Dangerous brake issue

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Aardvark

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Last time we were on holiday, the rear passenger side brake overheated. I thought the hand brake had maybe been left on slightly, but didn't know for sure. It seemed ok after the smoke had cleared away and it was left to cool down.
I decided to have a look at it a few days ago and immediately noticed that the wheel cylinder was leaking. So ordered an axle set of shoes, a fitting kit and 2 new cylinders. When I went to remove the old shoes, the brake linings just dropped onto the floor. The overheating must have destroyed the adhesive that bonded lining to shoe. I nearly shit myself thinking what could have happened.
So anyway, fitted all the new bits easily enough and went to bleed the brakes I have an Easy Bleed kit that pressurises the system. I've used it for years on loads of vehicles including the front brakes on the van after I changed the pads last year. The drivers side rear bled no problem, but the other side would not get fluid through. Thinking maybe the new cylinder was faulty, I loosened the brake pipe to see if it would come out there. But nothing at all. I got my wife to sit in the van and pump the brakes and doing that I could get a small amount of fluid to flow. But the brakes would lock but not release.
I removed the drum and got her to slowly depress the pedal. The cylinder expanded ok. But would not retract, so this was holding the brakes on. The only way to retract the cylinder was to open the bleed valve. I don't quite understand why though, as the lines to both sides are teed off the common line going forward. So why one side works and the other doesn't is weird.
My van is a non servo one. So the only other things in the system are the pressure regulator and the master cylinder. I thought of just changing the master cylinder anyway as its probably due. But everywhere is sold out. So in the mean time, I'm wondering if the problem could be at the pressure regulator.
Does anyone have any ideas what the hell could be wrong. Is it the master cylinder, the regulator or something I'm missing?
The hoses and pipes all look in good condition from the outside.
Cheers
Aardvark
 

Clem

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I’d change the flexi hoses, they can look ok but collapse internally.
Otherwise/also remove and flush the cylinder to make sure it has no swarf in it.
 

ozziedog

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I’ll join in just for fun and say ‘
Change them damned flexis!! :msn4:
They frequently fail internally before there’s any external visual evidence. This was most likely the cause of locking your rear brake on as its allowed the pressure to reach your cylinder / shoes but the collapsed section in the hose acts like a one way valve and dosent allow the pressure to release instantly. It will eventually drop pressure but at quite a slow rate. Once you’ve changed them, do an auto topsy <<<( look a new word ) on the pipe just to prove to yourself how this can work. Then you’ll be 100% confident in your brake repairs and that’s great for peace of mind :mrgreen:

Ozziedog,,,,,,,,,,,guess who’s home bored to tears :mrgreen:
 

KateLovesPurple

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Agreed, change the flexis, but also you may want to have a look for the T piece at the back, one line splits to both sides. If I remember rightly, it is over the gearbox. It is a 90 degree join, easy for swarf/debris to collect in the joint.
 

Aardvark

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Update.
Thanks guys. I did as suggested and that has definitely solved the problem. A pair of new flexies on the back did the trick. It wasn't the easiest fix as I ended up making a new brake pipe to go from front to rear. But it is now working.
I do have one more question to ask though. The handbrake was always rubbish, and I thought with the new cylinders and shoes that I would get an improvement. I adjusted them as per Bentley book. And the lever pulled right out. So I centralised the shoes again, re-adjusted the shoes centred again and be adjusted. (Slight drag then back off a wee bit)
The handbrake lever now feels good, and the near side brake locks on, but the offside can still be moved by hand. The 2 cables are wound right up to close to their shortest length. I would have thought they should be about the middle of the adjustment range. My van is a 72 so has the equaliser bar and adjusters underneath.
Any advice on getting the handbrake functioning properly greatly received.
I'm pretty sure the shoe adjustment is ok and centralised. I have checked several times.
Cant do a road test just now as the front offside balljoints are removed. Went to fit the new ones and they are WAY too tight. Ended up snapping the flange off trying to get them in. So just waiting for new better quality ones to arrive. Running out of time now as we are hoping to get away on a camping trip to the highlands next weekend.
Cheers
Aardvark
 

ozziedog

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So far then so good. Did you do any measurements of the drums while they were off? Are they both the same size? Maybe ones come from another bus at some point in time. I’m guessing you adjusted the brakes up as much as you could before you popped the drums back on, any pics? You might have noticed a lot more thread showing on one side on the adjusters before the drum went on. Just thoughts mate . Are these old cables ? :mrgreen:

Ozziedog,,,,,,,,,,these were once maintained on a budget of three smarties and an elastic band :mrgreen:
 

Aardvark

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Thanks guys.
The brake drums both look almost new. I think they have been changed very recently as they aren't covered in rust and there was no discernible lip on the inside.
I didn't adjust the brakes with the drums off. I had the adjusters turned right in and then adjusted them from the back through the holes. I guess from your answer, that wasn't the correct method. In the book, they keep banging on about centralising the shoes by pressing the pedal. That's why I did it that way. But will to try anything from your expertise tool box.
My guess is that the cables are far from new. I will order new ones but it's just surprising that they are taking all the adjustment. Especially as the shoes are brand new.
There is one oddity. I rebuilt the shoes exactly as the were previously. One side had the handbrake lever inboard and the other was on the outer face. I could find any reference in the book as to the correct way, and YouTube wasn't much help. Any ideas?
Aardvark
 

Mechanoid

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Update.
Thanks guys. I did as suggested and that has definitely solved the problem. A pair of new flexies on the back did the trick. It wasn't the easiest fix as I ended up making a new brake pipe to go from front to rear. But it is now working.
I do have one more question to ask though. The handbrake was always rubbish, and I thought with the new cylinders and shoes that I would get an improvement. I adjusted them as per Bentley book. And the lever pulled right out. So I centralised the shoes again, re-adjusted the shoes centred again and be adjusted. (Slight drag then back off a wee bit)
The handbrake lever now feels good, and the near side brake locks on, but the offside can still be moved by hand. The 2 cables are wound right up to close to their shortest length. I would have thought they should be about the middle of the adjustment range. My van is a 72 so has the equaliser bar and adjusters underneath.
Any advice on getting the handbrake functioning properly greatly received.
I'm pretty sure the shoe adjustment is ok and centralised. I have checked several times.
Cant do a road test just now as the front offside balljoints are removed. Went to fit the new ones and they are WAY too tight. Ended up snapping the flange off trying to get them in. So just waiting for new better quality ones to arrive. Running out of time now as we are hoping to get away on a camping trip to the highlands next weekend.
Cheers
Aardvark
The handbrake problem may be caused by the steel tube rusting out where it passes through the chassis rail. I had the same problem. Could also be the flexible outer rusted inside. I'd check both!
 

ozziedog

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So it was. Not sure why it showed up as recent activity!? Would be nice if the cause was identified though.

I sometimes get stuff show up as recent activity and also I get similar threads pop up and I reckon that’s wots happened here. I fall for it on a regular basis.

Ozziedog,,,,,,,,,, should be compulsorily to fess up even if you was just bein dim :)
 

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