CBX550 - Bleeding front brakes from dry

NoRiders

NoRiders

Over 1,000 Posts
Hi, Hoping someone on here might be able to help me please.

I thought I'd try and bleed the front brakeson my CBX550 project today, filled the reservoir, opened one caliper bleed nipple and pumped the lever...nothing. Not much fluid movement save for a small/slight blow back from the transfer hole to the main piston chamber? Undid the M/C flexi pipe connection and nothing coming out of the M/C. Despite repeated lever pumps no fluid moved out of the M/C at all.

I've stripped the M/C to check all is well with the seals and they appear to be in good order, small amount of remaining crud but nothing too bad.

I get the feeling I have to prime the system before bleeding....never done it on a bike before.

System comprises, handlebar mounted M/C and reservoir, single braided flexi to T splitter then two single braids to each caliper. I had only opened one caliper nipple. Using a pipe and jar with 2cm of fluid in it to bleed....like I would do a car.

Can anyone shed some light on how to do it from dry please? I think priming will help, if I can figure a way to do it that is.

I have a syringe and 1ltr of brand new DOT4 synthetic fluid.

Hope someone can offer advice?

Thank you.
 
You can bleed them from dry...it takes a while, though. If reservoir is full and the system is hooked up, pump up the lever 10-15 times until you start to feel some pressure. Squeeze brake lever, turn bleeder nipple 1/4-1/2 turn to open it, then close nipple, then release lever. Repeat 100000 times. Some manuals tell you to put a small spacer between lever end and handlebar grip so you don't max the lever out when "purging" the air.

When my system was dry it took over an hour to bleed the "old fashioned" way.

Once you start getting some fluid out of the bleeder, go up and down the line a few times with the handle of a screwdriver and give it some taps. Helps to work air bubbles up to the MC
 
if this is an MC that you have rebuilt double check to make sure the fluid return passage is not clogged. it is usually a very tiny hole that can easily be overlooked. once you have verified that open the caliper bleed screw and use the syringe to fill the system from the bottom up. 50% of the time there is nothing else necessary, however sometimes bubbles will trapped. Once the system is filled you can then bleed the brakes in the traditional manner to remove any additional airbubbles.
 
If you have a syringe then push the fluid through the bleed nipple and up the line(s).


Whilst it is dry, take out the bleed nipple and wrap some teflon (plumbers) tape around the threads first up.


By far the easiest, quickest and least messy way to do brakes IMO.
 
Wow, thank you for taking the time to reply to my plight. I'll try the syringe bottom to top up as well as the pump the lever to buggery as well.

Doc - I have stripped the M/C to check all was well and give it a more thorough clean as it was clogged with a gell like substance after sitting for many years.
Fluid came out of the brake lines, gel was in the reservoir only. I've changed the lines to braided so the entire system is dry.
I have cleared out both of the holes in the bottom of the reservoir bowl, the smallest is like a carb jet and is clear as I blew through it.

Hillsy - I'll certainly give your option a good go tomorrow. is PTFE absolutely necessary as I've never seen or heard of this before?

Adventurco - I'll be tapping like fury as the braids do take a serpentine route to the calipers, the T piece could trap air as well. I hope with the system purged with fluid the pressure will build enough to bleed completely.

See the gel gunk here: http://www.dotheton.com/forum/index.php?topic=68417.120
Thank you.
 
NoRiders said:
Hillsy - I'll certainly give your option a good go tomorrow. is PTFE absolutely necessary as I've never seen or heard of this before?
Click to expand...


Not necessary, but it helps when you are drawing fluid out via the syringe because the tape stops any air going past the threads and making you think there is still air in the system.


That's the beauty of using a syringe - you can draw the fluid back and forth as many times as you like to ensure all the air is gone and you waste pretty much no fluid ;)
 
the only thing to watch out for with the syringe technique is the hose can pop off the nipple when you are pushing the fluid in. makes a huge mess. ask me how i know ::)
 
If the mechanical bits are in fact working properly, you can ALWAYS bleed the system to perfection in just a few moments. This is a bit messy, but in my experience not significantly more so than using sealant around the bleed screw, using a cup and bleed tube, syringe etc etc. Simply fill the reservoir, and remove the bleed screw on the caliper completely. Place your finger tightly over the bleed screw hole and pump away with the lever. As the system fills, you well get air escaping past your finger when you compress the lever, but don't let air back in when you release. When it is full, you will get only fluid escaping past your finger. When you are done, simply re-install the bleed screw. On most bikes you can do this quickly and you are done. Rarely you will need to crack the screw and give another pump or two to eject the last bit of air, but invariably this only happens if your caliper bleed screw is upside down on the bottom where gravity is your enemy. I have used this technique on many hundreds of bikes (and cars, airplanes etc) and it always is quick and easy - and mostly pretty clean. I put a paper towel around the bleed screw opening to try to catch the fluid, and often it only takes the one towel - but I have had a lot of practice. You do not have to take a lot of time. Just seal the opening with your finger and pump away. If the system is functioning, you should have pressure in just a few pumps for a single caliper.
 
hillsy said:
Not necessary, but it helps when you are drawing fluid out via the syringe because the tape stops any air going past the threads and making you think there is still air in the system.


That's the beauty of using a syringe - you can draw the fluid back and forth as many times as you like to ensure all the air is gone and you waste pretty much no fluid ;)
Click to expand...

Yeah, I get what you're saying now, thank you.
 
jpmobius said:
If the mechanical bits are in fact working properly, you can ALWAYS bleed the system to perfection in just a few moments. This is a bit messy, but in my experience not significantly more so than using sealant around the bleed screw, using a cup and bleed tube, syringe etc etc. Simply fill the reservoir, and remove the bleed screw on the caliper completely. Place your finger tightly over the bleed screw hole and pump away with the lever. As the system fills, you well get air escaping past your finger when you compress the lever, but don't let air back in when you release. When it is full, you will get only fluid escaping past your finger. When you are done, simply re-install the bleed screw. On most bikes you can do this quickly and you are done. Rarely you will need to crack the screw and give another pump or two to eject the last bit of air, but invariably this only happens if your caliper bleed screw is upside down on the bottom where gravity is your enemy. I have used this technique on many hundreds of bikes (and cars, airplanes etc) and it always is quick and easy - and mostly pretty clean. I put a paper towel around the bleed screw opening to try to catch the fluid, and often it only takes the one towel - but I have had a lot of practice. You do not have to take a lot of time. Just seal the opening with your finger and pump away. If the system is functioning, you should have pressure in just a few pumps for a single caliper.
Click to expand...

I think the m/c internals are OK but the pump effect was non existent.....I figure priming the system in some way will get it working to some extent and then the bleeding can begin. The pipe and jar method can be cumbersome and I like the idea of using a finger, thank you.
 
Yes you pretty much need to prime the MC to get fluid to flow.


You can do it manually or push fluid up the line and fill the MC that way. That's why the syringe is the best IMO.
 
doc_rot said:
the only thing to watch out for with the syringe technique is the hose can pop off the nipple when you are pushing the fluid in. makes a huge mess. ask me how i know ::)
Click to expand...

:'( I fear for my painted calipers.
 
hillsy said:
Yes you pretty much need to prime the MC to get fluid to flow.


You can do it manually or push fluid up the line and fill the MC that way. That's why the syringe is the best IMO.
Click to expand...

I'm on it....later today when I have time......looking forward to having brake fluid on absolutely every-bloody-thing haha!

I gave ti some thought last night and think a staged prime could work. If I undo the T to caliper pipes, take the nipples out and syringe fluid down the pipes until it reaches the nipples holes...then plug. Then prime single pipe to the T joint, tighten it all up and prime m/c. Then syringe from nipples upwards to expel air, then pump and bleed using the finger over nipple hole method or pipe n jar?

Thanks to all who took the time to offer advice, mucho appreciated chaps.

I'll report my efforts.....
 
I´ve had terrible times bleeding brakes on my RD rear master....spent 60 dollars for a fancy brake bleeding tool...

then:
I spent 2 dollars buying a big syringe in the drug store and 1-2 meters of clear hose which just fits over the bleed nipple (by just i mean just, i really need to push it onto it, never jumped of the bleeding nippel even at high pressure from the fat syringe).
Since then i never ver had problems bleeding ANY brakes, even when dry.

filled the syringe with fluid,connected the hose, pushed the fluid trough the hose till no air was left.
then opened the bleed nipple connected the hose and pushed the fluid directly up till the little container was half full.
then used the gold pump and release technique and youre done.
 
NoRiders said:
I'm on it....later today when I have time......looking forward to having brake fluid on absolutely every-bloody-thing haha!

I gave ti some thought last night and think a staged prime could work. If I undo the T to caliper pipes, take the nipples out and syringe fluid down the pipes until it reaches the nipples holes...then plug. Then prime single pipe to the T joint, tighten it all up and prime m/c. Then syringe from nipples upwards to expel air, then pump and bleed using the finger over nipple hole method or pipe n jar?

Thanks to all who took the time to offer advice, mucho appreciated chaps.

I'll report my efforts.....
Click to expand...


You don't need to undo anything. Get a 40 or 50cc syringe and 6" of clear hose. Push the fluid up the lines. Don't fight gravity - work with it.


Then suck the fluid back down. Do this on each side. Do it a few times (push / pull).


When you are done, tighten up the nipple, then draw the syringe to create a vacuum. Then pull the hose off so you don't squirt fluid anywhere. It's pretty easy.


After all this, put the reservoir cap back on and strap the lever back to the handlebar. Leave it overnight. Next morning undo it and your brakes will be done.
 
hillsy said:
You don't need to undo anything. Get a 40 or 50cc syringe and 6" of clear hose. Push the fluid up the lines. Don't fight gravity - work with it.


Then suck the fluid back down. Do this on each side. Do it a few times (push / pull).


When you are done, tighten up the nipple, then draw the syringe to create a vacuum. Then pull the hose off so you don't squirt fluid anywhere. It's pretty easy.


After all this, put the reservoir cap back on and strap the lever back to the handlebar. Leave it overnight. Next morning undo it and your brakes will be done.
Click to expand...

Righto...this method first :D
 
Ryan Stecken said:
I´ve had terrible times bleeding brakes on my RD rear master....spent 60 dollars for a fancy brake bleeding tool...

then:
I spent 2 dollars buying a big syringe in the drug store and 1-2 meters of clear hose which just fits over the bleed nipple (by just i mean just, i really need to push it onto it, never jumped of the bleeding nippel even at high pressure from the fat syringe).
Since then i never ver had problems bleeding ANY brakes, even when dry.

filled the syringe with fluid,connected the hose, pushed the fluid trough the hose till no air was left.
then opened the bleed nipple connected the hose and pushed the fluid directly up till the little container was half full.
then used the gold pump and release technique and youre done.
Click to expand...

...and this :D
 
NoRiders said:
...and this :D
Click to expand...

had a typo on my comment.

...after doing the syringe method i closed the nipple and went on with classic pump and nipple release tecnique.

be sure to have 1-2 shop rags ready and a spray bottle with water and some dishsoap in case you spill some fluid...helps a lot!
 
Ryan Stecken said:
had a typo on my comment.

...after doing the syringe method i closed the nipple and went on with classic pump and nipple release tecnique.

be sure to have 1-2 shop rags ready and a spray bottle with water and some dishsoap in case you spill some fluid...helps a lot!
Click to expand...

Thanks Ryan.

I tried the syringe through the nipple method and I couldn't push any fluid up, past the calipers. Sringe locked solid, nipples are clean...but not having any of it.

Kept pumping the lever although there didn't seem much going through, save for a small amount of blowback through the main feed hole in the reservoir. I tried to get some down the m/c single pipe, made a right mess. After that fluid was seeping out of an open nipple when the lever was pumped, so something is happening.

I have tied the lever back for now.

Hope the rears aren't as problematic?

More anon... :D
 
Do you have one way bleeders? Some bleed nipples only allow fluid or air out, not back into the caliper. Can't use a syringe if that is the case. If they are the one way you can leave them open and just pump the MC until fluid comes out. A good trick to get the fluid going is also Start at the master, Grab a rag, loosen the brake line bolt and put the rag under, pump until fluid comes out around the line and bolt. Tighten back up, move to the next bolt in the system, whether it is the splitter or first caliper, loosen it, hold the rag, pump until fluid comes out, tighten back up, move to the next repeat until all have been done, then open bleed screws and pump, should have fluid then and can do the pressure build and release. Also make sure you keep adding fluid to the master so you don't suck air during the process.

I am about to do this on my GL dry system and hope it works for me, I think I can use the syringe because I do not have the check valve/ one way bleeders.
 
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