Parking Brake

Discussions related to braking systems.
Post Reply
DennisO.
Posts: 2
Joined: Sun Nov 17, 2019 8:38 am

Parking Brake

Post by DennisO. » Sun Nov 17, 2019 9:14 am

I recently purchased a 1937, 120. The parking brake lever only budges slightly from the retracted position, but it seems to hold the car as long as I pull pressure on the handle - maybe moving one inch. Once released and driving in reverse you can fell the vehicle movement restricted, making a bad initial sound (in the rear end) when you start backing. It rolls forward without restriction. Looks like the parking brake release handle linkage is disconnected too. Any suggestions where I should start diagnosing?

Howard56
Posts: 1292
Joined: Mon Dec 24, 2012 11:35 am

Re: Parking Brake

Post by Howard56 » Sun Nov 17, 2019 2:54 pm

It is possible someone has really tightened the adjustment clevis on the front cable at the equalizer bar to the point there is no travel or adjustment remaining and the shoes are partially applied but there is also another more frequent issue to check.

The emergency brake cables are steel which are protected and slide inside a steel sheath. The cables should be able to move fairly freely inside the sheaths and if not, there is every chance water has gotten inside one or all of them and rusted the cable to the sheath causing the stiffness or worse. Worse would be a possibility the old cable has broken a strand or two of the wire wrapping and that has come loose and bent back or jammed inside one of the sheaths. Since the cables rely on a fairly small spring at the rear wheels to pull the cable back to return the actuating bar and release the brakes, any rust or broken strands could cause the cables to stick in the sheaths so the spring cannot pull back. At the least, assuming cables are free and intact, after all these years I would apply some lube to the cables and work it down inside the sheaths.

My suggestion would be to disconnect the cables at the equalizer at the center of the car and see how the cables move in the various sheaths. The front section between the handle and equalizer can be checked fairly easily but the cables inside the sheaths at the rear wheels cannot be done without a bit more work. After the rear cables are disconnected from the equalizer bar, best procedure would be to obtain the proper large drum puller and pull the drums. Once those are off disconnect the cable from the pull bars actuating the shoes so you can pull the cable thru a few inches to examine it. Pulling the drums would also allow you to inspect the cylinders and shoes which should be done anyway if you don't have a good history on the car. Without pulling the drums, on most but not all models it is possible to carefully unbolt the sheath from the backing plate and frame support so it can slide on the cable but use caution in doing that procedure. There is risk that instead of a threaded hole in the backing plate there may be a nut and washer inside which would fall off. Also, without the spring pressure from the sheath the end of the cable could disconnect from the actuating bar between the shoes. Either situation would require pulling the drum to fish out a nut or reconnect the cable.

Here is a drawing from the parts book that is representative of the 120. There could be some minor detail differences between years and models but the basic layout should be the same. The sheaths are pointed out by the arrows.
Attachments
brake.jpg

DennisO.
Posts: 2
Joined: Sun Nov 17, 2019 8:38 am

Re: Parking Brake

Post by DennisO. » Mon Nov 18, 2019 9:26 pm

Gosh! Thank you so much for a very in-depth explanation - once inspected I'll post a response of my findings and action taken. What a great organization!

Post Reply