Brakes: How to twist caliper puck back to 20 degrees?

[Jdub]

Rebuilt my calipers some years back, have them off now and surprised to find two pucks, same rear caliper, are no longer oriented in the 20 degree fashion I left them in. All the others show a perfect 20 degree.

The pucks are extended (by pad wear) right now from the caliper body. Is it possible to twist as I push the puck back in to gain my 20 degrees, or is this just asking for a ripped seal?

If I cannot get this oriented I will just have to re-do the caliper, seals and all I would imagine.

Thanks in advance!

[DRACO A5OG]

use some brake fluid along the edge between the pucks and boots and gently twist. This happened to me after rebuild. I just twisted back into place.

[Jdub]

I used a 12 or 13mm wrench to rotate the puck. Inserted upright, then levered over, it catches the puck edges nicely and allows a grip. GENTLE rotation with lube from brake fluid helps, and doubles as allowing the puck to set back into the body of the caliper.

[BK911]

Notice any adverse effects when braking? I bet many are like yours and nobody notices. That being said, I would have to fix too if I noticed they were off.

[NICE 69 S]

Apparently this was done to keep the pads from wearing unevenly. Did you notice that one side of the pad wore faster than the other? If so, then the pads should be replaced.
Bob B

[Cook&Dunning]

I thought the 20 degree rule was to prevent brake squealing?

[Jon B]

Originally Posted by NICE 69 S

Apparently this was done to keep the pads from wearing unevenly.

Yes, that is correct.

[Jdub]

Nice tool porn there Jon!

One caliper was indeed squeaking, so my assumption is that the puck was off of the required 20 degrees. I did note uneven wear on those pads as well.

But I almost took a chance on not rebuilding the calipers with fresh dust seals as a minimum. When I pulled off the mildly sticky masking tape after painting, the seal came up with it! I think the inner "O" ring in the bore is okay, but I am taking no chances and am replacing all of the seals.

EDIT: What did I learn? Don't trust the appearance alone on evaluating the rubber, and have a care applying brake fluid to these rubber seals - they will decay very quickly. I have a tube of brake grease (presumably silicone-based, like the NAPA stuff) coming and will apply that ABOVE the inner bore "O" ring to both ease the seal onto the puck, and to ensure a grease barrier as well (of sorts - beats old brake fluid!).

[Quicksilver]

Originally Posted by Jdub

. . .

EDIT: What did I learn? Don't trust the appearance alone on evaluating the rubber, and have a care applying brake fluid to these rubber seals - they will decay very quickly. I have a tube of brake grease (presumably silicone-based, like the NAPA stuff) coming and will apply that ABOVE the inner bore "O" ring to both ease the seal onto the puck, and to ensure a grease barrier as well (of sorts - beats old brake fluid!).

Silglyde is the lube of choice. Should be available at any good autoparts store. The part I don't like is the "leave some moist lube out there to collect dirt and dust" part. There is enough trouble in that area.

I use a heavy duty snap ring pliers designed for transmission work to turn the pistons.

I really like the sound of the "wedge the end of a box end wrench" method. I'll try it the next time I do the brakes.

[BFT3.2]

Perfect timing for this thread! In the process of installing new rotors, pads, brake lines up front. When I had the caliper off brass brushing it "clean" today I noticed one of the pucks was definitely rotated about 30* off from the other side which was correct. Sat there for a while thinking how am I gonna spin that thing? I'll try the box wrench end tmrw. Yes, my pads had worn unevenly too. Is it agreed that applying some brake fluid on it is ok to help in spinning it?

Also, one of my dust covers is half gone. Is it worth replacing as Im probably gonna fry it at the track?

[Jdub]

I'd use the silicone-based grease where the puck touches the seal. Use a wooden nail cuticle to get some penetration. Not sure if the covers are resistant to brake fluid corroding them (what material?).

You only risk the long-term use of any caliper with a blown dust cover. The fronts will degrade faster than the rears.

[midnight911]

Like! for that wrench method...ingenious.

the dust covers were long gone after a track day or two, especially the front.

[BFT3.2]

Thanks guys

[Neel]

Originally Posted by cook&dunning

i thought the 20 degree rule was to prevent brake squealing?

+1..

[Dave 86 930 Fl]

I use these ...

[Jdub]

Removing the dust cover boots revealed some nasty stuff. I will guess that 10 years is about my limit on R&R'ing these:

[DRACO A5OG]

Was the one on the right the new one that ripped?

[Jdub]

All of these are over 10 years old - so no new boot failure. But, the one on the right is the one that I pulled the masking tape from only to see it tear. Age, and possibly application of brake fluid to this material?

[Jon B]

Originally Posted by Jdub

Age, and possibly application of brake fluid to this material?

More likely age, heat and possibly the gaseous emissions from braking.

[krshome]

Originally Posted by Jon B

Yes, that is correct.

I would like to get a hold of those tools, anyone have them they want to sell?