Following on from the recent MOT failure I decided a good start would be to inspect the rear brakes.

Problem #1: how do I get the drums off?

Having watched a few YouTube videos on rear brake drum maintenance (albeit not Skoda) it seemed easy enough, but these look different. Does the cap in the centre need to come off, and if so how?, or does it simply require more brute force and ignorance?

#2: I was going to have a go at freeing up the seized brake balance valve. Assuming photos 3 & 4 are the right thing, what should I do? I've watched the MOT tester fix this before - he just sprayed it with WD40 and used a pair of pliers to wiggle something in there - but I didn't see close up so not sure exactly what he was doing.

Photo 1, Photo 2, Photo 3, Photo 4.

Does the cap in the centre need to come off, and if so how?, or does it simply require more brute force and ignorance?

I'm not sure if it does need to come off. On many cars it is a push fit and can be partially levered out then repeatedly knocked around until it comes off. Because of this they generally look pretty battered.

The grease cap has to come off, and so does the nut retainer and split pin. My preferred method to get the cap off is careful use of mole grips, tight enough to grip but not so tight to bend. Not the correct method, but it's quick and easy. You will need a new split pin, and it would be ideal to have a new grease seal for the back of the drum ready. You remove the drum with the bearings. You therefore have to adjust the bearings when you put the drum back on, do not over tighten. They should be finger tight and there should be no play. Check and readjust if necessary after fifty miles or so.

The correct procedure is to slacken off the handbrake cables first, then remove the drums. Chances are the self-adjusters are not working and you need to adjust the wedge downwards which expands the brakes, until you can just get the drum back on. Carefully peel back the rubber bits each end of the wheel cylinder a little. You're looking for signs of dampness which would indicate the cylinder is leaking and needs replacing. When all back together again adjust the handbrake cables.

Update - I've freed up the load sensing valve (photos 3 & 4 in OP), it now moves up and down nicely with a pair of mole grips attached (I have the car on stands placed just inside the sills, ie. the rear axle is "hanging").

MOT tester said the uneven rear braking could be due to the seized valve but he suspected more like shoe contamination due to it also being uneven with hand-braking.

I have also tweaked the self-adjuster "wedge" *up* on both wheels, which freed up the brakes, and then determined that with operating the hand-brake a few times the wedges are both pulled back *down* to jam into position.

What's the betting that the above actions have rectified the uneven rear braking?

Is it still worth taking the drums off or just present it to the garage for re-test as is? To be honest I'm not so confident in what needs to be done putting the drums back on _safely_, esp. wheel bearing adjustment.

The wedges are supposed to drop down in order to self-adjust but it is widely recognised this mechanism often does not work effectively.

You could jack and axle stand the car, or use the jack that came with the car. Turn each rear wheel with the handbrake unapplied - spin and hope to get a similar number each side, and with the same number of clicks on handbrake each side to check.

I guess I need not mention to be extremely careful when applying the handbrake, particularly if using the emergency wheel change jack, and keep the car in first gear.

Wheel bearing adjustment is quite easy and described in the Haynes manual. You tighten up a certain amount (can't remember how much, but fair enough to say tight. Slacken off, and then tighten up finger tight. The most tedious bit is getting the nut turned such that you can get the split pin through the nut retainer thingy (forget what these are called).

If you are careful and clean up the self-adjusting mechanism properly it will work perfectly - I've done this on several, and as long as you clean out the grooves OK on both parts it'll work fine, and with everything else OK your rear braking should be fine. You can use a torque wrench to check the braking efficiency - it's far more accurate than trying to do it on spin etc, because that relies on something that won't even register on the brake tester; see what torque is actually needed to turn the wheel on each side and it should be pretty even.

The adjustment of the rear bearings is simple - just make sure that the thick washer behind the nut is JUST ABOUT moveable with a small screwdriver, then it'll be fine.