Commando brake upgrades

This may be of interest to anyone looking for a little more stopping power and front brake feel for their disc brake Commando.

When I restored my 73 Roadster, I replaced the stock caliper with a Lockheed racing caliper. I also replaced the stock brake disc with a Hyde 13" disc. I used the stock master cylinder with this combination. The stopping power was okay, but it required massive pressure on the lever and the feel was much like squeezing a block of wood.

After some research, I found that this was caused by a mismatch in the sizes of the caliper piston and the master cylinder piston. I had the master cylinder re-sleeved by Vintage Brake in Sonora, CA. I think that the re-sleeve went from 15mm to 12.5mm. I also got some Ferodo Platinum pads for the caliper. These pads were recommended by Vintage Brake as the best selection for street riding. The combination of these changes made a huge difference. The brake has a good progressive feel and the stopping power is a big improvement over stock.

For the rear brake, I replaced the drum/sprocket with a new unit and upgraded to the softest Ferodo brake shoes that Vintage Brake offered. The result is not much improvement. It's good enough to keep the bike from rolling if you're stopped on a hill and that's about it. The good thing, I suppose, is that there's no danger of locking the rear brake unless you're riding on a very slick surface.

Correction; it's a 12" Hyde disc.

mgrant,
Center the back plate and it'll stop you. If I remember rightly you slacken the rear spindle and tighten with the rear brake full on. Instructions are in most manuals etc.
Get the front working better and you wont need the back one :wink:
Cash

Commando brakes upgrade

Hi there, I second your comments on the front brake upgrade, which really works. The sleeved-down master cylinder definitely makes a difference.

I talked today with Les Emery at Norvil, England about my rear brake. He recommended enlarging the hole in the spindle slightly (a few mm on radius), so that when you apply the rear brake while tightening the dummy spindle, the brake plate can centre itself properly in the brake drum. This is necessary to make allowances for the lack of precision with which the brake plate was manufactured. He also recommended tightening the main wheel spindle before you tighten the dummy axle. Finally, he recommended inspecting the shoes to see if they are contacting parallel to the drum surface.

When I inherited my '73 850, the drum surface, while smooth, had a varnish which may have originated from grease which escaped from the unsealed bearing over the years, or excessive grease applied to the pivots and cam. It took a rub down with 600 emery, a thorough de-grease and several repeats to get it to a nice satin finish, but the difference in braking performance, with new Ferodo shoes, was noticeable.

Please forgive me if you know this already. I just thought I would share my experiences for what they are worth.

I am surprised that Les didn't sell you the alloy backing plate that already has the enlarged hole. He is very proud of them. It's kind of funny he told you to tighten the long axle first. He told me the opposite many years ago.

Maybe I should buy an alloy brake plate! Yes, it does seem funny that the main wheel spindle should be tightened first. I guess I should try it and see how it works.

I read some of your previous posts, Norbsa; they were very useful. I find that the search engine for this forum doesn't isolate each author's entire posts. I was looking for some of your earlier ones on brakes.

Daveh, You deserve some kind a metal or gold star for going over a brake with 600 grit. 60 grit-rocks on paper for me. Some years ago I wrote a post about using 60 grit glued into the drum to sand in the arch on a fresh set of shoes. The search function can get a little troublesome going that far back. I wouldn't spend the money on the back just drill the old backing plate. I think 7/8 but check me on that, and sand in fresh shoes, your good. You will find that now that the front works so good all the weight comes off the back and it locks too easy.

Re: disk brake upgrade

Sent: Wed Sep 26, 2012 6:42 am
From: mightydaj
To: hobot
Sorry I did not reply back sooner. I wanted to do your upgrade and get some riding time on it for evulation of the difference. Plus I am not known here so I get no private messages and don't even think to look here for them.
Well I did do your upgrade, but only partially evualted the difference. I haven't gotten in very many rides on it since then (lots of different reasons) but at least enough for an initial aprisal. However I cannot make a true direct comparison as there were other factors also. This is what I did.
My Norton (1974 850) had a master cylinder leak since I got it (2 years ago). It did not leak too bad, but every once in a while the front brake lever would go all the way to the grip with no resistanse (scarry sensation). The next pull or two would restablish fluid pressure and it would hold good pressure. So it was ridable as long as space was left in case the first pull failed. But the cylinder did need fixing, so that was done along with your upgrade. The cylinder was cleaned then honed out with fine sandpaper (it had some rust and lots of crud but mostly in the area not swept by the piston). It looked good after I was finished. The piston was pretty rough and rusty (about 1/2 of it) but it also cleaned up ok. I cleaned everything up real good. I got a brake kit from Old Brits and replaced the rubber parts. I then did your upgrade on the old black rubber part with the hot 6 penny nail and put it all back together. I also took the front wheel brake disk off and used a "scott brit" pad on my drill to deglase the disk on both sides. I am no expert on doing that so I hope I did it right. I haven't noticed any puslating so it is probably ok.
So the master cylinder was brought back to normal and the disk deglased along with your upgrade.

My initial finding from the short rides I have done are positive, but not as rosy as your postings. I have found that now it does indeed stop better. I can now even lock up the front wheel if I pull very very very hard. Before that was not possible at all, you could get maybe 1/2 as much stoppage as that, plus it felt totally wooden as they say. It does stop much more evenly now too. Before it seemed to stop somewhat ok at first but then less well as it slowed down (like the same pressure was not slowing it down any further), requiring even harder pulling to get it to stop fully. The stopping distance is now a good bit less, somewhere between 1/3 and 1/2, depending on how hard I pull. It does take less pull to stop, but is by no means an easy pull. The lever still has to be pulled hard, very hard for fast stops. Before it had to be pulled very hard to stop at all. But compared to my 2007 Bonneville, you have to pull more than twice as hard on the Norton. Plus the modulation is way better on the Bonneville, meaning I can lightly change how much pressure and immedeatly feel the difference. The Norton still can't match that, you have to pull hard and pulling harder doesen't have as much effect. It is still more of a on/off brake than a modern. I know I didn't explain that part very well. There is definate improvement. I can't say how much came from any one part of what I did. It is now much much better than it was and is far safer to ride. Before I had to leave lots of room to stop, now I can ride with normal traffic spacing confidently. Thank you for sharing your upgrade with me. The only thing I am dissapointed with is still having to pull so hard. From your posts I was expecting 2 finger operation like my Bonneville. I have a good grip so it is no problem to pull hard, just was looking forward to more, plus I worry that someday I will forget which one I am on and pull the Bonnie's lever at Norton strength and crash. Anyway I do thank your for your help, it has made a big difference. I may still get a sleeved master cylinder later, but for now I will stick with this upgrade and see how it feels as I get more used to it.

I saw your post about Lake Of The Pines. Are you going this year? I want to take my Norton up there this year if I can get 1 more leak fixed, otherwise I will take my Bonnie. I would very much like to meet you in person. How could I identify you (provided you don't mind meeting)?
David Johnson.