I need to upgrade my Brakes 75 850

concours said:

"I'm wondering about the effect of removing the chrome plating off the factory rotor. Does the rotor now rust? Did you have to change the type of pads?"

The effect is a greater friction coefficient. Of course it will rust. The Ferodo pads work great.
Many people have removed the chrome.

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My one owner '73 has the original master cylinder and caliper. I've rebuilt the master cylinder a few times and change out the fluid periodically via gravity. No mush. Caliper has stainless pucks and Feroodo pads. AND I've run a chrome disc for years. I'm pleased with it and I've locked it up. Not that I wanted to..

The first thing to do is get a 12mm master cyl for the front.

850cmndo said:

My one owner '73 has the original master cylinder and caliper. I've rebuilt the master cylinder a few times and change out the fluid periodically via gravity. No mush. Caliper has stainless pucks and Feroodo pads. AND I've run a chrome disc for years. I'm pleased with it and I've locked it up. Not that I wanted to..

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That's a good result.

I feel so strongly about getting the chrome off, I bought 2 bare iron rotors for my new-to-me T160.

The fact that chromed brake rotors are no longer used speaks volumes to how valid an engineering design it was.

I found this 13 mm sleeve kit om Ebay here in the U.S. The guy selling the kit doesn't provide instructions, but said there are you tube videos out there showing how to do it. The knirling on the sleeve makes me think it is just pressed in the existing MC. The groove may be to allow fluid to flow with out needing to align a hole. Does this make sense to anyone who has done a 13mm sleeve? https://www.ebay.com/itm/135749778070

richlandrick said:

The groove may be to allow fluid to flow with out needing to align a hole.

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Yes although there should be two grooves as the RGM cylinder sleeve has as I've never really agreed with the idea of the system refilling through the bleed hole plus the RGM cylinder screws into a thread cut in the master cylinder.

Note that the RGM website isn't working at the moment.

Yes it makes sense, the groove means you do not need to align holes to the insert as you press it in. By the time its near the holes and you look there is so much of the insert in the body it won't twist. Use blue loctite on the OD. I also drill in on the master cylinder from the handlebar recess and tap it 3mm for a grub screw to lock the insert.

acotrel said:

The rear brake on a motorcycle is not relevant, unless you need to steady the bike in a corner, or put the bike on the ground. A single disc on the front will never stop a bike as heavy as a Commando which is being used to it's full extent. Fitting the second disc involves doing something to accommodate the caliper on the other fork slider. My Seeley 850 has Ceriani forks, and the caliper mounts on both sides are a bodge job. My front hub is Honda CB750, the two discs are both undrilled steel off a 1970s Suzuki - cheap from the wreckers. Both calipers are Lockheed AP with the master cylinder designed for one caliper but operating two. I ride the bike with my fingers wrapped around a quick-action twin-pull throttle, and my forefinger operates the brake. For racing, it needs to be like that. On a road bike, a larger master cylinder might be better - safer,

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Poor old Al seems to have never had a single front disc fitted bike that the bakes never worked and a Commando isn't such a heavy bike as he says, my Commando front brake worked great when it was new could even lock the front up with ease, but as it aged the front brake power got worst.
My front single disc 2013 Triumph Thruxton the single disc brake worked great as well the 1981 Triumph Thunderbird (they did stop), never had any problems stopping with a single front brake, but of course modern single disc brakes do work better than old 50+ year old singe disc.
My Norton now running with a full upgraded Grimica front brake system works great, 1 finger operation if I wanted to use 1 finger, stops easily even at high speeds, but then I am also smart in how I use my brakes, out riding the tight twisties and high speed straight to the next corners I learned a long time how to slow my bikes down before the next corner without using my brakes at all, I never use my brake while in the corner even if I was still going a bit faster than I should, relying on my skill and great handling bike to get me through without any panicking, but I had my time losing it on corners but wasn't from braking, 2x lose gravel and pushing my tyres way past their limits when hitting those gravel on the corners at speed didn't help.
Of course putting chromed disc on any bike brake system is not a good idea at the time, but also brake pads are so much better these days and the stock Commando pads weren't that big and being round at that, no wonder the stock disc were bad as they wore and a single piston caliper didn't help.

Ashley

I've been the route of having the chrome ground off and the rotor drilled as well as a sleeved MC. It was better for sure but ultimately I went with a larger diameter rotor and AP caliper and moved the ground and drilled rotor to the rear. Brakes are quite adequate now.

I don't see any reason to sleeve the rear MC as in the present condition it's more than adequate and unlikely to be too much brake. You've got plenty of power in your foot to lock the stock rear especially with the chrome ground off and good pads. See the Youtube videos of rear end motorcycle crashes with the rear brake obviously locked and where it seems there's room to stop if only the front brake had been applied aggressively. Sadly most of those videos are HDs. Mom wouldn't let them have a bike and now they've got their big cruiser and drive it like a car. Sorry for the rant.