To bleed or not to bleed?

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Mar 24, 2016 | 10:19 PM

#11

hattitude

Seasoned HDF Member

Joined: Sep 2008

Posts: 14,160

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From: San Diego, CA

Quote:

Originally Posted by skratch

common consensus is that as long as you don't turn your ignition on, you can bleed the brakes normally.

That's the way it should work..

I read an article about how the Tech II bleeds the brake system. I should have saved it for reference. If I remember correctly, the ABS has two or three valves that trap fluid. When the valves are activated, they cause the brake pulsing. If you let air in the system, you should be able to bleed it out as long as you don't activate those valves and trap air in the closed portion of the ABS. Those valves activate when the unit is powered up. In theory, if you don't turn on the key and trap air in the closed off portion, you shouldn't need to use the tech II to get the air out.

I just flushed my ABS brake system with a vacuum bleeder. I made sure to not let the reservoir go dry (suck air). I didn't want to take any chance of getting air into the system if I didn't have to. All went well, brakes work great....

OP, you'll have no issue just changing reservoir caps! Don't spill/splash any brake fluid as most have mentioned!

Last edited by hattitude; Mar 24, 2016 at 10:27 PM.

Mar 25, 2016 | 06:42 AM

#12

Campy Roadie

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Joined: Aug 2011

Posts: 11,814

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From: SW Ohio

I have ABS on one of my bikes.

I bleed my brakes, refill with fresh fluid and remove all air bubbles; then I go ride the bike and engage ABS a couple times. Then I return to the garage and flush the caliper(s) again. It takes a little more time, but it does prevent old fluid with moisture from being trapped in the ABS pump.

Mar 25, 2016 | 03:39 PM

#13

ultra_classic

Club Member

Joined: Jan 2011

Posts: 937

Likes: 22

From: Ontario, Canada

Quote:

Originally Posted by Nomadmax

This. /\

OP no need to bleed to change the cap, but you should bleed for PM ( preventive maintenance)
With ABS just don't let the master run dry during bleeding.

Master replacement question a few posts back.

You could trap air in the HCU (Hydraulic Control Unit) and that is why they suggest the tool to cycle the pump and solenoids to help push the trapped air out.
As earlier posted, you can fill the. New master and let gravity do most of the work, then bleed normally, the on a careful road test, engage the ABS ( read: lock the wheel) and then re bleed

Mar 25, 2016 | 04:14 PM

#14

vboxmark

Novice

Joined: Jun 2015

Posts: 22

Likes: 0

From: Brampton, Ontario

Nomadmax

What do you mean "( read: lock the wheel) " ?

Mar 25, 2016 | 05:46 PM

#15

skratch

Seasoned HDF Member

Joined: Jan 2007

Posts: 20,616

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From: anacoco, la

Quote:

Originally Posted by vboxmark

Nomadmax

What do you mean "( read: lock the wheel) " ?

that's how you engage the abs. the rear is easy, the front, a little more difficult. the abs will keep the wheel from locking up, but you have to be at that point for the abs to engage.

Mar 25, 2016 | 05:46 PM

#16

markwolula

Tourer

Joined: Jan 2012

Posts: 373

Likes: 90

From: australia

Quote:

Originally Posted by Nomadmax

+1, +1 ,,,
Great advice above,,,
Also use Mity Vac or similar ,,
Dont let the fluid in the reservoir drain low, (ie, when flushing , keep reservoir half full at all times),,
Dont turn ignition switch ON during the whole procedure,,,

Do all of the above, and you will have no problem bleeding/flushing brake system with ABS ...

Mar 25, 2016 | 06:00 PM

#17

mcain49

Road Master

Joined: Mar 2010

Posts: 943

Likes: 41

Quote:

Originally Posted by peddler

First bike I have owned with ABS brakes. I'll be removing the stock clutch & front brake master cylinders and replacing them with chrome ones sometime in the next couple of weeks. The instructions and repair manual indicate the ABS brakes can only be successfully bled using the Digital Technician II. The only way to bleed ABS brakes is to take the bike to the dealer and have them do it?? Anyone have an alternative method that works?

Any input is appreciated.

The ABS brakes can be bled normally as long as you don't cycle the ignition switch during the process. Just make sure you keep the reservoir filled while you're doing it to avoid getting air into the lines. I use the speed bleeders which makes it super easy to do by yourself very quickly. Also be sure to cover your tank to prevent brake fluid from contacting painted surfaces.

Mar 26, 2016 | 04:05 AM

#18

Campy Roadie

Seasoned HDF Member

Joined: Aug 2011

Posts: 11,814

Likes: 5,120

From: SW Ohio

Quote:

Originally Posted by skratch

that's how you engage the abs. the rear is easy, the front, a little more difficult. the abs will keep the wheel from locking up, but you have to be at that point for the abs to engage.

I have a downhill near my house that has some stutter bumps on it. That makes it easy to engage ABS on just the front, just the rear or both wheels. Usually, stutter bumps (undulations in the pavement) on flat ground will engage ABS as well. You can feel it when the caliper(s) depressurize and the bike surges forward. The way you engage the lever or pedal has a great deal to do with the loss of traction and ABS engagement.

Skratch I know you know this, I just wanted my answer and your answer to be together so someone later could find it in a search.