Driver Drum dragging I think

[Zedyone_kenobi]

Scratch Scratch scratch...

Well that was the sound my drum brake on the drivers side made today when I took it out to get some lunch for the family. I also noticed that when I let off the gas and shifted into neutral, the car slowed and came to a less than smooth stop. Meaning it felt like the brake was dragging. To test this theory, I put it in first and let the clutch out slowly without giving it gas. THe car will die before it is able to move it under its own power while idling.

There was also a lovely smell coming from the rear of the car like pads overheating.

So, I got it home,

Pulled the wheel off

disconnected the E-brake cable

rotated the drum so the inspection hub hole was over the wheel cylinder

Loosened it up until the drum easily rotated. Since I just put pads on there about 500 miles ago, I greased up the hole in the drum and the guide edge on the axle and it just poppet right off. Lovely.

now the mystery comes in. The drum was full of dust, so it was dragging. Now I have to decide if it was dragging due to one of two things.

1) worn rear bearings allowing the rear axle to droop and touch the pads, I do not think this is it, as it was going scratch scratch scratch as the wheel turned, indicating that there was a high/low spot, if the bearing was bad it was just grind and grind constantly. However, when I grab the wheel studs and move them back and forth and up and down, I cannot see or feel it move no matter how hard I look, but I can hear a faint click as I move it side to side. It takes about 2.1 lbs of force to turn the axle so that is about right, and it spins smooth as silk. My gut tells me it is not the bearings although I have NO idea when and if they were ever changed. My car has 70900 miles on it.

2) bad wheel cylinder hanging up from being stored for a while and sticking. When I redid my brakes, I did not change the wheel cylinder as it looked fairly good. Now I do not know. Is there a test I could do on the wheel cylinder, or should I just replace it. By the way, the passenger drum spins beautifully, this is only the drivers side. When I stomp on the brakes the scratching sound stops and but the sticking is far more pronounced.

Advice is needed. Me thinks it is a sticking wheel cylinder... but I would love to hear opinions.

I know I need a brake vacuum booster, now I may need a wheel cylinder.

[SteveJ]

Considering I had a similar problem on the right rear of my 74, I vote #2. At least that's what Eddie Radatz suggested. He replaced the wheel cylinders for me, and I don't feel the brakes dragging any more.

[Zed Head]

Your 71 probably has the same floating single-piston cylinder that my 76 did. The cylinder itself slides back and forth (floats) in a slot in the backing plate to self-center as the shoes wear. Maybe the cylinder is stuck in its slot or jammed, or even one of the clips has come loose, allowing the cylinder to jam. They are only held in place with two bump style detents, under the rubber boot. There's a good drawing in the 1972 FSM. The backing plate tends to rust under the cylinder, and get road grime, gumming things up.

You should be able to slide it back and forth by hand with the drum off, against the pressure of the brake springs trying to hold the shoes in place. Or you can take the shoes off and it will slide easier.

They went to dual pistons in 77 or 78, allowing the pistons to extend to whatever distance needed to keep the shoes centered.

[tlorber]

I spent $27.00 for a new brake cylinder for my '73. If you have any doubts you should replace it. I would imagine that it is more likely the cylinder than the rear bearing.

[Zedyone_kenobi]

pray tell where? Everywhere I look I am getting 90 dollars and up.

[SteveJ]

I think the 73 uses a different wheel cylinder. Rockauto had a 71 wheel cylinder for $61.79 + S&H

[Casey_z]

Wheel cylinders changed halfway through 72.

The only difference is the angle the steel line attaches to the back of the cylinder.

I used later wheel cylinders on my early 72 but had to bend new steel lines to match the angle.

Casey

[Zedyone_kenobi]

thanks very much. I am going to source a new wheel cylinder when I can find one. I may even disect mine and take some pictures to see if I can document the problem for future folks.

[Zedyone_kenobi]

UPDATE:

I like to keep my threads with an ending, so I did replace my driver side (LH) wheel cylinder this morning (with OEM one from Courtesy) and the scratching stopped. I adjusted it so it spins freely, but is tight as nails with the ebrake pulled. I am quite happy. Pedal is firm so I know I bled it correctly. (Just want to give a shout out for the inventor of the speed bleeder!)

I will go on a test drive today, but I am sure things are as they should be. Now having said that. I did notice while I was messing with my hub while all the brake stuff was off, that I can feel it move slightly up and down. I cannot see it no matter how hard I try. To confirm, I left the car jacked up with the wheel off the ground. There is definite movement in the up and down (or was it in and out) direction. Nothing at all side to side (or front to back)

Anyway as for the up and down (or in and out) this smells like worn bearings. It turns smooth as silk, so I am not sure.

[ZCurves]

Anyway as for the up and down (or in and out) this smells like worn bearings. It turns smooth as silk, so I am not sure.

Yep, sounds like the bearings have seen better days. You might also be looking at a Spindle Pin job when you get into the the bearings

[Zedyone_kenobi]

I have reviewed the bearing replacement, and it seems relatively straight forward. If I need to pull the spindle, then I will get the tool. Some things are just worth it.