6 replies to this topic

[JeremyduP]

Does anyone know where I can get a bleed nipple seat re-cut near Chichester?  I had to replace the nipple but the old seat is damaged and doesnt match so fluid leaks through the threads

 

 

[Spider]

I generally don't like re-dressing the Nipple Seats, it does need to be done with great care to be sure you get them dead square or they won't seal. You also need to keep to to a simple dressing and not a re-drilling as some seats don't have a lot of material behind them. You also need to take care you don't remove material from the threads.

 

You can make your own from sharpening a Drill Bit to a 100⁰ included angle, though I've used ordinary 118⁰ drill bits without issue when making Brake Parts.

 

For a 3/8" UNF Bleed Nipple use a 25/64" Drill Bit

For a 1/4" UNF Bleeder  17/64"

For an M6 Bleeder, use a 5 mm

For an M7 Bleeder, use a 6.1 mm

 

An alternative here, and my preferred method, is to grind the pointed end of the Bleed Nipple flat, (and likely take some more back), then find a Ball Bearing around 4 mm in dia (go no smaller than 3.5 mm), then drop the Ball on the Bleeder Hole and Screw the modified Nipple in. You may need to adjust the length of the Nipple to ensure you have a good number of threads engaged while being sure it's not bottoming out on the Hex. 

[A-Cell]

If it's a wheel cylinder I would replace it. If a calliper and therefore more expensive, then as Mokespider I would use the ball bearing method

[GraemeC]

http://www.fraserbro...t&product_id=51

[Spider]

Yes, as A-cell suggests, if it's a wheel cylinder, replace it ! A Caliper might be worth repairing.

 

http://www.fraserbro...t&product_id=51

 

That's a nice neat kit there Graeme, but I also express some caution with some calipers as I've found out - the hard way,,,,,

 

I know for a fact, on the Factory 4 Pots, you can't make some of those nipples (or the drilling for them) any bigger, there's a pressure fluid passage drilling that runs close to one of the nipples. Taking them from M7 to 3/8" UNF just (in the roots of the threads) break in to that passageway. I didn't find out until trying to bleed them !

 

Could be a fix in some instances for sure - just look before you leap !

[JeremyduP]

It's a Mk1 Cooper S caliper.  The seat has become damaged from overtightening over the years.  The nipple is no longer pyramid shaped but rather teepee shape.  A new nipple would not seal and leaked through the threads.  

[JeremyduP]

Well it’s fixed. I tried Moke Spider’s ball bearing trick but in doing so I discovered the threads were actually damaged so although it seemed to work, I was worried about the threads giving way. So I ordered the Nipple Therapy kit recommended by GraemeC. I removed the calliper to ensure I drilled and tapped straight. It was really easy to do. The drill is designed to also shave a collar for the brass washer. It’s worked really well. I can highly recommend it.