brake problem: right diagnose?

The rear drums are different in that there is a return valve in the system (all drum brakes - I've see anyway))which has an influence on the hoses in holding pressure. Whereas discs don't have that restriction its flow through.

I neither have not experienced any problems as you suggest with hoses.

rm

I've seen one instance where a metal-braided brake hose failed in an interesting way. It was on a car that had welding work done on the front crossmember. Welder had connected the earth-clamp to the front suspension lower-arm! - the current had earthed to the bodyshell through the braided brake-flexy, which cooked the pipe inside. Fortunately it burst when the car was being driven off the ramp rather than on the road.

snip

Likewise I share similar doubts about PTFE hoses and would only use them on a road car if no alternative exists, the style of end fittings used introduce too many possible leak points, to be safe they must be checked at least every 2,000 miles. Also many moons ago I had a new Aeroequip hose on which the one of end fittings wwas not drilled through properly -- caused a lot of head scratching, discovered when bleeding the system the night before the first race of the season -- nothing the attention a 1/8" drill couldn't fix but dammed annoying. Ever since then I have always blown through hoses before fitting.

The worrying thing is the "Nova/Corsa/Civic Boys" think fitting these aircraft style hoses is sort of magic ammulet that will give them instantly better brakes, I have actually seen them recommended in another NG as a cure for brake fade ! truth is if you notice much difference either the system needed flushd and bled or the fabric reinforcing had already failed on originals and they were about split.

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On what model of car, Mk1/2 Escort or Mk1 Marina by any chance ?

Unless it was IRS I suppose.

I've seen it prevent bleeding, brake action was OK though, the gunge just moved back and forth in the hose. What I have also seen, which is relevant to what's been said so far, is where the inner rubber has started to break up and a flap of rubber has acted as a one way valve.

No, nice try - actually a Dolomite Sprint that had been standing for many months... because PO couldn't fix the brakes...

Allan Bennett

I can't see why it just cause one wheel cylinder to stay on then, was the O/S cylinder lazy ?

...some stuff snipped...

I was thinking, maybe informed, that the smooth inner lining of the rubber (reinforced) hose **can** swell due to longterm influence of brake fluid (rather than desintegrate to separate particles) and 'thicken' the hose's wall to the inside, narrowing the lumen of the hose substantially and eventually closing this up.. As the 'ballooning' of the wall is flexible, the pressure given by pressing the brake pedal overcomes the internal resistance of the hose, the 'relaxing pressure' of the pads/pistons willing to go back a bit will not easy overcome the resistance, and therefore the brakes tend to stay on...

As the car is 40+ years old, it may have hoses of that age.. What stuff will withstand 40 years of soaking in brake fluid??

On the theme: 'why only one hose is affected': the new hoses I got from the (specialist) dealer had different production dates and different makes... Maybe even Rover themselves used different makes on one car; what about one hose changed in the past due to failure, another reason hoses may have different qualities on one care..

Tx, rob

Maybe, but as the shoes are spring-loaded, there might be some discrepancy there. The flexi-hose is not central on the axle, either.

When I got the car, the n/s cylinder had already been replaced, plus a new spare in the boot!

I have to say that none of the 'experts' with whom I consulted were even close to an accurate diagnosis - resulting in systematic checks and overhaul of the complete system: wheel cylinders, back-plates, compensator valve (which was a bit crudded-up), load compensator valve, master cylinder, hand-brake mechanism etc...

All worked perfectly afterwards.

Allan Bennett

Sort of shows that it's not exactly a common problem, then. But it's trotted out regularly here and elsewhere like it happened every day.

Perhaps they assumed you'd replaced the hoses, or are you saying they looked perfect from the outside?

Though none were at all surprised and could recount similar tales after the discovery...

Yes, /it/ was perfect from the outside.

Allan Bennett

It sounds like you need to understand how hydraulics works, the hose not being central would make no difference what so ever to the above. Sorry, flame me if you like !

There is well kown problem on rwd Escorts and early Marina's that causes problems with the left rear brake caused by the design of thandbrake cable, Although the rear brake assemblies were similar to the Ford and Morris I don't think it applied to the 1500/Toledo/Dolomite as I seem to remember they used a seperate cable running from the handbrake lever to each wheel.

The Escort/Marina problem is due to a combination of cable stretch and the rubber hinge thing on the axle going hard with age, in theory you can centre up the linkage but the nuts on the crossbar rod are always rusted solid, the cure was to use a late model Ital handbrake cable which dosen't use a cross link rod and rubber hinge and suport the cable as on the Ital with a large cable round the axle case.

should read "cable tie round the axle case..