My 64 Morris hasn't seen the road for a couple of years mainly because I can't get the handbrake to work.
I've put in new cables which appear to pull up smoothly with plenty of travel on the cable. The slave cylinders "were" quite new and appear to work. I can't understand how the movement of the lever at the back of the drum causes movement of the slave cylinder. The cylinders appear to be sliding although maybe not smoothly. Does anyone have any advice?
When the handbrake cable is pulled the lever part of the slave cylinder pushes out one of the brake shoes, when that shoe hits the brake drum the slave cylinder moves in the back plate slot pushing the other shoe against the brake drum so equalising the braking pressure on both brake shoes. The same process happens when the hydraulic part of the slave cylinder expands.
The slave cylinder must move freely in the backplate. Use white grease to lubricate the sliding surfaces of both slave cylinder and backplate.
When adjusting the rear brakes make sure that when the wheel is rotated the brake shoes do not rub or make contact with the brake drum. It is a mistake to have the rear brake shoes adjusted up too tight which can then restrict the slave cylinder piston movement which can lead to piston seizure. The same with the handbrake - there most be sufficient movement of the slave cylinder in the slot of the brake backplate to keep the movement free.
Thanks guys for your helpful comments. Yes the brakes are adjusted, hopefully not too tight.
My understanding is that the movement that causes the handbrake to push/pull the shoes to make contact with the drum is a slide of the body of the cylinder (so the lever doesn't push/pull the piston out?)
If that is the case then I need to focus on lubricating the backplate (both sides?), will it be best to remove the cylinder? In which case I might as well replace the cylinders.
Have I got that right?
There should be no problem just taking the wheel & brake drum off and then getting some grease in behind the cylinder.
As Phill says, use White Grease; you can get it in a spray can which is ideal for all sorts of lubrication job, hinges, catches, etc and over the battery terminals too. Just be careful not to spray it on the shoes...
The lever does in fact press on the underside of the wheel cylinder piston so pushing the piston out of the cylinder body.
The piston moves until the shoe hits the drum and then further movement of the lever makes the cylinder body move in the backplate so pushing the other shoe against the drum.
It is easy to remove the wheel cylinder, clean the contact faces between wheel cylinder and backplate, lubricate with white grease and fit the new cylinder. Make sure that the rear/inner face of the backplate is also lubricated with white grease.
Good luck.
Phil
Thanks again Phil,
I'm now pretty certain that I need to replace the slave cylinders. I couldn't understand how the lever was pivoted to move the cylinder body but now I understand that there is a pivot pin in the cylinder body which enables the lever to push the piston out of the cylinder, that makes sense. Your helpful comment that the slide of the body of the cylinder on the backplate only happens when the piston is pushing one brake shoe to then equalise and push the other brake shoe. I think I now understand how it works!
Unfortunately it is very common for the rear cylinders to seize in a car that is used infrequently. I have had them seize quite a few times over the years, usually with the handbrake on which makes it very difficult to remove the brake drum. The reason for this seizing is water in the brake fluid and corrosion inside the cylinder. The brake fluid must be changed at appropriate intervals to prevent this. The alternative is to switch to silicone brake fluid which is not hygroscopic. I did this after a complete braking system rebuild.
1969 1098cc Convertible “Xavier” which I have owned since 1989.
A cautionary tale. A couple of years ago my cylinders seized all round as a result of regularly visiting a house that was just across a deepish ford.After a couple of weeks of doing this daily, I noticed the car wasn't pulling very well up the hills and I discovered the regular soaking in the water had caused them to go rusty and seize up. Because the house was so close to the ford, I had parked up every time without the cylinders having any chance to dry out.....
You can often free up cylinders that are seized. Much easier to do it once you have removed them, which of course means you will need to bleed the system.
As a 1st move, i would removed the brake shoes, and handbrake cable and manually move the lever to see if there is any movement. Often by working it you can get them to free off a bit . Assuming you are getting some movement i would continue to do this until the metal piston can be removed (this can all be done without toughing the hydraulics). IF you can get this far, you can clean up the cylinder bore and metal piston and reassemble with red brake grease.
