Morris Minor Owners Club

Can somebody please help diagnose my brake problem?

The rear brakes have been sticking, so I took off the drums and got somebody to press the brake and release. The cylinders push out when the brake is pressed, but don't retract when the brake is released. I unscrewed the bleed nipples and a small amount of brake fluid rushed out and the cylinder retracted.

Am I right in thinking this is therefore not a problem with the cylinders themselves, but perhaps the flexi hoses? Or is it something else?

I'm quite ignorant of these matters so any help will be much appreciated!

It sounds like you are probably right. Assuming the return springs are fitted correctly to the drums, I would start by replacing the rear flexi hose, as that is the cheapest and easiest starting point. The rubber can swell inside leading to the problem you describe. There's just the one hose for the rear brakes. If that doesn't work, then it could possibly be related to the master cylinder.

Ignore the flexi hose - I have copper(?) brake lines instead.

Could it be a mastercylinder problem if the front brakes are okay?

You have a flexible rubber hose between the body and the rear axle and onto the rear brake cylinders.
http://www.moss-europe.co.uk/shop-by-mo ... ulics.html

Item No: 58...............Pt No: 17H7719.

Ah, okay. Is this the most likely offender? Shall I replace this first? Thanks!

I would replace as a matter of course. It may have been on the car for some considerable time.

Thanks for your help. I'll do that and let you know how I get on.

Inspect the flexible hose first under a good strong light , bending the hose in a number of places as you do so. Look for obvious degradation of the rubber , tiny splits and surface damage. Observe the usual safety precautions jacking up the rear of the car , putting the car on axle stands , on firm level ground before getting underneath , of course.

Because you said only the rear brakes are affected , it's " less likely " to be the master cylinder. The brake fluid has further to travel to the back of the car. The master cylinder seal might be on it's way out. The return spring might be weak/ broken or as in my mates car, the
metal hook attachment for the return spring had totally rusted through. I had to fabricate a new strip of metal, bend it to shape and weld
it in , in situ.
My fellow forum guys and gals can only pass on suggested solutions from their experiences and your description of the problem. We are
problems solving " blind " which is not easy and sometimes there are several "solutions " and occasionally " more than one problem existing " to solve. We try to be good detectives .. from a distance.
Lets us know how you get on.
Bob

Thank you, Bob. I will let you all know.

can you put a photo of the shoes in situe with the springs fitted,its easy to have the springs in the wrong place.

kennatt wrote:can you put a photo of the shoes in situe with the springs fitted,its easy to have the springs in the wrong place.

Are you sure? It is only that I recently had a Problem with my rear Brakes -see separate thread if you wish - and in following the manual it seemed that the position of the two different springs was interchangable i.e near to or away from the wheel cylinder.
However, it proved impossible to refit the solid spring nearest to the cylinder as shown in some pics in the Manual, due to the bulge in the backplate. Only the double spring could be fixed here.

Perhaps on earlier models, I have a '69 Traveller, it was possible.

yes the springs can only go on the correct side but its possible to fit them in the wrong holes,and therefore not giving enough pull off pressure.bear in mind that the design of the minor system is that it holds positive pressure to hold the shoes close to the drum,if not enough pull back from the springs it will may hold them too tight,.

Okay - I am in the process of fitting a new brake hose, slightly delayed because I can't detach the old one from the 3-way union; they have rusted together.

See here for a picture of the old hose:

https://goo.gl/photos/ucrNtwDwTYv8wZhFA

Not sure how small the hold in the middle is meant to be, but is this swollen? It's date is 1977.

The flexible ( not an adjective that can be applied to your current hose ! ) brake hose at 40 years old is only fit for rubbish tip.
I wouldn't expect anything to flow through the centre.
Compare your old pipe with the new pipe , you'll see that the hole is a large knitting needle / big nail size.

By swollen , we mean that although the brake pipe internal diameter is clear for fluid to flow through , the rubber wall of the brake pipe has weakened. You might just be able to see a minor blister on the rubber at rest but in most cases the swelling can only be observed whilst someone else operates the brakes for you , whilst you watch the re-action.
When the brakes are applied , the pressure has to overcome the resistance of the wheel cylinder pistons , to move the brake shoes and stop the car.
If the walls of the pipe are weak then " much less" pressure will " blow up / inflate " the pipe , just like a balloon. The braking system will always go for the weak resistance point. If the pressure is blowing up the rubber pipes like balloons then very little pressure is trying to move the brakes cylinders and therefore the car doesn't stop.

Stuck nuts on the three way union.
Wire brush the joint and apply Plusgas dismantling fluid ideally , leaving for as long as possible before attempting to shift the nuts. Always use two spanners , other wise you will probably twist / bend /weaken / destroy the pipes themselves. You can try tightening the joint , a fraction , no more than a millimetre or so. Then try loosening , just working it back and forward to get movement. More Plusgas and eventually it will move. Don't go mad. An application of boiling water over the joint will sometimes work. Take care and use a Thermos flask or other receptacle if the kettle won't fit . The pipework nuts will be very HOT. Approach the task calmly , firmly and patiently. If you can support the joint with blocks of wood and rags, still allowing access for your spanners , so much the better.
Bob

If the joint is that bad remove the whole brake pipe assy from the rear axle/brakes. that way you can deal with the seizure problem with the three way union in the vice or on the bench.
A brake pipe in the condition shown in the photo above is only fit for the scrap bin.
Flexible brake pipes do not last for ever and need to be examined on a regular basis and renewed say after 10 years as a matter of course.

Thanks for both your advice. I thought it looked a bit funny! I have removed the 3-way union as well, but still no success. I have ordered a new one as they aren't too dear.

philthehill wrote:I would replace as a matter of course. It may have been on the car for some considerable time.

PTH is quite correct re the age related perspective. As otherwise stated, at 40 years old it has likely exceeded its service life at least a couple times!

But changing it otherwise, on a whim, is folly unless the problem arises, to some extent, with both rear brakes. A simple symptom for diagnosis of the real fault before costing time and expense - particularly if directing a garage service to do the job!

It's never a bad idea to change a flexible hose if its history is unknown and you're working In that vicinity. The hose in question confirms that. Prevention is better than cure.

Les,

If your post was a riposte of mine, I think you missed the point.

Diagnosis is simple and costs nothing. Changing random parts is a carp way or repairing anything. In this case it is very likely the flexible brake hose. A simple test was taken on one pair of shoes - that of releasing the pressure and the shoes retracting. If that self same bleed nipple loosening also allowed immediate retraction of the shoes on the opposite side as well, it clearly shows that the residual pressure is the problem and that the problem was before the rear brake shoes.. One simple diagnosis before tearing the system apart (and then finding difficulty in even getting back to where you were before) gives a good clue.

Same with intermittent engine failures (a recent topic on the electrics section). If the poster had simply checked for a good spark, when the engine would not start, that would have ruled out a '99% electrical fault' and it would have been 99% a fuel problem at a stroke! Just look how many times the first repair suggestion, for the ignition system, is 'change the condenser'!

Same here. Isolate and recognise the problem, then put it right.

No problem with your opinion, the reply was just expressing mine, in regard to hoses. I have no problem with the art of deduction. We all use it to some degree.