1976 Eldo with dragging brakes

[240cpa]

Trying to get this car on the road but mechanic can't get the rear brakes to quit dragging.  We've replaced the master cylinder which is an improvement but I can feel the brakes dragging at low speed.  Parking brake went to the floor this last time I pushed it after taking car for quick spin.  Any advice would be welcomed!  I read somewhere that you need to push/reset the parking brake up to 30 times for some models.  Is this true and can it help?

[Jeff Rosansky CLC #28373]

They are dragging either mechanically or hydraulically. If they are adjusted all the way out then the only way they could drag mechanically as if there is friction in there that's preventing the shoes from retracting all the way. What I would suggest is that you open the bleeder just after you stop (foot off brake, system at rest).See if the fluid shoots out like it is under pressure. If not then you know it is mechanical. If so then it is hydraulic. Your new master could be bad. Could also be the flex line for the rear brakes. Most people forget that one.
Jeff

[savemy67]

Hello 240cpa,

Has this car been sitting for any period of time?  If you are trying to get it on the road, think about how important brakes are for your safety and the safety of others.  If your mechanic replaced the master cylinder and he/she is still flummoxed with the brakes, ask him/her how much it would cost to overhaul the entire brake system, and whether he/she feels qualified to do the job.  If the price is outrageous - more than $1000 - or he/she cannot do the job, you might consider taking your car elsewhere.  Brake work is not that complex, but on a 40 year old car, the system should be looked at holistically.

Respectfully submitted,
Christopher Winter

[76eldo]

The rear calipers cannot be compressed like a normal front brake caliper by pushing in on it. There is a tool to wind the piston back in. It's threaded in due to the E brake actuators.

Pumping the E brake a bunch of times pay free up the actuators which might be stuck. It happens sometimes when you do not use the E brake for a long period of time.

The other suggestion regarding opening up the bleeder is also good advice.
With no pedal pressure nothing should squirt out.

Brian

[TJ Hopland]

Yep need to figure out if its mechanical or hydraulic.   Opening the bleeders will tell you if its hydraulic.  Hydraulic would most commonly be caused by an internal failure in a hose.

You could have a mechanical bind just from age in any of the 4 calipers.   The rears are extra complicated due to the parking brake mechanism.  There are a lot of extra moving parts that have to survive in a hostile environment.   Sitting is very hard on these.   There is no quick fix to get them working again if they are stuck.  This caliper is popular for rear disc conversions on trucks among other things so they are not too difficult to find.

[TJ Hopland]

Here is a link to a thread where there is a link to a video showing how he had to repair a rebuilt caliper.   The video is a 79-85 but its basically the same as the earlier ones.   It gives you an idea what you are dealing with in there.   If its done a lot of sitting you can imagine how much rust is in there and how those parts are not going to want to release after operating the parking brake. 

http://forums.cadillaclasalleclub.org/index.php?topic=140281.msg330465#msg330465

[waterzap]

Maybe rust in the brake lines? I have seen that on another Eldorado before. Rear hose was plugged up because of rust.

[waterzap]

I had some issues with my brakes at one point too. After so many decades, brake lines rust from the inside out. I replaced all the lines, and all is good again. Actually did all the calipers and rotors too. Not that expensive if you do it yourself, and you are good for another couple of decades.

If you intend to drive the car for a long time, new brake lines are worth it. I tried putting stainless lines in there, but its too difficult to get the bends.
Even the pre bent ones dont work. They come bent, but to get the lines though the frame, you have to unbend them. And then bend them again. Plus some of the pre bent ones were just wrong. I would have had to cut and fit them myself anyway.

So in the end I used the Nickel/Copper alloy ones. Worked really really well. They are easy to bend, easy to flare. The only disadvantage is that they arent as strong as steel lines. If you go banging around the car with tools, you can probably damage them. Or with a jack at the wrong spot.

The advantage is that they dont rust. These old cars stand most of the time, so things rust. The brake lines will now probably outlast the car and me.