cleaning old brake fluid

I am replacing the master cylinder and brake lines with new. Also rebuilt the caliper with new seals and piston. What is the best tking to clean the old fluid out of the junction block where the lines and brake light switch hook together? Thanks

new brake fluid would probably be best to flush out all the old crud.

Denatured alcohol is the only solvent safe to use in a brake system. Anything else will make rubber parts swell.

There is no rubber in the junction block.

I'd take it off and shoot some brake cleaner in there. If you have a rifle brush that could be use to scrub it out as well.

BTW, nice job of updating the brake system properly.

What year bike are you talking about?

Thanks guys. I have the junction off of the bike so that I can do a good job of cleaning it. The rifle brush sounds like a good idea. I have one so that is what I will use. I am a firm believer in using the front brake every time I stop.
Jerry

I just rebuilt the rear master cylinder of KZombie last evening.
Almost the entire thing was packed with hard, whitish powder from reservoir to bottom of main cylinder bore where it took a lot of working it over just to get the main piston free enough to extract from the bore. That same #6 screw extractor that I used to rebuild the front forks worked out as the best tool for this job too I love when a single-use tool has more functions!

The only thing I used was PB Blaster (which did not affect the rubber seals at all) to get the piston or parts moving again and all the hard crusty yuck just kinda fell out. Later I gave the whole thing a vigorous bath in soapy water to flush all the passages.

I did have to invent a tool for one passage which went from the larger port diagonally down into the main bore. Turned out a 4" piece of coaxial cable was like perfect!

When I got my ZXR brakes from the postie,I drained them and dumped them straight in a bucket of soapy water. Let them sit for a while then give them a good scrub. For getting into the very small holes,dental brushes are usefull.