Mk 3 Commando front master cylinder resleeve

Since my Mk3 is apart, I figured I’d get the master cylinder for the front resleeved for better braking action. Has anyone in the group had this done recently, what was the cost, and did it do what you expected? Thanks in advance!

I installed an RGM sleeve kit on a MKIII, but I used it with a Brembo 4 piston caliper and 320mm floating disc. They work great. The kit is about $80 and you need a decent drill press or mill, 16.5 mm drill, and an 18mm X 1.5 mm pitch tap. You will need to devise a jig to hold the cylinder in alignment while drilling and tapping.

Alternatively, Andover Norton sells a complete new master cylinder with a 13mm bore for about $385 plus shipping.

Done quite a few of the RGM sleeve conversions for customers and my own Mk3, and Ive also dealt with the AN 13mm bore M/C for other customers. I prefer the RGM sleeve kit as you can 'tune' the piston pusher length to its optimum to maximise the fluid moved and get the best lever feel, and its cheaper as well!
According to the fitting notes that come with the RGM kit there is a variance between Norton M/Cs of about .080" on the optimum piston pusher length, hence the adjustable piston pusher.

Power,
Unless you feel comfortable and have access to the tooling to do this procedure, I would suggest that you sent it off to someone that has done this before.Just my 2 cents.
Mike

IMHO ,had bad luck with sleeves, just get this and be done with it

I would never resleeve the master cylinder for the front brake myself. The front brake and the gearbox determine how fast you can ride. I had my front master cylinder resleeved by a business which specialises in brakes. It did not cost much. I use a master cylinder which is used for one caliper to operate two calipers, in association with a twin-pull quick-action twist grip. I use the palm of my hand and three fingers to rev the motor while changing down, while operating the front brake with my forefinger. Combined with close ratio gears there is a lot of advantage in my set-up - it helps me to win dog-fights. I am systematic and not a maniac. It is important to have fun when you race.

Hi, I resleeved my master cylinder with a RGM kit. I did it with a minimum of equipment other than a drill press. The operation was straight forward and I believe can be performed by people with a minimum of technical skill if carried out with care. The kit had clear instructions and was exactly as described. It transformed my bike from having appallingly heavy brakes to acceptable brakes, more than fulfilling my expectations. No, it obviously is not a substitute for more expensive modifications with complete new discs, callipers etc but it does retain original appearance whilst massively increasing safety and riding pleasure. I can’t understand why Norton specified such a large bore diameter at a time when they were playing catch up with the Japanese opposition as it involved no extra cost. I have read from other contributors that Norton didn’t want overly light brakes so as not to catch out riders unused to discs but this seems unlikely to me as even with the reduced cylinder diameter the brakes are by no means overly powerful. Out of interest the brakes on my Trident and Bonneville are far superior to the original Norton brakes. I am not familiar enough with Honda and other large Japanese manufacturers to make a direct comparison but presume whilst not great by todays standards they did not require a vice like grip to get any meaningful retardation.

Alan L said:

Hi, I resleeved my master cylinder with a RGM kit. I did it with a minimum of equipment other than a drill press. The operation was straight forward and I believe can be performed by people with a minimum of technical skill if carried out with care. The kit had clear instructions and was exactly as described. It transformed my bike from having appallingly heavy brakes to acceptable brakes, more than fulfilling my expectations. No, it obviously is not a substitute for more expensive modifications with complete new discs, callipers etc but it does retain original appearance whilst massively increasing safety and riding pleasure. I can’t understand why Norton specified such a large bore diameter at a time when they were playing catch up with the Japanese opposition as it involved no extra cost. I have read from other contributors that Norton didn’t want overly light brakes so as not to catch out riders unused to discs but this seems unlikely to me as even with the reduced cylinder diameter the brakes are by no means overly powerful. Out of interest the brakes on my Trident and Bonneville are far superior to the original Norton brakes. I am not familiar enough with Honda and other large Japanese manufacturers to make a direct comparison but presume whilst not great by todays standards they did not require a vice like grip to get any meaningful retardation.

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It wasn't only Lockheed / Norton that got it wrong. My 1980's Yamaha XV1000 TR1 had appalling brakes, and they were twin disc. (single piston calipers though). I seem to remember the master cylinder was something like 18mm !! I fitted a Yamaha Fazer 14mm and it was transformed. My 2019 Himalayan, awful front brake too, so just did similar, and it's now far better.
Honda CB750 of the same era as the Commando, terrible front Brake.

Upgrade the whole front brake system, I did mine 14+ years ago when my stock front brake let me down without warning lucky was slow speed accident but still fractured arm and broken thumb, could have been worst, upgraded to a full Grimca front brake system while recovering, 12" floating disc, and Grimica caliper, SS line and Grimica MC and longer brake lever all part of the full kit, at the time was under $600 all up delivered to my front door from RGM, one of the best upgrades I done in 49 years of ownership, one finger braking if I wanted too, yes there are other brake upgrade kits around.
I brought the sleeve kit for my stock MC from RGM but my brakes let me down before doing it and decided the full front brake system was a better choice, my life is more important than a sleeve kit and 50 year old braking system that was not real good to begin with, the stock system worked good when new but as it got older they got worst, my Norton stops as good as my modern Triumph Thruxton S, one day the stock front brake will let you down as it did with me without warning and the Grimca kits looks good as well.
I am not a heavy brake person, it handles great, is a lightweight bike but stops great when I need it, I very rarely use my brakes when riding only when stopping, 50+ years of riding you learn how to slow down without using your brakes, but it's good to know they will be there when needed.

Ashley

That conversion would cost even more than Drink bill for 2 months !!! Will stick with (the late) mick hemmings norvil disc conversion and rgm sleeve ! Big improvement. And saves me facing the present world, Psssttt ! 4th.

Simple fact of life - a road bike IS NOT a race bike. If a road rider tried to ride my Seeley 850 without instruction - they would probably almost immediately crash. It goes fast enough to give you a tweak of adrenalin which can cause you to grab the front brake. It is one finger operation. When I sold my 500cc Triton back to my mate who had originally built it. I almost immediately got a phone call from him asking about the linings which were in the drum front brake. The other thing about my race bikes - when you are halfway around a corner and going fast - if you do not gas them fairly hard, you will not get around the corner. Both my brother and another guy ran off the corner at the end of the front straight at Calder when they tried to ride my Triton 500 like a road bike. Road bikes are made so beginners do not neck themselves. A bigger bore master cylinder, and the tendency to understeer when gassed are features of a road bike. When you need to counter steer a Commando as you enter a corner - that is understeer - very few road bikes have more than neutral steering. On a two-stroke or 4 cylinder super bike, on the road - oversteer when gassed would be fatal. The thing about it is - when a bike handles like that, it is not obvious to the rider, until they get stupid.

One of the things which really frustrated me when I began racing, was I could never use a lot of throttle in corners. Riding on public roads is very different. But I do not believe people should road race before riding road bikes. Casey Stoner went from go-kart racing to MotoGP. Others race in Motocross, so are probably very situationalist - both ways seem dangerous to me. Riding on public roads teaches you to stay ahead of the game. I have watched interviews with Casey Stoner and Wayne Gardner - I do not know how they stayed alive.

ashman said:

Upgrade the whole front brake system, I did mine 14+ years ago when my stock front brake let me down without warning lucky was slow speed accident but still fractured arm and broken thumb, could have been worst, upgraded to a full Grimca front brake system while recovering, 12" floating disc, and Grimica caliper, SS line and Grimica MC and longer brake lever all part of the full kit, at the time was under $600 all up delivered to my front door from RGM, one of the best upgrades I done in 49 years of ownership, one finger braking if I wanted too, yes there are other brake upgrade kits around.
I brought the sleeve kit for my stock MC from RGM but my brakes let me down before doing it and decided the full front brake system was a better choice, my life is more important than a sleeve kit and 50 year old braking system that was not real good to begin with, the stock system worked good when new but as it got older they got worst, my Norton stops as good as my modern Triumph Thruxton S, one day the stock front brake will let you down as it did with me without warning and the Grimca kits looks good as well.
I am not a heavy brake person, it handles great, is a lightweight bike but stops great when I need it, I very rarely use my brakes when riding only when stopping, 50+ years of riding you learn how to slow down without using your brakes, but it's good to know they will be there when needed.

Ashley
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Ashley - with my bike, I play it like a piano - I ride it up and down through the gears while braking and accelerating. Riding a road bike is more dangerous for me - unless I am riding with intent, I become mentally lazy. When I was a kid I rode road bikes for about ten years, however even then I rode with intent - I should be dead. I now know how stupid I was.

I had two different re-sleeved MCs fail. Both were done/suplied by a professional company. First failure occurred overnight in the garage. Worked fine on a ride one day, next day in the garage getting ready to ride the lever went to the handlebar. 2nd time similar failure but this was out on the road. Good brake at a stop light, NO brake at next stoplight. Based on my experience I wouldn't use a re-sleeved master cylinder under any circumstances. I don't need the excitement.

Thanks for all the solutions!

MexicoMike said:

I had two different re-sleeved MCs fail. Both were done/suplied by a professional company. First failure occurred overnight in the garage. Worked fine on a ride one day, next day in the garage getting ready to ride the lever went to the handlebar. 2nd time similar failure but this was out on the road. Good brake at a stop light, NO brake at next stoplight. Based on my experience I wouldn't use a re-sleeved master cylinder under any circumstances. I don't need the excitement.

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So, Who made the kits or parts, what brand? Did you ever try to find out what caused the failure?