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May 3, 2025

Rear Brakes

The rear brakes on this car are of a very ordinary drum design using a single slave cylinder.  The generous 10 inch drums may be a little larger than expected on such a light car.

They apparently had been home to generations of critters while in storage.




The inside of the backing plates looked pretty good.  The outside, not so much.  There isn't really much to disassemble.




The abutment that locates and supports the shoes opposite the slave cylinder proved to be interesting.  First, the nuts holding it on seemed to be an odd size.  Bigger than 1/2", but smaller than 9/16".  The only wrench I had that fit it well was a 1/4" Whitworth.




It's a good thing I kept those nuts.  They turned out to be not UNF 5/16-24 as they appeared, but rather 5/16-22 BSF threads.  Some components of these brakes seem to be holdovers from before the Unified system was adopted in the 1940s.  I wonder how many folks bully a UNF nut onto those studs.




Blasting and powder coating made the backing plates look a lot more presentable.  One of the plates had some strange damage to the central flange that had to be welded up.




Since the slave cylinders were frozen solid, I got new ones, and they had some issues.




When I tried to insert the cylinders into their slots in the backing plate, they balked.  They were difficult to get in place, and once there, they would not slide (as they must do to keep the shoes centralized).  I was mystified.

I finally traced the problem to a manufacturing issue.  There is a transverse hole in the cylinder body for a pin that the hand brake arm pivots on.  Apparently when that hole was drilled, it displaced some metal into the slot that the edge of the backing plate hole fits into.  This made the slot too narrow, and made the cylinder bind.  Both cylinders were like this.




I was able to file the surface flat, and even improve the as-cast surface finish.




Finally, two backing plates, ready to go.




Cleaned up and re-plated some of the original hardware.  I always anneal copper washers, even if they are new.  These are originals.




I went to the garage and dug out the re-built rear axle, complete with refurbed road springs.  I put them up on a makeshift stand.




Almost forgot the handbrake arm boots.




Let's do it...




Last step was the shoes.  These were replaced in my 70s restoration, and have very few miles on them.  They were rusty though, so I stripped and painted them.




The shoes went home without complaint.




I got new drums to replace very pitted ones, but I can't install them until the hubs are on.




Hubs and axles are next.




This job was mostly painless, except for the unpleasantness with the slave cylinders.  And it moves the overall project forward one step.

Cost was around $160 for the cylinders and drums.

Comments to Ed at elhollin1@yahoo.com

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