burbdually73]

Adjusted brakes again. Back to locking up

 

[Burbdually73]

Mfg 11/80

 

[Burbdually73]

Cleaned the heck out of the fronts to try more bleeding. Noticed the left caliper is painted red and casting marks are a little different. Not sure if this was a junkyard part or what.

 

[Burbdually73]

Cleaned the heck out of the fronts to try more bleeding. Noticed the left caliper is painted red and casting marks are a little different. Not sure if this was a junkyard part or what.

 

[Burbdually73]

Bled the front again and polish and greased the pins. Still the same