Morning all and Happy Easter!
I'm hoping for a bit of advice on a problem with my 1999 Skoda Felicia 1.3 rear brakes. I live in Sweden and on the recent registration check the car failed because of an imbalance between the left and right rear drum brakes.

I've stripped down both wheels and discovered that one of the pistons on the right rear wheel cylinder was stuck, presumably causing the problem. I have freed this, so that both pistons now move freely in the cylinders, rebuilt the brakes, adjusted the little wedge so that the drum is a reasonable fit over the shoes, bled the brakes (for that wheel) but the problem still persists. As I live alone with no near neighbours, I have tested the brakes by using a length of wood to hold down the brake pedal and attempting to turn the rear wheels while up on axle stands. The left wheel locks OK, but the right continues to be able to be turned, as if the brake shoes are not being activated. The parking brake works fine on both wheel, the shoes are almost new so have plenty of meat on them.

When the shoes etc. are removed, I can compress the pistons with my fingers and the spring between the pistons does force them out slowly when I release pressure. I'm not able to confirm if the pistons move when the brake pedal is pressed, as I can't press the pedal and watch the pistons at the same time! However, as I am able to bleed the brakes on that wheel (I have one of those 'one man bleed kits' with a glass jar, a length of plastic tube and a one way valve, I can see that brake fluid is reaching that wheel. After bleeding, the pedal feels firm with no sponginess, so I assume there is no air in the system.

At this stage I'm stumped as to why the brakes are not activated on that wheel when the pedal is pressed and would be very thankful for any suggestions. Replacing the wheel cylinder would be my next option, but this could be difficult as the holding bolts for the cylinder appear to be very rusted and I'm not sure if I'll be able to move them - or the pipe connector at the cylinder....

Thanks anyone for any advice......

7 hours ago, Sympol said:

Replacing the wheel cylinder would be my next option,

Mine too as FIRST option. On BOTH wheels. Replace the brake fluid too if it is older than 2 years.

 

PS

Easter is in a month.

Edited 3 April, 20215 yr by RicardoM

Thanks - I've ordered 2 new wheel cylinders and new brake fluid, but I'm uncertain of removing the old cylinders. When I tried to unscrew the pipe union, the union appears to be seized onto the pipe and I'm afraid I'll break the pipe if I continue turning. Also I'm uncertain of the bolts retaining the cylinders - these appear to be either torx or hex socket bolts, but not sure of the size because of the rust....

I don't want to use a blowlamp to warm up the union - perhaps I could use a heat gun instead?

PS - it's Easter weekend here in Sweden just now.......

1 hour ago, Sympol said:

I don't want to use a blowlamp to warm up the union - perhaps I could use a heat gun instead?

Either way, heat is the last solution.

@Sympol Do you have a correct size brake spanner, like a ring spanner with a gap so it can hold 5 sides of the union, or are you trying with a conventional open ended spanner which will only hold 2 flats? To change wheel cylinders or brake calipers you need the correct size brake spanner.

18 hours ago, Sympol said:

...bled the brakes (for that wheel) but the problem still persists

That can happen if the system is not tight. Although the bleeding might be/look perfect, after the bleeding tools are removed the air seeps in.

Use a 50/50 mix of transmision fluid and acetone works wonders, bleed brakes properly and most of the fluid is going to be gone by that point anyway

14 hours ago, KenONeill said:

@Sympol Do you have a correct size brake spanner, like a ring spanner with a gap so it can hold 5 sides of the union, or are you trying with a conventional open ended spanner which will only hold 2 flats? To change wheel cylinders or brake calipers you need the correct size brake spanner.

Thanks, yes I have a set of brake spanners! I can turn the union slightly, but the problem is that it is stuck on the brake pipe itself, so that turning the union begins to twist the pipe and I'm afraid of shearing the pipe. I've heard that if I can undo the cylinder retaining bolts I can move the cylinder inwards and then rotate that while holding the union, so that the cylinder unscrews from the union, tather than the other way round. However, not sure if I can undo the cylinder retaining bolts as these seem to be hex sockets - or torx? - and are very rusted. I'll try cleaning those again and scraping out the sockets with a very fine screwdriver to see if I have a hex or torx key to fit. Another alternative is to let the pipe shear, then remove the back plate so I can get to the cylinder bolts more easily and perhaps cut a slot in them so I can use a screwdriver - or simply grind or drill the heads off to remove the old cylinder. And then flare the ends of the pipe again to fit the union (I have a flaring tool). But I need to make sure I have new bolts on hand otherwise I'm stuck in the forest with no transport! I'm assuming the new cylinders don't come with new bolts......

2 hours ago, Thefeliciahacker said:

Use a 50/50 mix of transmision fluid and acetone works wonders, bleed brakes properly and most of the fluid is going to be gone by that point anyway

Do you mean use that to flush the old fluid out?! Never heard of it before......

7 hours ago, RicardoM said:

That can happen if the system is not tight. Although the bleeding might be/look perfect, after the bleeding tools are removed the air seeps in.

I can't feel any sponginess in the pedal and the other rear wheel works fine. Perhaps I need to repeat the bleeding(!) process a few times to get a result......

How free is the actual handbrake arm (can’t think of the correct, technical term for it!) inside the drum??
 

I had a very similar problem on a car last week that I fixed by removing the shoe that its attached to and freed it up in a vice with a bit of oil and some brute force back and forth. 

 

1 hour ago, jars said:

How free is the actual handbrake arm (can’t think of the correct, technical term for it!) inside the drum??
 

I had a very similar problem on a car last week that I fixed by removing the shoe that its attached to and freed it up in a vice with a bit of oil and some brute force back and forth. 

 

You mean the little wedge-shaped piece that drops down as an automatic adjuster? I did wonder about that as it seems quite stiff to move. I'll strip it down again after lunch and see if I can loosen it up a bit......

No, I’m mean the actual silver arm attached to one of the shoes ...... 

2 minutes ago, jars said:

No, I’m mean the actual silver arm attached to one of the shoes ...... 

OK, no, that part is free! The handbrake works fine on both wheels, it's just the 'normal' brakes which don't seem to be working on the right rear. I'm having another look at everything after lunch! Thanks - I'm not allowed to add any more reactions today, apparently!

On 03/04/2021 at 08:13, Sympol said:

as I can't press the pedal and watch the pistons at the same time!

 perhaps set your phone up to video the cylinder /shoe and then run round and press the pedal - just a passing thought....

8 minutes ago, Sympol said:

OK, no, that part is free! The handbrake works fine on both wheels, it's just the 'normal' brakes which don't seem to be working on the right rear. I'm having another look at everything after lunch! Thanks - I'm not allowed to add any more reactions today, apparently!

I had the same .... handbrake on MOT test was ok but the foot brake failed. When I took it all apart, the very first bit of movement was very stiff and freed up once I had done my thing. The foot brake doesn’t pull the silver arm as much as pulling up the handbrake, so pressing the foot brake wasn’t strong enough to get passed the initial sticking point. 
 

Not saying this is 100% your issue, but the symptoms are the same as I had last week. 

I've stripped everything down again and rebuilt, bled the brakes (a lot) and now seem to have brakes on that wheel. Not been able to loosen either the brake line union or the cylinder holding bolts, so for now I'll have another retest at the MOT station and see if they can measure any improvement. If not, I'll have to give up and book a time at my local repair workshop. Either way, I'll need to get a professional to change the whell cylinders eventually, but the priority is to get mobile again, as I have a Covid-19 vaccination booked the week after next...

Thanks everyone for the comments and tips

35 minutes ago, Sympol said:

Either way, I'll need to get a professional to change the whell cylinders eventually, but the priority is to get mobile again, as I have a Covid-19 vaccination booked the week after next...

Between brakes job and vaccination, I would choose the brakes. You will get a true improvement and life safety, not a gamble.

5 hours ago, Sympol said:

I can turn the union slightly, but the problem is that it is stuck on the brake pipe itself, so that turning the union begins to twist the pipe and I'm afraid of shearing the pipe.

In that case, I start wondering if the union and pipe have had it... Nothing further since I'm not allowed to go to Sweden so can't inspect the job in meatspace.

2 hours ago, Sympol said:

Not been able to loosen either the brake line union or the cylinder holding bolts

Remember that you will replace the brake cylinder. In other words, you can butcher it any way you want to free it. The only stress in the process is to not allow the brake fluid level drop below reservoir bottom.

Thanks again all - i'll let you know how it works out. At least now I've changed over to summer tyres as a bonus for all the faffing about with the wheels.....

8 hours ago, Sympol said:

Do you mean use that to flush the old fluid out?!

NO WAY IN HECK NOOOO PLEASE NO!!!
I am talking about a rust freeing homemade blend

4 hours ago, RicardoM said:

You will get a true improvement and life safety, not a gamble.

True story brother

 

I suspect that you might have a faulty brake pressure regulator valve, if your car has them. 

They are screwed in to the side of the master cylinder, and limit the hydraulic pressure to the rear. I had to replace one of mine about 3 years ago, so I did the pair for safety, genuine skoda items were only about £9 each, but my dealer has stopped selling felicia parts now. 

I can only suggest that you try swapping the two valve positions to see if the problem then moves to the other rear wheel. Unless you can find them for sale. Good luck