Bleeding brakes

[damienga15de]

So iv rebuilt my calipers I can't get anymore air out of the system but I still have no brakes, the Pistons move out and return but don't seem to move out and stay out to keep moving the pads along .




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[Craig380]

Is the brake lever coming all the way back to the twistgrip? If so, there's still air in it somewhere.

Best thing to do is to put the bike on its sidestand, with the handlebars turned full left lock, and leave it alone overnight. This way any air can rise to the master cylinder and into the fluid reservoir. Then you should be able to pump the lever a couple of times and have brakes.

[damienga15de]

Yeah iv done that , hopefully it will work iv broken bleed nipples so using banjo bleeders I'm sure the calipers are OK as I bled hem with the nipples straight up . It must be at the master cylinder .


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[Nutsinatin]

Might well be the master cylinder, build up pressure, crack the m/c banjo open (using a cloth to catch any fluid), close and repeat until pressure returns. It's where I've had the air trapped last two times this year.

[andrewsmith]

Also give the rubber hose connecting the fluid reservoir a good squeeze as air does get trapped there

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[damienga15de]

There is no reservoir, it's a naked bike


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[Red Herring]

Is the brake lever coming all the way back to the twistgrip? If so, there's still air in it somewhere.


Not necessarily so. Sometimes when you have just rebuilt callipers as the OP says he has the pistons move so freely that the suction caused by the master cylinder returning is enough to pull them back in, which is what the OP says he can also see happening.

The easiest way I've found to get round this is to rattle the brake lever back and forth really quickly with your hand. Don't come all the way back to the bars, all you are trying to do is get a little more fluid into the active side of the plunger before the suction has time to move the pistons. It should only take a few seconds. Once you have some pressure then give it a really good squeeze to seat the piston seals, then there should be enough friction to allow you to bleed the brakes conventionally.

[NedSVS]

When you fit banjo bleeders you may have to remove the calliper and adjust the angle of it so the banjo bolt is at the highest point - because the banjo drilling often enters well below the highest point of the cylinder and therefore traps some air.

[tom_e]

There is no reservoir, it's a naked bike


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I'm pretty sure there's still a reservoir, it's integral to a fluid based braking system.

[RedTop]

The reservoir is the black box that sits next to your right hand grip (throttle)

[damienga15de]

Sorry no external reservoir.


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[Red Herring]

In fairness to the OP it's often part of the master cylinder (as it is on an SV) so he may not have known it as such. I'm sure he found somewhere to put the fluid after he had rebuild his brakes.....

[r0ddy]

no resevervoir? surely not

[Corny Gizmo]

Yes there is a reservoir, I have pointed it out on a photo of your bike...

http://s29.postimg.org/wwdyrqt07/Reservoir.jpg

[damienga15de]

So I'm not getting anywhere iv bled it conventional way, iv reverse bled it, iv bled the master cylinder iv tied the lever in for 2 days. I have some brakes but the lever pulls to the twist grip and doesn't really firm up. AL the pistons move smoothly. The only thing I can see is the pistons return when I release the lever mabye they return too much leaving extra travel. I'm thinking of the master cylinder mabye an internal seal is buggerd and not able to make the needed pressure


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[Red Herring]

I did try and explain to you how if the pistons are moving that freely they get sucked back to far and you won't be able to build any pressure. Have you tried the trick I suggested by moving the brake lever in and out really quickly? Don't just pull it in and let it spring back out, grip the end between thumb and forefinger and wiggle it back and forth really quickly.

If that still won't get the pistons out and staying against the pads and discs then do you have a syringe? If so fill it up with brake fluid, attach it to one of the bleed nipples, then squeeze the brake lever so that the piston is down the master cylinder (it you don't do this you don't seal the system) and force the fluid in from the syringe. This should introduce enough pressure in the system to bed the piston seals and stop them moving so easily.

You may need someone to help you as you tend to run out of hands trying to hold the lever in and the hose on the syringe/bleed nipple.

[damienga15de]

Thats exactly it. Iv clamped the pistons in and the brakes are rock solid. I have tried the fast pumps. I'll try the syringe now


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[damienga15de]

So I have just got somewhere. Rigged up a oil can to the nipple and introduced some pressure with the handle closed. There better but still not 100%. I have the lever cable tied up for the night hopefully the seals will settle a bit. I'm hoping that with some riding the heat produced will help settle them some more and improve them more.

Thanks for the help/advice


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[Bibio]

cable tie does nothing but gas the air. when you pull the lever you close the system so nowhere for air to escape.

if the lever is firm then slowly pulls to bar your MC seals are fubar.

tube on nipple, jar with brake fluid in, pop tube in jar so end is under fluid, pull lever then open nipple till lever is against grip on bar then close nipple and release lever. repeat this till no more air can be seen through tube (do not open nipple then just pump). doing this will ensure that you create pressure to force air out the system. if your clever you can tap the calliper and brake line at the same time as bleeding which dislodges trapped air.

if you have freshly serviced your callipers then it will take a while for the pads to settle in on the discs and you will have a slightly squidgy lever till so, if after 100odd miles its still the same then do a second bleed. i always do a second bleed anyway.

[timwilky]

You have buggered your bleed nipples and therefore never going to get all the air out of your calipers. Unless you replace the bleed nipples and bleed as intended. Banjo bleed will not purge the caliper.

Best bet source a set of second hand refurbished calipers and start again.

[damienga15de]

IV banjo bleeders fitted iv no air in the system. Lever is rock solid when the pistons are clamped. It's the new seals being very tight and allowing the piston to return when they shouldn't


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[Fordward]

Don't take this wrong way. It's meant with all the love for a fellow biker I can give, and having read this thread it's the best advice for you. Your brakes need to be right, they may be needed to save your life. Get help from a professional mechanic, or at least get someone that genuinely does know what they are doing, to do it with you and show you how. Next time then maybe you'll be better equipped to do it yourself. Everyone has to learn somehow. All the best mate and good luck with it.

[damienga15de]

IV all the equipment needed been working on cars and bikes for years. Thus is just something iv never came across before.


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[Fordward]

IV all the equipment needed been working on cars and bikes for years. Thus is just something iv never came across before.


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It doesn't come across that way on this thread, i.e. no reservoir because it's a naked bike. But good luck with it whatever you decide to do.

[damienga15de]

No external reservoir I meant as the person before posted it could be air in the connecting line.


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[r0ddy]

Are you 100% there's no air in the system?

Calliper seals the right way round?

Have you rebuilt the mc?

[Red Herring]

No external reservoir I meant as the person before posted it could be air in the connecting line.


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Actually mate air in the line between the master cylinder and any remote reservoir is very rare as it's invariably higher up and there is nothing to stop the air evacuating, but even if it was present it wouldn't make the slightest difference to the feel at the lever because it's outside of the pressurised part of the system.

I think what folk are missing on here is that you have said you have a firm lever when you clamp the pistons fully in so there clearly isn't any air in the system, even if you have had to bleed in unconventionally via the banjo's.

[damienga15de]

IV been out all day, the brakes work fine. I'd like more lever feel but it's improving a lot. New pads are bedding in. I found many other issues, the clutch needs adjustment I had to replace the mirrors as they were useless


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[Bibio]

when you serviced the callipers did you just put new seals in or clean anything as well?

i would like to know what you done to the callipers and pistons prior to you installing the seals.

could others refrain from answering this as to 'what you do' as i would like the OP to tell me exactly how he '''rebuilt''' his callipers.

[damienga15de]

Removed pistons seals sliders, cleaned the bores out scraped the hard built up stuff under the seals. Cleaned the sliders Soaked the lot overnight in degreaser. Scrubbed everything with a stiff brush and a scotch pad. Blasted everything off with compressed air and dried out with a kitchen towel to be sure. Replaced seals lubed them up with brake fluid and refitted the pistons as they were in decent condition no pitting etc. after being cleaned up. Refitted sliders and new boots using plenty of copper grease.


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[Bibio]

your about 90% correct.

copper grease does not mix well with rubber and will eat/swell it in no time. the only place copper grease belongs on callipers is on the brake pad retaining pins and nowhere else and yes that includes the backs of brake pads... under no circumstances use copper grease anywhere on brakes apart from retaining pins.

although seals can be put back using brake fluid its not advisable due to it being washed out in the first time you go out in the rain which then lets the elements at the bare alloy which results in corrosion. Red Rubber Grease (RRG) or indeed silicone grease is the preferred method to install seals and inside boots for the sliding pins. RRG is very high temp grease and is not petrochemical. RRG to rubber is like moisturiser to skin it keeps it from drying out. RRG is also very 'washout' proof so protects the bare alloy from the elements. with RRG being very high temp you can use it on the backs of pads instead of copper grease to stop squeal. if you have anti squeal shims then dont use anything.

service your callipers once a year using RRG and you will never have to buy seals/pistons/pins again and you have the added bonus of the brakes always being in tip top condition. i do mine every year near the end of the summer so they will be protected during the winter.

[damienga15de]

I will buy some rrg so. Clutch fun tomorrow I hope it goes better and a tps adjustment


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[Bibio]

clutch adjustment the easy way.

step one.. get some oil and grease cleaner and blast the shizz out of the lifter mech paying more attention to the bearing cage. brake cleaner is not a degreaser. if you must you can use WD-40 or paraffin (kerosene) in a spray bottle.

step two.. once the cleaner has dried blast spray grease into the bearing cage and let dry.

step three.. move top adjuster (lever end) to 1/2 way.

step four.. loosen locknut on lifter mech and adjust pushrod with screw till it just touches the release rod at the back then lock it off making sure you dont move the position of the screw.

step five.. adjust the top adjuster (lever end) till you have the required play at cable/lever. your adjuster should now be near the bottom which will allow for fine tuning while out and about.

under no circumstances take the lifter mech apart unless you want to spend the next day finding bearings and putting it back together. if you decide that you are brave and remove the lifter mech then remember that the return spring bracket goes on top of the mech and directly under the bolt heads. you would be amazed at how many people install it under the lifter mech and wonder why they cant get a proper adjustment.

if you cant get a good adjustment then its a sure bet the lifter mech is fubar.

[Craig380]

Bibio's right about RRG, although I've found that copper grease doesn't kill rubber so much as just dry out after a few weeks, so it doesn't lubricate the pins very well, nor help to keep the rubber boots etc flexible.

RRG IS like rubber moisturiser, it's worth rubbing into the boots that cover the sliding pins with your fingers as it keeps them really supple.

[Blapper]

Oo-er missus! I just rebuilt my rear caliper and I didn't use RRG, just lubed the seals and piston with brake fluid.

Is my world gonna end? Am I gonna pop my pistons prematurely? Or maybe just leak brake fluid slowly?

Seriously, do I need to get some for the front calipers?

I've never used it before in years of bike and cars...

[Fen Tiger]

Rest easy....you won't have a problem in the short term but it will be worth taking the pads out and greasing the exposed part if the pistons sealing outer sparingly with red rubber grease or silicon grease before the winter. Move the piston out a couple of millimetres and clean around then grease. If you can't turn the piston some grease on a piece of string wrapped round the piston helps to grease the difficult to reach part.

[Craig380]

Your world will not end :) but definitely get some for when you do the front calipers, especially the sliding pins. You can buy it dirt cheap off eBay.

I wouldn't worry about the rear caliper now, leave it until later in the year then just unbolt the caliper, do the sliding pins and clean & grease around the visible part of the piston. No need to pump the piston all the way out or re-bleed the brake, as Fen Tiger said. On a pointy (where the caliper's on top of the swingarm and only held by 2 bolts), you can do this in 15 minutes.

[Bibio]

on the rear pointy calliper its not to bad as the calliper is anodised after the machining so the seal recesses are anodised behind the seal which mostly stops the build up of corrosion which is the main problem with pistons seizing.

the fronts are a different kettle of fish and are bad for corroding under the seals due to not having any form of protection. using just brake fluid when you build the callipers back up is the main cause of the corrosion due to brake fluid being hygroscopic and actively sucking moisture under the seal which in turn leads to corrosion of the bare alloy which in turn causes the seal to clamp to the piston. RRG was developed to help keep the seal supple and also stop the corrosion for longer due to not being hygroscopic.

pumping pistons out and squirting with brake cleaner does absolutely fek all to help corrosion. pumping pistons out and smearing RRG then pushing them back does the same. its not the piston that is seized its the seal clamping against the piston due to build up of corrosion under it that causes it to seize.

all it takes is one day a year to strip and service your callipers. this makes sure you dont need to buy pistons or seals for a very long time and also keeps the bleed nipples free but the biggest bonus of doing it once a year is you always have perfect brakes. yes the first time is a nightmare but the rest takes no time at all. especially on 2 pot sliding callipers like the SV ones

for getting problem air out the lines then its a simple case of back flushing with a syringe. you can also use the syringe for sucking/filling the fluid at the empty stage to get the fluid into the system then bleed in the traditional way afterwords.

my preferred tool for getting the corrosion out the seal recess is a rotary multitool (dremel) with a wire disc wheel and some autosol. using a 'pick' just gouges the recess face.

it amazes me that people will wash, polish and change the engine oil and filter quite readily but pay no attention to the rest of the bike until something goes wrong.

[Blapper]

Thanks Guys.

I have a vacuum pump arriving any day to assist with the bleedin' bleedin' so I'll splatter the RRG all o'er the place then. I am not totally certain that the rear is 100% air free as it bled too easily although it feels OK. I am also changing my top yoke so I will need to replace the front brake lines then - I'll pop my front pistons then.

@Bibio: If you don't change your seals every time you strip your calipers, how do you ensure that you do not damage them when you remove them?

[Craig380]

I remove the fluid seals using a pair of blunt tweezers I got ages ago from a pound shop. They don't have sharp edges so they don't nick or mark the seal, but have enough grip to pull the seal out of the groove.

The best trick for brake bleeding I've learned is, don't open the bleed screw too much. It should be only just cracked open so that fluid will flow, but there should still be something like the normal resistance at the brake lever as you pull it gently. Also, only open the screw AFTER you've got gentle pressure on the brake lever, and close the screw BEFORE the lever reaches the end of its travel. Helps avoid air getting in around the bleed screw.

[Bibio]

as Craig said, but i use a wooden cocktail stick or a blunt darning needle. i do like the idea of the blunt tweezers though :-)

another thing i forgot to mention is i use plumbers PTFE tape on the threads of the bleed nipples. this serves two purposes. 1.it creates a good seal on the threads and stops air or fluid passing the thread and 2.it stops the threads seizing ever. you must be careful when applying the PTFE tape as not to cover the bottom hole and also wing the tape the correct way so when you screw it in the tape does not wind up the threads and bunch at the top. you only need about 3 full turns of tape.

how to put PTFE tape on the threads of a bleed nipple. the tread is 'righty tighty' so you apply the tape 'lefty loosy'. holding the nipple part in your right hand you want to wind the tape 'over the top' towards you. once you have the tape on then put the tape and thread part between the thumb and forefinger then turn the nipple 'righty tighty' so it flattens the tape into the threads. if the tape unwinds then you have put it on the wrong way. the tape is usually the same width as the thread part of a bleed nipple, you dont have to cover the lower part of the thread at the bottom hole as long as there is thread from 1/4 way up. what ever you do dont cover the hole with tape.

dont over tighten the nipple when you finish the job, it only need to form a seal so a little 'nip up' is all that is required.

unlike Craig i like to crack the bleed nipples wide open which allows more flow which dislodges any air gripping to surfaces.

like Craig i also do a final 'pull, open, close, repeat'. after a few hundred miles i will do a final bleed just to make sure.

dont ever use seals that have come off a seized calliper no matter how good they look.

one other thing. the night/day/week before you know you are going to be tackling a seized set of calipers is to put some plasticine/putty/clay round the nipples and pour some penetrating oil in there to help with the threads. when you go to undo the nipple use a socket and not a spanner. when undoing the nipple use a quick sharp push on the ratchet handle or an impact driver while the calliper is still connected to the forks then close the nipple again. then take the callipers off and leave the pads in and start pumping the pistons out using the lever.

once you have the seized callipers off the bike then take the pads off leave the pistons in and put the callipers in a pot of boiling water with some bio washing up powder and boil for a good half hour or more.

well thats about all the tricks i know of.

https://s32.postimg.org/5nkrgsr45/IMG_0936.jpg

[Craig380]

Using the tape means you can really open the bleed screws, as you say, the tape stops air passing down the threads when you bleed. I haven't fully stripped my calipers yet so I've not had the chance to apply tape.

[damienga15de]

Turns out my master cylinder was shot , left bike into mechanic for fork seals and he replaced the master cylinder said the original was off a Honda of some sort


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