Series III CSW rear brakes

[Reiny]

A friend of mine has just taken delivery of a lovely 1978 Series III LWB CSW. It's been immensely well looked after but has not been used much over the past few years so some things have decided to go AWOL. The first issue we have is the rear brakes. I haven't worked on a Series for about 10 years now so my memory's getting a bit hazy. First of all, when he drove the vehicle home, he realized that it was a bit down on power and when he got home he noticed smoke coming out of the right hand side wheel (which was of course very hot to the touch). I drove it yesterday and it drove fine, freewheeled nicely, etc. Time to get the drums off. No hassles whatsoever. I thought that I'd find the shoes welded to the drums. Right hand side wheel cylinder moves in and out without gentle pressure. Still no braking power though. Left hand side cylinder will not budge. Am I right in suspecting a collapsed flexible hose?

[secondjeremy]

No - seized cylinder. If the hose had collapsed - both sides would be the same.

Pistons often seize when vehicles are used infrequently.

[Gremlin]

Rien, if you crack the bleed nipples does fluid come out from both sides?

G

[Reiny]

That's what i wanted to do Grem but time was tight and i didn't want to risk introducing air into the system. will try that first. thanks.

[Gremlin]

If its been idle for a while be careful, as they can/could be siezed solid, and snapping one off is a real headache, if you need some bits i have some backplates with wheel cylinders still attched. Just call.........

G

[Reiny]

Thanks a lot Grem. Just in case you see the air turn blue over the Fgura / Tarxien area, you know what would have happened.

[Tanuki]

New cylinders are a guaranteed fix: once a cylinder has corroded enough to seize then even if you manage to free it off and re-rubber it, it's more than likely to be a future leak-source.

I *always* cost my time when doing these jobs: spending an hour stripping, freeing-off and re-rubbering a cylinder is just crazy if you can get a new Lockheed/Delphi one for £15.

Be aware though - apparently minor brake problems tend to "extend" their scope once you start work: you'll probably find that the rusty old metal pipe shears off the union where it goes into the wheel-cylinder so you end up replacing the pipework on the axle. While you're doing this you might as well replace the flexibles as well. Then shortly after you've finished all the bleeding, the master-cylinder seals will give out. And when you've repalced the master-cylinder the stupid pressure-differential valve will stick at one end of its travel. . . .

[Gremlin]

Oh how very true.............

G

Be aware though - apparently minor brake problems tend to "extend" their scope once you start work: you'll probably find that the rusty old metal pipe shears off the union where it goes into the wheel-cylinder so you end up replacing the pipework on the axle. While you're doing this you might as well replace the flexibles as well. Then shortly after you've finished all the bleeding, the master-cylinder seals will give out. And when you've repalced the master-cylinder the stupid pressure-differential valve will stick at one end of its travel. . . .

[Reiny]

^{Sorted. It was the flexible hose. Opened bleed nipple, pressed pedal, pedal solid, no fluid. Removed flexible hose, blew threw it, NADA. Replaced. Opened bleed nipple. Nice flow of filthy brake fluid. Flushed around half a litre through the system. Rock hard brakes. Mate is a happy chappy!}

[Snagger]

That still doesn't explain the solid brake pistons in the cylinder - pushing one in should force another out, and if there is no movement when pushing against one, then it has corrodes solid.

[Reiny]

Sorry Snagger, I only saw your post now. I'm just as stumped as you are. Everything's working fine. The only theory I can come up with is that perhaps the cylinder was full of fluid, the collapsed hose couldn't let the fluid out when the pedal was released so the pistons wouldn't budge. No idea really. I'm letting sleeping dogs lie.

[Snagger]

With the shoes off the assembly, and everything else left alone, as you press one piston in, the piston at the other end of the cylinder should move freely out. This should work both ways. If there is a lag or a piston doesn't move out by itself when the other is pressed, then the cylinder is seized.

If you take the drums and shoes off the whole axle, then pushing in both pistons on one side should force the pistons out on the other side (one might po out and the other stay still unless you limit the travel of the moving piston. If this doesn't happen, then you again have a failed cylinder.

With the drums off but the shoes and return springs fitted, pedal movement should move each shoe out and back in. Investigate any shoe and piston which does not move in both directions on pedal movement.

The smoke and heat from the first drive may have been from the pads removing rust ad accumulated contaminants, and it could all be working ok now. It might be worth taking it to an MoT test station and checking the brake readings on their roller testers.

[Reiny]

The fun continues. Mate was supposed to pop over this evening so that we could do some more work (front brake cylinders, fuel lift pump and perhaps a general service) but he texted saying that braking power has gone totally awol. He gave no further information so I really don't know what could have gone wrong. I don't even know whether he has used the vehicle or not since we freed the brakes off and bled the system. Let's just say that there are no apparent leaks, where should I start?

[ejparrott]

To be honest, I'd consider a complete rebuild of the braking system if you don't know its history. I've had nothing but problems with the brakes on The 109 and its what she really needs, although she passes the MoT better than the 88 does and thats had a rebuild! It does tend to cascade with brakes, once change hoses, cylinders will give up. So you change the rear cylinders and then fronts give up, so you change them and then the master goes, so you change that and then a pipe springs a leak! If you're not careful you end up pouring gallons of fluid through it. Its not hard to do, and its possible to do a complete rebuild in a weekend.

Remember, it is the brakes we're talking about.... poorly engines and not going is one thing, but poorly brakes and not stopping........

[Reiny]

Leaks traced to wheel cylinders on the front and master cylinder.

[Gremlin]

That poor series spent too much time in a garage, now that its starting to be used it will start to play up, probably the bleeding with new fluid weakened the seals further. Not to dishearten you but a full system rebuild of the brakes will be needed as you will have a domino effect. (i might also be wrong)

Also expect the clutch hydraulics to play up after some use.

G

ps call me if you need anything..........

[Reiny]

I'm expecting the same thing too Grem. We'll play it by ear. Must admit that I'm enjoying every second I spend working on it. Haven't touched a series for 10 years now.