Brake help lease
 

Long story short, sort of.

1968 C-20, manual drum brakes all around

Several weeks ago, I tried to flush out all the old brake fluid and bleed my brakes. I found a lot of crap in the lines when I flushed them but was able to get it done. The only issue I had was driver front bleeder did not let any fluid out. I took the bleeder out and cleaned it out and it worked.

I have been driving the truck with no problems and today drove about 80 miles. Towards the end of the ride I seemed to feel the pedal drop a bit when stopped at lights, still worked but not the high hard pedal I was getting before.

I decided I would bleed them again tonight. Started at passenger rear, went to drivers rear and then passenger front. Passenger front had a lot of dark color in the line again but it flushed out and bled fine.

Went to bleed drivers front and again, nothing came out of the bleeder. Took the bleeder out and nothing came out at all. So I disconnected the rubber line from the hard line and fluid came out of the hard line.

This leads me to believe that either the rubber line or the cylinder is clogged.
Since I have new rubber lines I figured I would change it out to see if it helped.

I am having trouble with removing the rubber line. Does it simply screw into the cylinder and can I just unscrew it from outside the drum? It is not just coming out easy and is the first thing that seems to be frozen on the truck.

Here is pictures of the new line and the old one where I was hoping I could just get a wrench on it and unscrew it.
The hole is where the bleeder goes.

https://photos.imageevent.com/happy_...e/IMG_7372.jpg

https://photos.imageevent.com/happy_...e/IMG_7370.jpg

I really have no experience with old drum brakes. I am wondering if I should be replacing the master and reservoir since there was so much junk in there.
Maybe even need to replace the lines?

Looking for advice here.

Inside the drums looked really good when I had them off last time.

https://photos.imageevent.com/happy_...e/IMG_7116.JPG

The wetness on here is just penetrating fluid to get the screw out that holds the drum on.
https://photos.imageevent.com/happy_...e/IMG_7119.JPG

Re: Brake help lease
 

To remove the hose cut it off just above the fitting and use a 6 point deep well socket to loosen the fitting. If it starts to twist off or strip you may have to replace the slave cylinder. Or unbolt it from the backing plate, disassemble the cylinder and after the rubber components have been removed use some soft heat to break up the corrosion in the threads.

If there was as much crud in the fluid as I am imagining from your description, at the very least you will need to remove the slave cylinders, disassemble them and clean them with fresh brake fluid. The same for the master cylinder. Then when they are off you should blow all the lines out with air. For this to work well the lines will need to be disconnected from the proportioning block and it blown out separately. The lines and proportioning block should have air blown through in both directions.
Once this is done then you can reassemble the master cylinder and proportioning block to the lines. And then put fluid in the master cylinder so you can pump fluid through the lines to further flush crud out. This is very messy but if you get 3 caps to put on the lines you can do them one at a time with a hose to catch the dirty fluid. If you put the slave cylinders on before this step you will push more crud in you freshly cleaned slave cylinders. Once you get clean fluid from all the lines you can install your new hoses and hook them to the slave cylinders and then bleed your brakes.
Now this is a fair amount of work with no real guaranty that you won't have further problems. Instead of doing this on my Burban I made replacement lines out of NiCopper tubing and installed them with cleaned cylinders and calipers. No more rusted lines to crud up the fluid.
.

Re: Brake help lease
 

Thank you. I was hoping to just drive the truck this summer and take care of them for good over the winter. I will try to get them work good enough to get to the winter. I guess the first step is to cut the hose off and get a socket on it and see if that helps. If I can't get it off or if the slave is clogged and I have to replace/clean it, then I may just do it all now at the expense of tying up the truck for a while.

I GREATLY APPRECIATE THE RESPONSE

Re: Brake help lease
 

You are welcome sir. And good luck!

Re: Brake help lease
 

I would replace the wheel cyl. along with the new hoses. They are cheep ( only a few bucks at Rock Auto) and if they fail an accident will cost a lot more money and down time.

Re: Brake help lease
 

Makes a lot of sense but as you can see in the pictures above, everything inside the hub is in great shape. I am trying to get this done quick (but be safe) so I can get back on the road. Of course it's still entirely possible that it is the wheel cylinder that is clogged and not the line and that will make it absolutely necessary to change it or at least clean it all.

Thanks again for the response. It really is very much appreciated. I have much to learn

Re: Brake help lease
 

i dont know if you can find the rebuild kits anymore or someone that has the brake rubbers for the wheel cyl anymore. If you can they are easy to rebuild . All you need is a wheel cyl hone. Disassemble them, hone them some ( dont over do it) and clean and reassemble. Its very basic. If you take the cyl out the brake likes thread right out them too. Good luck

Re: Brake help lease
 

I am in the middle of replacing my brake system.
I noticed your brake bleeding order. Passenger rear then driver rear.
On my truck the brake lines go from the front to the passenger rear, then over to the driver side rear. Now correct me if I am wrong, but shouldn't one start the bleeding process at driver rear? I see an opportunity for trapped air. What do you think?

Re: Brake help lease
 

When bleeding you always start with the wheel that’s furthest from the master cylinder as a general rule. For most vehicles, the brake lines are plumbed in a way that this works out, with the T fitting on the rear axle being on the drivers side of the axle. Sounds like your truck has the axle T fitting on the passenger side of the axle making the drivers side rear the longest plumbing route from the master cylinder. If that’s the case then for your truck you should start bleeding with the drivers side rear.

As much as I hate doing things twice I typically will do each corner twice, pass rear, drivers rear, pass rear again, driver rear again, and so on. Much rather bleed each corner twice than put it back on the ground and have the pedal go soft on the test drive.

Re: Brake help lease
 

I agree with Overdriven. I do them twice while I have it on the lift. You may be right about doing driver rear first but I have always done the passenger rear first.

In case it help anyone else, here is what I did and the brakes are good now. Hopefully the wheel cylinders are good and I don't have to get back to that.

I took off the rubber brake line on the driver side since that is the one that wouldn't bleed. The hard line was free and fluid flowed freely. I filled the reservoir with brake cleaner and pressurized it enough to push it all through the lines. It was actually pretty clean.

When I removed the rubber hose, it didn't look very good at all. It was all corroded inside (I cut the hose to get a 6 point deep dish on the line and it came off easy).

I took the bleeder out and sprayed brake cleaner thought the bleeder and also through the hole the brake line goes in. Then I cleaned that out with air (just a few lbs pressure) and let it dry it out good. I put the new rubber line on.

Then I went to the passenger side and did the same thing.

I then filled the master with brake fluid I had (opened bottle). I flushed that all through the front lines and they bled out great. Finally I put fresh brake fluid from a brand new bottle in and flushed that all through.

Brakes seem to be ok now. I will probably do the rears at another time. I am hoping I don't regret changing the wheel cylinder but it won't be that bad to do if I still have to. I just don't have any experience with all those springs and parts and I really don't want to take it all apart since it looks so good and pretty new in there. I will if I have to and will take a lot of pictures but I'll see how they work for now. I am not going to do any autocrossing or anything with this truck, it is a just a cruiser around town, but it has to be able to stop.

Thanks for all the help. I can't tell you how much it means to someone like me that is not that savvy with these old trucks.

Re: Brake help lease
 

Just an update in case anyone cares. ;)

While pulling the truck out of the garage, the pedal dropped again. I pumped up the pedal and sat there for a minute with my foot on the brake. It held and then suddenly dropped. Again, not all the way to the floor but an obvious drop in the pedal.

Decided to get a new rear brake hose and a master cylinder. I would think if it was air, the pedal would be mushy all the time. That is not the case. Sometimes it is fine for a while and then all of a sudden it drops.

That is why I am replacing the master. It was really a mess before I cleaned it all up anyway so decided to replace it. The rear brake house is just because I already replaced front and may as well have all new ones.

I'll report on findings.

Re: Brake help lease
 

Sounds like you're headed in the right direction. Keep us posted.
Good luck!

Re: Brake help lease
 

When working with tubing fittings, these make life easier..

https://www.lowes.com/pd/CRAFTSMAN-5...MOCQ&gclsrc=ds

Re: Brake help lease
 

Yessir, I have two sets of fitting wrenches. I'll make use of the SAE ones for this job. I have them all soaking in Kryoil now before I even try. The front ones released quite easily. The truck is really in pretty good shape. Just the usual neglected brake fluid absorbing water and causing corrosion when not replaced.

Re: Brake help lease
 

when ever in doubt the rubber sections of break lines are the problem.

replace all rubber sections going forward.

Kryoil is the best product out there. no match to anything.

Re: Brake help lease
 

Hello all, just wanted to update this thread. I replaced all rubber brake hoses and finally the master cylinder. The brakes are great now. It was the master cylinder.

Re: Brake help lease
 

Congrats Dan, glad it all worked out....and your parts arrived
(unlike mine, ...arghh) :)

Re: Brake help lease
 

A very high percentage of brake problems are caused by old or cheep master cyls. Stopping is more important than going. Don't scrimp on the master cyl.

Re: Brake help lease
 

Excellent! There was one time it took 3 different "REMANUFACTURED " master cylinders before I got one to work correctly.
It's good to hear you have it repaired and thanks for keeping us in the loop.

Re: Brake help lease
 

Well, if I scrimped it wasn't on purpose. I never scrimp on any parts really. I bought it from LMC trucks so hopefully it's a long lasting one. It is heavy.

I am a little disappointed that it doesn't have the stock looking cover and spring. There is a screw in the middle to hold the cover on. I wanted it to look stock. But it's working and it is really nice having good brakes!

Re: Brake help lease
 

Happy_dan It wasn't meant as a put down on you. More of a note to other people how important it is not to scrimp on important parts. Save your money on other stuff. I meant no offence sorry.

Re: Brake help lease
 

Oh, no offense taken at all. Sorry if I sounded that way. I totally agree with you. My point was that I am really new to the trucks. I don’t know best suppliers. I am hoping LMC sells good stuff but I will check forum sponsors first from now in