Master Cylinder Repair

NASAman · Jun 13, 2018

I have a 1974 Norton 850. The master cylinder is in dire need of repair. The piton measures .620 inch so i Believe this is the standard 5/8" piston. I have read about replacing this with a 13 mm kit. Can someone recommend a place in the states that can rebuild this for me? is this something normal people can do in their shop or does it take a machine shop? I plan to bead blast all the corrosion and paint off the outside of the cylinder and repaint it. Any recommendations on the paint?

Tornado · Jun 13, 2018

Look up user Madass on this site...he sells a resleeve kit to take it to 13mm...not hard to perform with his instructions. Seals/piston rebuild kits readily available on-line. Note you might want a new brake light switch as well...mine turned out to be failed but only discovered after got the system all bled and ready....had to repeat the bleed following replacement of switch....might be hard to test switch without having it under oil pressure though.

Guido · Jun 13, 2018

x2 on the Madass kit from Don Pender. I did the rebuild myself. Your MC has been rusting for some time. What you'll need is to get a cylinder hone to clean up the bore prior to install of the insert. I couldn't get the insert to go in so I honed it a little at a time until it was a sliding fit. I thoroughly washed it, glued it in, assembled it, bled it and it was done. The difference in braking was amazing.
As far as paint, I used "hammer paint".
I also found stop light switches online for about $10 ea

JimNH · Jun 14, 2018

Another possibility is an exchange MC from Clubman Racing. It will have a fresh powder coat and look like new.
More money though, of course.

Jdub · May 6, 2019

I have had good luck painting selected motorcycle parts using spray paint. However, the M/C and corrosive nature of brake fluid has me wondering what to apply to this item.

Hammerrite is robust and includes versions with texture. Can anyone recommend a non-powder coat method of repainting the M/C that has worked well for you?

Esmerela · May 6, 2019

NASAman

You could just spoil yourself https://andover-norton.co.uk/en/shop-details/18719/front-master-cylinder-cte-13mm-bore-06-1938-
When you read what some of these guys put themselves through trying to bleed a sleeved cylinder

others can't park their bike in the sun because the front brakes locks

Tornado · May 6, 2019

Jdub said:
I have had good luck painting selected motorcycle parts using spray paint. However, the M/C and corrosive nature of brake fluid has me wondering what to apply to this item.

Hammerrite is robust and includes versions with texture. Can anyone recommend a non-powder coat method of repainting the M/C that has worked well for you?

Never used but this claims to be brake fluid resistant:

https://www.eastwood.com/eastwood-brake-gray-aerosol.html

Seems only in grey? Description says it's a polyurethane ester...so if having a guess, I'd base a paint selection on that type.
Generally, you might just need to suck it up and live with susceptible paint like the rest of us. No biggie as with care, cleanup after drips, and even a touch paint occasionally it is not a problem.

lazyeye6 · May 6, 2019

I had a good outcome having my MC powder coated, which is
allegedly impervious to brake fluid.

Niagara850 · May 6, 2019

I installed a re sleeved master cylinder from Walridge Motors a number of years ago. It's an exchange program, you send them your old one. Can't remember the cost but it was easily installed and a big improvement. Not to modern bike standards but has a progressive feel and better stopping power. Also no issues since installation.

CanukNortonNut · May 6, 2019

I bought the RGM Kit through Clubman Racing and Installed it myself.
You need some machining skills. A mill would be great. A metric tap is required as well.

batrider · May 6, 2019

My powdercoated mc is bubbling up on the sides of the bowl. Like a hard goo.

acadian · May 7, 2019

If you have the option of relocating the switch gear, this Nissin MC is a very nice option, and it looks very similar to the stock unit

Tornado · May 7, 2019

A better option that keeps the stock switch gear is Don's (aka Madass) MC with proper bore size;

His website:

http://www.tritonmotorcycleparts.com/297620485/product/515646/norton-brakes?catid=146825

Jdub · May 8, 2019

Wow, Don's M/C looks very nice! Is that the original Norton lever being re-purposed in the body of that M/C?

Tornado · May 8, 2019

Paging Mr. @madass140 !

madass140 · May 8, 2019

no it doesnt use the standard lever. my lever is a fairly good match for the original

o0norton0o · May 8, 2019

Tornado said:
A better option that keeps the stock switch gear is Don's (aka Madass) MC with proper bore size;

His website:

http://www.tritonmotorcycleparts.com/297620485/product/515646/norton-brakes?catid=146825

I got sick of the stock master cylinder leaking every few years and ruining the paint on my fuel tank again and again... so I sold it here and bought the madass one pictured above. It's never leaked a drop in the 2 years I've had it, and it retains the perch to mount the stock switch gear. My front brake system is a mix of parts. lockheed caliper, yamaha disk, and madass's master cylinder. It all works well...

Anything you buy from Don is going to be quality...

Tornado · May 8, 2019

o0norton0o said:
I got sick of the stock master cylinder leaking every few years and ruining the paint on my fuel tank again and again... so I sold it here and bought the madass one pictured above. It's never leaked a drop in the 2 years I've had it, and it retains the perch to mount the stock switch gear. My front brake system is a mix of parts. lockheed caliper, yamaha disk, and madass's master cylinder. It all works well...

Anything you buy from Don is going to be quality...

Re. leaking of the oem MC....I believe this might be related to the cap not having one of the original seals. Note the rubber accordian "seal" is not the only one needed and the cap threads will bottom out before applying a good snug pressure on the accordian unless there is another spacer seal fitting inside the bore of the cap itself. I made one up out of some teflon sheet I had laying around...but even clear plastic packaging sheet can be used. Besure to leave an opening in the middle of the sheet to allow for the vent hole to breath as needed.

Master Cylinder Repair

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