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3rd February 2005

Tech: Norton Commando Brakes

It started with a simple post about Norton Commando brakes and ended up keeping the message board buzzing for days. NVNL shares what he's learned so far...

First things first, my Mark3 Commando front brake is improved rather than sorted. This is a summary of the show so far.

I have consulted widely and made my choices based partly on my experience with my much loved, long owned T140ES which now has a most acceptable front stopper comprising two standard Meriden discs, two Grimeca single piston calipers, four disc pads of some unknown sort, braided hoses, the original Meriden master cylinder and a dog-leg lever from Harwoods of Richmond (whom God preserve).

'Predictable, Progressive and Powerful' - The Meriden set-up.

One disc, four pistons... and USD forks probably help.Until I bought my wife a Ducati I was content with the single disc factory set up. With the current arrangement I find I can charge up to obstacles much harder and brake much later using two fingers. I cannot remember having locked the front wheel. This may be because it's not my style.

Anyway the Mark3 Commando I got for Christmas came with an RGM 12" drilled floating disc, a Grimeca single piston caliper, a pair of Bonneville disc pads which not only fouled the pins at the rotor's hub but also failed to wipe the outer quarter inch of the braking surface, Goodrich hoses and a factory standard master cylinder and lever.

The braking was dire in my view although it had the MOT tester's certificate of approval. The charac-teristic I disliked was a feeling of woodenness which required a hefty heave from long, strong fingers. It was a set up I was uncomfortable with and I was certain that Mrs NVNL would hate it so much she wouldn't ride the bike. It also had very tired looking hydraulic fluid. Time for some changes then.

Frank W gave me a nice set of sintered pads which missed the hub pins and the inner quarter inch of the braking surface while bearing nicely on the outer quarter inch and cleaning the rust off. I changed the brake fluid (twice - big bottle of DOT4). Things were less bad.

Anarchy sent me an Australian NOC article about re-sleeving the master cylinder and one of the Italian-loving RealClassicists (memory fails as to his name) suggested I talk to Stuart at North Leicester Motorcycles about brake-pads.

I decided against modifying the factory master cylinder for two reasons - firstly it would mean having the bike off the road for a while (cardinal sin), secondly Norvil ( tell me there's no dog-leg lever available. I did talk to Stuart about pads, he did lots of research and the pads are in the post. Sound.

Commando Stuff on

Dog-Leg Makes the DifferenceSticking with what and who I know and trust I talked to TMS of Nottingham ( TMS explained the piston diameter of the Norton and Triumph master cylinders are identical but the fulcrum arrangements differ.

I fitted a Meriden spec. master cylinder with dog-leg lever from TMS, and changed the brake fluid again (just showing off). After a hundred miles or so the disc has been "skimmed in service" and I'll fit the new NLM DP500 pads at the weekend.

Norton Master Cylinder, with brake light switch.

'Not a bad setup': Official.The Editor of the Norton Owners' Club ( magazine rode the bike a few days ago and pronounced favourably, but I'm a lot more picky about front brakes than he is.

I haven't ruled out the twin disc option, but my wallet is reticent. Unless I can train myself to start using the back brake occasionally I'll need to fit a front brake light switch.

Thanks to everyone on the Board who helped out.

Right that's the who, how, why, what and when of the work in progress. I've got 'flu and I'm going back to bed.

Hope this helps.


And then this arrived, which looks useful if a little scientific:

Looking at the Vintage Brake web page I realised that I was no longer confident about classifying wheel or slave cylinders by the number of pistons they contain so I took some advice from An Expert. It has always seemed to me that slave cylinder pistons (and pads) are provided in pairs that move more-or-less together to "bite" on the moving disc with a view to slowing it down. Not so. Some brakes have pairs of pads only one of which is moved by a single piston, the other coming into play as the caliper moves on its hinge. Frank W tells me this and I know it to be true because I've had bikes with cable operated disc brakes, however I have been quite successful at expunging this from my memory.

Two fingers to Triumph...And to conclude

Grip is at the root of this as far as I'm concerned. The grip I use to activate the handlebar lever; the grip the braking device exerts on the front wheel and the harmonious grip the front tyre and the road surface arrange for themselves. As a callow and excitable youth my wrists and elbows suffered many affronts on and off the rugby field, with the result that my own ability to exert fierce finger pressure on a front brake lever can be unpredictable. I can reliably do soft squeezes one hundred times out of one hundred, so my bikes are adjusted to suit.

While Ducatis get the single finger treatmentAs a schoolboy I was often chided by my peers for riding with a slack front brake cable. Did I care? Well yes, but I wasn't going to let them know, heartless brutes. Later on when despatching in London's fashionable and sporting West End a light and progressive front brake lever action remained important and a new factor came to the fore - getting instantly back on the throttle to accelerate away from the next moving article.

In those years I developed the habit of working the twist grip with my thumb and forefinger while resting fingers two and three on the lever.
No story from NVNL would be complete without a gratuitous photo of a tractor.This is a habit I've never felt the need to change, and I set my brakes up to suit.

Short version - light fingered braking good, ham fisted braking bad. See also Michael Atherton on "Batting With Soft Hands".

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