Rear brake problems.

Ok so i changed myy pads the other day cus the old 1s were shot. But for some reason wen i tried the brake nuffing is happening. I can pull the lever right in and nothing happens. Ive tried bleeding them several time but still nuffing cratch: . When i take the cap off the reservoir and pump the brake all i get iss litttle bubbles and not a stream of brake fluid coming from the holes in the reservoir. Does anyone know what the problem might be cus its really anoying me now as i dont have a back brake and i need my bike to get to work. Cheers lads, hopefully someone will have the answer.

 

it does sound like its an airlock mate, i know youve bled it already but sometimes it does take a long time, try again but maybe bleed it for longer. ive had the same problems on runner rear brakes

 

bin in the shed for 2 hours now still nuthing :banghead: :banghead: :banghead:
Time to book it in at the garage i think .

 

You may think this a daft Q....but HOW are you bleeding it?

Make sure the res is full. Attach a hose to the nipple and leave the end in a jar of OLD fluid so air can't get sucked back in when you crack the nipple

Then pull in lever...hold it. Open the bleed nipple (may see some bubbles in the tube) CLOSE the nipple release the lever

Keep repeating the sequence...keeping a close eye on the fluid level

You WILL eventually get a solid lever.

Another way is to leave the nipple cracked open and wait...the fluid will run through taking the air with it

Another is to back bleed. use a syringe full of fluid to PUSH the air to the top

Another is to remove the system from the bike and hang vertically...lets the air have clear passage to the res


If its spongy try clamping the lever to the bars overnight....you'll have a good solid lever the next morning.....but it won't stop that way...you'll need to bleed

 

cheers stig ill give it ago 2moz. Thanks so much for the advice mate :grin:

 

who says people don't use the search topic nowadays....


i'm having a similar problem on my DT.. press the pedal and it goes ALL the way down and NOTHING happens... tried pumping fluid through but it just makes a gargling noise as though it's trying to but theres a blockage in the system, there's fluid in there (as i put some in the lil bit with min + max on i forget it's name..) tried looking in the manual but it just says "go to a yamaha dealer" hah maybe not then

any suggestions as to what i could do?.. as reading through this when you say "Crack the nipple open" mines more of a bolt... so i couldn't really put a hose over it then do w/e you said above..

thanks in advancee

 

When bleeding any front brake thats not been completely drained empty...

Start off concentrating on the top, remove the fluid cap and make sure you get it to the highest point possible, normally full lock to the LH side and use the side stand if you have one, if not stick a bit of wood under the centre stand one side so its leaning slightly to the LH side. This helps move air bubbles towards to master cylinder which is good.

Now keep lightly flicking the brake lever and youll see lots of small air bubbles appearing as any trapped air gets forced out of the system, keep doing this until you get no more bubbles, you can try wiggling the brake hose if its easy to get at and do lock to lock steering a few times just to try move any possibly trapped air bubbles, now try the lever again and look for more bubbles, if they arrive keep going on the lever until they stop, if you get none then all air in the pipe is gone and now its just a case of doing the caliper.

Bleeding calipers is again easy, forget one way valves, one man bleeding kits, vacuum pumps etc, they are all a waste of time in 99.9% of routine jobs... just get a piece of pipe run if off the bleed nipple and upwards for a length then downwards into a container of any type, doesnt have to be clean as nothings gonna get sucked back up from it... now just loosen the bleed nipple slightly and pump the lever completely in and out, no need to lock the nipple off each time, just keep pumping the lever and adding fluid, after a short period all the air will be forced out and youll just have a pipe full of fluid and you just pumping new fluid into the container below, when this is done just tighten the bleed nipple and your done.

The only thing to remember with bleeding the caliper is make sure the bleed nipple is at the top, some bikes use "off the shelf" calipers and when fitted onto the bike, the bleed nipple can be pointing across or even downwards, not upwards like we need, so if yours is like this, youll be best to undo it off the bike, or remove one screw and pivot it etc... air will always want to head upwards, so make this route as easy as possible for it, and your job will be a breeze.

The only time i use any form of bleeding help tool is to fill a system completely empty, and even then i dont use it to bleed the system, just bulk fill, and then i use a simple tube to finish the job.

 

totally agree, they're a waste of money

sorry, dont agree

Unless the end of the hose is submerged in fluid at the bottom of the container (can be old fluid but not dirty), every time you release the lever the suction will draw in air....if the nipples not closed whilst the lever is released..... :good:

 

No no no no... not if the pipe runs upwards from the nipple first then makes an arch, any air bubbles head upwards away from the nipple and you end up with the length of pipe above the nipple full of fluid, so all it can draw back is fluid :grin:

As long as you have about 8cm of pipe upwards from the nipple before it head downwards theres no need to have the pipe in fluid at the bottom... ill happily bet my life on it as i change brake fluid daily

 

when theres air in the system, its usually hit and miss. i'm VERY surprized the air dont push the fluid up and over the arch in the tube...thus opening up the tube to the external pressure allowing it to be forced back into the system

I'll give it a go and if it works, i'll sure be doing it that way from now on....seems much easier than keep locking off the nipple :thumbsup:

 

No it doesnt push the fluid, it just creaps past it and heads off upwards, so as long as the piece of tube heading upwards is long enough to contain more than a single strokes volume of fluid, then even when you release the lever it cant pull enough fluid back into the caliper to reach the level of the air... simple fluid engineering principle :good: