seriously infected…!

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Jul 16, 2004
Hi chaps!

I discovered this forum through CLASSIC BIKE Magazine and I am completely taken away by the spirit and enthusiasm of you guys!
Must be the bike, eh?
I recently purchased my first ever Norton Commando! Big deal! What a beauty it is. It is a 1972 750 Commando and both the engine and gearbox have just been completely rebuilt. I bought it from a quite competent bike shop here in good old Hamburg, specialized in British singles and twins exclusively. The bike is an absolute minter, with Boyer Bransden Ignition, Hagon shocks, leadfree valves and the lot. The paint is spotless and the bike drives like a dream.
I never ever thought that a 32-year-old bike would have such a modern driving feel to it. To me that isolastic frame system is a complete one off.
It is a dream come true to me anyway, because I always wanted one from the start but could not get my head straight. I used to own several bikes beforehand (all singles and twins), but no other bike has fascinated me like the Commando does.
I am so much looking forward to as much driving pleasure as possible.
As this is my first Brit bike ever, I might be asking you for advice sometime.
Some backlane scratching is on now, folks!

Hooray! Congrats and best wishes are always welcome!
Congrats on the new bike! Post some pics when you get a chance. I have a 71 750 Roadster with a 72 motor. It's going to have a 72 front end one of these days also; I'm converting it from drum brake to disk.

Hi Debby!

Thank you very much indeed! I am picking up my Commando this week. I will post pics asap.
As my Norton has got those interpol silencers, I want to swap them for peashoters. I prefer that stile. Is there anything I have to watch before changing, or does it work right away? I know I have got to change the downpipes as well, as they got a slightly different line to make the peashoters fit. Will I suffer any power loss or doesn’t that make any difference at all? It’s only a stile thingy, but I won’t proceed doing it if that is the case. Which make would you recommend? Toga silencers a quite scarce over here. Decent ones are worthwhile the money.

Have fun and drive careful ya’ll!
Hi Matt,

Yes, the peashooters look and sound great. That's what pretty much everyone here in the USA has on their bikes. I can't answer the technical issues, I'll defer to someone with more expertise for that. Regarding brands, if cost is no object there's a company in New Zealand called Viking that makes stainless steel mufflers and headers. Supposed to be the best available but they're about twice as expensive as the british ones over here.

I'd think any of the British-made ones would be ok. I'd avoid the cheap ones made in Taiwan. I had a bad experience with cheap taiwan petcocks. No more chinese junk for me. Some of the pattern exhaust headers have clearance problems - they don't tuck in tightly enough and the kickstarter hits the muffler. Then you have a dent in your nice new muffler :( I don't know which particular brands are good or bad though.

Hope that helps,
Tip - To avoid the kickstarter hitting the pattern pipes and mufflers, use a '75 MkIII kickstarter. It gives about 3/4 inch additional clearance.
As I just found out, it's Toga-Peashooters, so everything should be alright, shouldn't it?
I will also fit that spring/washer/whats it's name-thingy to prevend the rearbrake-lever
from dropping to the tarmac as well. Safety comes first.


Good luck with the discbrake conversion. I heard rumours that the tls- drumbrake is more up to the job than the single disc. Well, it's rumours... do you plan to go for some aftermarket equipment (Norvil etc) or stick with the original? Checking out quite a bit. Fantastic website, beautiful design, incredible rebuilds. That guy Matt Rambow seems to know his business.

Does anybody drive such a bike? They're so much more appealing than any custom H-D at half the price. Damn shame I don't live round there. The classic scene must be quite lively over there in the U.S., mustn't it?

Anyone up for a chat?
Hi Matt,

I'm planning to use the stock Norton caliper and rotor with a different master cylinder. I'm thinking of using the brembo master cyl that CNW sells. I also had the rotor resurfaced and drilled. That saves some weight, should improve braking in the rain and (mainly) looks really nice.

I've heard the same rumors that the TLS brake can be made to work well. I don't think anything would help my brake though. I can stop just about as fast using only the rear brake. It looks really cool, just doesn't work. I think it would be a great brake for a show bike.

Deb - It's no rumor. The front drum brake on my '69 Commando S type was superior to the front disc on my '75 Commando. But if a drum brake doesn't work for you and you feel it's unsafe, then by all means do whatever it takes to make the bike stop safely.

Matt - yes, the classic bike scene is "quite lively" over here; there are quite a few of Brtitish bike shows to attend, which bring out the real classics like the Vincent Black Shadows. With respect to exhaust, the Toga brand is popular, so the quality should be reasonable.

Drum vs Disc

Hi Debby & Matt,
A friend of mine had his TLS brake worked over (stiffener plate, high friction linings, etc) and it is a very respectable brake, better than the stock Norton disc setup. That being said, it will always still suffer the problems associated with drum brakes: Fade, performance changes due to moisture, need for constant readjustment, etc.

In my professional life, I am a brake engineer for a large defense contractor, and as a pet project, I have performed numerous paper evaluations of different braking setups that could be fitted to the front of a Norton. I have also evaluated some other modern motorcycle front brakes that I consider quite powerful and user friendly that I had access to (BMW & Ducati, both Brembo setups). What I found was that (no surprise), the single best thing that you can do to your Norton disc is to go to a 1/2" (or 13 mm) bore master cylinder. This single change will increase your hydraulic line pressure by 56% with the same lever force. This may be increases further by selecting a master cylinder with a better lever ratio (pivot to grip distance divided by the pivot to cylinder piston distance; the higher the number the better). I found a master cylinder from a Kawi ZX-7 fit the bill quite nicely, but I have also retrofitted bikes with Honda CBR600F3 MC's and Kawi GPZ 750 MC's. The GPZ MC has a long enough lever that it actually alows you to keep the stock RH switch gear (I cut down a broken clutch lever perch to make a cover for the switch).
Not being one to leave well enough alone, the next stage in my analysis addressed the caliper. While the stock caliper is a good design and has adequate piston area, the choice of pad materials available to the general public and the small pad surface area prevent optimal performance. I first started looking at the Brembo setup on my Ducati and tried to locate a similar caliper at a price that wouldn't break the bank. No luck. I then found a right hand caliper from a Honda CBR600F4 was nearly identical to the Brembo and for an added bonus, has higher friction pads as stock. It is easily fit with an adapter plate to the stock fork leg and works with the stock Norton rotor with no necessity to thin the disc. This modification completely transformed the front brake. It is very predictable and controlable while providing 2-finger operation. I think that it is actually more powerful than the brake on my '02 Ducati Monster.
If you would like more details or pictures, let me know.
Interesting. How did you figure out which master cylinders would have the right size bore etc? I'd thought about using a japanese one (cheap, readily available) but didn't know how to choose the right one. I also didn't know if something designed for a dual disk system would work with a single disk. If you could post some pics that would be great.

I guess we mutated this thread huh? :)


Gee we seem to have a lot of people on this forum who own Ducatis. I myself have a 97 900CR. The brakes on that bike work great!

Master Cylinders

As a rule, most single disc set-ups use 1/2" bore master cylinders and dual disc's use 5/8" MC's. The CBR600F2/F3 (not the F4) are an exception, using 1/2" MC's with dual disc's. Most master cylinder's have there bore diameter embossed (in inches) on the body of the MC. All of the MC's that I listed are 1/2" bore and say so on the outside. A word of warning about buying them off Ebay: get the seller to verify the bore size before you bid. You should also be able to get a suitable MC from a local motorcycle wrecking yard. The one in my area sells them for $60 CDN ($45 USD).
Ron L is correct about the Ducati Monster MC: they are a nice product, just make sure you get one from an '02 or older Monster Dark. All other Monsters have twin disc's and 5/8" MC's.
Well, we've done it again, gone from "seriously infected" to master cylinder bore sizes. Where is the eyeguy? We mutated from carburetors to seat covers during a discussion with the eyeguy, very amusing!

I am fascinated by your post and have had similar thoughts. But why would the 13mm cylinder working through a similar caliper (Nissin/Brembo) and using only a 10-inch (254 mm) stock disc offer better braking than the 320 mm dual disc of your Monster? More predictable? Smoother, less grabby? Inquiring minds want to know.
I am currently converting two of my Commandos to a 13mm m/c, one with a Dunstall double disc (9-inch) using a Magura and the other with the stock caliper (for now) using a Brembo. At some point I'd like to then change the stock caliper for a Brembo and use the larger disc (300-320mm).
My reasoning is the larger disc offers greater mechanical advantage and more powerful brake. The Dunstall with its 9-inch discs is pathetic. It looks good, but as with most of the old Dunstall stuff the quality is horrible.
It came as a surpise to me as well. FYI, my Ducati is a Dark, so it only has a single disc. As far as I can see, there are two differences:
1. The Ducati pads uses GG friction code linings (friction coefficient of 0.45 to 0.55), where the CBR pads use HH linings (CF = 0.55+).
2. The Ducati uses a stainless steel rotor, where, as you know, the Norton rotor is cast iron. Even though it is heavy and it rusts, cast iron is the very best brake rotor material you can get. A friend of mine actually machines old Norton rotors to fit airhead BMW rotor carriers as a brake performance improvement.

I have toyed with the idea of modifying a GSXR rotor to mount to a Norton hub, but I really doubt that I will get any more performance out of it, as the different rotor material may negate the increase in diameter.

By the way, another bonus you get with the 4-piston caliper is that the centerline of the pistons are closer to the edge of the rotor, which does increase your mechanical advantage. In the case of my Nissan caliper / Norton rotor setup, it is equivalent to installing a 20 mm larger rotor.



P.S. - Ron, why are you not at the National Rally right now?
Hi guys and gals!
I really think it is quite amusing as well, to switch from one topic to an other. :wink:
The frontbrake of my Commando is working reasonably well from my point of view. Saying that, I even got used to the single disc on my BMW 75/6...
The single disc on my BMW R 100 GS, which I still own, is a lot more ”agressive” since I fitted a steelbraided hosing (missing the right vocabulary here). It’s so damn easy to lock the front brake and I find that quite irretating, ecspecially in the wet...
I reckon I will stick with that Norton front disc, as I prefer to really give it a handfull to make it do it’s job. It’s nearly impossible to lock the frontwheel.
I like that. It’s some kind of workout as well :lol:
With my wife on the pillion seat maybe things will look a bit different...
big deal, even more workout!!
That Ducati brake idea looks interesting anyway.

Keep on rolling!

I'm interested in the CB600 caliper option you are looking at. If you have a photo that would be great.

I have already gone down the 13mm M/C - next is the steel braided brake hose.

What is the size of the pistons on the CB600 caliper?

I'd be at the INOA rally except for that nagging! Actually I feel a bit guilty because our local club is manning the Concours for the CONO's and NONO's and I'm here at work.

Thanks for the insight on the pad differences. Also I was thinking you had dual discs with cast iron rotors on the Monster. That's what's on my 900SP. My R1100RS BMW has Brembo's with stainless discs and comparing the brakes, the Duc's are fabulous, BMW better than average. However, my bevel drive Duc uses cast iron rotors and the two piston F08 Brembo caliper and they are better than the BMW, so I can appreciate the difference rotor composition makes.

I have an extra late model Duc cast iron rotor (floating) that someday I'll get around to getting an adaptor/spacer made for. Meanwhile I'll have to look into the CBR caliper/stock rotor.

I hear you on the work thing.

The CBR600F4 caliper pistons are 32 mm in diameter. The Norton caliper has 42 mm pistons. Because the CBR caliper is 4 piston, it has about 13% more piston area than the Norton one.


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