Brake Master Cylinder Bench Bleeding

Spongy, soft brakes no matter how much you bleed? Here is the FIX!

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00:00 Intro
00:30 Why Your Brakes Are Soft
01:09 The Slow Bleed
02:51 Master Cylinder & Brake Line Issues
04:20 Bench Bleeding The Master Cylinder
06:17 Brake Fluid Tips

#rodrideswrenches #brakes

[johnschlesinger]

I remember the service manual for my 1980 Kawasaki: it said "Remove the master cylinder cover and gasket. With the handlebar level, slowly squeeze the brake lever several times. This removes air from the master cylinder." These weren't the exact words, but they told one to start by bleeding the top of the system. I would often see tiny air bubbles emerging. This saves a ton of time, as these tiny bubbles don't have to be pushed all the way through the system.

[guzzrav]

Vacuum bled my brakes not a single bubble but still a soggy lever. After hitting the caliper with a rubber mallet and repeating the bleeding process a couple times, success. Thanks for this video learned something new 👍

[DavidM]

Here's a tip from a friend who swears by this simple method. With the wheels off the ground, and the bleeder open, spin the wheel which will set up a vibration of the brake rotor against the brake pads and into the caliper. That vibration will break loose the bubbles. He didn't say how long to do this ( maybe that's why I haven't seen him in weeks...) but I suspect it would be until you saw the bubbles come out assuming there are any.

[Baldhills]

After installing steel braided brake lines on my 2018 Kawasaki Z900 RS, I had a terrible time getting the air out of the system.
I used vacuum bleeders, and everything I could think of to no avail.
What ended up fixing the problem was to fill the front brake reservoir, leave the cover off and putting a Velcro strap around the front brake lever and grip to apply the brake.
I let it sit in my garage this way over the weekend. It had firmed up considerably but still not to my liking. So I tried it again for 3 days.
It worked like a champ this time. No air at all in the front system now.
The air will gradually bubble up over time and purge itself.
It takes patience but works like a champ!

[FREE_PUREBLOOD]

Nice video as always. I use the old fashioned bleed process to start with after cleaning out the old fluid from the m/cyl's and topping up with fresh. I then use the syringe method from the bleed nipple to inject new fluid from the calipers to the m/cyl if theres any spongy feeling still. Once completed I zip tie the levers in the activated position overnight to free up any remaining bubbles.

[mattthomson]

Performing a 50k inspection and repairs on my “new for me” Honda, I am soooo looking forward to that day I am ready to bleed the Honda ABS brake system! A few basic recollections: If the manuals state having the handle bars rotated to full lock, one side or the other, do that. When operating any pumps or levers or bleeder valves, know that rapid operation almost always will introduce air into the system as piston seals can easily succumb to ambient air pressures. SLOWLY operate control levers, bleeder valves and pump handles to avoid sucking air. Vinyl hoses are great for visuals, and famous for back-leaking air into the system; make sure the vinyl fits snugly over the bleed valve. As pointed out in the vid, keep that vinyl hose upright in order to maintain a good seal, as any drooping may easily cause a vacuum and subsequent introduction of air. Oh, and bleed valves are machined by design to a taper, and taper fits require only gentle torque pressure. Good luck; keep that master cylinder wet and ride on!

[Kisqee]

wasn't getting any pressure on my brake lever after bleeding right and left caliper several times. after seeing this vid and bench bleeding finally got it working again. thanks for the vid! keep up the great tips :D

[saginaw]

As an old, experienced, mechanic, I have been amazed at how much better brakes work with fresh fluid. After 50 years, a physics teacher explained to me, that when two liquids mix (brake fluid+water) the result is thicker. Yes temperature excursion slowly brings water into your system. Don't expect you to believe this, no one else does.

[wayneknodel]

Great video! I also have a 2010 VFR1200 with only 8000 km and the brakes went super mushy. I did bleed the calipers and saw and improvement, but being lazy, I stopped there. This will give me a kick in the ass to finish the job completely using your tips!

[Tofu_tim]

Thank you so much!!! This weekend was a headache and I wish I found your video sooner

[mattdrat]

After changing the master cylinder with plunger/spring/washer/circlip, dust boot, brake line, everything in the caliper including the piston, rubber washers, dust seal, dust seal spring (all genuine Yamaha parts) on my Nissen brake for my Yamaha XT350 1991 model, I tried bleeding the brake. No luck.

Two friends, independent of each other, with a combined 60 years of experience in motorbike maintenance couldn't get it to work either. It just wouldn't build any pressure, no matter what equipment or procedure we used. The piston popped out nicely when they applied pressured air, but not when using the lever. Then one said that when bleeding just doesn't work, I could try just parking the bike, with the master cylinder at the highest point and give it a few days. I did so, but still no pressure. Due to bad weather and no garage, I had to wait another week or so, then decided to take it all apart, for the 4th. time. Before draining the brake fluid I thought I'd give it one last go. Wheeled the bike around, pulled the lever and the brakes worked! So, if all else fails, might want to try that!

[happyacresminifarm]

Thanks for the tip on bench bleeding, I replaced the brake line on my 99 Triumph Adventurer and it would not build pressure. Cracked the banjo bolt on the master cylinder and went through the process, I had pressure in no time.
Thanks again and have a great day!!

[nickx]

no banjo bolt work…. just put the cap back on the master cyl, turn handlebars to the full left lock w/bike on side stand, and quickly flutter the brake lever. bubbles work their way up into the master cyl reservoir, lever gets firmer. no mess.👍

[Johndoe]

Thank you out of the 100 videos i watched this is the best one that actually explains it

[dventura]

I'm headed to do that now. It felt like you were talking to me lol... Great video!

[stevepatterson]

This is the simplest and best/proper technique to use on your motorcycle. Trust this method it worked like magic for my two bikes! - Thanks for another awesome vid!

[MichaelWysocki-ksxt]

My nephew and his friends always used one of those vacuum bleeder tools when bleeding brakes.
Then they called uncle up to help make it work again when they filled the system with air.
What I have found is most brake lines go on some form of
‘ roller coaster ‘ ride with at least one good hill for air bubbles to rise into. If you don’t move the fluid fast enough and far enough the bubbles just keep going up the hill.

[Drakos]

brilliant, i've been working on my bikes for 35 years but yesterday was having a completely nightmare trying to get pressure at the rear brake on my 05 ducati multistrada, the trouble is with the single sided swing arm the hose takes a terrible path from the low calliper along the under side of the swing arm and around the front of the swing arm then over and back to the m/c. i changed the m/c and line and used a syringe to try to pull fluid out of the bleed valve on the calliper, i was getting clean new fluid coming through but the lever was still totally soft, i tried tapping the line and moving the m/c about to try to get bubbles up and i was trying normal bleeding pumping the lever anbd releasing the bleed valve, all in all for hours yesterday and still couldn't get any pressure. i gave up and hoped bubbles would work their way up overnight, but this morning i still couldn't get any bubble to come out into the reservoir. in desperation i looked on youtube to see if there was anything i hadn't thought of or that i had forgotton or missed, and found your video, the tip at 5 minutes of cracking open the banjo bolt to release air trapped in the m/c made sense so i tried it, in only 2 or 3 goes i had all the air out and a really lovely firm lever, the whole thing took about 2 thank you.

[martinlim]

Thank you Sir! Such an informative lead to troubleshoot the soft sensation.

[Wooskii]

I have the Brembo brake curse on one of my bikes (Let it sit too long, air gets in). My lever will go to the bar, no resistance. The only fix I've found (besides switching parts) is to put a rubber band or zip tie on the brake if storing it for a while, which doesn't seem right to me, but it does seem to work.
I have no idea what is happening, but other people are having the same problem on brand new bikes. No fluid leaks, the level stays the same, and the brakes are extremely nice (when they work)