Topic: Brake Question - Preventative Maint.

[mwvachon]

Hi All,

Question has to do with an oft covered topic here - brake calipers. I did the requisite search and saw a lot of threads on stuck calipers and piston issues, but couldn't find anything related to my question - which is: What are folks doing to prevent/minimize the crud/corrosion that occurs around the piston and moveable brake pad on these SOHC bikes?

My restoration is 99.9% complete, and the last thing I'm having to wrangle with is the front caliper. I originally intended to replace the entire unit as I've rebuilt this a few times already. Unfortunately I soon learned that this part is no longer available (no luck with NOS search, either). Every time I tear the caliper down, I note that there is corrosion in the piston bore between the seal cut and the outer edge of the piston bore. Also, the larger bore that holds the brake pad itself is usually in VERY bad condition (typically been the reason for my stuck caliper). Newer bikes that I've worked on have a wonderful boot that fits around the brake puck and caliper housing to prevent all this, but in 1971, I guess disc brake technology wasn't that far advanced.

I have no problem with replacing the piston (mine now has surface corrosion that others have mentioned), I just want to prolong the life of the investment/work. Looking for input here from those who may have some insight.
[Note - bike in question is a 1971 CB750-K1]

[mcpuffett]

hi mike , i usually give everything a coating of copper slip,  round the outide of the brake pad and also in the caliper recess to,  usually keeps things moving and moisture out ,  mick.

[mwvachon]

Thanks Mick, but what is copper slip? (not familiar with the term) Where do you typically find this product?

[mcpuffett]

hi mike , it is an anti seize type grease copper in colour, i think you can get other colours but no idea what or why ?, perhaps someone more in the no might step in?   mick.

[Mark M]

Copperslip is not recomended for use on brake calipers (although I must admit I also use it) you should realy
go for a high melting point grease. Either way yopu should avoid getting it in contact with any rubber parts as it will
make them rot. Also you only want a very light covering and no where near the friction material.

Or you could do the same as the PO of my 400/4 and neglect the leeking fork seals, everything is then well
preserved in suspension oil for ever more. Stopping on the other hand, is no longer a controlled event.

Strangely although bike manufacturers did start to add rubber boots to the pistons in the early 80's they
have since stopped - possably because mutlipiston setups are now so small there isn't much room.   

[merc2dogs]

 Mine does that every year, normally have to pull it apart and clean it up every spring, last year I cleaned it up and then sanded it shiny with 800 grit wet paper, and threw a coat of paste wax on it,  seems to have helped as it's still clean now, but I  expect it to be a yearly practice anyway.

  There are a couple types dry lube out, and I've been looking at them to see if they'd work.
 have actualy thought about boring it out larger and turning down a bronze or brass liner for it.

 The good thing about them is that there a lot of aftermarket makers of disk brake setups for bikes, so unless you're after a true restoration, you can get completely new brakes.

ken.

[mwvachon]

Well, from the sounds of things, there is no 'magic bullet' for these assemblies. I've simply cleaned up the caliper as good as possible. Heck, even invested in a brake hone kit from good ol' NAPA. Polished up all the nasty surfaces [used the progressive steps of 600/800/1000 grit paper] and located a good automotive synthetic caliper brake lube. Talked with a mechanic and he noted that the important thing to do is get a thin coating of grease on those surfaces that tend to corrode [being mindful not to get any on the friction pads themselves]. Had to re-shoot the caliper body with primer/paint [I just knew I should've tossed those in with the powder coated items!] Will re-assemble, bleed, and adjust in the AM. Hopefully this New England rain pattern will let up and I can take it out for a REAL test ride!

[Jonesy]

To answer some of the questions about greases, etc:

The 2 primary types of anti-sieze are copper and aluminum. They are compounds of copper or aluminum powder suspended in a heavy grease-like carrier. The copper is typically used for high-temp applications.

I've found silicone brake grease to work well for lubing the sides of the moving brake puck so it won't hang up on the walls of the caliper. It's available at most auto parts stores.