1968 Chevy C10 manual drum brakes problem

[HeavyHauler]

The problem I am having with my 1968 Chevy C10 manual 4 wheel drum brake systen is that I have to use ALOT of foot pressure to stop the truck and when the pedal gets to the bottom of its travel I can hear a grinding noise. You literally come to a grinding stop barely. I replaced the master cylinder,all the shoes and drums look fine and I have bled the system but I dont know how well i bled it.

Is there something else I could be missing that is wrong? I highly doubt that the 4 wheel manual drum brake setups on these trucks were that bad?

[OldBlue70C10]

They were always pretty bad. We've had my 1970 since new, and my Dad always said, it came from the factory with no brakes, lol

[toolboxchev]

Definitely sounds like a complete rebuild time for sure. Napa for the hardware kits, Advance for the shoes, drums and wheel cylinders.

[HeavyHauler]

Originally Posted by toolboxchev

Definitely sounds like a complete rebuild time for sure. Napa for the hardware kits, Advance for the shoes, drums and wheel cylinders.

The wheel cylinders do not leak and the rubber looks fresh. The shoes look fine and the drums are within spec.

[mr48chev]

Shoes installed correctly with the shoe with less brake material a the front and the one with more material at the back? I lost track of how many home brake jobs that didn't stop good were brought into me with the shoes on wrong when I was doing brake jobs every day in a Firestone store in the70's.

Springs installed wrong or one popped out or broken and bouncing around in the drum

Shoes not adjusted right?

Dirt or sand or whatnot inside the drum from the roads you have driven on lately or have to drive on. Fought a rig with noisy brakes for over a week one time an then found out that the woman who owned it lived three + miles down a gravel road. Everything I did was wiped out when she went home that night.

Lining not matching the drum well because the lining was set up for new drums and you have maybe .060 cut out of the drums to true them up.

Last, in those years of working on brakes I came to the conclusion that some lining is just flat noisier than others and cost or the quality of the stop has nothing to do with it being quiet or noisy. Sometimes the best lining rated for the best stopping and longest life is the noisiest.

The quietest lining around then was some cheap stuff that a discount parts house sold that only lasted about 10,000 miles but I never got a complaint on it from the people who's cars I put it on. Normally those were people who never put many miles on a car and seldom went outside the city limits.

[FirstOwner69]

^^^^^

Drum brakes, if properly set up, should stop you just fine. In fact, about the same as discs except under extreme conditions. It's easy to add a power booster if desired, but it's doubtful that would solve your problem.

Did you properly bleed the master cylinder?
Did you adjust the brake shoes prior to driving?

[72c20customcamper]

Something isn't right . I can lock up all 4 wheels on my 68 manual drum brakes. Like said earlier makes sure shoes are correctly installed and adjusted correctly . Check the wear pattern on the shoes make sure your getting full contact with the drum.

[weim55]

Duplicate

[weim55]

51-year-old truck and likely no one has ever had the hydraulic system completely apart and inspected everything. If you don’t know how old those wheel cylinders are replace or rebuild all of them. While you have the hardlines of the system open carefully check all the lines for free flow with compressed air, then flush the system completely with clean brake fluid. After 51 years many of these trucks have spent a lot of time sitting idle. Brake fluid can varnish and harden in the lines restricting or blocking flow.

Important stuff to check:

Are the brake shoes mounted backwards front to rear.

Is the brake clearance ( adjustment ) shoe to drum Correct?

Is the proportioning valve stuck One Direction allowing only one side of the system front or rear to actually function?

Are the parking brake cables to the rear functioning smoothly and correctly? ( you can never get a proper adjustment on the rear brakes if there is a problem with the cables )

With everything correct and ready to go properly bleed the master cylinder then properly bleed the rest of the system. The pedal should never go to the floor even under heavy stopping if everything is correct. While half ton drum brakes are not great, for anything under about 50 mph, they should stop the truck just fine. And yes, manual drum brakes do take a pretty heavy foot, though not excessive. With everything working properly, you should be able to Lock up all four brakes in a panic stop under 50 mph.t

Final words: Don’t try to do a piecemeal repair, this is one area where it’s important to just do the whole thing front to back one time correctly. If this is one of your first rodeo’s with drum brakes get a factory service manual to guide you properly.

Steve weim55 Colorado

[67C10Step]

I read this whole thread with great interest due to me currently working on the original manual drum brakes on my 67. I am not trying to hijack the thread, maybe answers to my questions will help the OP as well.

I have a new master cylinder and have currently gotten the old master off along with the distribution block. I have taken the rear brake lines loose at the rear wheel cylinders and cannot blow air through so I am going to pull the whole system apart it appears.

Have shelved that just a bit while I get the bed off for easier access to the rear section but I do have a question.

I have seen front and rear brake kits on RockAuto and one other site that include shoes, drums, wheel cylinders, and hardware. The big concern I have is RockAuto is half the price of the other place. Anyone got recommendations down this road?

I will eventually convert to power brakes and front disc. If I end up replacing my hard lines will I have to replace them again to swap to power disc?

[weim55]

Originally Posted by 67C10Step

I read this whole thread with great interest due to me currently working on the original manual drum brakes on my 67. I am not trying to hijack the thread, maybe answers to my questions will help the OP as well.

I have a new master cylinder and have currently gotten the old master off along with the distribution block. I have taken the rear brake lines loose at the rear wheel cylinders and cannot blow air through so I am going to pull the whole system apart it appears.

Have shelved that just a bit while I get the bed off for easier access to the rear section but I do have a question.

I have seen front and rear brake kits on RockAuto and one other site that include shoes, drums, wheel cylinders, and hardware. The big concern I have is RockAuto is half the price of the other place. Anyone got recommendations down this road?

I will eventually convert to power brakes and front disc. If I end up replacing my hard lines will I have to replace them again to swap to power disc?

This is exactly what I’m talking about. Usually the blockage In the fluid lines are at the junction from hardline to soft line. If you split them apart The blockage is almost always on the soft line side right at the connection. The soft line will be a throwaway and the hardline can usually be cleared easily. Only once have I had to trash the hard line because the blockage was impossible to clear.

Steve weim55 Colorado

[HeavyHauler]

Originally Posted by mr48chev

Shoes installed correctly with the shoe with less brake material a the front and the one with more material at the back? I lost track of how many home brake jobs that didn't stop good were brought into me with the shoes on wrong when I was doing brake jobs every day in a Firestone store in the70's.

Springs installed wrong or one popped out or broken and bouncing around in the drum

Shoes not adjusted right?

Dirt or sand or whatnot inside the drum from the roads you have driven on lately or have to drive on. Fought a rig with noisy brakes for over a week one time an then found out that the woman who owned it lived three + miles down a gravel road. Everything I did was wiped out when she went home that night.

Lining not matching the drum well because the lining was set up for new drums and you have maybe .060 cut out of the drums to true them up.

Last, in those years of working on brakes I came to the conclusion that some lining is just flat noisier than others and cost or the quality of the stop has nothing to do with it being quiet or noisy. Sometimes the best lining rated for the best stopping and longest life is the noisiest.

The quietest lining around then was some cheap stuff that a discount parts house sold that only lasted about 10,000 miles but I never got a complaint on it from the people who's cars I put it on. Normally those were people who never put many miles on a car and seldom went outside the city limits.

I will double check all of these things tomorrow. Although when I adjusted them today everything looked in order but ya never know.

[68Gold/white]

The rubber hoses are the biggest potential problem. I would NOT even try to diagnose them, just replace them, same with the cylinders.

I've never seen a steel line be plugged, but have no doubt it happens. I have seen the steel lines rust apart...A 50-60 year old vehicle could fall prey to anything...

When you bleed the wheels, make sure the shoes are adjusted, even if they are a little tight against the drum.

Firstowner, drum brakes will do the job, BUT driving in todays world, drums can be dangerous when driving with modern vehicles that can stop on a dime. My 67 and 68 will both be converted to front disc before they ever move under their own power again.

I COMPLETELY rebuilt all the drum stuff on my 68, it had a booster too. Still didn't stop good enough...

In my opinion, you only need front disc. Rear disc on these awesome old pickups is just a bragging deal. Does help stopping, not nearly as much as the initial conversion to front disc...

[HeavyHauler]

Well I checked the brakes again this morning and nothing looks out of place. The shoes are installed correctly and there are no loose or missing parts. After I adjusted the brakes yesterday I took it for a drive and I saw improvement. But when I checked the btrakes a few minutes ago I noticed the driver front wheel cylinder had leaked. It had NEVER leaked until after I adjusted the brakes.

I dont think that I will invest any money in repairing these drum brakes. I will just convert to power 4 wheel disc brakes all around. Thanks everyone for your input.

[96blazr]

Originally Posted by HeavyHauler

I dont think that I will invest any money in repairing these drum brakes. I will just convert to power 4 wheel disc brakes all around. Thanks everyone for your input.

That was my response 7 years ago, except I did a Disc/Drum setup.