Topic: Caliper parts lube

[Kouros]

So I read here to lube the caliper piston O-ring with "caliper lube" or with Dot 3 brake fluid.

I have both, but have never used caliper lube. This stuff has the consistency of grease, its thick. Is this what I should use? And if so, on which parts? Can I lube around the caliper piston, the O-ring?

It just seems this could get mixed with brake fluid somewhere inside the caliper.

Any help would be appreciated.

[DarcyCB400F]

I have a favorite saying... "when in doubt, there is no doubt"...

[City Boy]

Hi.Iam not familiar with the caliper lube you show the pic of.However,myself,I put a little brake fluid on the piston seal before inserting the piston.Then,I put a thin film of copper antiseize on the exposed portion of piston,pad seat,and caliper housing where pad contacts it.I also thinly coat the steel pad backing where it contacts caliper housing.Emphasis on the thin.All the exposed steel components get the same thin coating. Every spring,I repeat all of above cept  installing the piston.This procedure keeps all corrosion at bay and makes for a very smooth operating caliper.I think you would likely see similar results using the caliper lube.    Rock On

[TwoTired]

You want Brake parts assembly lube for the caliper seal.  It is compatible with DOT3 and does not attract moisture from the atmosphere to corrode metals.  Half the seal gets exposed to humidity and rain water.

For all the metal surfaces on the puck side of the piston, Dow Corning High Vacuum Grease in a thin coat, shields from water ingress (and subsequent corrosion) and stays in grease phase without creep, for temperatures to about 500 degrees.  Lube qualities aren't required.  Just water shedding qualities and the ability to stay put, away fro the fiction components.

For the permatex stuff you posted, note it contains moly for lube purposes at high temp.  It is not 100% silicone.   And, I would first test it for creep at elevated temps before putting it near my friction pads.  Most of the modern disc brake lubes are used in places where there is a containment or a separation barrier (rubber seal) between lube and fiction components.  The SOHC4 caliper doesn't have that.

Cheers,

[Kouros]

TT,
I did further search and came across that thread where someone did a oven test. It got me more confused and more info than I wanted. I'll simply follow direction here.

Just one thing, please define "puck side".

So the piston, groove and seal gets brake parts assembly
The puck side stuff gets the DCHVG. Is that the backside of the dome and top of the piston and cylinder walls?
Don't assume I know anything, cause I don't. Never dealt with bikes except the one I'm re-building

edit:
Almost forgot to ask a brand for the Brake Parts Assembly Lube. What do you recommend?

Thank you

[TwoTired]

If you examine the assembled caliper, you'll notice there is no seal to keep water from behind the brake pad.  Anywhere that water can get to behind that pad needs a thin coat of DCHVG.

The Brake Parts Assembly Lube I have, came from two places.  The oldest from Mckay,  and the newest from Raybestos (BAF-12, if memory serves).
I put some assembly lube in the seal groove; enough to wet the surface, and smear some on the rubber seal before putting it in the caliper.  The caliper housing bare aluminum, gets the thin silicone treatment from the seal position outward toward the rotor interface.  I estimate how much of the piston will be exposed outward of the seal and apply a thin coat of DCHVG to the piston that will be exposed outward from the seal, before it is inserted into the caliper.  Insert just enough to get the forward edge into and held by the seal, it'll find a deeper position once the brake pad is inserted.  (I'm assuming the piston is metal, I don't think the Phenolic types need the silicone coating)
Put a thin coat of DCHVG on the friction pad backing steel, too.  Don't forget the caliper stationary side behind the brake pad gets DCHVG as well.
The caliper piston and pad will find final inward position as the caliper is assembled onto the rotor with the two big bolts.  You would like to avoid getting the silicone past the piston seal and into where the DOT3 lives in the caliper.  It probably takes longer to read this than actually do the assembly process. 

FYI: I did the oven test on both Sil-Glyde and the DCHVG in the early 90's, I think.  Sil-glyde failed miserably.  The Dow corning stuff seemed to get a little shiny at very High temps.  Otherwise, it was completely un-phased by by 500F oven.  I remember thinking that it may have been from another planet. 

Cheers,

[Kouros]

Couldn't find either one of Mckay,  and Raybestos. Pointed to JC Whitney but no products in page. Will try to search further.
Many thanks again for in depth explanation. I will follow directions.

[dave500]

use brake fluid if its to used straight away,the greasey lube if its going to be stored for a short while,,like say a brake place might do with change over rebuilt components which are on the shelf.