Nortonbrake m/c

Hi Comrades,

I dug out a m/c reconditioned by "nortonbrake@sbcglobal" (located in Seattle) which I bought new many years ago. It came with an installation letter, unfortunately the letter doesn't say which size of piston is fitted, except all internal parts appear to deviate from Norton's parts.,
so I expect piston size to be larger than the original piston (15 mm ?). The rebore and rebuild may have been performed to metric standards. It may still be acceptable as I will fit twin disc and calipers at the front end.

The company who made the reconditioned m/c appear to be out of business.

Does anyone know about the details of this m/c?

- Knut

Knut,
The original bore size was 5/8" which was not the best ratio unless you wanted anti -lock braking systems. I.E. you couldn't squeeze hard enough to lock up the front wheel unless you are a silver back gorilla.
My guess it is 13mm with your kit. So please verify for your own best interest.

13 mm or 1/2 " is the optimal bore size. I believe Andover Norton has new M/C at that diameter.
Cheers,
Tom

Is it anything like the Old Britts (13mm conversion)?
Old Britts wasn't far from Seattle.

"It may still be acceptable as I will fit twin disc and calipers at the front end."
If this is your path, then 5/8" may work better.
I was first assuming that you are using original single disk system.
Twin disks changes the ratio.

L.A.B. said:

Is it anything like the Old Britts (13mm conversion)?
Old Britts wasn't far from Seattle.

Old Britts, Upgrade Commando Master Cylinder to 13mm Bore

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Possibly. Maybe this company was a suppier to Old Britts? I guess I will have to take the m/c apart to find out.

CanukNortonNut said:

"It may still be acceptable as I will fit twin disc and calipers at the front end."
If this is your path, then 5/8" may work better. <....>
Twin disks changes the ratio.

Click to expand...

Yes, it does. I will report my findings.

Thanks,

- Knut

Wasn't there a comment awhile ago that original 5/8" MC was intended for dual disc, calipers but they never produced before going bust?

Tornado said:

Wasn't there a comment awhile ago that original 5/8" MC was intended for dual disc, calipers but they never produced before going bust?

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A 5/8" bore is generally more suited to twin discs (depending on the number and diameter of the caliper pistons) but I think they were either playing safe or the size Lockheed was more interested in manufacturing because Triumph twins/triples single disc master cylinders were also 5/8" (0.625") diameter.

The Triumph twin-disc master cylinder, however, was 0.70" although 5/8" works with Triumph twin discs although some owners prefer the 0.70" master cylinder.
https://www.triumph-spares.co.uk/twin-disc-mcyl-barrel-assy-stainless-070ins-99-9883

mdt-son said:

Possibly. Maybe this company was a supplier to Old Britts?

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Their supplier was Al Miles. He did 13mm conversions on Lockheed M/C's. I've had one for many years now. Al refurbished mine again maybe 8 years ago. He lives near San Jose CA. and was looking to retire last I talked too him.

maylar said:

Their supplier was Al Miles. He did 13mm conversions on Lockheed M/C's. I've had one for many years now. Al refurbished mine again maybe 8 years ago. He lives near San Jose CA. and was looking to retire last I talked too him.

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I see. "nortonbrake@sbcglobal" was a different outfit apparently. I guess I will have to pull the m/c apart then.

Thanks for the info.

- Knut

Big diameter MCs was an early disc brake Thing,
I think that the designers were scared that owners would lock up the front wheels with this new dangled device and gave the brakes MC ratios that resulted in wooden brakes (BMW did the same) and for both Nortons and BMWs a 1/2” (13mm) will work well even with twin discs.