Technical Rubber flange on brake caliper pins

[Ralf S.]

I removed one of the rear brake calipers this weekend, to change a wheel bearing and I discovered that one of the sliding pins was stuck fast. It would rotate in its slide/hole but it would not move in and out.

Obviously this is not condusive to proper brake performance, so I drifted it out (requiring quite a bit of force).

It turns out the caliper pin is one of those with a cut-out and a rubber sleeve over the bottom third. The rubber is ancient/14 years old and had expanded, which jammed the pin in the slide.

I could not refit the pin with the rubber sleeve in place, so for now I put the pin back without the sleeve. I'll have to get old of a new pin and sleeve....

But out of curiosity, what does the rubber sleeve do? I suspect it's some kind of anti-rattle device but (bearing in mind it's on the rear caliper) I have not noticed any difference using the pin without the rubber sleeve attached.


Ralf S.

 

[Davren]

An anti rattle sleeve was my guess too. I had the same problem of not being able to refit the pin and swollen rubber sleeve, so cut about 1mm off one end of the sleeve.
.

 

[Ralf S.]

Still no adverse symptoms running without the rubber.

Meanwhile/in any case I've ordered a set of new pins from brakeparts.co.uk...

A tenner per caliper, including new bolts, two pins and a sachet of the proper grease and wont be much bother to fit, so seems rude not to.


Ralf S.

 

[Mytheroo]

I refitted mine with just loads of copper-grease instead of the rubber, no issues after 6 months

 

[portland_bill]

I refitted mine with just loads of copper-grease instead of the rubber, no issues after 6 months

Copper grease is not really the right stuff for this. It is not a lubricant. It is called grease, but only because of its consistency. It is an anti-seize compound, used to prevent fixings corroding together. As a lubricant on moving parts it is poor.

Having said that, the correct grease for these pins is incredibly difficult to find, unless you want a 15kg barrel. I found a small pot on ebay, where someone is presumably filling the pots from a big tub. If I can find a link sometime I'll post it. Ordinary grease is not right, and moly grease a bad idea as it may dry out with the heat and become abrasive.

 

[Ralf S.]

Aye! I've use either graphite or regular grease in the absense of anything more "silicone". Graphite seems to last longer before drying out compared to the regular grease... but there's not much in it.

I've also thought about using CV joint grease since CV's must get quite hot too... but I can't recall if I ever have or not.

I do remember one time using de-greaser (Gunk) to clean all the parts and the Gunk made the rubber bellows expand to about 3 times their normal size... slightly amusing until I realised I had to go out and buy new ones (although I found some old-but-good ones in the garage which saved the day.. ) so I dunno if my rubber sleeves have been similarly affected over time by the grease I've used.

Anyways... new pins on the way with new grease, bellows and retaining screws so that's that I hope until December 2020 (the MOT after the next one.. )


Ralf S.

 

[portland_bill]

I've also thought about using CV joint grease since CV's must get quite hot too... but I can't recall if I ever have or not.

CV grease is moly grease. The stuff that makes it black is molybdenum disulphide, hence 'moly'. (There, you've made me spell it now, just to prove I can. And no, this clever, smug, idiot, didn't have to look it up.) Next spellin test pleese.