Tore into the brakes, have a few questions

[The Neck]

Hey everyone,

I picked up a 67.5 1600 this week and have really enjoyed digging into it. I've done a few preliminary engine things, and was able to fire it up. It sounded great! before I went to drain the old oil I checked the dipstick for the heck of it and low and behold it was full to the exact full level. I took that as a great sign.

As I wait on a part for the fuel system, I dug into the brakes. Cause there's no sense in going if I can't stop. I pulled apart the front calipers with barely any issues, and they look surprisingly clean. The old pads had barely any wear to them, and the rotors are dropped off at a local shop to be turned tomorrow.

The fronts look surprisingly good and there was no pitting or damage to the cylinders. I'm going to be ordering a rebuild kit depending on if the rotors can be turned. If not I'm unfortunately at a bit of a cross roads with what direction I really want to take if that's the case.

I pulled the rears apart, and that's where I have a question. The passenger side was clean as a whistle. Drum came off super smooth, and the inside is in great shape.

The drivers side however, had a bunch of dirt caked on the outside of the hub plate. Inside was pretty dirty with what seemed like grease that had also collected quite a bit of dirt and the cylinder was also covered in some yellowish speckles. I'm at a bit of a loss as to why this drum was full of so much dirt and grease and the yellow speckles.

Am I looking at a bad cylinder or something else? I'm replacing the shoes regardless, and wanted to make sure I get the cylinder if need be.

Mike


EDIT: I also noticed there are a few people suggesting a switch to silicone brake and clutch fluid. Why is that? Just less damaging to paint? I have both systems to flush and refill so I figured this is the time to make the jump.

[Skyman]

I can't comment on the yellow specs. The buildup could actually be a bad axle seal allowing some oil to get through. This would be my guess unless you can verify any leakage from the rear brake piston or lines.

[C.Costine]

Mike, your description of the yellow speckles sounds just like what I had growing on my master cylinders a few months after cleaning them. At the time I decided that it was simply corrosion of the white metal that the masters are made of, which is probably the same material as the rear wheel cylinders are made of. I asked here about preventing it and the answer was clean, prime, and paint. I did that and they have been good since. I don't recommend going to all that work for wheel cylinders, but once you are driving it now an then the heat generated should keep the moisture away and stop the oxidation. You could have the oxidation on just one side because the dirt would have held more moisture.I have switched to Silicone break fluid mainly because it is supposed to be less prone to absorbing water. The fact that it doesn't harm paint is another huge bonus though, because I had removed everything from my engine compartment, and I had a couple leaks from the new brake line fittings that would have done a lot of damage to the paint.

[The Neck]

I broke down that corner tonight and found some interesting things. That entire corner was unlike any other in the rest of the car, and had a very thick layer of dirt and some sort of car based fluid to help it all stick. I either had a brake fluid leak, or oil leak from the axle.


After taking it all apart and cleaning everything very well, I'm leaning more towards brake fluid as the culprit. I initially was going with axle oil, but due to the location from where it looks like the build up originates from, and the fact that the rubber around the brake cylinder has deteriorated, that leads me to believe it's brake fluid.

I have a few more pics for you to take a look, and if someone else is having a similar issue, maybe this will help. I have to replace a couple parts from the axle regardless, and will be rebuilding the cylinder too.

[nismou20]

Mike, Be aware that the rear shoes can be mounted 2 different ways. I believe the shoe braking material should be 180 degrees apart. Yours look to have the left shoe mounted upside down. They work both ways but don’t wear evenly. If you look at the distance of material on bottom right ends, they are farther apart than top left. I’ve done this myself.

[The Neck]

Excellent observation. I've read that this is a common mistake, and thank you for pointing that out in this case!!

As far as the leak goes, I'm going to replace the metal seal/shim that was found to be demolished and keep an eye on the corner once I get the car up and running. It took me all of 15 minutes to pull it apart, I love how simple this car is to work on, and I'll see what I find before I start throwing parts at it.

[mraitch]

not only should the shoe material be 180 degrees apart, there is a 'leading' edge and a 'trailing' edge. The 'leading' edge is slightly more chamfered than the 'trailing'