Rear Brake Problem?

[dirtrack49]

Hi everyone,

I finally got the drum off and thought I would post the results.

First, evidently the thing that was holding up the removal of the drum was the emergency brake cable not moving on the pulley inside of the brake.

Since I could barely move the drum, I was able to slowly pull the drum off by using three 8mm x 1.25mm bolts. Make sure you buy the longest threaded ones available which in this case were 50mm in length. This will give you the ability to pull the drum out far enough to use brute force to pull it off the rest of the way. Or, if you are unable to get it off all the way, you will hopefully be able to force the shoes back inward somewhat to give you a little more release of the drum.

After removing the drum, the first thing I noticed was the pulley where the e-brake cable enters the brake dust cover was not moving. Lucky for me, it only took some PB Blaster along with some gentle tapping to get the pulley to free up. If there had been more corrosion, it would likely require disassembly.

Further to my surprise, the brake shoes and drums were in good shape.

Thanks everyone once again for all of your input. It certainly has been a great help in resolving this problem.

Tom L.
66 230sl

[seattle_Jerry]

I feel robbed...that was way too easy!

[ctaylor738]

Suggest that you look at the shoes closely to be sure that the linings are not starting to separate from the shoes.

Cheers,

[dirtrack49]

Thanks Chuck, I will take a closer look at the linings.

Well Jerry, it seems things really are not that easy after all. Now I have a new problem. I can not get the brake shoes to back off far enough to replace the drum. Not as tight as when I took the drum off, but shoes expanded enough to prevent the drum to going on.

When I move the adjusters I can see the shoes go in and out. And, bye the way, I am assuming that these adjusters are concentrics since they will go in and outward with the same direction of movement of a wrench. The full deflection of the adjuster bolt heads seems to be about 3/4 of a turn.

Now I am wondering if the handbrake is not releasing all the way, or if the wheel cylinder is hanging things up? When I check the handbrake, I see considerable movement of the two shoes, in and out.

I only need a very little more inward movement of the shoes to get the drum on. The shoes measure from about 3/16 to 1/4 inch, so they should be what I would guess about normal in thickness.

Anyone have any suggestions as to what to do or look for next?

Thanks again,
Tom L.

[seattle_Jerry]

did you play under the car making sure with the hand brake off that there is slack in the cables?  Did you put the same drum back on the same hub? Yes the adjustment bolts can be turned the one direction and loosen and tighten. Did you check that the shoes went back on in the right order? I had trouble with mine too.

[dirtrack49]

Jerry,

I will check for slack in the handbrake hopefully tonight when I get home.
Yes, I am putting the same drum on as I took off. Only dealing with the left side so far.
Shoes are on the same.

One thing I noticed yesterday, when I finally got my wife to step on the brakes, there is no movement of the piston pins in the wheel brake cylinders. It appears that the pistons in the wheel cylinder might be frozen. I am thinking that there are two things going on, the handbrake pulley was seized and the wheel cylinder has become contaminated from the car sitting too long. Or possibly the master cylinder has gone out. I did notice that when pushing on the brakes, I here a sound like air escaping from the brake booster/master cylinder area. When I first got the drum off, it seems to me that I did have movement in the shoes when applying the brakes, but none now.

If it ends up being the wheel cylinders or master, can you hone these cylinders and buy rebulid kits, or only replace the entire unit?

Thanks again,
Tom L.

[Benz Dr.]

Uh, I know that. But that's not an aluminium bolt, although it does go through an aluminium housing and the pulley that has a steel sleeve, it's actually a steel bolt as I'm sure you are aware of. 

[seattle_Jerry]

wheel cylinders are cheap in Mercedes dollars, I'd just replace them...$75 each

[dirtrack49]

I thought I would follow up on my brake problem to let everyone know what all took place.

First, the hand brake pulley was corroded and seized up on the left brake from the car sitting for a long period of time with the handbrake applied. In this case, the remedy was to apply PB Blaster over several days to the pulley and lightly tap on the pulley with a drift and hammer. After a few days of coaxing, it is now operational.

Although I was able to free the handbrake, I was still not able to place the drum back on the car. This ended up being the wheel cylinder for the left rear brake, had corroded inside the cylinder and seized the rear piston. After several days of PB Blaster applications, and tapping of the rear brake shoe with a hammer, the piston finally released. There is only one reason I went through this exercise versus a more reasonable approach of removal of the brake components.  I wanted to get the drums and wheels back on the car so I could move it to another location.

Thanks to everyone for their help.

Tom L.