Series III, only one brake working after full replacement

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It is, yep - the valve just controls the dash light.

There's definitely no leaks anywhere, the level in the reservoir doesn't drop and the whole system is completely dry. The shuttle valve isn't leaking fluid between front and rear sections of the piston either, I've removed the switch and it's bone dry inside.

I've even adjusted the front shoes up to the point where they bind and adjusted the rears all the way off just to see if the extra travel was the front shoes moving fractionally more, but it didn't make a difference.
 
you say there are marks on the front shoes, is this along the whole length of the shoe or only in a small part. Sometimes they need rubbing down so they contact across the whole shoe. It sounds more like contact area than fluid problem.
 
Interesting - there's contact marks along about half of the front shoes, nearest the cylinders as expected. I'll rub down the part contacting first and see if that helps things.
 
arkas said:
Interesting - there's contact marks along about half of the front shoes, nearest the cylinders as expected. I'll rub down the part contacting first and see if that helps things.
Click to expand...
Have you ground chamfers on the leading and trailing edges of the shoes?
The more I read about your problem, the more it looks like it might be a shuttle valve problem. If you've backed off the rear adjusters and are still getting weak front braking it can only be shuttle valve or possibly master cylinder and as you've changed the master and still have the same problem the light of guilt is shining at the shuttle valve. Get some pipe joiners and disconnect the valve; bypass it completely and see what you get then.
 
While som emaster cylinders are one way around and others the other way its not a show stopper as the bores are eitrher thee same or simialr. The connections will affect the brake balance so they should be right, but they are a lot less likely to explain your fault than a defective or stuck shuttle valve.
 
On mine i methodically swapped bits over, ie i first put the drum then shoes on the other side,one dragging brake changed over so i knew where to concentrate on, the all round dremel shoe chamfering and new snail cams certainly helped,i have even contact all round the shoes on all wheels,
As i have written before i was not making progress 'til all the wheels were up,
All the best and good luck
Ryn @sunny west cornwall
 
Its a "hydraulic fuse" - it shuts off the circuit with the leak, great in theory but actually it can get stiff and not work because it seldom moves, or move when there's a modest imbalance and disconnect half the circuit. In my view the bad reputation is fully deserved. The best set up is a dual cicuit master cylinder and a fluid level warning in the researvior.
 
Mine is front tls,double the front wheel cylinder capacity so needed the larger m/cylinder,iirc the rear pipe on the master goes to the front via a 't' union,
The front m/cylinder pipe goes to the 't' near the back axle as standard,a simple,basic system.front and back on seperate systems,on some older cars they were diagonal systems.
regarding The shuttle valve,apologies if off topic.
As the thing can cause problems when bleeding due to the shuttle moving from the high to low pressure i was looking to refit it once i knew my brakes were fixed,i have not got around to it yet but i have an idea of getting a correctly shaped/threaded set screw or similar to put in where the switch goes,this would,in effect 'lock' the shuttle and bleeding would be fine,
Also if i left it like that the shuttle body and pipe fittings are a darn site more substantial than the brass junctions,combined with the cap switch as Rob says it will be a better system and will work.
all the best and Good luck
Ryn at sunny and warm west cornwall
 
Thanks for all the replies.

Re-piped the system to bypass the shuttle valve yesterday (straight from master cylinder to front/rear unions) and chamfered the shoes, no improvement. Took it in to a local Land Rover specialist this morning as I was going mad, they've put it on their rolling road brake tester and diagnosed the nearside front has an issue. Asked them to sort it as long as the price isn't massive, just want to use the vehicle after almost a month of trying to solve this problem!

Once it's MOT'd and they've fixed it, I'll update you guys with full diagnosis and what they've replaced.
 
Well...

They spent all afternoon with it, on and off the rolling road and ended up replacing the TRW front wheel cylinders/shoes with different OEM ones, bled the system and all works fine now. Apparently both leading shoe and one trailing cylinder (brand new!) were sticking under pressure. Don't mind paying £££ for them to sort it as I'd never have worked it out otherwise.
 
Well I have to say I don't think I could have sussed that one! Intersintg re TRW, have ally BP ones on the rear and because they seemed so poor quality I bought Delphi iron ones for the front. so the BP ones are going strong 5 years on and the iron Dephi ones corroded and had to be honed out.
 
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