Advice when disassembling calipers

Momaru · May 23rd, 2012, 10:45 PM

1) Don't do it if you don't need to
2) When you reassemble it, only compress the pistons half or 2/3 of the way. Then fill the space behind the pistons with brake fluid via the banjo bolt hole before you reattach it to the hose/MC, and rock/tap it to clear as many bubbles as you can.

Before coming to these two realizatons, I got to spend well over 4 hours trying to purge the air from my brakes. Much of that time was spent pumping the brake handle to get ~5mm of fluid/pump into the bleeder line via the bleeder valve. The air just compressed that much. After using ~4oz of brake fluid doing this and almost falling asleep from the repetition, the calipers still wouldn't budge. I went to Advance Auto & got a vacuum bleeder. Another 4 oz of fluid and 2 hours later, every pump got huge amounts of bubbles and no brake pressure/power.

Tried compressing the brake handle overnight, as well as tapping the lines. It got out a bunch of small bubbles, but not even a drop in the bucket for the amount of air remaining.
Finally decided that I must've reassembled the pistons wrong & they were leaking. Nope. Seals were good, I'd done it right. Just huge amounts of air behind the pistons that refused to be displaced by fluid from the banjo bolt & hose.

Once I back-filled the caliper and reassembled, 5 mins to purge the system and get real braking power once again. Gonna check it again tomorrow.

Learn from my mistake, do it right the first time

dubojr1 · May 24th, 2012, 05:22 AM

Hmmm...

I didn't have any of those troubles when I had my caliper powder-coated. After re-assembly I let them gravity bleed then I used one of these from Harbor Freight to bleed the system. Worked like a charm!

Here's another method that I've had good luck with too.

Francis · May 24th, 2012, 06:03 AM

4 hours? Hah!

I recently made a mistake of taking the pistons out while changing brake pads because I was curious (pushed the levers, saw wtf was happening to the pistons and kept going..)

Anywho, close to 3 hours that night.. and another 4-5 more the next morning trying to bleed it.

Racer x · May 24th, 2012, 06:34 AM

Excellent advice.

On some bikes like the Aprilia Millie R.I take the caliper off the bike and bleed it. The hoses trap air because they run over the seingarm.

Momaru · May 24th, 2012, 06:48 AM

Quote:

Originally Posted by dubojr1

Hmmm...

I didn't have any of those troubles when I had my caliper powder-coated. After re-assembly I let them gravity bleed then I used one of these from Harbor Freight to bleed the system. Worked like a charm!

Here's another method that I've had good luck with too.

Yeah, I let 'em gravity bleed as well for a bit, then did it the basic way for two hours with nothin. Just like the guy in the other post you listed, I had zero engagement of the brakes.

Meh, got it sorted eventually. Thanks for the suggestion though re: recycling the fluid. Sadly my vacuum pump doesn't allow that arrangement but I may do that for standard bleeding in the future. This time around the fluid did need to be replaced, was scungy.

GlassAnkles · May 24th, 2012, 08:29 AM

you gotta get a push/pull bleeder if you plan on servicing brakes the rest of your life. this is what i use, its wicked fast from simple bleeds to bone dry caliper rebuilds

phoenix system v-12, you can find it for 65 at some places, http://www.brakebleeder.com/products.../v-12-diy.html

Momaru · May 24th, 2012, 01:09 PM

Quote:

Originally Posted by GlassAnkles

you gotta get a push/pull bleeder if you plan on servicing brakes the rest of your life. this is what i use, its wicked fast from simple bleeds to bone dry caliper rebuilds

phoenix system v-12, you can find it for 65 at some places, http://www.brakebleeder.com/products.../v-12-diy.html

Derp. I burned $59 at Advance for their pull-only bleeder. Not real happy with it, but it's mine now that I've tried it...

Thanks for the link though, that looks like it'd be super handy

Racer x · May 24th, 2012, 01:28 PM

With any of those things is is a good idea to wash them out . Break fluid will swell rubber and corrode metal.

CZroe · June 13th, 2012, 08:21 AM

Subscribing to this thread.

May 23rd, 2012, 10:45 PM	#1
Momaru ninjette.org certified postwhore Name: Paul Location: Roanoke, VA Join Date: Jun 2009 Motorcycle(s): 2008 Candy Plasma Blue 250R Posts: A lot.	Advice when disassembling calipers 1) Don't do it if you don't need to 2) When you reassemble it, only compress the pistons half or 2/3 of the way. Then fill the space behind the pistons with brake fluid via the banjo bolt hole before you reattach it to the hose/MC, and rock/tap it to clear as many bubbles as you can. Before coming to these two realizatons, I got to spend well over 4 hours trying to purge the air from my brakes. Much of that time was spent pumping the brake handle to get ~5mm of fluid/pump into the bleeder line via the bleeder valve. The air just compressed that much. After using ~4oz of brake fluid doing this and almost falling asleep from the repetition, the calipers still wouldn't budge. I went to Advance Auto & got a vacuum bleeder. Another 4 oz of fluid and 2 hours later, every pump got huge amounts of bubbles and no brake pressure/power. Tried compressing the brake handle overnight, as well as tapping the lines. It got out a bunch of small bubbles, but not even a drop in the bucket for the amount of air remaining. Finally decided that I must've reassembled the pistons wrong & they were leaking. Nope. Seals were good, I'd done it right. Just huge amounts of air behind the pistons that refused to be displaced by fluid from the banjo bolt & hose. Once I back-filled the caliper and reassembled, 5 mins to purge the system and get real braking power once again. Gonna check it again tomorrow. Learn from my mistake, do it right the first time __________________________________________________ Proud member of the Blue Army Last futzed with by Momaru; May 24th, 2012 at 01:15 PM. Reason: clarification

May 24th, 2012, 05:22 AM	#2
dubojr1 ninjette.org certified postwhore Name: Jason Location: Jacksonville, Florida Join Date: May 2010 Motorcycle(s): 09 Ninja 250R SE, 07 Honda CRF230F, 06 Honda CRF150F Posts: A lot.	Hmmm... I didn't have any of those troubles when I had my caliper powder-coated. After re-assembly I let them gravity bleed then I used one of these from Harbor Freight to bleed the system. Worked like a charm! Here's another method that I've had good luck with too. __________________________________________________ 09 250R SE: Paying it forward one post at a time! Don't forget to add yourself to our Member Map

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May 24th, 2012, 06:03 AM	#3
Francis ninjette.org newbie 2,000 Name: Francis Location: Vancouver Join Date: Jan 2011 Motorcycle(s): Ninja 250r Posts: 160	4 hours? Hah! I recently made a mistake of taking the pistons out while changing brake pads because I was curious (pushed the levers, saw wtf was happening to the pistons and kept going..) Anywho, close to 3 hours that night.. and another 4-5 more the next morning trying to bleed it.

May 24th, 2012, 06:34 AM	#4
Racer x ninjette.org certified postwhore Name: Eric Location: Iowa City Join Date: May 2009 Motorcycle(s): 2008 Kawmeracchi 350 2010 Project X Posts: A lot. Blog Entries: 54 MOTM - Sep '18, Feb '16	Excellent advice. On some bikes like the Aprilia Millie R.I take the caliper off the bike and bleed it. The hoses trap air because they run over the seingarm.

May 24th, 2012, 08:29 AM	#6
GlassAnkles ninjette.org member Name: Mo Location: KS Join Date: Jan 2012 Motorcycle(s): 02 zx-12r, 13 zx-10r abs Posts: 245	you gotta get a push/pull bleeder if you plan on servicing brakes the rest of your life. this is what i use, its wicked fast from simple bleeds to bone dry caliper rebuilds phoenix system v-12, you can find it for 65 at some places, http://www.brakebleeder.com/products.../v-12-diy.html

May 24th, 2012, 01:28 PM	#8
Racer x ninjette.org certified postwhore Name: Eric Location: Iowa City Join Date: May 2009 Motorcycle(s): 2008 Kawmeracchi 350 2010 Project X Posts: A lot. Blog Entries: 54 MOTM - Sep '18, Feb '16	With any of those things is is a good idea to wash them out . Break fluid will swell rubber and corrode metal.

June 13th, 2012, 08:21 AM	#9
CZroe CPT Falcon Name: J.Emmett Turner Location: Newnan, GA Join Date: Apr 2009 Motorcycle(s): '08 CP Blue EX250J, '97 unpainted EX250F, 2nd '97 unpainted EX250F (no engine), '07 black EX250F Posts: A lot.	Subscribing to this thread.