Dark Brake Fluid
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Cruiser
Joined: Jul 2014
Posts: 179
Likes: 2
From: N/A
Dark Brake Fluid
hello there, re-installation of my rear brake setup with a braided brake line on my 14 dl. Got the line bleeded and brake look to be working fine, the thing is that after 2 complete flush i still get grey/dark brake fluid out of the nipple. Pretty sure that i did 2 complete cycle but i just cant get clean fluid out of the caliper. I use BelRay dot4 and nothing leak. What it can be? What are my option keep flushing fluid until i get good fluid? Front is clean as hell just rear give me trouble. Thanks.
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Joined: Feb 2015
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From: Galt's Gulch - MI
Keep flushing 
The rear fluid tends to be much darker and dirtier on mine as well; I do a complete bleed and flush every 12 months and the front always looks like new and the rear is much darker. The rear master is mounted low and more exposed to the elements and there's no chance it's 100% sealed, so moisture contamination is much more of an issue with the rears....
The rear fluid tends to be much darker and dirtier on mine as well; I do a complete bleed and flush every 12 months and the front always looks like new and the rear is much darker. The rear master is mounted low and more exposed to the elements and there's no chance it's 100% sealed, so moisture contamination is much more of an issue with the rears....
Thread Starter
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Cruiser
Joined: Jul 2014
Posts: 179
Likes: 2
From: N/A
Keep flushing
The rear fluid tends to be much darker and dirtier on mine as well; I do a complete bleed and flush every 12 months and the front always looks like new and the rear is much darker. The rear master is mounted low and more exposed to the elements and there's no chance it's 100% sealed, so moisture contamination is much more of an issue with the rears....
The rear fluid tends to be much darker and dirtier on mine as well; I do a complete bleed and flush every 12 months and the front always looks like new and the rear is much darker. The rear master is mounted low and more exposed to the elements and there's no chance it's 100% sealed, so moisture contamination is much more of an issue with the rears....
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Cruiser
Joined: Jul 2014
Posts: 179
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From: N/A
I got the front really firm almost no pressure for locking wheel but rear is more softier. Is it just me or the rear need more leverage to feel firm. Is it just how the master/pedal is designed/build or i can get it pretty much tight like the front???
Extreme HDF Member
Joined: Feb 2015
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From: Galt's Gulch - MI
I've found the easiest way to do the bleed and flush on the rears is to use plastic syringes. I start with the rear and a new 12 ounce bottle of DOT 4; I use one syringe to draw out the old fluid from the master then use a clean uncontaminated syringe to draw fresh fluid out of the new bottle and add it to the master; I'll end up running over half the bottle through the rear to be certain it's completely clean.
The front is much simpler, and I'll use the remainder of the bottle flushing the front; no point in keeping an open bottle of DOT 4 sitting around
Edited to add:
It will take more pedal movement on the rear; the rear is running pistons on only one side of the caliper so it does take a bit of pedal travel before the rear locks up firm. At least, that's my theory
The front is much simpler, and I'll use the remainder of the bottle flushing the front; no point in keeping an open bottle of DOT 4 sitting around
Edited to add:
I got the front really firm almost no pressure for locking wheel but rear is more softier. Is it just me or the rear need more leverage to feel firm. Is it just how the master/pedal is designed/build or i can get it pretty much tight like the front???
Last edited by TinCupChalice; Mar 19, 2017 at 10:42 AM.
Seasoned HDF Member
Joined: Jan 2015
Posts: 15,944
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From: Sandy Eggo's North County
Rear brake system may pick up heat from the exhaust system. This oxidizes the brake fluid, turning it dark.
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Thread Starter
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Cruiser
Joined: Jul 2014
Posts: 179
Likes: 2
From: N/A
I've found the easiest way to do the bleed and flush on the rears is to use plastic syringes. I start with the rear and a new 12 ounce bottle of DOT 4; I use one syringe to draw out the old fluid from the master then use a clean uncontaminated syringe to draw fresh fluid out of the new bottle and add it to the master; I'll end up running over half the bottle through the rear to be certain it's completely clean.
The front is much simpler, and I'll use the remainder of the bottle flushing the front; no point in keeping an open bottle of DOT 4 sitting around
Edited to add:
It will take more pedal movement on the rear; the rear is running pistons on only one side of the caliper so it does take a bit of pedal travel before the rear locks up firm. At least, that's my theory
The front is much simpler, and I'll use the remainder of the bottle flushing the front; no point in keeping an open bottle of DOT 4 sitting around
Edited to add:
It will take more pedal movement on the rear; the rear is running pistons on only one side of the caliper so it does take a bit of pedal travel before the rear locks up firm. At least, that's my theory
I got a Mityvac pump it work quite well.
I use radial Brembo calipers of GSXR in the back and front, i think it the way the rear master is designed that make it need more leverage but this might get better when i successfully flush all old fluid
Last edited by Cafard; Mar 19, 2017 at 02:16 PM.
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Cruiser
Joined: Nov 2015
Posts: 192
Likes: 20
From: MN
I gotta agree with TinCup...The rear is a single piston and the caliper runs on a slide. As for the Fluid color?...there are so many nooks and crannies in the system for particulates to sit you 'll never (opening the internet equivalence of Pandora's box here) get all of them out. Most yes, all..probably not. If you are only spitting a little bit of discolored fluid when you crack the bleeder I think you'll be fine.
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Joined: Mar 2015
Posts: 2,840
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From: Philly Suburbs
Did you make a bracket for the rear caliper? I would love to see a picture of it...