Leaking Nipple?

[A100man]

Trting to trace a soft front brake .Replaced almost everyting, caliper seals/pistons, M/C seals copper washers - one hose ettc..

Left for a couple of days with teh lever tied in too and noticed a small patch oil fluid benetah a caliper.. and teh nipple looks wet, however it is done up tight.
Could it need reseating like ytou do with a domestic tap? Caliper type is Yamaha 1980s as found on XJs and RDs. Hints and tips welcome.
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Now: A100, GT250A, XJ598, FZ750

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600

[Nobby the Bastard]

Assuming not your bike....

Ask the owner if they have recently replaced the nipple, if I remember correctly there are two sorts of nipple angle and if you have the wrong nipple the thread will be right ut the seat wont be flush.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[A100man]

[Nobby the Bastard]

Not sure why the original nipples would leak. Did you gorilla the new nipple trying to stop the leak?
____________________
trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[A100man]

[WD Forte]

I'll assume the caliper is made of cast aluminium?
bearing in mind the new kit you've fitted I'd wonder if the casting
has cracked or got some grit in there to score the seat.
you'd have to remove the nipple to check maybe even the caliper, dry out the hole with cotton buds and take a very close look down the hole with say a jewellers loupe
The ring around the nipple doesn't necessarily mean the seat has a consistent mating surface as well.
Cutting the seat could be tricky unless you get a cutter with the same angle as the nipple, drill bits can vary and you still have the issue of
holding it on the same axis as the hole.
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bikers smell of wee

[Mysteriass]

It's the estrogens in the water making the frogs gay...

I've been asked several times why I don't replace the knackered, leaky, bent parts of my bike with new stuff.

It's because the new aftermarket parts are worse than the knackered 50 year old stuff.

As for putting on NOS stuff... I'm not worthy. I'll just keep those to go in my tomb when I'm dead. They say some people were buried with the things they'd need for their next life; swords, grains, seeds, gems, gold...

I'll need a NOS fuel tap next time round because you sure as hell can't buy a new aftermarket one that doesn't leak worse than the half'a'decade old one you've already got that was made with competence.

https://www.palladiummag.com/2023/06/01/complex-systems-wont-survive-the-competence-crisis/

We're getting to a point where we'll need to visit a machine shop to get replacement parts. Even simple parts. (So keep old stuff for technical specification)

Expect to see threads on these forums over the next few years of people getting parts manufactured in machine shops and spreading the costs of a production run with other people who need those parts too. Most of the new stuff on ebay is junk from day one so what other choices will there be?

It's almost like some certain special somebodies imported the third world and made the first world become third world. Now you can't even buy a nipple that doesn't leak. Who'd a seen that coming. It's almost like the biblical prophecy's of the end times are being artifically arranged to come true. Now just QUI would have the nerve to try and trick G*d himself with such a ruse?

If it's still leaking then the thread on the aftermarket nipple might have shagged the thread in the caliper? Take the old nipple back out and loctite it... or put some PTFE plumber tape on it.

[stinkwheel]

[A100man]

OK chaps.. confession time.. looked again this morning (I've only just moved the bike to my house from it's winter storage place).

Leak may well turn out to be fork oil (I changed teh seals over winter) from a poorly sealed damper rod bolt drippig onto the same patch of floor.

Nonetheless the nipples still look damp even after a wipe with some paper towel. and the feel is abysmal. Next step is to replace the whole M/C I think...
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Now: A100, GT250A, XJ598, FZ750

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600

[pdg]

When you put new seals in the master, did you "bench bleed" it?

Certain masters are a total git for retaining a little bit of air - put a short bit of hose from the outlet looped up into the (full) reservoir and cycle the lever while changing the angle it's at a little. If my description is shit I can draw an equally shit picture to explain it just as badly...

That, and making sure the lines aren't loopy while bleeding of course, but everyone knows that already.

Pressure bleeders usually, but not always, negate the need for any of that.

[pdg]

[Robby]

You mentioned a caliper rebuild kit, did it include new sliding pins for the pads?

Pins corrode and get notchy, which can contribute to an awful feel at the lever. Decent replacements are also surprisingly expensive. So if you didn't replace them, it's a good place to check.

New master cylinder is a good shout. Whilst I would like to say rebuild it, I don't know if the rebuild kits currently available are any good. It's also one of those jobs which is easy to get wrong, and bad news if you do get it wrong.

I'm also assuming that you replaced the caliper seals using the rebuild kit, and scraped out any corrosion from behind the seals or on the piston when you changed the seals.

Front brakes on old bikes. They can go wrong in so many fun little ways, and when they work perfectly they're still a bit shit.

[pdg]

[A100man]

[A100man]

[pdg]

[MCN]

[pdg]

[MCN]

[pdg]

[MCN]

[pdg]

[MCN]