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no brake pressure

3K views 14 replies 9 participants last post by  riverszzr 
#1 ·
hey all!
(2006 zx6r)
I have been trying to bleed a dry front brake system (new s/s lines and a new oem m/c), but I cant get any sort of progress towards getting a trapped air pocket out of the system. Bleeding brakes should be easy for me but I am having loads of difficulty getting this air out of the system. I’ve already done everything short of buying a vacuum bleeder. Is there anything I haven't thought of?
What i’ve done so far:
- confirmed all parts in the new m/c are there and put together correctly.
- confirmed the m/c can build pressure via bench bleeding.
- bled the system multiple times from both calipers and the m/c with no bubbles coming from the bleeder nipples.
- raised the m/c to be the highest point possible during bleeding.
- reverse bled the system through both calipers with a syringe (making sure not to introduce more air).
- tapped and whacked all parts of the system to try and coax the air out
 
#3 ·
I’ve been replacing the crush washers after the second or third time I took off the m/c as insurance against them being the issue. I did crack the line open but all I got coming out was fluid. I think i’ll attempt to leave the banjo bolt cracked for a longer period of time while both bleeding with the lever and reverse bleeding to see if I can get the air bubble to dissipate through the banjo fittings.
 
#4 ·
That happened to me once. Could not get pressure for the life of me. I walked away from it for a day or so and then it bled fine and I got pressure. A vacuum bleeder is cheap and works miracles, that's my go to now.
I've been using the vacuum bleeder I listed below for the last five years or so for my cars and bikes. It works wonders. First I pump the old fluid from the MC reservoir, than I pump the oil through the calipers. It haven't failed me once...
https://www.ebay.com/itm/Hand-Held-...967296?hash=item41d4da8e40:g:ltsAAOSwdW9aFZER
 
#5 ·
Run a hose from the nipple on your caliper back to the fluid reservoir. Leave the nipple open and pump your brake lever real fast for like 2 or 3 mins. That will push any air bubbles out. Then do the other side.

Are u sure your master cylinder is actually pumping? It might be cavitated.
 
#10 ·
I used to do this prepping race/road bikes. It often works. I don't know if your year bike has a nipple up at the lever... if so this is often a ball buster because it sits high - relative the system. So naturally air will rise to the highest point.

Ultimately, a vacuum bleeder is so much easier & faster. They are not overly expensive; I also swear by Speed Bleeder fittings. Again, they work and are price friendly.

https://www.sportbiketrackgear.com/...WChv-slP3vzNecoycmEHZS8IXH_wnjl0aAoq4EALw_wcB
 
#14 ·
** update **
I realized that since the bleeder nipples happen to be on the bottom of the calipers, it allowed air to be trapped at the top of the calipers. I ended up having to detach both calipers from their mounts and hang them upside down from the handlebars in order to bleed the air out of them. I now have a rock solid front brake feel.
 
#15 ·
Late to the party, but I was going to suggest that the small passageway hole between the lower piston and the upper pistons in the caliper may be plugged or even slightly plugged and as such may have the air trapped behind one that the bleeding can't push through


I often after installing new lines, or master or whatever......... will (with clean caliper pistons) once the whole system is back together- push all the pistons (starting at the bottom) all the way back in to push as much of the air and fluid behind them back up out of the caklipers and into the lines and ultimately through the master and into the resevoir (it has a side benefit of getting all the old shit out of there too)

then pump that lever long and fast keeping the master full in about 10 secondsbursts followed by a 2-3 second wait time and then one very slow stroke of the lever........you'll be surprised how you can get 99% of the air out withotu ever opening a banjo or a bleeder

and then yes, sidestand tilt to have the master and more importantly the hose fitting from the master to the resevoir at the highest point (may require creative positioning of the bike and bars) and tie the brake lever pulled all the way overnight or for the day..... walla- never opened a bleeder at all and brakes are 100% bled and rock solid
 
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