How to Lubricate Front Brake Calipers

I do not have the specs for which you ask but I did find this handy reference on brake lube:

http://www.aa1car.com/library/2005/ic80560.htm

 

I did general cleanup and inspection of my front calipers recently,
and found that simply sliding them back and forth a bit on the pins
yielded a definite "crack loose from old long-term position and then
redistribute the grease" feeling. It is possible that that's all you
need to do to restore free "float", and thus avoid opening up those
little rubber seals and possibly getting dirt underneath. Be careful
to not slide the caliper too far and distort the rubber thingie and
possibly pull it loose; keep tight control of range of motion when
you go to play with the things.
.
I figure this will suffice until the grease inside *really* starts
to go, and I have no idea how long that'll take given that the pins
felt absolutely fine [on a 2-year-old car] when I did this.
.
_H*

 

<div class='quotetop'>QUOTE(hobbit @ Jul 27 2006, 07:55 AM) [snapback]293167[/snapback]</div>

I haven't taken a close look at the front brakes of my Prius, but on other cars, those "rubber thingies" are just dust boots that fit into grooves machined into either end of the caliper pins (bushings). You won't damage them by pulling the caliper pins out with your fingers, and in fact, are expected to do so as part of normal maintenance. Brush some high temperature brake grease on them and shove them back into the dust boots, snapping the seals into place in the grooves at either end of the pin (I never did figure out how you were supposed to do this without having the dust boot scrape off half the grease on the pin).

In my repair manual, next to "Front disc brake caliper assy x Steering knuckle" it says 81 ft-lbs. Seems awfully high - on my Jeep it's only 12 ft-lbs., and lug nuts are only torqued to 76 ft-lbs. Maybe that's for the caliper mounts and not the calipers themselves. Typically a caliper mount attaches to the steering knuckle, and then the caliper attaches to the caliper mount.

 

Has anyone loosened or removed the brake piston dust boot and checked, cleaned, lubed the piston? How did you do it? Don't want to open it if I might damage the boot. The 05 Peoples Prius is coming up on 180K and I just ordered it's second set of rotors and pads for it when I found one inner pad down to metal on Sunday. A week of graunching noise when turning forced me to look for the cause. The mail route eats up brakes, the replacement set (generic Chinese) made it about 70K miles. Of note is one front rotor has a crack in it. Didn't seem to bother anything but....... The crack is about and inch long in the swept area of the rotor. it doesn't extend out to the rim. It might have been there since the rotor was cast. I kept my "best" pads from the last job and threw them in til the new parts arrive Thursday. Yeah I am primitive. The car is rode hard and put away wet. Even under my abuse the biggest maintenance so far has been front wheel bearings (three) One defective bearing died of big slop in 10K miles.
Since drilling holes in the rear drums to help the dust escape, rear shoe life has jumped to 50K plus from a low of 20K with nasty squealing when cold and extreme sensitivity to locking up. I may get an LLV on the mail route this summer and the Prius will be put out to pasture.

 

They are just conventional sliding calipers. Of course, take your precautions when working on this braking system - the procedures are well documented on this site.

Lube the slide pins with 3M silicone paste (not synthetic, not anti-seize). Remove the clips on the bracket and wire brush (or wire wheel the area). If you're in an area with a lot of salt, then applying a light film of Molykote M77 to the bracket before reinstalling the clips is a good idea. When reinstalling the pads, apply a light film of M77 to the pad "ears" only to allow for better sliding.

If you have access to Toyota Techstream or an aftermarket scanner that has the air bleed feature, then a brake fluid flush is a good idea as well - otherwise, do not attempt!

 

Not worried about the pins, I get that, it's the piston/pucks I'm wondering about. Yeah i can just push em back and put the pads in. But if it's not a cluster, I'd like to pop the dust boots and look at the pistons, swab them clean with brake cleaner maybe run a q-tip of brake fluid around them before retracting them.

 

I don't see how that would help improve the caliper's performance.


iPhone ?

 

Before you do any work on your brakes front or rear disconnect the 12 volt battery at the very leased. As the Critic said unless you have access to Techstream or similar do not attempt to open bleed valves open in any way the hydraulic system. Below is a diagram of the brake hydraulics system. You will find 10 two way electrically operated valves and seven pressure censers. Relieving pressure in the system or allowing air in will give you real problems.

John (Britprius)

 

I have had really good luck with this lube in the last 10 years. Avail at all Autoparts stores. Tiny bit behind the shims too and never any rattling. Synthetic.:

Permatex 24110 Ultra Disc Brake Caliper Lube 8 fl. oz. brush-top bottle

But really at 180,000 in an 05 even in a Prius I would buy reman' calipers. There not very expensive. The hard part is removing the calipers and bleeding the system which on a Prius is difficult and requires Techstream or jumping out the metering relays and apparently your ready to do that.

Doesn't matter how well you lube the pistons at that age if one gets stuck its a tow home.