bleeding brakes
 

I had to undo the brake line on the front master cylinder and now everthing is attached again i cant get the system to bleed. the master cylinder is pumping the fluid through to the calipers i have pumped a whole 500ml bottle through and still the lever is coming back to the bar. and i cant see any air coming out.

I also tried bleeding from the top banjo bolt but that did not help eather. any ideas. is there an air pocket in the top of the master cylinder?

I'm having the same problem but with the rear caliper on my 996 :(

All I would suggest is you can buy a banjo bolt for the joint next to the master cylinder on the clip-on with a built in bleed nipple which will make getting air trapped there out a piece of cake.

Hi

I have experianced this a few times I suspected air trapped at the top of the banjo connection to the master cyclinder.

Try the following in this order.

1. Pump the brake lever a few times and tie wrap the lever back hard against the bar and leave it over night. Hopefully the air will move up and into your master cyclinder. If not move the bike into the sun and let the warm sun heat up master cyclinder hoping the trapped air inside expands and then moves up into the cyclinder. Sounds daft but it works.

2. Use a syringe (cost coppers from a local store) attach the bleed hose to the end fill it with fresh fluid connect it to your caliper bleed nipple and force the fluid up through the system into your master cyclinder. Use a reasonable sized syringe to ensure enough fluid is pushed through the system ensuring no air remains (oh and don't forget to keep and eye on the expansion bottle as the fluid comes up empty it with a second syringe).

Just keep trying u will get there in the end.

Regards

Dave O

Henners

If its an under slung rear caliper they are a pain to bleed u need to lift it higher than the master cyclinder (ask the wife to hold it she'll luv that not lol).

Then bleed in the normal way with a non return valve its so easy then, when the air stops refit and it will be A OK.


Regards

DaveO

I would challenge the use of "forcing fluid in with a syringe as it would inevitably have air in it.

However, i would use a syring to draw the fluid through by attatching it to the bleed pipe. This does work and will draw out the air as well as you new clean fluid. With the undrslung rear calliper, you do need to unbolt it and mount it on top of the disc to bleed!

I had a similar problem after replacing the fluid in my clutch (air at/around lever). Initially, it was fine, but then the lever started coming further & further back to the bar.

There is a bleed valve in the reservoir itself (on the clutch side anyway!). Assuming there's one in the front brake reservoir as well, take cover off, then squeeze lever as you undo valve. Tighten valve as the lever gets close to the bar. Only took 3 squeezes & the clutch was perfect!

I seldom have a problem bleeding my brakes, thanks to my trusty Mityvac (and I know some people think they're a waste of money; you can do it just as easy with syringe, whatever, but what swayed it for me is: the professionals use them), bur came across a new prob the other day~: sheared the bloody bleed nipple off (the brake master cylinder one). This was undoing it too, so I can't say I was doing it up too tight.

Now that'll hasve to wait until I can get louigi to have a go at drilling it out for me. Or it might be as cheap/easy to fit a second-hand m/cylinder.

I think that folks are on the right lines. I just replaced the entire front brake system on my 888 with new billet callipers, new stainless lines and a 'new' master cylinder from an ST4S, so basically the whole system was full of air.

The master cylinder was pumping fluid through to the calipers, but not very effectively, and as you say the lever was coming back to the bar. So I had to bleed it at the master cylinder banjo end. I'm running twin lines from the master cylinder so there were two banjo bolts, a spacer and 4 copper washers in total, seperating the joints. There were plenty of joints for fluid to seep out from, so it can be a messy business and you'll need loads of highly absorbant rag underneath the master banjo. Then, just crack the banjo open and squeeze the lever slowly - don't squeeze it fast otherwise the fluid can spit out from between each joint (even if you only have a single line with two joints to worry about) and spray everywhere - don't ask me how I know. Hold the lever right back to the bar for a couple of seconds, then tighten the banjo up. Do this a few times until you're sure that there is just fluid seeping out of the cracks between the banjo(s), it may take more goes than you'd think.

It might help if you have a bottle of muc-off or similar and a hose handy as well. Once I had made sure that there was no air in the master, and put the master cylinder cap back on to make sure I didn't get water in the master reservoir I gave the whole area a good squirt of cleaner and rinsed it all down to make sure that I didn't have unseen splashes of brake fluid hanging around on my paintwork.

Once the master was bled through, I went back to bleeding the callipers as normal until I got a good lever feel, then I squeezed the lever back hard and cable tied it to the bar overnight. I went out the next day for a 200+ mile rideout and the brakes were fine all day although the lever was still a bit soft for my liking.

I think I will repeat the process again this weekend, and as often as necessary to get every last gasp of air out of the system. The other thing that might have affected mine was that I bought a fresh bottle of brake fluid before I started and filled the reservoir up once. I sat the bottle a good few feet away from the bike because I'm paranoid about brake fluid getting spilled, but sods law dictated that while I was busy bleeding the master cylinder the bottle fell over and emptied itself completely over my path. So, I had to finish bleeding the system with a bottle of fluid that's been sitting around half full for a couple of months, this may have absorbed a bit more water than ideal, so the system may need flushing through with fresh fluid before it's perfect.

thanks guys i'll keep trying

Always do mine by sucking it out with a syringe thesedays after a fruitless 2 hours trying to bleed them when i fitted a twin disc conversion.

Never have any problems now.

We've used the force through method for quite a few years on our pro race team downhill bikes, its how the brake manufacturer race techs do it.......

if you are concerned keep flicking hose and lever just to let any last drops of air out but even if you don't it'll still work a lot better than conventional bleeding. I've never seen them suck fluid through with a syringe, I'll try and check tomorrow and find out why they don't do it that way.

749 & 999 Master Cylinder tips

1 - let the fluid go down the brake pipes by bleeding as normal
2 - YOU ALSO HAVE TO BLEED THE MASTER CYLINDER - THE BLEED NIPPLE HAS A 6MM HEX HEAD AND IS ACTUALLY LOCATED IN THE FLUID RESERVOIR ITSELF BELIEVE IT OR NOT!!!!
3 - once you have bled the air out of the master cylinder you will get rid of all the air in the system when you next bleed the calipers which you should do finally in the bleeding process
4 - enjoy!

khushy


[Edited on 20-4-2006 by khushy]

The above method works 100%, well for me anyway, well done khushy for the explanation could,nt have put it better myself.

khushy is half right, for mine I used a 6mm socket, just undo it a bit like a bleed nipple and pump, if you need I can send you a jpeg but will need you emain address, one day I mite be able to use this bord, hope this helps
:flame::burn::burn:

"half right" LOL!!

:lol:

its easier to use a 6mm ring spanner - it is a bleed nipple!

:frog:

[Edited on 21-4-2006 by khushy]

i found the bleed nipple in the res
2 pumps and problem solved!

;)

ok so I didn't read your answer properly, sorry khushy
:flame::burn::burn:

:puzzled: ....seems nobody read my earlier post either :eureka:

ooooooooooops - skipped over your post - you are right - it was the other endless drivvle that I was reading!

:lol:

I have just fitted an underslung rear caliper bracket on my 749R and I cannot bleed it so it looks like I will have to lift the caliper as suggested to bleed it.

Cannot be as bad as the 2 days I tried to bleed the brakes and clutch after I fitted the cycle cat riser kit. I could not get any fluid to come through even using a hydraulic bleed kit from a local dealer, after taking the system completely to bits, guess what it was !!!!!!!

Yes, the plastic reservoirs had plastic bungs in them that I had failed to spot when fitting them, 15 minutes later the job was finished !!! :lol:

[Edited on 26-5-2006 by iang]

you mean you fitted the reservoir hose on top of the plastic bungs???

:lol:

maybe you should NOT be pi*sing around with your brakes - ever thought of that??

:eureka:

[Edited on 26-5-2006 by khushy]

Oh I very nearly did the same thing once, thought the hose felt a bit tight.:lol::lol:

scary!!!!

:o

khushy, I keep looking at your avatar and wondering what it's all about.

have guess - what do they look like?

is that better?

Antthing to do with Rossie?

good job you can spell!!!

who is Rosie??

:frog:

OK if you want to be cryptic then so be it, if you want to tell me what its all about then do so or don’t……:(

Thanks to louigi who painstakingly drilled it out for me. All OK now.

OK, when I look in my reservoir, I only see one nut, and it looks like the only think it does is hold the reservior on. Is that the one you bleed?? Doesn't look like it goes anywhere?? Got pictures?

Galaxy, that is the nut you use to bleed the front brake. Really simple and easy system, that!

both multi vac or syringe r good idea,s or what u can do is strip syringe ie remove plunger and connect to caliper and use as clear res for caliper to see if any air comes out .

bleeding brakes dont laugh
 

Promise not to laugh.....

I do it like this..

one meter length of plastic pipe, fill with fluid, attatch one end to open bleed nipple, other end to small fish tank air pump.

remove reservoir cap and make sure res is EMPTY !!

turn on pump, go have a cup of tea.

come back, and I find the lil pump has pushed the air up the pipes and followed it with fluid.

As for the rear, caliper needs to be higher than reservoir, and nipple on top, (air only goes uphill)

silly way I know, but hey, it works for me !!

Geoff M

I had loads of problems after fitting new brake lines, Ended up getting one of them bleeders that you connect to a air line and it sucks it through from the bleed nipple at the caliper, Did it in seconds as long as you keep topping up the resivoir. It was that easy I even replaced the clutch fluid aswell.

Found this article. May be helpful.

http://www.speedzilla.com/forums/att...h_bleeding.pdf