Calipers and Brake line

[jimmock]

I think the nut (on the pipe) is bottoming out on the threads before it is clamping the tapers properly.

[z1bman]

Hi Steve

Interior nipple? I have tonight removed the metal break line and checked the calliper inside the threaded hole. The bottom of the hole looks like it is slightly cone shaped and there is a hole in the middle which looks clean enough.
Threads are clean also but when I put the boreal line back in and tight there is a good 1mm slack movement and when I blow down the tube air escapes between the threaded bolt and the tube.
Doesn't feel right to me
Any advise?

the cone shaped metal seal inside the caliper thread is not removable & i have never seen one fall out or successfully removed? you do say in the above post that you can see the convex/ cone? if that is correct there is no logical reason why the pipe wont seal? unless someone has removed it by drilling it out

[Wayne1960]

Ok had both callipers off tonight and taken a good look inside the hole. This is what I see

The thread goes all the way to the bottom of the hole.
When brake pipe screwed in it bottoms out with only 1 thread visible.
The pipe is loose with app 1 to 2 mm up and down movement.
The bottom of the hole is clean and concave so higher at the thread lower at the small hole in the middle.
When the thread bottoms out the pipe because it's lower in the middle moves up and down.

The only way I can see it working is to grind the thread at the sides to let the middle drop further.

It doesn't look like anyone has tampered with the insides

Nightmare!

[jimmock]

Ok had both callipers off tonight and taken a good look inside the hole. This is what I see

The thread goes all the way to the bottom of the hole.
When brake pipe screwed in it bottoms out with only 1 thread visible.
The pipe is loose with app 1 to 2 mm up and down movement.
The bottom of the hole is clean and concave so higher at the thread lower at the small hole in the middle.
When the thread bottoms out the pipe because it's lower in the middle moves up and down.

The only way I can see it working is to grind the thread at the sides to let the middle drop further.

It doesn't look like anyone has tampered with the insides

Nightmare!

IS THE FLARED TAPER ON THE "NEW" ONE THE SAME AS THE OLD ONE??

I still think we have a taper problem here???

[Garn 1]

Wayne, I'm pretty sure there is a brass olive that should be in the bottom of the threaded section in the caliper. The tube illustrated should sit on this and the fitting is compressed by screwing the connection onto it.
RegardZ.

I have had this trouble and from memory, I purchased a small brass olive (read.. internal nipple) and fitted it into the flanged end of the brake tube and buttoned up!
RegardZ.

[jimmock]

Are BOTH flares on the pipe the same?

ie, operation 1 not operation 2 ?

In the pic it looks like ONE OF EACH??

If they are the same does the other end have the same problem??

[z1bman]

i am not 100% sure but i think the metal seat in the caliper should not taper inwards in the center. if someone has bolted a hose or pipe directly to the caliper with a standard banjo bolt chances are it would bottom out on the seat before the hose was tight + they have removed it by drilling + that's why yours is tapered in the center + normally there are at least 3 thread's left on the nut when fully tightened

[Wayne1960]

Wow I was hoping this would be an easy fix and something I had simply overlooked!
Ok flares are the same and I've tried both ends in the calliper with the same results.
The olive might work and it sounds plausible.
When I got the bike the flexible hose was connected directly into the calliper with a banjo.
I have checked the length of the banjo fittings that were used and they bottomed out allowing the flexible hosed to cramp down on top.
This probably worked ok but I wanted the original metal pipes.

Thanks everyone for a great forum and all your suggestions. If anyone has a clear answer please post.

I'll try to find the olive.

[oldzed]

The picture should show the different ends .
Concave is a funnel towards the pipe
convex is a bulge on the end of the pipe.

http://www.bikernet.com/docs/stories/10717/EPSN2958.jpg


If you have a flat surface , on the caliper, making a brake pipe with the convex end may seal.
Most garages can make a test pipe up to try this.

The problem is that most garages use copper or cunifer not steel .

If you want a couple of pipes made up in copper let me know and I can make a couple up. Just give me the overall length.

[Wayne1960]

Oldzed

Thanks for the offer. I have purchased the steel pipes from ZPower and are exactly the same as the picture in the previous post. You will see the bottom of the pipe is convex but the base of to hole is also convex leaving nothing for the pipe to pinch up on.
I cant understand why it is like this but it is.
Ill keep digging away.

[Garn 1]

Wayne, if the base of the hole in the caliper is convex (meaning it protrudes in the centre), then the tube that fits it must be female having a flange that should seal up against it.
I can only say that the nut is not compressing the tube flange onto the protrusion in the caliper! As most others have mentioned.
Maybe the previous fitting flattered the protrusion in the caliper?
RegardZ

[jimmock]

Wayne, if the base of the hole in the caliper is convex (meaning it protrudes in the centre), then the tube that fits it must be female having a flange that should seal up against it.
I can only say that the nut is not compressing the tube flange onto the protrusion in the caliper! As most others have mentioned.
Maybe the previous fitting flattered the protrusion in the caliper?
RegardZ

Or maybe the "new" pipe aint right???

[Wayne1960]

Thanks guys

Garn I will check out the nipple thread thanks and what you explained is exactly what I have pictured but I searched all day yesterday and found nothing. The new part looks right.

Keep you posted

[oldzed]

As per PM this is what I was thinking might work

[oldzed]

See Item 28 in the link 3/16 would be the size

ww.scparts.co.uk/sc_en/warehouse/tuning-internal-and-external-fixtures/braking-system/brake-pipes/male-unions-female-unions-solder-nipples-olives.html