Teach me: replace brake fluid

[Kurlon]

One person bleeding without speed bleeders:

Put a box end wrench on the bleeder, followed by a hose on bleeder, you want a snug fit over the nipple. Setup the hose and bottle so the hose goes UP for a few inches before arcing back down into your catch bottle. Occasionally I'll ziptie it loosely to the forks or something convenient to hold it in place. Once setup, pop the cover off the reservoir and have fresh fluid handy. Squeeze the brake lever and just crack the bleeder. If it's awkward to do this, use a ziptie to pull the lever back, and then open the bleeder. Open it just enough to get fluid coming out, you don't need to whack it wide open. A little resistance at the lever is what you want. Don't close it.

Start pumping. The column of fluid in the tube will keep you from sucking air, you'll suck back old fluid first. As you pump, make sure the reservoir never goes dry or you'll suck air from that end. You should see a change in fluid color in the tube when you've pushed most of the old fluid out. On most dual caliper setups I hit each side and then repeat to make sure any straggler old fluid in the junction gets caught. To finish, just tighten the bleeder and then test feel at the lever.

[breakdirt916]

dang...with all this info, if you can't get do it, you might as well bring it to a friend or a shop!

[Mr. Kurtz]

Why are we not just doing this next Friday night at midnight?

[jasnmar]

Because that's when you'll be redoing it Mike .

[tsorfas]

Lol

[tsorfas]

Because that's when you'll be redoing it Mike .

No faith?

[jasnmar]

Just thought you needed some hell .

[Jim]

get that clear tubing from Street & Comp to finalize your bleeding process to see any air bubbles leaving the bleeder.

[Ductard]

Related question, since we're on old/new brake fluid - do you guys really only use a bottle once? I understand not picking up a bottle of beeninmygarageforwhothefuckknows, but I've done a brake job and used the same stuff to top off a week or two later... I expect I'll hear the - it's 6 bucks, seems like cheap insurance argument, but given that bike reserviors hold a couple ounces...and there's maybe half an ounce between the min/max lines just seems really wasteful...

[Jim]

Motul says that if you cap a fresh bottle in a cool dry temp condition, you're ok. i usually squeeze the bottle a little bit to push out as much air as possible. then write the date on the cap with a sharpie to note when it was opened.

[nhbubba]

Do all your bikes at once.

(Yes, I have a half empty jug of fluid on my shelf.)

[tsorfas]

Hmmm my brake fluid is from April. I should probably use a fresh one huh?

[CBR929RE]

Hmmm my brake fluid is from April. I should probably use a fresh one huh?

mine is from....I'm not sure. maybe this winter/spring maybe last year. I'd still use it.

when I change fluid I usually soak up whatever is in the reservoir with some paper towels before I start. then fill with new fluid and start flushing.

[Kurlon]

If you're starting with brake fluid in a plastic container, you're already behind the curve. The fluid will already contain some water just from sitting on the shelf. Once you pop the seal more can get in via the cap especially when you increase the air space by using some of the fluid.

In short, you're already starting with potentially compromised fluid, so...

[tsorfas]

Done

[tsorfas]

Here's how I did it step by step

I opened the res first
Then went to the longest brake line caliper and tried using the vac which turned out a bit harder than I thought since it was sucking mostly air. I kept trying until there was almost no fluid left in the res.
went to the other caliper. Same thing until it was sucking out air.
I put fresh fluid in the res and did the same thing again on both sides.
In my head that was a way of flushing out old fluid. No clue if it works.
Filed up the res again and opened both bleeders. Fluid came out. I kept pumping one bleeder at the time until I had a good tight feel on the lever.
Now bleeders are closed and I zip tied the lever and will bleed again either tomorrow or Friday at the track.

Will I live? Lol

[nhbubba]

Certain death, likely by fire.

[Ductard]

Anybody know what the ziptie on the lever does? I've heard that suggestion before, but the suggestors never knew what it did, just that it made the brakes firmer (even without bleeding after taking off the zip-tie).

The only thing I can think of is that since gasses are more soluble in liquids under higher pressures....if you force the gasses into solution in the fluid the lever will feel firmer the next morning when you squeeze it because the bubbles are gone.... *But* - gasses are less soluble in liquids at higher temperature, meaning that the gasses would come out of solution when heated (probably a session or too). Now if all that is correct - it suggests that since you can't bleed out dissolved gasses, you shouldn't zip-tie the lever because all it does is give you a "feel good" brake lever in the morning but actually makes it worse when you use it. Anybody following and have a thought?

[nhbubba]

Anybody know what the ziptie on the lever does?

According to this post, nothing.

[carsick]

I dunno, I'm not old enough to need to ziptie my lever to make it firmer. Yet.

[Mr. Kurtz]

According to this post, nothing.

Sav, nevermind, don't do that. It's something that was suggested to me by someone more knowledgeable some time ago...but less knowledgeable than Graham. I never really considered why to do it.

[Jim]

Don't forget to put 7 layers of tape before bringing that bike to tech