Rear brake cylinder reconditioning guide

[shh120m]

Hi guys,

having booked the week off work on holiday, i thought i would get cracking on the car and make a good dent on the todo list. However, the missus put stop to that yesterday, coming home with a truck load of paint/wallpaper etc

So instead of working on the roadster im stripping bloody wallpaper! Shes gone to work for the afternoon so i thought id skive for an hour and recon my rear brake cylinders as they were in a right mess. It only takes about thirty minutes, and i thought id share it with you guys, im not trying to teach you boys how to suck eggs but it might be useful to those who have never touched brake cylinders before.

Anyway here goes:

to start with the cylinders looked like this:


(edit, this was after i had taken off the dust seals)
Both pistons were jammed tight with no free movement in each cylinder and they were really rusty. but after 30mins of work the pistons are nice and free and look like this:



The first step is to remove the old brake pipe union and bleed nipple. Its worth noting that these are imperial, so 3/8 socket for the nipple and 7/16 for the brake pipe union. Its important not to use metric sockets, being brass its really easy to ring them off. I held the cylinder in a vice to hold it steady as the nipple and union were mega tight.

Next step is to remove the dust seals from each end of the cylinder, just prise them off gently if they are in good condition, once off, just give them a tug to pull them off the bell end of the piston. If they are ok, just wipe them clean and get the crud from the inside and wipe with a bit of sylicone grease to reuvenate the rubber, if they are knakered just buy replacements at £4 a set from unipart.

Ok, now that the dust seals are off, its time to get the pistons out. They should be pulled out from each end because theres a fragile spring between the two, however it can be difficult if they are siezed, i generally put them in a vice and pull on the piston ends with a pair of mole grips.

With the pistons and springs put to one side, its time to have a look at why the pistons are siezed. As you can see, the bore of the cylinder is lined with corrosion and scratches, and for the brakes to work properly we need free movement.