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Reverse Bleeding Harley Brakes

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Old Aug 28, 2016 | 10:03 PM
  #1  
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Default Reverse Bleeding Harley Brakes


Hi all,
After minorly sucking some air into my master cylinder while bleeding my front brakes (yeah, I know), I discovered reverse bleeding as a way to not try to suck the bubble through the whole system.

I found a couple of posts that showed ways to do it, and I thought I would share how I did it for anyone who needs it.

I used a bottle of gear lube, empty and really cleaned out, along with a length of 1/4" vinyl tubing, plugged into the bike's calipers, and set it up so that the fluid flowed back up to the master cylinder. Here's a photo of the setup.
There is a bottle of brake fluid in the gear lube bottle, and a hole in the bottom of the bottle. Gravity takes the fluid into the system and the master cylinder fills up. We used a turkey baster to suck the fluid out when it filled.

I occasionally gently jiggle the brake handle, which pushed some accumulated bubbles out the recirculating holes in the bottom of the master cylinder.

Then I bled the thing back the normal way. The brake is really firm now, very nice.

Here are some links to the other posts I found about this.

http://www.harley-davidsonforums.com...ml#post1142929

http://www.moccsplace.com/images/bra...er/bleeder.htm

Best.
 

Last edited by sel53; Aug 28, 2016 at 10:09 PM.
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Old Aug 29, 2016 | 05:23 AM
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Well done - surgical precision by the look of it!
 
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Old Aug 29, 2016 | 05:54 AM
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I hope that bottle was as clean as you think it was....Brake fluid is contaminated very easily.

Idea is sound tho...
 
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Old Aug 29, 2016 | 07:16 AM
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I agree with the other posters ,good idea for sure.
 
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Old Aug 29, 2016 | 07:26 AM
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Reverse bleeding can be helpful. I prefer to use a 60cc syringe though. I believe it's more controllable.
Your arrangement, while functional, looks like a brake fluid disaster waiting to happen.
 
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Old Aug 29, 2016 | 12:55 PM
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nice 16' extension ladder, always wanted one.
 
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Old Aug 29, 2016 | 04:36 PM
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Wonder if that will work on the Rushmore with electronic linked and ABS brake system.
 
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Old Aug 29, 2016 | 05:46 PM
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Originally Posted by Punjabi HD
Wonder if that will work on the Rushmore with electronic linked and ABS brake system.
Yes, forward or reverse bleeding will work on ABS systems. The important thing is to not introduce air into the ABS system. So bleed them without turning the bike on. If you want the ABS module bled then you have a couple of choices. Either take it to a dealer to cycle the ABS module or make several stops rapidly enough to cause the ABS to engage.
ABS braking systems, at their core, are nothing more than a normal hydraulic brake system with a safety system piggybacked to keep the wheels from locking up. If the ABS system were to fail you would still have perfectly normal braking just like a pre ABS vehicle.
 
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Old Aug 29, 2016 | 06:08 PM
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Originally Posted by ORradtech
Reverse bleeding can be helpful. I prefer to use a 60cc syringe though. I believe it's more controllable.
Your arrangement, while functional, looks like a brake fluid disaster waiting to happen.
I agree. After seeing what dot4 will do to paint, I try to keep it contained and controlled as best I can. I use a mighty vac, you can use them in reverse to push the fluid too. I didn't think my clutch was bled out after changing lines for my bar swap. I bled and bled and bled. Then I reverse bled using the mighty vac. I have a long hose so I can stand and watch the master cylinder. Turns out the clutch was bled. The plates were sticking and wouldn't let the bike roll, after up to temp it was like pushing the bike around in neutral.
 
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Old Aug 29, 2016 | 11:50 PM
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Lot of good comments. I struggled with most of them before doing it this way.

It is probably hard to tell but that bottle is WAY over from the bike (yes, fear played a hand here), and letting gravity do the trick I didn't have to do much more than check the hose connections every so often (and of course suck the master cylinder often).

i knew I would get an appropriate garage comment from someone ... Thanks for being kind, Stoney
 
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