Morris Minor Owners Club

8 replacement wheel cylinders within 6 months is getting a bit tiresome, and my daughter's getting fed up with suddenly having to grab the handbrake to stop! I was buying patern items till the last one which is Lockheed, and I use Comma DOT4 synnthetic brake fluid. The cylinders fail quickly - flooding the entire drum and soaking the lining with fluid. On draining the fluid (which has only been in there for a few months), I find it very contaminated - dark grey and cloudy. The master cylinder was recently replaced with a new Lockheed unit. I can only assume that the rubber seals are dissintergrating somehow - poor quality???

Anyone had similar experience?

had pattern ones go in a few months

Certainly for the fronts - better to use 'genuine' cylinders.

Yes front pattern are no good and dont have a very long life in my experience. I always pay a few extra pounds for the lockheed ones for the front, I use pattern ones on the back as they are made to the same spec and seem to last fine.

Perhaps the suppliers should remove them from their stock as they are potentially very dangerous. Same goes for poor quality brake linings that seem to be currently on the market. Grumble, grumble, moan, moan!

I had a spate of cylinder failures on mine a few years back -both pattern and Lockheed, and similarly poorly coloured brake fluid. Eventually I solved the problem by changing all the brake lines. What appeared to be very good replacement steel brake lines (reasonably new) were corroding on the inside, and releasing fine solids into the brake fluid. I believe this is what was causing my premature brake cylinder failure.

Which is why you should use Kunifer brake lines........

mowogg wrote:I had a spate of cylinder failures on mine a few years back -both pattern and Lockheed, and similarly poorly coloured brake fluid. Eventually I solved the problem by changing all the brake lines. What appeared to be very good replacement steel brake lines (reasonably new) were corroding on the inside, and releasing fine solids into the brake fluid. I believe this is what was causing my premature brake cylinder failure.

Brake pipes on my daughters car are all copper and reasonably new. But I'm now wondering about the front flexi hoses = could be breaking down inside???

The attached may be of interest.
http://en.wikipedia.org/wiki/Bundy_tube
Though I would have thought discolouration would be caused by seals breaking down, perhaps the material used by the supplier is not chemically up to scratch.
The Kunifer tube is generally available at around £15.00 per 25ft coil from Bennetts and others.

Indeed - copper is not suitable for brake pipes. I suggest a good flush through with clean brake fluid will be wise when fitting new 'genuine' cylinders.

bmcecosse wrote:Indeed - copper is not suitable for brake pipes. I suggest a good flush through with clean brake fluid will be wise when fitting new 'genuine' cylinders.

Ummm... If true why does my supplier (probably one of the biggest MM specialist suppliers) only stock copper pipe???

Each time I have replaced a front wheel cylinder - I have bled the system completely till rfully clean.

I suspect either poor quality seals in the new master cylinders although I'm going to have a go at re-newing the front flexi hoses too.

I'm using Dot 4 synthetic brake fluid and I think it probably unlikely that this is rotting my brake seals. What fluid are others using?

rogerowen wrote:

bmcecosse wrote:Indeed - copper is not suitable for brake pipes. I suggest a good flush through with clean brake fluid will be wise when fitting new 'genuine' cylinders.

Ummm... If true why does my supplier (probably one of the biggest MM specialist suppliers) only stock copper pipe???

Each time I have replaced a front wheel cylinder - I have bled the system completely till rfully clean.

I suspect either poor quality seals in the new master cylinders although I'm going to have a go at re-newing the front flexi hoses too.

I'm using Dot 4 synthetic brake fluid and I think it probably unlikely that this is rotting my brake seals. What fluid are others using?

Sorry, I meant SLAVE cylinders!

COPPER is truly not suitable for brake pipe because it work hardens and cracks - they are probably (hopefully) using Kunifer. The brake fluid should be fine -unless it was contaminated in some way.

bmcecosse wrote:COPPER is truly not suitable for brake pipe because it work hardens and cracks - they are probably (hopefully) using Kunifer. The brake fluid should be fine -unless it was contaminated in some way.

Definitely Copper (well, as listed on Bull Motif web site anyway). Fluid is brand new, I've been through about 5 litres in the last few months! Daughter getting fed up with Mamaduke's continuous brake problems - and is now threatening to look for a modern car!

Hi interesting post here. I've have the same pattern cylinders on mine for several years. With no problems.

1st I always dismantle the cylinders and wash out with meths as this does not damage the rubber seals.
I've have found swarf in many cylinders in the past of different types.

2nd reassemble using red brake grease around the piston and seal.

3rd strip the master cylinder and replace seals.

Has there been silicone fluid used at any time as you cannot add standard fluid to the system this will make the seals deteriorate quickly. May be best to change all seals/flexi hoses and blow out the copper brake lines and start with a clean system.
I have copper brake pipes that have been on since 1990 and a servo all from BM
Alex

myminor1969 wrote:Hi interesting post here. I've have the same pattern cylinders on mine for several years. With no problems.

1st I always dismantle the cylinders and wash out with meths as this does not damage the rubber seals.
I've have found swarf in many cylinders in the past of different types.

2nd reassemble using red brake grease around the piston and seal.

3rd strip the master cylinder and replace seals.

Has there been silicone fluid used at any time as you cannot add standard fluid to the system this will make the seals deteriorate quickly. May be best to change all seals/flexi hoses and blow out the copper brake lines and start with a clean system.
I have copper brake pipes that have been on since 1990 and a servo all from BM
Alex

Thanks, that sounds like very sensible precautions. Swarf in a new brake cylinder!!! - doesn't bear thinking about!

New 'Lockheed' Wheel cylinder compared to leaking old one (pattern?) - significant design difference.[frame][/frame]

Indeed it is a 'different' design - but still it is a design that is used in many wheel cylinders. So I don't see why it was leaking - unless the brake fluid was contaminated. And since so many have failed in your car - I do rather suspect that is the reason.

bmcecosse wrote:Indeed it is a 'different' design - but still it is a design that is used in many wheel cylinders. So I don't see why it was leaking - unless the brake fluid was contaminated. And since so many have failed in your car - I do rather suspect that is the reason.

I'm replaceing the flexible pipes in case they are dissintegrating inside.

Which would be another sign of contaminated fluid...... I would do a complete flush through all points until you are sure you have frewshh fluid right through the system.