Brake rebuild: where and with what to grease

[bill_face]

Hello, I'm rebuilding rear brake caliper and master cylinder

I've been searching around and consulting the Haynes manual, and having encountered quite a few different opinions on what grease to use in which places

Just wondering if someone could give me a synopsis of which bits to grease, and with what type of grease

At the moment I'm thinking of reinstalling the pistons into the cylinders just using brake fluid.

Possibly using red rubber grease under the piston dust covers, or possibly using none at all (this is somewhere I've seen people advocating spray-on copper grease)

Copper grease on the caliper bolts and mounting bolts

Red rubber grease under the boot on the master cylinder

[Grimly]

Red rubber grease on the piston seals and boots - keep mineral grease away from any of them, even including the boots that cover the sliding pins on the front, as they will go weird and out of shape.
I use copper grease on the securing bolt threads, but just a touch enough to do the job - no need for more than that.

[Brendan W]

Yeah, rubber and copper grease have been the go to for ages and I've used them both with no issues.
There is a trend to silicone for any part that has rubber like the sliders and ceratec instead of copper grease and I have drifted that way.
There is a lot of discussion out there about the pros and cons of copper, mainly in the context of modern braking systems causing ABS to lose it's mind.
How much of that is marketing........who knows?
If you use anything at all you are miles ahead of the folks who neglect the brakes.
As Grimly said, just a touch and no mineral grease near rubber parts.

[KiwiAlfa156]

Yes, as above. Lubing the seals with just a smear of red rubber grease is very important. The caliper pistons need to slip through the seal to self-adjust for pad wear. A dry seal has too much stiction and pulls the piston back too far in to the caliper, eliminating the self-adjustment. If you rebuild with dry seals there is a very high chance you won't be able to take up the last bit of clearance between the pads and disc at assembly, and you will have excessive lever travel that you can't get rid of. You will then go through a gallon of brake fluid and a handful of zip-ties chasing non-existent bubbles in your brake lines. I speak from experience.

[salty_monk]

I use silicon but only because I've never seen the red grease here in the states. I'm sure either would work fine....

[unfocused]

High temp silicon brake grease as found in ANY auto parts store. I think I use Versachem? However I have some wonderful grease I sell for the massive generators I deal with. Only $300 a tube!

[bill_face]

Thanks all. Got it all back together today, and seems to work. I've also learnt a lot about grease along the way : )

[Suzukian]

I lube brake seals with brake fluid when installing them. Any grease could contaminate the brake fluid. When you use brake fluid, it causes the rubber to swell a little, this ensures no leaks, and is in essence what lubricates the seals inside the calipers anyways. The same with slave cylinders on hydraulic clutch systems. I learned this from working on British cars which come with Lockheed dual puck calipers.