66 C20 Brakes

[plmadding]

This last weekend I began working through the brake system on this truck. I've never worked on or even seen drum brakes before. Everything I've owned have been 4 wheel disk, so this was quite a learning experience.

The first major step was realizing I needed to knock out the stamped window to access the adjusting star through the front of the drum.


Then I continued to struggle to get the front drums off until I realized I could remove the spindle castle nut and pull the hub and drum together. I couldn't get one of the two screws out on each side that held the hub and drum together.

The inner and outer bearings look great and I'll put them back in. The wheel cylinders were shockingly bad! They were dry and crusty. When I cut the brake lines I got 2 drops of fluid out of one side. The other side didn't even drip once.

Piles of mud were packed around the back side of the back plate of the drum. I took a while to find the small screws holding the wheel cylinder on.

I've read some about how to remove the rear drums as they appear to be quite different since the axel is involved. Hopefully I'll be able to get to that as soon as my 6 point spindle nut wrench comes in.

The last picture is of the drums after I had them turned at Oreilly's. They said they didn't turn out right so they didn't charge me. The surface looks bad but is perfectly smooth. Is this an issue?

[plmadding]

These spiral pieces of metal were in the hub dust covers. In one hub it was twisted apart and destroyed but in tact in the other hub. I had no clue what they were, but my grandfather said they were supposed to help AM radio reception. Weird!

[vince1]

I hope for your sake that when they said they didn't come out right that they are at least cut true. If they are not then you will feel it through the pedal.

I have no idea what that spiral thing is.

[Steeveedee]

The spiral wire made contact between the spindle and the rest of the suspension to ground out any electrical energy generated by the rotating parts. And yes, it was for radio suppression. If you have a later model radio, you will may need to replace them.

Those are some of the worst wheel cylinders I have ever seen!

The shoes don't look too worn, so maybe you can reuse them, if they aren't too glazed. If you replace the drums (don't look bad, but could be oversize) be sure to have them mounted on the hubs before they are turned, to ensure that they are concentric to the bearings. In some cases they are not you will get a pulsating pedal.

[vince1]

I got my cylinders from Rockauto and as I recall they were really cheap. Shoes I think I got locally and they were also really cheap. All for around $50.

[plmadding]

I hope they are cut true also! I got an order from RockAuto today with all new wheel cylinders ($15/), bearing seals, brake shoes, and all the springs and such.

The brake shoes on one of the wheels were worn very unevenly. The front shoe was worn very thin and the rear shoe had tons of life left.

[vince1]

I can't remember where the short shoe liner goes. The front?

[Steeveedee]

Front. Just remember it as "big on the back". The front (primary) shoe rubs on the drum and pushes the rear (secondary) shoe against the anchor pin. Since the secondary shoe does most of the work, it has more lining. If the front shoe has most of its lining gone, I'd blame it on those wheel cylinders. It could be a weak spring, but as gunked up as those wheel cylinders are, I guess it's a toss-up.

If it were mine, I'd be replacing all three flex lines at the same time. They've got to be about the same age.

[plmadding]

I’m replacing all the brake lines, flex lines, master cylinder (from a 67) as well. Every brake component will be new except for the drums. I’ve never done brake lines so that will be interesting!

[65 GMC]

Originally Posted by plmadding

I’m replacing all the brake lines, flex lines, master cylinder (from a 67) as well. Every brake component will be new except for the drums. I’ve never done brake lines so that will be interesting!

I had never done brake lines before I did the lines on my 64 C20. They really are not that bad, just get a good double flaring tool and it is pretty straight forward.

[Steeveedee]

Originally Posted by plmadding

I’m replacing all the brake lines, flex lines, master cylinder (from a 67) as well. Every brake component will be new except for the drums. I’ve never done brake lines so that will be interesting!

Excellent!

[66x3]

I just did my 66 C20 this past fall. My wheel cylinders looked about like yours. Hope you have better luck getting the bolts out than I did.I had to use a cutoff wheel and a die grinder to get them off the backing plate. I also replaced the flex lines and added a 67 master cylinder.

[jocko]

66x3 raises a good point. Yes, it will take a little longer to get everything done, but now is a good time to upgrade to a dual res master, either non-power or power - it's a great safety upgrade. http://67-72chevytrucks.com/vboard/s...d.php?t=487384

[plmadding]

Took the rear drums off yesterday. It was pretty simple! Took much less time than getting the front drums off. Do you guys have any tips on how to separate the drum from the hub? It looks like the lugs need to be pressed out.

Also, I took them into Oreilly's to see if they could be turned. They said they were already out of spec. Have any of you had to order new rear drums for a C20? Where did you find them? I see LMC Truck has them...for $150 per. Ouch!

[65 GMC]

The rear drums on my 64 C20 were also unmachinable. After finding out how much a set of new ones were, I chose to upgrade my rear axle to a 14 bolt from a 1978 C20. Parts for the brakes were much less expensive. I was also able to get better gearing so now it pulls lower rpms at highway speeds.

[Captainfab]

That is one of the reasons that I recommend against messing with the Eaton HO52/72 and just change to a 14 bolt or a Dana 60.

[plmadding]

It may come down to swapping out the rear end, but I hope not. I really don't want to go to that trouble.

[Wrenchbender Ret]

I know its hard to tell from the photo but that rear drum doesn't look that bad. It looks as there is still some bevel on the edge of the drum. Some of these brakes are an odd size, with a fraction of an in over the even number size. They can be confused with being over way over sized when actually they come that way.
George

[vince1]

If I was satisfied they had enough meat left on I'd put them right back on. Look close, you might find a maximum size stamped in there somewhere. Maybe on the outside rim?

[plmadding]

Originally Posted by vince1

If I was satisfied they had enough meat left on I'd put them right back on. Look close, you might find a maximum size stamped in there somewhere. Maybe on the outside rim?

I decided they were fine and put them back on. I finally got back to working on the truck after a busy summer and early fall. All the bearings were in good shape and are now packed with new grease all the brakes are installed on the truck. Next step is to run the new brake lines.

[Softpatch]

Running the brake lines are easy
It’s the making the double flares is the hard part
It’s almost an art form. Same days I feel like a could make. Dbl flare to save my life



..... sp

[66x3]

I did pretty much exactly the same thing you did on my C20 except my drums were'nt bad. I had a terrible time getting the bolts out of the front wheel cylinders , ended up having to grind, drill, cut the bolt heads off due to rust
and a lack of room to get a wrench or socket on the bolts.

[plmadding]

Originally Posted by 66x3

I did pretty much exactly the same thing you did on my C20 except my drums were'nt bad. I had a terrible time getting the bolts out of the front wheel cylinders , ended up having to grind, drill, cut the bolt heads off due to rust
and a lack of room to get a wrench or socket on the bolts.

They were a pain!! Fortunately, my front wheel cylinder bolts were covered with ancient grease overflow from years of ball joint greasing. Once I chiseled the mud off, then the grease off, they were in good shape. The spot is tight! My rear ones were rusty and twisted off. But access is much better so it was no trouble.

[plmadding]

Finally got back around to this project with some warmer days. I finished forming and installing the new brake lines Saturday. Sunday I filled with fluid and nearly every fitting leaked! What a pain. What are the tips for getting them to seat and seal correctly?