New disc brake slider

Why would a chrome plated disc need a min thickness, its pretty apparent when it needs replacing, it's NOT DESIGNED TO BE SKIMMED

splatt said:

Why would a chrome plated disc need a min thickness, its pretty apparent when it needs replacing, it's NOT DESIGNED TO BE SKIMMED

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No offence, thats the oddest statement I've seen for a long time.
Commando brakes don't work until the (decorative) chrome wears off. !
(The coefficient of friction for cast iron is considerably more than chrome).
The chrome is to stop them rusting in the showroom ?!

Some car disks are thick enough they can be skimmed, more than once even.
Ask any Taxi Driver. (Taxi I was in recently had done 850,000 km).

All modern disks seem to quote a minimum thickness - disks wear with use, in case you hadn't noticed. When they are too thin, they are thrown away and replaced. No-where does Norton quote a minimum thickness (?), how will you know ?? When you can see through it ? When the caliper pistons fall out ? When you notice the other traffic can stop, and you can't ??!!

Somewhere on this form are photo's of a few drilled Norton rotors with cracks radiating from them but don't remember any failures reported. Norton rotors are thicker than need be and safer all around to skim off the chrome either all at once by machine or patchy over time by pad and grime friction. Best practice in not to spiral mill but cross hatch so tool lines don't line up with friction vectors. The thickness mostly matters on 'over heating' so if not racing Pikes Peak downhill then how hot can a street biker get them. Hienz Kulger had the lightest Norton disc ever with 5 kidney cut out and 128 holes barely counter sunk. New age rotors are the cat's meow and distinctly noticed in less spin mass to slow before the tire squeals StOP!. Dual rotors don't stop as easy as a single d/t mass but can slow almost as good longer-more often d/t sharing the heating before fading. Make the rotor much bigger and uneven heating across the friction band requires smaller pads so more needed to keep decent surface area to dissipate-spread the heat. The type of off the shelf pads for Lockheed are rather soft compared to the pads of used by tougher thinner modern rotors so tends less Norton rotor wear than might be expected. Norton rotors and rear drums make good bar bell weights. Elite racers brake on 120 front tires and Cdo's can fit 110 on front so should be a close contest in stopping distance if brake power enough to almost lock up. Then just diddle master cylinder ratio for ease to lock up and feather effectively. Cdo's were a stop gap product so Norton didn't expect them to hang around long enough to wear rotors out.

Rohan you are a f........t

You've used that line so often, its meaningless.

Like saying you will 'know' when to replace a disk.
Science/Engineering is all about measurement.

AND ISO standards are about how companies operate and keep records, nothing to do with meeting any mechanical (braking) specifications....

The TuV standard in Europe applies to testing and specification of all manner of things, did it apply to any of the Commando models ? Does it limit what can currently be fitted to Commandos ?

TÜV is a German (national) road safety organisation, privately owned and run. Founded originally to test steam engines I believe. They never did a full type approval on Commandos (including the latest offering, I hear), so only approved these things bike by bike in the local TUV station, following the "test procedures" of the local TUV "bike specialist". And, yes, I have seen my fair share of those, including good as well as totally incompetent ones.

As far as Norton brake discs go I have seen very poor imitations made in India which, if I read our Andover Norton sales figures of our discs to some "leading" Norton specialists correctly, these prefer to sell rather than our more expensive offering which is to factory spec.

Which is also, incidently, covered by a rather costly product liability insurance, something the Indian manufacturers and their enthusiastic distributors don't bother with.

The cracks in the radii of the Indian brake disc had to be seen to be believed.. not something I would like to entrust my life to.

Thanks Joe.
Are your disks identified in any way, so the insurance has some meaning ?
Are wear limits for it quoted anywhere ?
Old BM disk says (on it) minimum thickness = wear limit of 0.7 mm - thats 28 thou from brand new to worn out...

The computers we used to sell met some sort of TuV standard, or Euro sales would have plummetted.
And washing machines have it too ?

Rohan,
No identification yet- identification is something we gradually introduce now. Nobody before bothered at ANIL, naiively assuming our loyal dealers will only sell good stuff. Very naiive, looking at sales figures of certain dealers for brake discs. One has recently been removed from our distributor list. He prefers to sell parts of "alternative manufacture", many of which I have seen and was anything but impressed, and boasted about the fact to boot. Not something I want to tolerate in future.

I have no knowlegde of a minimum thickness given, but will enquire and report back when I find one.
Joe S.

Anyway, back to my brake upgrade, machine shop is playing around with machining of the sliders so I grabbed one that had been bored and finished the machining myself to show how the setup will look, well, it will all look much better than in this pic but you get the idea.

That's a hot creation, is there a term for that type of caliper mounting? Maybe we'll see some Commando wheelies yet!

Nice. Patiently waiting.

Mounting terms eh...so, are they named in relation to fork leg [static/fixed opposed 4 piston caliper - trailing edge mounted] or disc rotor [dynamic sweep-wise]?

" is there a term for that type of caliper mounting?"

Yes, I think its called NORMAL.

Ok, just I've seen elites with what they call radial mounted calipers but not sure what that refers too. If my Peel front brake don't work as hoped d/t the Lockheed big plucks on narrower disc rim I may have to shop with you.

hobot said:

Ok, just I've seen elites with what they call radial mounted calipers but not sure what that refers to.

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http://www.carbibles.com/brake_bible.html

Ah thats the ticket, cheers L.A.B.
The radial mount hype has caused confusion in some journos with poor mechanical comprehension however, when stating that it is having the mounting fasteners parallel with the plane of the disc/rotor, the real factor is in the mounting supporting the caliper at each end, thereby reducing leverage flex, much as the original AP/Lockheed type fitted to `73 Triumphs & Ducatis.
Note in Madass` pic where the long 6 piston caliper hangs out in a pendulous manner, the synergistic dynamics can [theoretically] cause flexing/fluttering moments, which may be [potentially] bothersome..

Opinions needed, as with most retro fit calipers on Commando's the rear fender stay becomes a problem, mine is no different, I was hoping it wouldnt be but it is,
Instead of supplying a new purpose built fender stay (trying to keep the cost down) do you think it would be asking to much of the buyer of the brake kit to cut 5-3/4" from his fender stay and bolt on my new extension
and weld it in place?

Why use the needlessly super-long [cantilevered way out from the mounts] 6-piston caliper? Would a 4-piston not fit [& function] better?
Check the `73 JPN AP/Lockheed set-up, will your mounting be suitable for that retro caliper, or is the 2-piston job too fat to clear the spokes?

that doesnt answer my question, Opinions only to my question please.

Proper problem solving will make the question redundant..viz the old carpenters saw, "measure twice, cut once"..