Rear brakes.

[cuk]

Hi,
Had a problem with a brake fluid leak. Where the brake pipe joins the union bolt that then goes into the brass banjo, there is a larger copper washer, and smaller one other side of the banjo.
My problem is although I have done everything up tight, I still have fluid firing out of the larger washer (never had this problem before).
Do the washers have to be round a certain way? Also the banjo?
I have taken apart 3 times and changed the washers but still its leaking. all absolutely clean free of dirt and no cracks.

Any help would be appreciated.
Paul.

[mogbob]

Paul
It sounds as though you observed the basics i.e two different sized washers Moss Europe diagram http://www.moss-europe.co.uk/media/cata ... _02_01.jpg
cleanliness , changed washers , no cracks , etc.
A couple more suggestions / observations. In addition to looking for cracks are there any nicks in the metal ?
It might be worth annealing the two washers so that they are more malleable. If you've got a blowtorch just heat them up and then immediately quench them in cold water. ( usual safety precautions ). Clean up again and reassemble. That should solve it but .. if you want a belt and braces approach you could use an application of Brake pipe sealant. ( importanatly , make sure the pipe sealant is suitable for car brakes ).
DON'T slap it on like polyfilla , you don't want to block the fluid holes , you just want to seal the threads ! Apply carefully and precisely. When all else fails , read the instructions carefully.
Good luck with that.
Bob

[oliver90owner]

When annealing copper there is no need to quench - air cooling is perfectly adequate.

[cuk]

Paul
It sounds as though you observed the basics i.e two different sized washers Moss Europe diagram http://www.moss-europe.co.uk/media/cata ... _02_01.jpg
cleanliness , changed washers , no cracks , etc.
A couple more suggestions / observations. In addition to looking for cracks are there any nicks in the metal ?
It might be worth annealing the two washers so that they are more malleable. If you've got a blowtorch just heat them up and then immediately quench them in cold water. ( usual safety precautions ). Clean up again and reassemble. That should solve it but .. if you want a belt and braces approach you could use an application of Brake pipe sealant. ( importanatly , make sure the pipe sealant is suitable for car brakes ).
DON'T slap it on like polyfilla , you don't want to block the fluid holes , you just want to seal the threads ! Apply carefully and precisely. When all else fails , read the instructions carefully.
Good luck with that.
Bob

Thanks Bob,
Will try all these. I did inspect for cracks and nicks before, and both banjo faces are polished and flat. The union bolt edge, which abutts the large copper washer is also fine. Whats strange is that I assembled it all together before, when I renewed the wheel cylinder. Drove the car a couple of days waiting for a new W.Cylinder rubber dust cover (rear cylinder). Dissassembled parts- put new cover back on, new washers, and then this Happened!
Thanks for your help, will let you know.
Paul.

[cuk]

When annealing copper there is no need to quench - air cooling is perfectly adequate.

Thanks Oliver,
Will keep you posted.
Paul

[Sleeper]

Just check with a magnet that the copper washer is " copper " and not copper plated....I bought a new pack of assorted copper washer just to find out the above.

John

[cuk]

Thanks John,
for your comment.
Paul.

[cuk]

Hi,
Thanks everyone for help. It was the washers, they were copper plated not solid copper, so would not squash up properly.
Thanks again.
Paul.

[Sleeper]

It made me so mad after having the same problem , lots of head scratching , until I found out....they don't give receipts at Newark Autojumble.

John

[mogbob]

Paul
You have a pm reply
Bob

[Pucketsport]

I have the same issue where brake fluid is leaking from the Banjo bolt washer. I still haven't found the root cause. I have new washers, new wheel cylinders but have re-used the bolt that connects the banjo / bleed fitting to the cylinder/ brake tube.
Having worked as a Brakes design Engineer for a large OEM I am surprised and a bit confused by this issue as banjo fittings with new copper washers and good mating parts should have no problem sealing ????
I saw the comment about copper -plated steel washers which is shocking , cant believe anyone would sell those as Brake sealing washers. Will inspect mine tonight.

[philthehill]

The threads in the rear brake cylinder that hold the banjo union bolt must be square (90 degrees) to the face of the brake cylinder that the copper washer fits against. Do not assume that the face is square to the threads.
If they are not square then no amount of soft copper washers will take up the mis-alignment.

Check the material of the copper washers with a magnet - even though it appears copper looking - if the magnet holds the washer the washer will be steel or similar.

[Pucketsport]

Thanks for the reply Phil. I assumed the new wheel cylinder was correctly machined and that the banjo bolt had parallel surfaces but you are right, these are likely causes of leaking. I'll check the washers tonight with a magnet.
Thanks

[Pucketsport]

Phil you were correct. The issue proved to be the wheel cylinder tapped hole is not perpendicular to the mating face. I lightly tightened the banjo fitting without the copper washers ( they are copper by the way) and noticed there was a gap on one side. I confirmed it was not the banjo mating faces that were the fault by rotating the fitting and noting that the gap remained on the same side.I took some pics and got an immediate response from Moss. They checked their stock and found a certain batch had this machining issue. I'm really impressed with Moss, this is the 2nd time I have had a really quick response to an issue and they don't waste any time sending out replacement parts.

[les]

Haven't heard no need to quench in water before. I always do. I'll have to do some googling on that one!

[les]

It appears some authorities say quench, (old school) ---some say don't. The quench school say it cleans the copper, I can confirm that. So it seems to be a matter of opinion/choice.

[philthehill]

Red hot and then quench does it for me

[oliver90owner]

Haven't heard no need to quench in water before.

Surprising! I knew that over 50 years ago when I used to anneal the head gasket for my Honda 50 motorbike. I never bought a new gasket and the head was removed several times. I've never bothered to water quench, unless in a hurry to handle the item.

It is not opinion, it is fact. It matters not how copper is quenched (air, water - or any other way). Copper is not like steel - which is an alloy, so can have different phase compositions at different temperatures. The need for different quenching routines being to 'freeze" the particular phase composition before it has time to change to another.

I'm not totally certain but I expect most (or all) elemental metals behave in a similar way.

[les]

As I said, from quick research, that it appears to be matter of opinion as to the method used. Surprisingly I too know copper is not like steel, heat treatment wise!) However I will continue with the quench method, as I have had no detrimental effects as a result. Being reluctant to blow my own trumpet, I won't recount my experiences.

[oliver90owner]

as I have had no detrimental effects as a result.

You won't. There is no difference between water or air quenching or any other cooling regime. Another regime might be to put it in a kiln and just turn the power off and wait for it to cool, with the same result.

"Appears" is just too subjective for me. Hard facts are much preferred.

You and everyone else can choose how you cool copper after annealing - it won't make a jot of difference. It is a choice and not a rule.

Doubtless nobody else has had a problem, either. Heated adequately does the job, not the cooling!