13 mm Front disc kit (2020)
- Thread starter mean gene
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mean gene
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Ok got Andover Norton rebuild kit for 13mm front master cylinder today. Cup, O-ring and new piston. Comparing the two Miles is Nylon, Andover is steel, the O-ring and cup are 1/8 forward from those in the Miles kit. I have rebuilt breaks all my life just did my MK III and this MK II will not build pressure. I back filled the cylinder before mounting, Bled from the bottom up. Even opened the bleeder and left it run, NO bubbles. Cup is in correctly, no other leaks but it will not build pressure. What am I doing wrong????
Try find a large syringe ( often used on fork oil kits ) put a plastic clear flexy hose that fits the bleed nipple tight push both pistons back and crack bleed nipple and fill lines with brake fluid from the bottom
this purges all the air from the lines then do the final bleed by pumping master in conventional way also make sure there are no leaks on the nipple thread a turn of plumbers tape may help
i have also seen an alternative 13mm master set up in the UK very similar to the CNW conversion using a japanese rectangular top type master with adaptor bracket to fit the Lucas switches
i recall it was very well priced at around £60.00
this purges all the air from the lines then do the final bleed by pumping master in conventional way also make sure there are no leaks on the nipple thread a turn of plumbers tape may help
i have also seen an alternative 13mm master set up in the UK very similar to the CNW conversion using a japanese rectangular top type master with adaptor bracket to fit the Lucas switches
i recall it was very well priced at around £60.00
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The position of the primary seal in relation to the feed hole in the master cylinder in the off position is critical for both bleeding and effectiveness of the brake. The primary seal should be clear of the hole so the reservoir fluid has access to the pipe and caliper with the lever in the off position. It also needs to be close to that hole so that the free movement of the plunger is as little as possible before the hole is passed by the primary seal and the fluid can be compressed. Before you mount the master cylinder whilst its still empty of fluid you can test this by moving the lever whilst watching the hole and noting when you see the primary seal pass by.
mean gene
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Will try to post pics but here it is in frustrating nut shell. Removed bleeder and wrapped with teflon tape, hung a iv bottle from the rafters left fluid run from the master cylinder reservoir into the lowered iv bottle, refilled the reservoir 5 times then reversed . Raised the iv bottle and filled the master cylinder NO BUBBLES either direction. Closed everything up anddddd no pressure when lever pulled. WHF Took everything apart. cleaned saw nothing wrong. Decided to use my rifle bore scope on master cylinder sleeve. I know there are supposed to be two holes but mine has a third hole, why, I believe the fluid is flowing between the third and second hole essentially flowing around the cup. Who makes a good sleeve kit? Can I send it to them for install? Tried to contact the $100 one but web sight shut down. Contacted old Brits but no response Thanks again for info
Re bleeding the front brake.
I had exactly the same problem with a bybre/Brembo) brake system. I too bleed from the bottom to the top too fill the system and had brake fluid coming out of the hole into the master cylinder but the brake would not pump fluid down or build any pressure. The problem was trapped air in the master cylinder caused by the hose end of the master cylinder being higher than the reservoir (clipons). I removed the master cylinder from the bars and lifted the lever up (hose end down) and pushed oil up from the calliper again. A large burp of air came out followed by a long string of bubbles. When that was clear the brake worked perfectly. Hope that helps.
I had exactly the same problem with a bybre/Brembo) brake system. I too bleed from the bottom to the top too fill the system and had brake fluid coming out of the hole into the master cylinder but the brake would not pump fluid down or build any pressure. The problem was trapped air in the master cylinder caused by the hose end of the master cylinder being higher than the reservoir (clipons). I removed the master cylinder from the bars and lifted the lever up (hose end down) and pushed oil up from the calliper again. A large burp of air came out followed by a long string of bubbles. When that was clear the brake worked perfectly. Hope that helps.
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Re: the diagram for the Norton Lockheed Piston MkII.
I have made two pistons using these dimensions and sleeved the stock master cylinders down to suit.
Both brakes were massively improved and never gave me any trouble in bleeding or operation.
I have made two pistons using these dimensions and sleeved the stock master cylinders down to suit.
Both brakes were massively improved and never gave me any trouble in bleeding or operation.
I finally forked over for the full AN 13 mm m/c kit. To my surprise, it came fully assembled. Given this, is it OK to just install or do I have to take it apart and soak the seals in brake fluid ?
Second question: I can only use DOT-3 brake fluid, correct ? Thanks everyone.
Second question: I can only use DOT-3 brake fluid, correct ? Thanks everyone.
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Not exactly. DOT 3, although still available is basically an obsolete specification superseded by DOT 4 and DOT 5.1 with higher boiling points. DOT 5, however, is a silicone fluid.
https://blog.amsoil.com/dot-3-and-dot-4-brake-fluid-whats-the-difference/
"Are DOT 3 and DOT 4 Brake Fluid Compatible?
Yes. DOT 3 brake fluid is compatible with DOT 4 brake fluid. However, DOT 4 offers a higher boiling point.DOT 5.1 is used in high-performance and heavy-duty applications due to its high boiling point. It’s compatible with DOT 3 and DOT 4 fluid.
DOT 5 brake fluid is silicone, meaning it doesn’t absorb water. It’s not compatible with the other brake fluids and is used mostly in classic cars that remain in storage for long periods and need a brake fluid that doesn’t absorb water."
jaydee75
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My Yamaha XT225 has a 12mm MC on it, I put it on my Norton before I made my own sleeve and used a Harley kit.
You should be able to get seals for the 12mm Yamaha.
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Grant, your master cylinder will be OK to use, once you fill it with DOT 4 brake fluid. Avoid moving the piston until the reservoir is mounted and filled with brake fluid. Another advantage of DOT 4 fluid compared to DOT 3 is that it is less hygroscopic [absorbs moisture].
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Hi Jaydee. I was speaking to one of the local m/cycle repairers about it and he get me a pair of 12mm seals not so long after I asked that question. Many thanks for your reply though.
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