Draining front brake fluid

[Garandman]

Changing the front brake lines on the GSXR750 to SS braided lines. Got the style that goes from a banjo at the master cylinder to each caliper.

What is the best way to drain the brake fluid? I think shops pressurize the master cylinder but not sure I could make that work.

Seems if you remove both ends everything leaks out, so that seems sub-optimal.

[union]

Pump up the calipers with fluid unless you're going to change the fluid. Helps refill the new lines. Drain the reservoir. Set up the new lines. Then be quick changing them over. You'll lose a little so have a shop cloth with you.

[ZX-12R]

I use a Mightvac with a catch reservoir when I do mine. Prior to owning one, I used large irrigation syringes with some vinyl tubing for all things brake related.

[golden chicken]

I like to pump most of the fluid into the calipers, then use a syringe or turkey baster to empty what's left of the fluid in the master. Then change the line and squeeze the piston back, forcing fluid and air back up the line and into the master. Then I would fill the master and bleed the system normally or with a mightyvac.

Plain water will rinse away any spilled brake fluid.

[nhbubba]

Syringe and reverse bleed is the way to go in my opinion.

[LuvDog]

When I switched over my front lines to SS, I just used a syringe to drain the master and then shoved some paper towels in there.

Then disconnected the lines from the master cylinder. I put those ends in a cup and then placed that lower than the calipers and opened the bleeder valves.

[Garandman]

“Just goes to show how a body can see and not see at the same time.”

Turns out plastic syringes are called “Fluid Extractors.” Surfed to buy one and MityVac came up. Duh. If I remove the one way valve, I have a “fluid extractor” and can stop procrastinating.

Then I realized a turkey baster is the same thing....

[Garandman]

Found this video very helpful before changing the lines.

[nhbubba]

I have NEVER had a rear line swap go as easily as he shows. I usually have to remove the caliper and place it well below the master (ie the floor) with a bit of wood jammed in it and bleed it that way.

Honestly he had better luck with a gravity bleed on his fronts than I usually do.

I'm telling you, reverse bleed. Way easier. Especially on an empty system.

[Garandman]

Rear is all set. Overall very easy process.

Is this the correct routing for the left caliper? This is the “Alternative” setup where each caliper line runs to the master cylinder. So it goes behind both fork legs.

[TheIglu]

Should be ok, provided it doesn't snag or rub on anything fur full steering travel at min and max fork travel.

[Garandman]

Guy on TTD FB page posted his: in front of L leg, behind R leg.

[golden chicken]

Pictars on the interwebz show MotoGP bikes with the lines in front of the forks.

[Garandman]

Spiegler sells three different kits. One mimics the OEM routing (one line down to R caliper, 2nd behind fender to L), the alternative is a single line from master cylinder to each, and a “RennSport” (Rennen means “Race” in German) which brings a single line down to the forks, then splits.

This seemed to be simplest. Probably overthinking it.

[Garandman]

Future reference for GSX-R owners that can read: here is what their tech support sent.