bad disk brake performance

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Flo said:
So why 4 & 6 potters?

More piston area and thus more pressure exerted on the disk. Brake swept area is the most important factor in brakes. Huge drums could have as much brake swept area as disks, but the weight of those big drums adds too much unsprung weight upsetting handling. So in order to make a good brake, it must have lots of swept area, lots of pressure on the pads and low weight. Rotors with lots of holes make for light wheels. Perimeter brakes are probably the best way to implement disks on motorcycles, the braking force does not have to all the way through the wheel, it is a direct path to the fork leg and you can get away with fewer pistons because the rotor is bigger.

Jean
 
powerdoc said:
Has anyone done the RGM sleeve kit themselves and can they recommend that a non-shop do it (i.e. the likelihood of f'ing the whole thing up)? When one fits another type of master cylinder, is there a standard screw pattern to hold it to the switch assembly or is it a custom job to fasten it down to the switch?
I'm intending to do it this winter, trawling through the forum revealed its not too tricky, the main thing seems to be a good pillar drill or vertical mill & machine vice.
As far as performance goes, I've only owned old brit bikes, & in 2009 I bought another commando after a 30 year break. Having got it running (just) I took it for a spin, & everything was pretty much as I remembered from 30 years before. My mate (a modern jap bike owner) took it for a spin & on return said he loved it (of course), but wondered what was wrong with the front brake?
As far as I was concerned there was nothing wrong with it, it was just as I remembered! It was only from looking at this forum that I discovered that it seems the brake is now a days an issue.
Different riding techniques in those days perhaps? Anyway, I shall do the mod this winter just to see what I'm missing.
Terry
 
Probably, the single most important thing in the disc brake system is to have the proper ratio between caliper(s) and master cylinder. The stock Commando disc brake system ratio is far from being optimal. If you are going to modify your braking system, by all means read this.
 
Flo said:
So why 4 & 6 potters?

If you increase the number of pistons but leave the total piston area unchanged then the pistons get smaller. Smaller pistons allow the pads to get narrower. The centre line of the narrow pad can be at a bigger diameter than the 2 piston type for the same size disc.
So the braking force acts at the bigger diameter = more stopping torque.

The same logic applies to the clutch mod of narrowing the friction area of the bronze plates.
 
More swept area = more stopping power.
2 discs = 2 x swept area = 2 x stopping power.
Drill half a disc away = 1/2 swept area.
Turn 1/2 clutch plates away = 1/2 swept area.
Although the same pressure applied could exert a bit more pressure on the area that is left.
More pressure required.
 
The very tiny area that is drilled away in drilled discs is more than compensated for by the improved braking, IMHO.
Removing heat, dirt, dust, rust and water far improves the braking, vis a vis the tiny lost area.

BTW, if bigger discs was the complete answer to everything, bikes would have 4 monster discs ?
ABS is the way of the future, squeeze as hard as you like without it spitting you down the road if you overdo it... ? (Not that Nortons suffer from this !!, 961 may differ...)
 
As a physician, I'm exposed to what is termed "evidence based medicine" all the time. Treatments that MD's felt were helpful when critically compared with larger numbers of patients and outcomes compared shows the treatments have been debunked as not helpful or even harmful compared to other treatments.

Now applying evidence based medicine here, has anyone actually done brake tests with different combinations on the same bike? There are various theories that have been advocated and many of these are said to be untrue by various other posts. The internet, like the Bible, can be used to support most any theory. Holes let out gas; no, holes catch little edges of pad and create more friction; no, holes make the disk run cooler; no, the amount of heat they dissipate is not significant; no, modern pads don't produce gas, etc etc etc.

lets see some real tests, not just ..." it feels better."
 
Ugh, its not so simple as twice this and 1/2 less of that. There is more mass to stop on dual rotors so its not double as good. The pressure on pads alone is about all that determines the grip per the materials used, the area swept has more to do with heat dissipation. There a science of friction with a funny name i had to study up on when miss matching too big a pad on too narrow a rotor. Still don't know if I really understood well enough but think so or wouldn't of done Peel's mods differently.

In general frictional forces are independent of the area of contact ... this is an empirical observation not a theory.
more to get up to speed.
http://zebu.uoregon.edu/1999/ph161/friction.html

Cage oriented but much applies to all brakes.
http://www.stoptech.com/tech_info/wp_wa ... disk.shtml

Edges vs smooth or little holes
# The wave rotors are designed to work excellent with all brake pad compositions for added cooling benefits. Magazine testing used wave rotors in combination with Galfer HH pads for optimum performance.
# Although the Wave Rotors were initially designed for weight savings, this will vary by application and may not apply. We are unable to give stock v. wave weight savings for particular models.
# Sport Bikes, Super Motard & Other Racing: The added amount of trailing edges gives the racer better brake response at first touch of the brake lever. The Sport Bike application rotors by Galfer are race-ready units that perform excellent on the street. Many top race teams in national and local super-bike races currently use Galfer’s rotors. When you are at the track, stop and ask any Galfer sponsored team what they think about these rotors. You’ll be amazed. It’s likely that you’ll meet a factory representative as well.
http://www.galferusa.com/html/me-videos-p.html
 
Then why does my Beemer stop 10 x better than my Nortons? :mrgreen:
Both bigger front discs with 4 potters each side. :D
And it has ABS, just like my Norton!
 
Flo said:
And it has ABS, just like my Norton!

But Norton never intended to include the inability of the brakes to lock up the whheel as a feature :mrgreen:

Jean
 
If your ABS Bemmer stops 10'xs shorter than your Norton then I'm sorry for your poor Norton. Doubting what I've quoted on Tribology is pure emotional reaction, fun as that may be to react to - it don't apply to stopping physics. Doubting Galfer's rotor site is good awareness of product selling PR, even if its got some truth to it. If a modern sport bike could not stop shorter than factory Norton set up then its got some faults to fix. But even factory Norton brake in good fetter can haul them down with ABS like security from high speed then some feathering to prevent lock up under 40 or so.

My Trixie Combat brake has decayed so bad I can't even stop it at walking speed last time I tried to stop in garage, going so slow no issue if I couldn't so didn't thank you. Ugh prior to the rust leak and hose budging, just a simple rebuild and removing the Norton "fly over the bars preventer restrict-or" in m/c, gave Trixie exactly what I reviewed to expect above.

About 1/3 of Peel's deal is to out corner what ever else, ~1/3 to out sprint what ever up to some unknown limit and ~1/3 to stop faster from hi speed and on lose stuff than what ever else on two wheels. I may not measure up to hardly any of you seasoned experts, but I don't know of any one else having such good brake they seriously attempt C'do stoppies, which I now think are impossible on level surface, but not because of lack of brake power just CoG so low I can not hold myself down from flying over bars on max stops and rear lifts enough to want to swap ends. With the rear link I can use my butt steering skill as learned on THE Gravel to ride a total locked front tire for a few bike lengths. The Ninja I tried and my SV all stoppie at rather less G's than my past Ms Peel could. I no longer have much respect for moderns stopping any more than their crippled turning. I repeat you all do not know what you are missing out on with such simple mods a hillbilly can do them. Stay tuned as my plan is to tease the bike magazines into a shoot out on all parameters measured with what ever their best shots are.
No Ti, no carbon fiber, no EFI, no computer aids, just direct pilot to control interface, long in tooth air cooled push rod rubber baby buggy. 0-150-0 contest is on my mind and wallet. Hehe, ABS may be the cat's meow on panic stops but not planned practiced ones, especially on THE Lose Shit, done harsh enough there is no difference between the surface, except Tarmac is child's play compared.

Think you understand brake use and physics? I'm betting my life on mine.
 
Read up on what drilling does to expell the gasses created during braking and you'll see why people started driling discs in the first place, and why you never see solid new ones any more.
 
Much more important to read the site I left above on bedding in new pads, then the holes are mostly needed-noticed for less rotating mass.

bad disk brake performance


bad disk brake performance
 
powerdoc said:
When one fits another type of master cylinder, is there a standard screw pattern to hold it to the switch assembly or is it a custom job to fasten it down to the switch?

As far as I'm aware, only the original style Lockheed Norton (or Triumph) style master cylinders or the Andover Norton Grimeca master clinder conversion (which has an adaptor plate) will fit directly to the Lucas switch assembly.

There's no other type of replacement master cylinder design I'm aware of which uses that type of 4-screw fixing as the majority of master cylinder units are usually clamped directly to the handlebar.
 
Flo said:
Then why does my Beemer stop 10 x better than my Nortons? :mrgreen:
Both bigger front discs with 4 potters each side. :D
And it has ABS, just like my Norton!
Stopping is for whimps, going is for "The Boy's" My Mk3 as stock brakes, I think...well there is some sort of retarding device ,lucky i have a vice like grip, Came down "thorncliff" last month, very steep ..trucks not allowed ...i think i bent the lever ...but stopped OK...ish.

OK, i admit good anchors are a must...thats if you are a lazy pilot, keeping your eye's on the road is more important than super brakes...it's no use having 6 pot.350mm double rota's if you aint looking where your going!!!!!!! is it Dave? Sorry mate but you are just the rider i refer to.
Stock brakes and lookin is 10x better.
 
jrb, I sure hope you are just being flippant as there is no way to see everything in time or situation to avoid w/o good brakes but one thing I've learned in spades going fast, that steering is usually way more effective than brake rescue. As to going fast I already know braking s last thing that gets ya around faster, especially on a Commando. A floating rotor is standard on the metrics nowadays but the caliper is mounting floating on many Harleys. Might study the HD's to adapt this type float feature to C'do's with fixed rotors.

http://www.hotrodheaven.com/tech/brakes/
 
So what are you all getting at?
Bugger the brakes?


The fact is, I have an Andover Norton Master Cylinder & drilled brake hub & here are the reasons why.
1, The brake used to be useless for the first few revelutions in the wet, but is better drilled.
2, A lot of drivers in this area slam their brakes on, turn then indicate.
If you say you are constantly vigilant all of the time, well then you will never get caught out?
I do a lot of 2 up riding & the front brake leaves a lot to be desired.
Maybe I should slow down? I didn't buy a Commando to poodle around.

Good game, good game!
 
Flo said:
So what are you all getting at?
Bugger the brakes?


The fact is, I have an Andover Norton Master Cylinder & drilled brake hub & here are the reasons why.
1, The brake used to be useless for the first few revelutions in the wet, but is better drilled.
2, A lot of drivers in this area slam their brakes on, turn then indicate.
If you say you are constantly vigilant all of the time, well then you will never get caught out?
I do a lot of 2 up riding & the front brake leaves a lot to be desired.
Maybe I should slow down? I didn't buy a Commando to poodle around.

Good game, good game!

Flo, If you have shite brakes , No one will run in the back of you when you "slam on"...beats me how pre war manx nortons with single 7in drum laped the island at 90 mph?

Not Poodling around is it? Mayby they looked where they where going :?: PS have you noticed the rear brake? its good
 
john robert bould said:
..beats me how pre war manx nortons with single 7in drum laped the island at 90 mph?

In racing, a lack of whoa can be made up for with more goa.
Doesn't work like that in traffic, however....

Good question though - fearless is probably a word that is involved here. ?
 
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