Don't use copper grease on caliper sliding pins

[TamSV]

I've stripped the front calipers on my Dad's Mk1 Bandit which were badly siezed after a long period off the road. The Nissin calipers are two pots with sliding pins, much the same as the SV calipers.

The pistons were OK - the piston recess/dust seal looks to be a better design than the Tokicos. The problem was the caliper wasn't moving on the sliders - they took some separating.

Once I got them apart I could see the cavities where the pins go were rammed full of copper grease which had dried into a solid lump. The rubber boots that protect the pins had swelled up and were no longer sealing the dirt and water out so there was all kinds of corrosion to deal with.

Here's the new boots I got from the Suzuki dealer today along with the swelled up items I took off the calipers. You can see there's a big difference in size. I'll reassemble with rubber grease but wondered if it was likely the copper grease that caused the rubber boots to swell?

copper grease reacts to rubber same happen'd on my rear calliper

I received a set with larger ones on, i had assumed they were just aftermarket, they worked fine though.

the new boot i got direct from suzuki, was smaller than the original ones

How do you know they were original? same markings on the rubber?

yup, and was a fair bit smaller

Naa, i meant the fat ones. How odd though.

the fat one was very soft and wasn't like that to start with only went like that after using copper grease so now use rubber grease

[mikerj]

Don't use red rubber grease on the sliders, it dries out quite quickly and almost completely seizes the pins. My old man rebuild the calipers on his SV just before Christmas, but in a fit of optimism used the original and slightly scabby pistons and use RRG (Castrol brand) on the sliders when he reassembled them. One piston was leaking, so I bought a complete set of pistons and rebuilt them again a couple of weeks ago and I had a hell of a job to get the carriers to part company with the caliper they were so tight.

Silicon grease is the stuff to go for IMO, doesn't dry out and doesn't rot rubber.

Red rubber grease is the only thing I'll use in that location. Seen too many rubber boots swell up and jam the sliding mechanism. I bought a tub of RRG a few years ago and have hardly made a dent in the stuff despite rebuilding loads of brakes since. Same as my pot of copper grease, must have had that 5 years and use it every weekend.

I'm sure there are grease fairies who come and top them both up when I'm asleep