13 mm Front disc kit

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New to this forum but have owned Nortons for 8 years. My 74 850's front disc master cylinder stuck in when pulled on lever. "Time for rebuild" When I disassembled it ,it had a 13mm sleeve and serial number etched on it . Called Al Miles and it was one of his rebuilds. He wanted $265 to rebuild it!! I told him it was perfect on outside and didn't need powder coated. His reply was $200. Not bad profit for $15 worth of parts. He wouldn't sell me a rebuild kit either! I think he needs a lesson in customer service. Refuse to deal with him!!
So I get a kit from Andover. Parts look the same but after bleeding from bottom up, the lever has NO resistance. Bleed things again, no air bubbles but again won't build pressure. Both holes in bottom of master cylinder are open. Miles uses a Nylon piston with one 'O' ring and one cup. Andover has an aluminum piston one 'O' ring and one cup. Is there supposed to be an expander, if so not included in rebuild kit. There was no valve which I have read is to be removed? So what an I missing? Thanks
 

Time Warp

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The piston unit would need to be in the correct position in the bore in relation to the two orifices in the floor of the brake fluid reservoir for starters.
The method used to reduce the bore might come into play as would the lever to piston.
 

RoadScholar

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The piston unit would need to be in the correct position in the bore in relation to the two orifices in the floor of the brake fluid reservoir for starters.

Totally on the money.

You might find that the Magura 13 mm internals fit. correctly, it might not; measure twice, buy once...

Best.
 
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New to this forum but have owned Nortons for 8 years. My 74 850's front disc master cylinder stuck in when pulled on lever. "Time for rebuild" When I disassembled it ,it had a 13mm sleeve and serial number etched on it . Called Al Miles and it was one of his rebuilds. He wanted $265 to rebuild it!! I told him it was perfect on outside and didn't need powder coated. His reply was $200. Not bad profit for $15 worth of parts. He wouldn't sell me a rebuild kit either! I think he needs a lesson in customer service. Refuse to deal with him!!
So I get a kit from Andover. Parts look the same but after bleeding from bottom up, the lever has NO resistance. Bleed things again, no air bubbles but again won't build pressure. Both holes in bottom of master cylinder are open. Miles uses a Nylon piston with one 'O' ring and one cup. Andover has an aluminum piston one 'O' ring and one cup. Is there supposed to be an expander, if so not included in rebuild kit. There was no valve which I have read is to be removed? So what an I missing? Thanks
Yeah , I had the same issue with the Miles rebuild. Wasted a lot of money and not much got resolved.
 

Onder

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Painful story. Hope to hear you resolved it but if not sometimes best to just write off the loss and start over.
 
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If you are going off the same holes in the Norton Lockheed MC then you need the plunger to match the dimensions of the original plunger in terms of total length and positions of the seals regardless of your chosen diameter. Even then you need to adjust it so that the primary seal leaves the reservoir with access for fluid to the caliper in the relaxed position by adjusting the position of the lever. Make sure any adjustment does not create a binding in any position of the lever.

 
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Did the original guy makes his own pistons? Just wondering as the older AN 13mm conversion kit for the REAR cylinder uses a plastic/nylon piston. Perhaps that's where he sourced his?
 

cliffa

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New to this forum but have owned Nortons for 8 years. My 74 850's front disc master cylinder stuck in when pulled on lever. "Time for rebuild" When I disassembled it ,it had a 13mm sleeve and serial number etched on it . Called Al Miles and it was one of his rebuilds. He wanted $265 to rebuild it!! I told him it was perfect on outside and didn't need powder coated. His reply was $200. Not bad profit for $15 worth of parts. He wouldn't sell me a rebuild kit either! I think he needs a lesson in customer service. Refuse to deal with him!!
So I get a kit from Andover. Parts look the same but after bleeding from bottom up, the lever has NO resistance. Bleed things again, no air bubbles but again won't build pressure. Both holes in bottom of master cylinder are open. Miles uses a Nylon piston with one 'O' ring and one cup. Andover has an aluminum piston one 'O' ring and one cup. Is there supposed to be an expander, if so not included in rebuild kit. There was no valve which I have read is to be removed? So what an I missing? Thanks
Welcome mean gene. Personally I would not risk mixing parts on a front brake. I think the Miles kit used a different spring. If you don’t have the expander what does the spring bear on?
some good info on this thread:

maybe it would be worth considering changing the complete sleeve kit to the madass140 which seems to be well regarded.

Cheers,

cliffa.
 

Yorkie

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I am suffering the same issue with a 13mm kit. I cannot get a hard brake lever. I think the piston is positioned too far in when assembled so I’m slowly removing material off the brake lever to allow it to move outwards. I tested this theory by replacing the pivot screw with a smaller diameter screw and now I can get fluid to move.
 
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Thanks for info! Going to try Andover piston and see. Be delivered in a week or so. 25 degrees here , don't think I'll be riding soon. The other thought I have had is the washer between the spring and cup could act as a expander if it were floating on piston allowing pressure to expand cup. Right now it is a real snug fit. Cup is on correct direction, but doesn't act it. Piston drawing is great but where are the holes in relation to front cup at rest. Thanks
 
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I don't know why anyone tries to perservere with rebuild kits when you can get a new MC kit sized down to 13 mm direct from Andover. I also tried the rebuild kit, from RGM, lasted about 3 years and failed on me on a ride.
 

madass140

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I don't know why anyone tries to perservere with rebuild kits when you can get a new MC kit sized down to 13 mm direct from Andover. I also tried the rebuild kit, from RGM, lasted about 3 years and failed on me on a ride.
I'm inclined to agree with you even though I've sold 100's of resleeve kits, but a lot more 1/2" mastercylinders for pre MK3's
 

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I had mine sleeved to 12 mm and a piston made especially. I designed a cap for the push end that had removable shims in it to get the alignment correct.

Unfortunately when I went back to the supplier to get 2 more 12 mm brake seals, i was told they cant get any more.
Does any one know of a manufacturer of 12 mm brake seals?

Dereck
 

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Does any one know of a manufacturer of 12 mm brake seals?

Dereck

Brembo for one ( to suit 05 calipers)
Would the ID of the cup be compatible is another thing but they might be forgiving.
 
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Deets55

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I had mine sleeved to 12 mm and a piston made especially. I designed a cap for the push end that had removable shims in it to get the alignment correct.

Unfortunately when I went back to the supplier to get 2 more 12 mm brake seals, i was told they cant get any more.
Does any one know of a manufacturer of 12 mm brake seals?

Dereck
Dereck,
I think Honda uses 12mm on some of their bikes. I might have a part number in my garage. I’ll take a look next time I’m out there. Might have found it on the XS650 web site under the parts section.

EDIT:
It was Mike’s XS site and I don’t see them listed anymor.
 
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Thanks guys. I could always make a new piston to suit the alternative seals.

Dereck

i have just made an inquiry via Brembo NZ.
 
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Looking at the spec on a couple of sites the Brembo PS12 master cylinder as a 12.7mm piston not 12mm.


Dimensions: Solid piston 12.7mm OD x 65mm


brembo ps12 piston seal kit. 12.565mm


brembo ps12 piston seal kit. 12.565mm

Not the first time wrong info gets propagated so worth checking
 

Time Warp

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Not the first time wrong info gets propagated so worth checking

Those are all for round cap master cylinders, at no time did I mention the PS12 but agree.

The kit I linked to is for the rectangular cap 12 mm piston unit but confirmation of it and the actual bore of the OP's M/C might be prudent.

Reposted.
This clearly says 12mm piston.
 
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