Rear brake disc rubbing

johnmolly92

Well lads,

Got a new paddock stand yesterday and threw the SV up on it, after giving the wheel a few turns i could hear the disc rubbing.

Seems to be the same spot rubbing each time. I only took a quick look but the disc doesn't seem to be warped from what I can see. Brakes started to squeal a bit last week but im not sure if that has anything to do with the rubbing.

Any ideas on a fix? Or am i replacing the disc?

CJhaughey

Its likely to be a partially siezed caliper, either the piston or the caliper sliders.
First thing to do is undo the caliper and remove it from the carrier, you won't need to undo the hose just take the caliper off.
Then have a look at the sliding pins and make sure they are moving freely in the caliper itself, if not then pull them out and relube, I think the specced lube is a heat resistant grease that doesn't attack rubber and I have seen LM grease used but I can't vouch for it. In any case they should move easily back and forth.
Then check that your pads are still OK and not worn down too much.
Then make sure the piston is able to move freely and isn't seized in place from corrosion, you may have to pull the boot down the piston to clean and check it.

Max Headroom

....and with the caliper off spin the wheel while holding a pencil or similar lightly against the disc and check for warping

johnmolly92

Sound lads, will take a look at it tomorrow and report back!

Ayrtonf7

Copper Grease does the job for the calipers

CJhaughey

Ayrtonf7 wrote: »

Copper Grease does the job for the calipers

I am very slow to use copper grease near rubber components, I had some sliders swell up and disintegrate after copper grease was used, I think there is a special grease for them but its not widely available.

mobfromcork

CJhaughey wrote: »

I am very slow to use copper grease near rubber components, I had some sliders swell up and disintegrate after copper grease was used, I think there is a special grease for them but its not widely available.

You can buy a tub/tin of grease specially for use with rubber parts. I had to do a few sets of car calipers so bought a tub but it was around 25 euro. I'll have enough for life I'd say as you only need a small but for each slider. If you're anywhere near Carlow pure more than welcome to grab enough for your caliper.

blade1

Red rubber grease or silicone grease for anything with rubber.
Little tins can be got on eBay for a few quid.

Mesrine65

http://www.woodiesdiy.com/product/lubricants-silicone-grease-12-oz-tin/13177/6.0.0.15

Max Headroom

If you're stuck you could use chain grease/wax...safe on rubber

CJhaughey

CJhaughey wrote: »

I am very slow to use copper grease near rubber components, I had some sliders swell up and disintegrate after copper grease was used, I think there is a special grease for them but its not widely available.

On the sliders you use regular grease,copper grease is supposedly only for the back of the pads, although I have used it on sliders before and didn't notice any damage when I went to re grease years later.

CJhaughey

I have seen LM grease used and it seems to work on some calipers post#2^^
However I don't think all the rubber used in the sliders is the same, some react with grease some don't, Most are EPDM rubber from what I can gather but not all. Red rubber grease was designed for use inside the caliper, for greasing the seals and around the boot for the piston, its not really the same as a grease designed for sliders.
The correct stuff is specced on most Japanese bikes and cars is Nippon Grease Niglube RX, which is factory fitted and hard to get at least in my experience.
Its yellow and looks like butter.
If you have nothing else I would go with Silicone grease it won't harm most rubber and is high temp resistant.