Brake Repair


Situation

Soon after I had taken possession of the Rod, we took it to an Alignment Shop for a running gear inspection (Sept 2001). Fortunately they gave it a clean bill of health and even complimented the quality of workmanship. The chassis was square and true, the rear end perpendicular to the centre line and all the front end adjustments were within the required limits.
There was adiscovery that did require attention though it wasn't related to the running gear per say. The Master Cylinder had a leak. Slow as it was, it was going to require attention. Now you must remember, the master cylinder is underneath the Driver's floor and the only time you can get to it is when the car is up on a lift or jack stands. We chose to attend to it at a later date.
This slow leak didn't present a problem until the end of the season when it became rather difficult to stop the car as we had lost nearly all of the fluid.

Master Cylinder Replacement

Cylinder Removal

As the Rod was already up on jacks stands for the winter (see Shock Replacement) it was a perfect opportunity to replace the Master Cylinder.
As shown in the photographs, the unit is located right under the Driver's floor, approximently in line with the front of the seat. As the Cylinder ports were on the right side, the two brake lines loop underneath before they head fore and aft along the Driver's side frame rail.
There is about 2 inches of clearance between the top of the Cylinder and the floor. Removal of the unit involved disconnecting the Brake Peddle arm and the two mounting bolts. Of course the brake lines were disconnected first.


This view is looking forward underneath the Driver's side of the car. The transmission and drive shaft is on the right and the exhaust pipe is on the left. The Master Cylinder is the grey / biege unit straigh ahead.

Here is a closer view of the Master Cylinder where you can see the two brake lines as they loop under the unit. The front of the car is to the right.

In this view facing forward, the brake peddle linkage is visible along with the two mounting bolts.
The two grean wires are attached to the transmission switch.

Locating A Replacement

Now onto the next challenge - locating the appropriate replacement. Normally this wouldn't be an issue witha productino car. but as we had a hand built car with no records, we didn't know for sure what brand of cylinder this was. Did the Builder remain true to Chev and use one of their units, or did he go the traditional route and use a Ford?
With Cylinder in hand (well actually, in a box as it was oily) we went to our favourate auto parts store. The sweet young thing behind the counter gave me a blank stare when I mentioned I neded at Master Cylinder fot a 1935 Chev. I just love playing that trick on the Parts Staff! With the held of a another chap we were able to determine it was a FORD likely from the early '70's Mustang or Maverick. A new uit was ordered and in hand within a couple of days. A quick comparison verified it was an exact replacement, so we were in business.
The first task was to clean all the grease off the new unit so that it could be painted.


The new Master Cylinder is on the left with the old, leaky unit on the right. The plunger has been removed.


Here the new Master Cylinder has been hung up to dry after a coat of primer has been applied. The two front turn signal brackets have also received a primer coat. Everything was painted black next.

Installation

Installing the replaement unit was essentially the reverse of the removal process.

Following the instructions provided with the unit, I primed the Master Cylinder at the work bench prior to installation. The unit was then installed with the two mounting bolts, the brake peddle arm connected and return spring reconnected. The two brake lines were bolted back on being careful not to cross thread the connectors.

The next challenge was to fill the chambers with brake fluid. As you remember the Master Cylinder is only a couple of inches below the floor thus it is impossible to get a bottle up there. By attaching a tube to the nozzle of a clean mustard squeeze bottle I was able to "squirt" brake fluid up into the chambers. By carefully sticking my finger up into the bowls, I was able to determine when they were full.

Replacing the lid, I hopped back up into the Rod and pressed the brake peddle. Wow, it felt like everything was workng as planned, except what was that noise? Sounds like running water. A quick look under the car confirmed my worst fears, the Master Cylinder was purging it's contents all over the floor!
Apparently I had not tightened up the brake lines as tight as I thought. A few more turns on the connectors rectified the leaking problem.

With the gracious assistance of my neighbour, the brake lines were successfully bled.

With this work completed, I'll have you know the car has performed flawlessly over the past year.

This Web page is written and maintained by Grant Knowles.
This page was last updated on March, 2002.