Topic: Leaking brakes at caliper

[SKTP]

Ok, I finally have all the parts bolted together to get my dual disks working

They are leaking at the brass fitting and the caliper...

Is there anything in there that I am not thinking of?  Is this just a metal-to-metal tighten the crap out of it fit?

It's pretty tight already but both are leaking. I'm really afraid to strip them...suggestions?

[flybox1]

ive always used a few wraps of teflon on the first threads.

[bjbuchanan]

Teflon on the end threads and make sure you have matching mating surfaces at the flares. What I mean is is the brake line a normal double flare female end and your brass fitting a bubble type male? Vice Versa? If so they will weep, the mating surfaces usually don't seal up. If you hack it they might seal but good luck ever getting it to seal right again if you need to touch it for maintenance purposes

[JD]

i had the exact same issue with my 1978 CB 550K3 i solved the issue by stripping the caliper body and using a dressed piece of metal rod and valve grinding paste to reface the sealing face inside of the caliper. it took a bit of work but it now seals perfectly,, it also take a lot of cleaning after.
hope this helps.

JD

[Powderman]

Are you sure both threads are the same? Is the hole in the caliper a machine thread or a pipe thread? The fitting looks like it might be a pipe thread (tapered) and the caliper may be a machine thread. Did that caliper have a banjo bolt a one time?

[SKTP]

all brake lines and fitting are from Slingshot cycles and from what I understand made to be used with HONDA motorcycles

I'd put a link to the parts but the site says Slingshot is on vacation

[SKTP]

ive always used a few wraps of teflon on the first threads.

Do you mean a for a teflon that comes in a tube or are there actual wraps? What type?

Thanks

[bjbuchanan]

that cheap white tape roll is the teflon I use. I just had to use some on a buddy's kz550 to seal it up. The threads and sealing surface were just not good enough anymore. Fresh bleed screw and tape and it is all good now

[Powderman]

If you have a choice Teflon paste is better than tape.

[RAFster122s]

Is it leaking between the brass fitting and the caliper body?  That is where I am betting it is leaking. I would suspect the brass fitting is bottoming and not sealing. You may need to machine it to the profile in the bottom of the caliper port you are trying to get to seal with.
Chucking it in a drill and using a file or sandpaper to get the proper angle wouldn't be a bad thing.
Maybe lube up the opening, press some clay into the opening, caliper and clay into freezer, then unscrewing the frozen clay plug will give you the profile of the seat. This can be used to form a female template from the clay plug...

[Dave Voss]

The threads in the caliper body are straight threads and they are not intended to provide any sealing at all, the sealing is at the tapered seat at the bottom of the threaded hole, where the flare on the end of the stock hard line forms a compression connection when the stock hard line fitting is tightened in the caliper body.

Even if the brass fitting (in your picture) has the same shape tip as the stock compression flare, it won't seal as well, hence the need for teflon tape, paste, etc. on the threads to stop the seeps and leaks.  Also, with hydraulic circuits, the fewer fittings and connections the better, why not just use the stock hard line and a brake hose on each side, instead of several non-stock fittings and connections that are prone to leaking?

[RAFster122s]

+1 to what Dave said, that was what I was trying to say...

[xsmooth69x]

is the brass fitting the same on both ends? try flipping it around?

[SKTP]

Stock versus what I'm working with...going to try the tape now

[SKTP]

Ok...one wrap of Teflon tape





Both tightened down hard...

[SKTP]

Ok! The Teflon tape worked perfectly!

Brakes bled. But now it's double disk conversion issue time.

Both brakes are about 80 or 90% on...

...and I mean when they are suppose to be off

[flybox1]

I fought this when I did my conversion.
Please search my build thread...the mutt redux. Page3
It's your piston side brake pad.  It's not perfectly flush with the rotor.
My build goes into more detail on the fix.

right here...http://forums.sohc4.net/index.php?topic=105018.msg1344173#msg1344173


also, be sure to emory cloth or wire wheel all the paint off the sides of the brake pad backer.  it makes the fit too tight.  brake pad need to move freely without binding when inside caliper

[pampadori]

Hi Chris.  Flared connections need to be a little tighter than say banjo bolt connections.  This is because of how the seal actually works. The caliper uses a 45 degree flare to seal.  The threads serve no purpose but to allow the flare and the inverted flare on the adapter end to be drawn together.

The inverted flare seat angle actually isn't 45 degrees.  It is 42 degrees. The seat angles vary to the tube angle because it is important to seal the smallest diameter to get an effective seal.

If you notice any burrs on either the male or the female flare, use some very fine sandpaper to remove them.

I suspect the source of your leak is on the caliper side of the seal.  It is after all 40 years old and may have been distorted in it's life. Loosen and retighten the adapter to the caliper a few times.  This will help seat the flares as the metal surfaces need to actually conform to one another ever so slightly. 

Your teflon tape on the threads is just containing the leak not stopping it.

[Bootlegger56]

+1 on loosening and tightening several times.  That was the way I was taught in the Navy to seat flared fittings.  I don't mean using excessive torque either.  Just pull them up good and snug, loosen and repeat multiple times.  The repetition allows the slight mismatch that might exist between components to seat themselves especially when mating new to old.  That system has always worked for me when there is no damage to the flares.

[SKTP]

Shaun from Slingshot got back to me...reply pasted below:

Hi Chris.  Flared connections need to be a little tighter than say banjo bolt connections.  This is because of how the seal actually works. The caliper uses a 45 degree flare to seal.  The threads serve no purpose but to allow the flare and the inverted flare on the adapter end to be drawn together. 

The inverted flare seat angle actually isn't 45 degrees.  It is 42 degrees. The seat angles vary to the tube angle because it is important to seal the smallest diameter to get an effective seal.

If you notice any burrs on either the male or the female flare, use some very fine sandpaper to remove them.

I suspect the source of your leak is on the caliper side of the seal.  It is after all 40 years old and may have been distorted in it's life. Loosen and retighten the adapter to the caliper a few times.  This will help seat the flares as the metal surfaces need to actually conform to one another ever so slightly.  

Your teflon tape on the threads is just containing the leak not stopping it.

[SKTP]

Oh and he posted here, just noticed that.

Top notch shipping, product and customer service...thanks Slingshot!