Topic: Brake Caliper Assembly Lube - Again

[ZTatZAU]

I'm getting ready to start putting my front brakes together and found several old threads on proper lubrication of the piston seal and greasing all bare metal exposed to the elements.  The newest, well-reasoned posts I could find were over ten years old (2012) such as the following prevailing consensus provided by TwoTired, at that time...

There are multiple threads about this same topic:

http://forums.sohc4.net/index.php?topic=56544.msg610718#msg610718
  Lets' review.
There are four products needed to restore a caliper.
1. Brake cleaner
2. Brake parts assembly lube for the caliper seal only.
3. Dow corning High vacuum grease.
4. Brake fluid

Each has it own specific application and needs for the task to be performed.

#1 is used to get everything clean.  (given the confusion, it had to be said)
#2 is used ONLY on the seal and must be compatible with #4, as some of it will invade the brake fluid chamber.
#3 is NOT used on the seal, as that would put silicone inside the brake fluid chamber.  This is a bad thing as the compounds are incompatible.  It is used behind the brake pads and a thin coat is used on the parts of the calipers and piston that are exposed to the elements and subject to water ingression.  The Dow Grease will not mix with ANYTHING.  It is a simple barrier with the very important property that it will NOT melt when the parts get hot and then run/creep into the brake pad friction material and provide lubrication between pad and disk rotor.
#4 is what makes the hydraulic part of the brake function. (I hope that part is clear.)

Cheers,

Thanks Lloyd, if you happen to see this!
The Dow High Vacuum grease is still widely available in different sizes, but I'm concerned with finding the best (current) product for coating the piston seal (Step #2, above) that's compatible with DOT3.  A lot has changed in the last ten years and I can't seem to find anything that's still called "Brake Parts Assembly Lube".  Ditto for a Raybestos product that was also previously mentioned.

I did find a Permatex product #85188 called "Synthetic Ultra Lube - Brake Parts Lubricant" But the specs don't say anything about DOT3 compatibility.

Can anyone recommend a specific currently available DOT3 compatible "Brake Parts Assembly Lube" product suitable for TwoTired's Step #2 above?

Thanks!  ZT

[pjlogue]

I have used Dow Corning High Vacuum Grease for many years.  All O rings get a very thin film on them when I assemble parts.  The lubricating quality of the grease assures that all O rings seat properly.  I have used this grease on brakes for over 20 years now and never had any problems.  On my brakes I only ese enough to lightly coat the O ring.  Absolutely wipe any excess off.  I also coat the caliper piston the same way as well as the outboard side of the caliper well.  (i.e. from the O ring out.) The silicone grease does two things.  1, it lubes well.  2, it causes the piston and outer part of the caliper bore to shed water and greatly reduces corrosion of the piston and caliper.

I would not want gobs of the grease inside the piston well as I do not know how compatible it is with DOT 3 or 4 brake fluid but I have never had any problems with my motorcycles and my cars (two of them) have had well over 200,000 mi each without any problems.  I do clean the calipers well when I replace brakes and apply fresh grease after cleaning them.

-P.

[willbird]

I used Red Rubber Grease that I ordered from Amazon, worked great :-).

[70CB750]

I use Dow Corning High Vacuum grease.  It works great, there is no need to look for something else. 

[BenelliSEI]

I usually just rub a drop of whatever brake fluid I am going to use, around the seal, before inserting it. Has worked for many years…..

[TwoTired]

https://www.ebay.com/itm/322804745197?chn=ps&norover=1&mkevt=1&mkrid=711-213727-13078-0&mkcid=2&itemid=322804745197&targetid=4580153136941816&device=c&mktype=&googleloc=&poi=&campaignid=437225723&mkgroupid=1224856224320864&rlsatarget=pla-4580153136941816&abcId=9300907&merchantid=51291&msclkid=470e35349bb21a8aef3e51a1b4cdc183

I would use this as substitute for brake parts assembly lube. 
I don’t want any silicone in the brake fluid.  And I don’t want any bits of brake fluid on the outside of the piston seal where it can attract moisture out of the air or road puddles and promote rust in the caliper bore.

[ZTatZAU]

Thanks to everyone who replied!
I appreciate the sharing of your experience and expertise.
ZT

[Stev-o]

I usually just rub a drop of whatever brake fluid I am going to use, around the seal, before inserting it. Has worked for many years…..

+1...never an issue

[scottly]

I usually just rub a drop of whatever brake fluid I am going to use, around the seal, before inserting it. Has worked for many years…..

+1...never an issue

+2