Brake Fluid Change w/ABS
Grand HDF Member
Joined: Jan 2012
Posts: 4,459
Likes: 2,896
From: Oklahoma
What is the fluid "circuit" during an ABS activation in a CLOSED SYSTEM? If the released fluid is pumped in a circle, it winds up back inside the HCU. However, if it is flushed away during an OPEN SYSTEM activation with the Harley computer, it is truly changed. Personally, I have NO IDEA where the fluid goes, just asking the question for the guys who do the flush, then ride and activate the system, and flush again. That idea sounds great IF you know the old fluid is pumped into the brake lines and can be emptied with the second flush. Personally, I don't see how that would work, the fluid in the brake line hardly moves, the PRESSURE is relieved momentarily, but the fluid doesn't circulate.
Last edited by btsom; Nov 20, 2018 at 07:50 AM.
Banned
Joined: Mar 2008
Posts: 1,967
Likes: 206
From: Jax FL
my dealer measures the brake fluid (specific gravity? acidity?) and puts that on your service receipt, so you can predict when the brake fluid will erode the ABS module.
this is just another 'Pay to Play" until StoneCold develops an ABS module for the forum....
this is just another 'Pay to Play" until StoneCold develops an ABS module for the forum....
Outstanding HDF Member
Joined: May 2015
Posts: 2,172
Likes: 377
From: Georgia
It measures moisture content. You can buy the tool on Amazon for like $20.
Cruiser
Joined: Dec 2012
Posts: 107
Likes: 41
From: Vineland Ontario Canada
When purchasing my King in 09 I decided on cruise and theft deterrent but not the ABS. My reasoning was that it could be a added area of trouble and that I really did not need it. Boy, what lame thinking that was. Good or bad that it is, this can be a potentially life saving tool or at least help prevent loss of control. So all that I would like to add is that be glad that you have it and keep it operational to the best of your ability. Any of the above bleeding procedures are positive so take your pick.
Road Warrior
Joined: Oct 2008
Posts: 1,692
Likes: 22
From: Denham Springs, La
What is the fluid "circuit" during an ABS activation in a CLOSED SYSTEM? If the released fluid is pumped in a circle, it winds up back inside the HCU. However, if it is flushed away during an OPEN SYSTEM activation with the Harley computer, it is truly changed. Personally, I have NO IDEA where the fluid goes, just asking the question for the guys who do the flush, then ride and activate the system, and flush again. That idea sounds great IF you know the old fluid is pumped into the brake lines and can be emptied with the second flush. Personally, I don't see how that would work, the fluid in the brake line hardly moves, the PRESSURE is relieved momentarily, but the fluid doesn't circulate.
Road Warrior
Joined: Oct 2008
Posts: 1,692
Likes: 22
From: Denham Springs, La
When purchasing my King in 09 I decided on cruise and theft deterrent but not the ABS. My reasoning was that it could be a added area of trouble and that I really did not need it. Boy, what lame thinking that was. Good or bad that it is, this can be a potentially life saving tool or at least help prevent loss of control. So all that I would like to add is that be glad that you have it and keep it operational to the best of your ability.
Extreme HDF Member
Joined: Dec 2007
Posts: 13,402
Likes: 941
From: Illinois
You can successfully change all ABS fluids with just a little extra effort.
Drain front and rear as always. Then turn the ignition on and off many times. That is what the digital tech does but in rapid fire. Every time the ignition is turned on the ECM test fires the ABS.
Another method is to ride the bike for awhile. After either method drain and refill the two master cylinders. Keep the H-D $100 in your pocket. I have done these two methods many times on many ABS H-D's since 2010. Failures are at Zero.
The using ADS hard to activate may not be totally necessary as the normal application goes through the system under normal use. Just follow the lines they do not go from the master to the slave cylinder. They pass through the system to each one.
Every time you turn the ignition on and every time you use the brakes hard to activate the ABS the new fluid replaces the supply in the ABS system. Use that knowledge to your benefit.
I get the 1 quart DOT 4 at Walmart for about $8 and it will do 8 to 10 bikes. One heck of a long way from $100 per bike per H-D service dept.
Drain front and rear as always. Then turn the ignition on and off many times. That is what the digital tech does but in rapid fire. Every time the ignition is turned on the ECM test fires the ABS.
Another method is to ride the bike for awhile. After either method drain and refill the two master cylinders. Keep the H-D $100 in your pocket. I have done these two methods many times on many ABS H-D's since 2010. Failures are at Zero.
The using ADS hard to activate may not be totally necessary as the normal application goes through the system under normal use. Just follow the lines they do not go from the master to the slave cylinder. They pass through the system to each one.
Every time you turn the ignition on and every time you use the brakes hard to activate the ABS the new fluid replaces the supply in the ABS system. Use that knowledge to your benefit.
I get the 1 quart DOT 4 at Walmart for about $8 and it will do 8 to 10 bikes. One heck of a long way from $100 per bike per H-D service dept.
Last edited by lh4x4; Dec 11, 2018 at 05:47 PM.
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Extreme HDF Member
Joined: Dec 2007
Posts: 13,402
Likes: 941
From: Illinois
For those that think the master cylinder just adds pressure and fluid does not flow seem not to understand that the pressure has flow when it pushes (moves) the piston out to move the pad out. That amount of fluid does not flow backward when the lever is released it flows to the master cylinder. Every time all the time. So after awhile all of the fluid cycles back to the master cylinder.
Seasoned HDF Member
Joined: Apr 2015
Posts: 10,068
Likes: 5,320
Originally Posted by lh4x4
For those that think the master cylinder just adds pressure and fluid does not flow seem not to understand that the pressure has flow when it pushes (moves) the piston out to move the pad out. That amount of fluid does not flow backward when the lever is released it flows to the master cylinder. Every time all the time. So after awhile all of the fluid cycles back to the master cylinder.
