Removing a rear brake cylinder

Introduction

Now that I had the brake drums and brake shoes removed from the rear wheels it was time to tackle the brake cylinders. They were rusty on the outside and I’m pretty sure they will be the same on the inside.

I started with the right rear wheel.

Removing the brake cylinder

The brake cylinder (number 20 in the diagram below) is held on to the brake shield via two bolts, but it also has a brake tube connected to it which in turn connects to a flexible rubber brake hose and then on to the rest of the braking system.

Here is a break down of the parts involved.

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Below you can see the two pins (29) that are pushed out via the pistons (24) which in turn are pushed out when brake fluid is pushed into the cylinder. The rubber seals (23) behind the pistons need to be replaced when servicing the cylinder as they’ll more than likely be damaged and leak.

The pins sit inside a protective rubber sheath (25) which should protect the cylinder from dust.

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In the photo below the brake cylinder has the two protective rubber sheaths and the pins removed. The rust and general bad state are very evident to see. This happens when brake cylinders are not used for many many years, they rust up.

It can also happen when brake fluid is not changed regularly as brake fluid absorbs moisture and therefore the rust can come from within.

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The correct procedure for removing this is to undo the connection where the brake tube meets the brake hose.

Unfortunately I didn’t follow the correct procedure (it was a long time since I did it last) and as a result I broke the brake tube, no loss, it was old anyway and due for replacement.

Below you can see the broken and very corroded brake tube.

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A brake tube spanner is one that you can slide into a brake tube as it has a piece missing, below is a photo of the two spanners I used for this operation.

A 14mm brake tube spanner is required for holding the brake hose, and a 11mm brake tube spanner for maneuvering the brake nipple.

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Once the brake tube is released from the brake hose, you can undo the brake nipple from the back of the brake cylinder.

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Once that is done, remove the two bolts (and washers) holding the brake cylinder in place, I think it was a 14mm bolt.

Once removed you’ll see the hole present in the back plate where the brake cylinder was.

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