South West Bikers | Motorcycle Forum

Picked up a nail on the motard the other day, whilst the back wheel is out i thought I'd treat her to a mini service, the backs of the old pads were covered liberally in copper grease/slip, I have never used this when replacing pads on my trackbike, just wondering what the reasoning is behind it and if I should buy and apply before putting the new in?

can of worms opened there.

I just looked in that can billi and it said NO.

On modern bikes (or should I say modern calipers) there should be no grease, and that is what will likely be written in the workshop manual.

Some people (and even professional mechanics) still do it though. Really old calipers use to need the grease on the piston side but it hasn't been like that for a long time now. Some believe it stops the pad from squealing, and I think it did help on my van but I used ceramic brake grease instead.

Still... having grease and brake disks/pads in close proximity can't be good thing can it.

no it is then

You can get an anti-seize/anti-squeal compound to do the job better than slathering the whole lot in coppaslip ......

As said above, generally on more modern calipers and pads it's a no.
I use sparingly on the pistons on my old (pre-divi) xj600 because large steel pistons act straight onto the back of steel pads which don't have stainless cover, and the bike is generally used when there's salt on the road then left to stand without cleaning. But note sparingly on the piston faces not slapped on back of pad.
On my CCM (sort of SM) which has Brembo calipers i don't use it, the pads have that stainless perforated steel on the back.
On my Z which has aluminium pistons it's defo not, but i do smear a very small amount of silicone grease on the piston faces, bike is used most of year.
On modernish machines with semi or fully floating discs, if u get squeal it's usually because the disc pins need a clean.

I saw something about using rubber grease around the external sides of the brake pistons?

Kata wrote: ↑Jun 11th, '20, 17:45 I saw something about using rubber grease around the external sides of the brake pistons?

when you're putting in new seals you use the red rubber grease provided, not much though as it can bind the piston.

Right new pads fitted, front wheel will barely turn a good spin of the tyre and the wheel will do 3/4 of a rotation before stopping where as my other bike will do a couple of rotations before coming to a stop, it looked as though the brakes had not had a decent clean for quite some time, my gloves were black when I took them off, i gave them a good scrub with brake cleaner and a toothbrush, it was a real struggle to push the pistons back to fit the pads, the fluids seemed nice and clean so i didn't bother changing them.
I'm guessing the issue is sticky dirty pistons ? Therefore the brakes need a strip and good service, new seals etc in which case it'll have to go into Riders and their horrendous labour rates

You can service the calipers yourself. Plenty of youtube clips show the way. Just be methodical and scrupulously clean. Binding brakes could be due to the fluid return in the master cylinder being blocked.

The binding might go after a quick ride as the new pads haven't yet worn to the shape of the old disks, though having fresh seals will help them to relax easier.

I recently fitted new front pads and despite spending serious time on piston cleaning I still had brake binding issues. Decided to try the easy option first as it worked once before on my Aprilia. Namely, taking the bike for several short runs, making sure to use that front brake lever A LOT - no stoppies or sudden hard braking though. It worked, 30-odd miles later and the front wheel spins like a dream. Those pads just needed bedding in to the discs it seems.

Another cause of binding brakes can be the fitting of aftermarket levers - go for the top level brands such as ASV, Brembo, Harris and you’re paying top dollar for top-grade components. The temptation is often to make the bottom line the leading consideration in choice of levers. It may be less of an issue nowadays as the quality of Chinese-made parts is improving, but not so long ago it was easily possible to buy cheapo aftermarket levers that seemed to fit and work fine but resulted in binding issues as the geometry of the lever prevented the piston in the master cylinder from fully retracting and permitting flow of brake fluid back into the reservoir. As the brakes were used and generated heat, it was transferred to the fluid which expanded (not by a huge amount, but by enough). As the pressure relief passage back to the reservoir was blocked, the expansion went in the other direction and forced the caliper pistons outwards, creating binding which exacerbated the situation.
It might be a less prevalent issue nowadays, but there is some wisdom in choosing a good quality brand for safety-critical systems like brakes.