brake bleeding ... i'm gonna go nuts!

[bikerzx7r1981]

Being trying to bleed the front brakes, and posted earlier... but got no joy.

i have bought a syringe and tried pushing fluid through, but its quite hard to do and ended up with brake fluid in the face , I have tried to suck the fluid through and that is also difficult... I get some fluid but mainly air.

can anything be blocked i.e lines etc? Im really at a loose end with it.... when i try using the syringe there is force behind it so its not like its sucking air in... just cant get the fluid down.

i'm i missing a trick.. i.e should the brake lever be back of forward... any help appreciated. ... i will go wash the burning brake fluid out of my eyes now

[Frank Z.]

Follow BassCliff's tutorial and you should be good to go... and stop.

http://members.dslextreme.com/users/bikecliff/images/bleedbrakes.pdf

[Steve]

To minimize the amount of air you get when sucking the fluid from the bleeder nipple, remove the bleeder from the caliper and wrap the threads with Teflon tape.

The lever should be in the normal, relaxed position while bleeding the system.

.

[hampshirehog]

Sometimes you have to resort to bleeding these systems in stages. Stage 1 is the MC - remove the banjo and put your thumb over the hole, pull in the lever. let the air out, put your thumb back over, release lever. Repeat until the MC is bled.

Reattach the first section of brake hose, and disconnect at the splitter. Do the thumb trick again but popping your thumb over the banjo with your index finger on the other side.

When you have bled that section reconnect to the splitter and repeat the operation down to each caliper in turn. Note my comments about angling the caliper if you have fitted the banjo bolt bleeders.

With this technique watch your eyes (!) and make sure you cover your paintwork with a sheet.

[Hoosier Daddy]

...and yes, the old flex hoses can collapse internally. But that sould not allow air to get into the system.

[Normk]

Wash all painted areas onto which brake fluid was spilled (it often gets onto areas no expected!) and wipe every place possible with a wet rag. Brake fluid will adhere to the surface of the paint and may not be completely flushed away by simply rinsing. It can spray up and shower onto areas quite far from the bleeding job if you are not practiced. Ask a shop near where I worked years ago.....$30,000 Corvette paint job all bubbled

As for bleeding, the recommendations and suggestions posted should get you through. If you're not experienced with bleeding it will be much easier if you stop and look at a break down of how the master cylinder works and then to trace the brake hoses. I think hampshirehog has alluded to this in some of his past posts, but air can be trapped in areas which have a pocket above that of the surrounding passage. An example would be a hose leading from the master cylinder if the bars are not positioned properly. Unless you have a professional vacuum brake bleeder (shop air powered) you cannot expect to achieve sufficient flow rate to move all air downward to the caliper.

If the posted recommendations fail to solve the problem, you may wish to consider whether the issue is really trapped air or whether you have a damaged master cylinder sealing cup.

[Kevin Strumpher]

Wash all areas where you dropped brake fluid with a solution of Bicarbonate of Soda which will clear up the spill. Always keep a box of Bicarbonate of Soda on hand in your garage.

Kevin Strumpher

1982 GS450S, 1992 GS500 E Slingshot, 1982 GSX750E, 1980 GS850G, 1980 GS1000G and 1977 Moto Guzzi 850T3

[Hoosier Daddy]

... And I'll ask, are your calipers on the proper side? As in the bleeder is at the top? If you have them swapped side to side the bleeder is not at the highest point and you never will get all the air out. Never hurts to ask because I have seen it a few times.

[bikerzx7r1981]

Thanks For the advice... and a Happy new year to you all.

Just to update

Yes the calipers are on the right way, but ive had to get bleed banjos as both the nipples are broken so they are lower then the bleed nipples.

I'm not sure if the brake master cylinder is just goosed, if i put my thumb over it it has some pressure but not alot, also I noticed is has a few drops of brake fluid out of the brake switch area. So maybe its time to change them ,

I have seen one from a 1200 bandit that I think may do the job.....

[Road_Clam]

Thanks For the advice... and a Happy new year to you all.

Just to update

Yes the calipers are on the right way, but ive had to get bleed banjos as both the nipples are broken so they are lower then the bleed nipples.

I'm not sure if the brake master cylinder is just goosed, if i put my thumb over it it has some pressure but not alot, also I noticed is has a few drops of brake fluid out of the brake switch area. So maybe its time to change them ,

I have seen one from a 1200 bandit that I think may do the job.....

Bleeding brakes can be a frustrating PIA. I've been doing it for 30 years and STLL get pi$$ed off ! All's it takes is a small stubborn air bubble to create a spongy feel. About 5 years ago I finally smartened up and invested in a Mityvac. Hands down the most efficient and quicker method for completely "pulling" stubborn air from your brake systems !

http://www.mityvac.com/pages/products_bcbe.asp

I had a b!tch of a time with my twin 4 piston calipers on my GSXR, even the mityvac was not getting all the air. I ended up removing the calipers and rolling the caliper around in my hand, and pumping the Mityvac at the same time. After about an hour I finally had a precise firm feel to the lever.

[1_v8_merc]

Yes, twin pistons can be a bitch!

My buddy gave me a mighty-vac, and I use it on everything now.

--Heres how I check my MC---
To determine if your MC is putting out pressure...plug your thumb directly over the MC port, good and hard. Now start pumping the Lever a bunch of times, then lift One side of your Thumb Off, just enough to purge out the air, then plug it back up again before letting off the lever(don't want any air to get in)
Now start pumping the lever again, maybe 10 times or so(just a guess), and by now you should start feeling A LOT of pressure on your thumb. Now keep a little pressure on the lever and let your Thumb off again( just alittle).
This time you should get Just fluid shooting out, No Air.
(you might have a tad bit of air, sometimes you gotta repeat this process a few times)

But if your MC behaves normally like above, you can be sure the problem is Below the MC, somewhere in the lines or Calipers.

[Sci85]

+1 on the Mityvac. And even using it, you have to use a combination of vacuum and lever action pressurization. And lots of fluid. I alternate Mityvac and lever back and forth and eventually all the air gets out but it can take awhile and even a whole bottle of fluid for one brake! Follow the instructions in the kit and it shouldn't be a problem assuming there are no air leaks in the system.

Good luck.

[Road_Clam]

The issue is with an air bubble is it want's to rise verticle. while fluid will want to generally flow downward. So you have these two aspects fighting each other. Air bubbles will find a nice vertical confined "pocket" to rest against that disallows to be extracted. (peticulary in the caliper piston bores ) . This is why I have found the method for rolling around the caliper in your hand under vacuum this dislodges the bubble and gets the bubble to float towards the bleeder valve.

[bikerzx7r1981]

Update on brake bleeding

Well i opted to buy a Bandit master cylinder, hooked it up and instantly better, even when bleeding it I got all the air out.

The brake were ok but not good enough to ride with or MOT. The calipers were also sticking, so i stripped calipers and re-bled them. but now the brakes are rubbish again.

I have no air bubbles coming out at all but the brakes are still rubbish, i can see the brake moving slightly when i press them so there def working,just rubbish.

Any suggestions guys? could the calipers not be right? there no leaking fluid and no air bubbles, so how can they still be rubbish

[chuck hahn]

By rubbish you mean they just feel soft..like you dont get a stiff lever till about halfway pulled? Or its soft all the way to the bars?