Adjusting Cantilever Brakes (at my wit's end!)

[Yellow Saddle]

I'll change the post then...........I use Copaslip on my pivots and have never had a problem. Grease tends to be washed away by water sprayed onto the pivots by the brake blocks leading to corrosion on the Steel pivot pins.
Plus the bushing is in Bronze (an alloy of Copper and Tin) or Brass (an alloy of Copper and Zinc) on cheaper brakes.
Happy now?

I'm a pretty curious guy and that is sometimes misconstrued as a challenge to a belief or statement. It wasn't. I'm interested and you seem experienced based on your posts.
I am still trying to understand why it is done and how it works.
Copper compounds are not designed or recommended as a rolling or sliding element (bearing) lubricant and a cantilever pivot is exactly that. It appears obvious at first why it isn't a lubricant (it has metal flakes in it), but I think the obvious masks a better reason and I'm trying to figure out why. These products, no matter who makes them, all seem to have a high film strength, which is what you want in a lubricant. The addition of metal particles would seem counter-intuitive for lubrication but then, copper is soft, the particles are small and lithium, potassium and calcium (almost metal) are all used in other lubricants albeit in chemical composition rather than native. Perhaps the copper would separate and clump?
It would hardly be a problem in a pivot with a small angular movement and I can see why you "have never had a problem."
However, if you have very successfully used copper compound in such pivots and found it better than grease, I'm interested in reasons why it works.
I don't see the bushing material being copper alloys being a reason at all. By that logic we should then use steel grease in steel bearings and nylon grease in nylon bearings.
If it is purely a question of lasting longer i.e. being more resistant to a constant spray of water and its unsuitable lubricity being good enough for the job, then so be it.
If I can add a trick to my maintenance quiver by learning something, I'll do so.

 

[Yellow Saddle]

A tip from my LBS, before fiddling with the adjuster screws unclip the cable first, they are easily stripped if the arm is still under tension. Unfortunately I learned this only after stripping said screws

This is good advice and obvious once you think about it, which I haven't until now. Those screws act on a very short arm in a highly-levered spring and have to work far harder preloading that spring than what would appear to be if you judge it's stiffness by pushing on the canti's (Vs) themselves.

 

[Citius]

Copaslip is an anti-seize compound - not a lubricant. As mentioned, I wouldn't be using it on any moving surfaces.

 

[raleighnut]

I'm a pretty curious guy and that is sometimes misconstrued as a challenge to a belief or statement. It wasn't. I'm interested and you seem experienced based on your posts.
I am still trying to understand why it is done and how it works.
Copper compounds are not designed or recommended as a rolling or sliding element (bearing) lubricant and a cantilever pivot is exactly that. It appears obvious at first why it isn't a lubricant (it has metal flakes in it), but I think the obvious masks a better reason and I'm trying to figure out why. These products, no matter who makes them, all seem to have a high film strength, which is what you want in a lubricant. The addition of metal particles would seem counter-intuitive for lubrication but then, copper is soft, the particles are small and lithium, potassium and calcium (almost metal) are all used in other lubricants albeit in chemical composition rather than native. Perhaps the copper would separate and clump?
It would hardly be a problem in a pivot with a small angular movement and I can see why you "have never had a problem."
However, if you have very successfully used copper compound in such pivots and found it better than grease, I'm interested in reasons why it works.
I don't see the bushing material being copper alloys being a reason at all. By that logic we should then use steel grease in steel bearings and nylon grease in nylon bearings.
If it is purely a question of lasting longer i.e. being more resistant to a constant spray of water and its unsuitable lubricity being good enough for the job, then so be it.
If I can add a trick to my maintenance quiver by learning something, I'll do so.

Brass or bronze naturally slides on Steel (school metalwork classes @ 1973) the Copaslip just stops the steel pin corroding.
Also it may be result of my working on car brakes that Copaslip on the sliding pins and the back of the pads stops brake pad 'squeal' (especially on early SAAB front brakes where the piston rotates (similar to Jaguar IRS rear brakes) in order to provide a handbrake (these calipers do not push back by pressure but have to be screwed back in order to fit new pads)

 

[Yellow Saddle]

Brass or bronze naturally slides on Steel (school metalwork classes @ 1973) the Copaslip just stops the steel pin corroding.
Also it may be result of my working on car brakes that Copaslip on the sliding pins and the back of the pads stops brake pad 'squeal' (especially on early SAAB front brakes where the piston rotates (similar to Jaguar IRS rear brakes) in order to provide a handbrake (these calipers do not push back by pressure but have to be screwed back in order to fit new pads)

None of what you say explains your reasons for using a copper compound rather than plain grease.
We know brass or bronze makes for good journals on steel but that doesn't mean it requires an added layer of copper.
The way copper compound works to minimize squeal is irrelevant in this scenario. We're talking pure sliding lubrication here and as you said, wash-out by water.

 

[ChrisEyles]

Good tip about unhooking the cable before adjusting the screws - as stated, obvious when you think about it, but I hadn't, up until now.

Re the copaslip, my two cents would be that you probably don't need a super slippy lubricant on the canti pivots (just enough to keep things free), and that longevity and water repellence are probably more important? Having said that, I don't have any in the garage, so if I dissassemble I'll just be dabbing in a bit of the teflon grease I use for the BB (and headsets, wheel hubs etc etc... it is a one size fits all sort of approach!).

 

[raleighnut]

Cod on (you're right, must have been watching Guy Martin too much or its a Leicestershire saying as well as Lincolnshire)

 

[Yellow Saddle]

Cod on (you're right, must have been watching Guy Martin too much or its a Leicestershire saying as well as Lincolnshire)

I'm unfamiliar with that term, sorry, not from 'ere.

 

[raleighnut]

The full saying is "Cod on the nod", maybe I should post that in another thread.

 

[Yellow Saddle]

? but nevermind.

 

[ChrisEyles]

"Cod on the nod"

I like it!

... ... and I *think* I understand it