[Closed] Lubricants for brake pistons

The correct brake fluid for the system is a safe choice, you are guaranteed that it is compatible with the seals. For DOT fluid brakes, you can buy rubber grease from automotive parts suppliers. I would not put fork lubricants on brake seals.

Have used olive oil when didn't have any brake fluid.. worked and double bonus am alive to tell the tale...

If it's one piston sticking I made up a clamp out of some flat bits of metal and a couple of bolts to hold the freely moving piston and force out the sticking one rather than poke at the seal

Have used brake grease, the red stuff, in the past , and it worked fine.
Also used to blow sticky pistons out with compressed air, but be sure to hold a rag over the top to catch all the vapourised brake fluid , and also the piston should it pop out.

For hydraulic its Hunters silicon lube, recommended by hope for their systems and in their service kit they include a bottle. Outwith it costs about £6 and lasts forever.
https://www.pipekit.co.uk/hunter-silicone-lubricant-30ml.html

I use finish line stanchion lube on my Hope brakes. Tricky to get here in the UK but I normally grab a bottle when I order stuff from Germany.

Really fine straw and a very thin inert lube so you can get very small amounts exactly where it's needed. I save the Hunters for full rebuilds.

I bought a tiny little tub of red "DOT friendly" grease for my Guides from ebay.

I'm sure it was over priced as it's "for bikes" and no doubt the motorbike or car equivalent is the same and cheaper.

Edit:

I use finish line stanchion lube

@Onzadog, Genuine question as I have 2 cans of that, it's ok to get it near DOT fluid potentially, as in freeing up a stuck piston or such?
Cheers!

@Poopscoop I checked with Finish Line before using it due to the obvious trouble if it wasn't. They said it was perfect for use on brake seals and had no issue with DoT fluid. I've been doing so for years now without any bother.

I was surprised by the answer as I emailed them in the States and was expecting a risk averse reply but was pleasantly surprised.

Been using fork juice on my hopes for years without any issues (obvious proviso of not getting it on pads and rotors, of course).

Thanks for the info Onzadog, handy to know and will bear that in mind.👍

Why do people still believe brake pistons actually move in the seals? The movement happens thanks to the seals deforming and then resuming their original shape to pull the piston back. As the pads wear the pistons do creep slowly through the seals. You'll know how tightly they fit if you've ever tried to remove a set.

Why do people still believe brake pistons actually move in the seals? The movement happens thanks to the seals deforming and then resuming their original shape to pull the piston back. As the pads wear the pistons do creep slowly through the seals. You’ll know how tightly they fit if you’ve ever tried to remove a set.

True, but it doesn't mean the pistons don't need maintenance and a clean and lube from time to time.

You'll get sticky pistons that don't retract, and end up overheating your brakes and glazing pads.

The correct brake fluid for the system is a safe choice, you are guaranteed that it is compatible with the seals.

This. Greg Minnaars mechanic (Marshy) did a vid on brake bleeding. He just let the bled oil flow over the pistons a bit to lubricate them. If you are using the same stuff the seals are supposed to keep in, it shouldn't attack the seals.

If your brakes use mineral oil....

You’ll get sticky pistons that don’t retract, and end up overheating your brakes and glazing pads.

I've normally found the opposite, in that one piston will not creep forward through the seal as it wears so ending up with excessive lever travel.

I squirt some lube (silicon spray in this case) onto a cotton bud and give the piston a wipe round with that.

I’ve normally found the opposite, in that one piston will not creep forward through the seal as it wears so ending up with excessive lever travel.

I squirt some lube (silicon spray in this case) onto a cotton bud and give the piston a wipe round with that.

I used to commute on a motorbike over winter and that's exactly what would happen with the motorbike pistons unless I kept on top of the maintenance. Strangely my Hope V4's did the oppose, rear piston stuck out and wasn't retracting properly and I ended up with a squealing rear brake on a long descent, and glazed pads.

I've used silicone spray for years on my Hope's, never had a seal fail.

I bought A small pot of silicon grease from the local Screwfix. It will last me forever...

If you grab a handful of brake you can sometimes force the pistons to jump through the seals and stick.