Hi Mark. The Girling expander casting has an internal piece with a conical section, which bears against the two plungers, via small rollers to reduce friction. The external rod pulls on this piece. The conical shape gives a wedge action to multiply the pulling force on the rod and give a much greater pushing force on the two plungers.

From looking at the diagrams in old books, it would appear that if you remove the brake shoes to allow both plungers to be pulled out of the casting, and then remove the rollers with long nosed pliers it should then be possible to pull out the conical piece. Bear in mind that this is a suggestion only - if it won't come easily don't force it ! Once everything is apart it can be cleaned up and a suitable high temperature lubricant applied.

Note that the expander or the similar adjuster casting (I can't remember which) may be fitted to the backplate with captive bolts, castle nuts, tiny split pins and Thackeray washers. The backplate is slotted, and the nuts are tightened just enough to begin to compress the washers. The idea was to allow a tiny bit of "float" or sideways movement of the expander, to equalise the force on the shoes.

Location: New Forest

Hi Mark,

John's got most of the info to you. There's also a pin between the conical expander and the long brake rod that gives a little articulation. I can't remember where exactly but there's one in there somewhere. As John says the adjuster for these late Girling rod brakes have slotted holes in the backplate. I thought these were for centralising the shoes when adjusting and were then fully tightened. The Girling expander does have little 1/4"BSF studs, brass castle nuts and fiddly split pins. I find that the split pins are impossible to get out if they've been there any length of time, just shear them off with the nut. I reassemble with nylocs and it seems to work.

Hope of use.

Dave

thanks both I can make some sense in that, the 'pistons' are both seized although the rod does move in and out about 5mm. the pistons seem to have been held in by split pins as well.. they came out easy enough surprisingly. are the pistons flatt at the interior end like the front brakes ..will I be able to remove the pistons by twisting like I did on the front brakes where a little encouragement and much lubrication encouraged them out.. apologies for the questions want to get them out useable..

Yes, I recall they're flat on the inner end and the I think the split pin is to stop them falling out before the shoes are fitted. Try the things you described to get them out, a little heat helps as well. Even after being siezed they clean up well for reuse with a smudge of your prefered lubricant.

Success!! word of caution though. Although the descriptions above were close significant information was omitted.
so these are late girling rear brakes operated by rods from the cross shaft. The main rods for and aft join a pivot just behind and below the diff from this pivot rods run to the rear of each rear brake plate and via a rubber boot into the brake actuator.

to remove the pistons from the brake accutator you have to disconnect the appropriate rod at the pivot below the diff and pull the assembly ( rod and actuator) out through the back plate.

the pistons movement is restricted by small split pins which have to come out. To remove the pistons DO NOT twist they do not have flat bottoms like the pistons at the front.

remove the easiest piston by pulling on it or tapping the body with a hammer whilst holding the piston in a vice.

once the first piston is removed a roller about 1/4 may come out with it.. the roller runs in a sloping groove at the bottom of the piston. with the first piston fully removed the rod and its cone may simply come out.. if not the second piston will have to be about 1/4 inch out to simply pull the rod and the cone wjich is on the end of it out.

hopefully that leaves you with an actuator with a piston stuck in it.. lubricate and a little heat and a suitable sized drift ( the gear shaft from a triumph fitted lovely) and the final piston should pop out..

easy when yopu know how.. putting it back together though...