Convert an inverted flare brake port to a bleed port?

[rcx132]

Happy new year everyone

The donor wheel brake cylinder I've used on my buggy build has two M10x1.0 SAE inverted flare ports designed to connect to brake pipe. I need to change the top one to a bleed nipple. Bleed ports have a concave flare whereas brake line ports have a convex flare.

What are your ideas for a simple solution?

I found this repair kit which could potentially be adapted, though I'm not certain my machining skills are up to converting the adaptor.

 

[Chippie]

Machine the bleed nipple to have a matching flare to the cylinder port I‘d have thought easiest…??

 

[Wildefalcon]

Remote bleed, small pipe with the correct fittings at each end, and mounted away from the mud, and easy to get at.

 

[Morrisman]

What shape is on the lower sealing face of the adaptor?

 

[rcx132]

What shape is on the lower sealing face of the adaptor?

The eBay listing doesn't say but as it's a repair adapter I'm assuming it fits a bleed port so would need a concav flare machined into it.

Machine the bleed nipple to have a matching flare to the cylinder port I‘d have thought easiest…??

I'm not sure if a bleed nipple would work if the flare is changed.

 

[8ob]

A short bit of pipe out of the brake slave to a female brakepipe nut will work, op2 flare on the pipe in the nut will match the bleed nipple flare/taper.

Bob

 

[Ubique]

Those repair kits are ideal for what you need - forget the flare at the bottom, the adaptor is M10 x 1.0 with a copper washer so it seals at the top of the thread, not the bottom (like the 'banjo' connection used on disc brake calipers), the supplied bleed nipple seals in the bottom of the adaptor which is machined with a matching taper. We use them a lot on Brembo Aluminium calipers.
ETA - if the adaptor is bottoming out before the washer is compressed, you can shorten the adapter 'a bit', or use a thicker washer.

 

[Chippie]

I made my suggestion based on no additional parts needed and minimising potential leak paths….but hey ho….just another ridiculously stupid idea…

 

[rcx132]

I made my suggestion based on no additional parts needed and minimising potential leak paths….but hey ho….just another ridiculously stupid idea…

It's not stupid, it's the first idea I had and it may work.

 

[rcx132]

Those repair kits are ideal for what you need - forget the flare at the bottom, the adaptor is M10 x 1.0 with a copper washer so it seals at the top of the thread, not the bottom (like the 'banjo' connection used on disc brake calipers), the supplied bleed nipple seals in the bottom of the adaptor which is machined with a matching taper. We use them a lot on Brembo Aluminium calipers.
ETA - if the adaptor is bottoming out before the washer is compressed, you can shorten the adapter 'a bit', or use a thicker washer.

Yep those kits look promising but they rely on a machined surface for the copper washer to seal against, which my cylinders don't have. I can try to file or machine a suitable surface or get the adapter to seal by some other means eg loctite or brazing or by machining a flare into it. Not sure which method would be best.

 

[Ubique]

They work well enough on the un-machined faces on corroded brake calipers, yes, sometimes they need a bit of fettling first with some 800g wet & dry wrapped around a flat file, the copper washers do a good job of sealing - we always check for weepage after an enthusiastic test drive, just to be sure - looking at your photo again, there is a casting edge that would need to be removed, other than that, it looks OK.

 

[Keithmac]

For me I'd be using an M10x1.0 blead adapter (I think that's what you posted on first post), plus a bit of clean up on the sealing face.

I bought a brake pedal depressor and leave the system loaded up overnight to test for leaks. On thing you can't skimp on is brakes.

 

[rcx132]

They work well enough on the un-machined faces on corroded brake calipers, yes, sometimes they need a bit of fettling first with some 800g wet & dry wrapped around a flat file, the copper washers do a good job of sealing - we always check for weepage after an enthusiastic test drive, just to be sure - looking at your photo again, there is a casting edge that would need to be removed, other than that, it looks OK.

Ok I'll file off the casting edge and use some engineers blue to check for seal.

 

[Rrobson]

A standard bleed nipple would almost certainly seal that as long as you’ve got enough threads engaged between the threaded hole and the nipple

 

[RichardM]

Is that top left pic the actual thing it's going to thread into, if so take the casting ridge off it, put the copper washer on the adapter and some PTFE tape on the threads.

 

[rcx132]

Is that top left pic the actual thing it's going to thread into, if so take the casting ridge off it, put the copper washer on the adapter and some PTFE tape on the threads.

Yep the left photo shows the wheel cylinder. You can see I've made a pipe to the bottom port. The donor car then had another pipe that went to the next cylinder, but on my build I've used a T junction instead, so I need that second port to become a bleed port.

 

[Morrisman]

Is that top left pic the actual thing it's going to thread into, if so take the casting ridge off it, put the copper washer on the adapter and some PTFE tape on the threads.

PTFE tape is usually pointless on parallel threads, however, in the past I've done it as wipes off the threads and forms an 'o' ring under the head of whatever you screw in. Every little helps.

 

[8ob]

You can buy caliper bleed nipple repair kits, might be worth getting in touch with Big Red or the like to see what they have.

 

[RichardM]

PTFE tape is usually pointless on parallel threads, however, in the past I've done it as wipes off the threads and forms an 'o' ring under the head of whatever you screw in. Every little helps.

Exactly why I said put some on, helps to seal any small irregularities. I've found in the past that some does stay on the threads and makes a good anti-corrosion layer when using stainless fittings in alloy calipers.

 

[rcx132]

I wish i took a photo to show you the end solution but i forgot :/

The bleed nipple repair kit was too long to seal using the copper washer. I machined a concave flare into it on a mini lathe as that was the easiest solution. I used engineer's blue to check for seal. The flare is a little off as expected if you put something straight into a lathe without aligning it. However it was close enough to seal, which I guess is what the flare is for, to accomodate some mis-alignment.

It'll be a while before the systems gets filled with fluid and tested but I'm confident it should be fine.