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-   -   XT600 rear brake bleeding: neverending flow of bubbles????? (https://www.horizonsunlimited.com/hubb/yamaha-tech/xt600-rear-brake-bleeding-neverending-59782)

estebangc 19 Oct 2011 21:16

XT600 rear brake bleeding: neverending flow of bubbles?????
 
I was changing (or pretending I could change) the rear brake pads. Changed the brake fluid as well (didn't refill at the same time and air got in). And then started to bleed with a transparent hose and syringe. Well, some bubbles, logical, more, more, more, more and more! Never stopped.

What happened, where was the air getting in from? The bleeder screw? (it leaked fluid later: fluid out, air in?).

Thank again!

Esteban (aka, Dry Hands, too much fluid all over, now getting dry skin!)

PS: My gf is taking her exam, so would love to ride with her for the weekend!:taz:

Socks 19 Oct 2011 22:54

Estaban and girlfriend,
first of and most important for Anyone doing mecanical work involving oils and such like, Grt yourself some medical examination gloves to protect your hands. This is VERY important not just for you but your partners health also. I'm lucky and get mine from the Sunday market at £4 a box of 100. I guess you should be able to buy them online for a simlar price.

Bleeding and air getting in. You might check that the tube is fixed onto the bleeder nipple nice and tight, and when you open up that bleed nipple/screw only needs a slight turn to open it (maybe a 1/4 turn not much more). In the colder weather dip the tube into warm water to soften it before placeing over the bleed nipple, and hold a thumb over the other end to prevent water entering the tube.
These things are sent to test us :mchappy:

Sometimes it is easier to do this job with two people, one opening and closing the nipple the other doing the rest (instructing:smartass:)

Mezo 19 Oct 2011 23:53

May seem a silly question but have you done it before? do you know how to bleed brakes? i had a mate who claimed he knew it cocked it up completely.

Method,

Open nipple, press pedal & hold, then shut nipple, release lever & then repeat the steps over & over until pressure starts to build, stop to top up reservoir every five or so pumps, dont let it get low or you will just suck air through the system.

Mezo.

*Touring Ted* 20 Oct 2011 01:11

My guess is that all those bubbles were coming from a bad seal from the bleed hose and the nipple.

If you were getting THAT much air out of the system , your brakes must of been soggy bastards.

Pboko2388 20 Oct 2011 20:00

mezo has the right idea but slightly off. you should push pedal, open and close bleeder quickly, than release so you do not suck air back into the line. pump a few times to build pressure and repeat. some brakes are tricky ive spent up to 45 minutes on a front caliper but i tend to be a bit meticulous with my brakes as they are life savers.

estebangc 20 Oct 2011 20:23

Thanks to all for your help and the very useful advice.:thumbup1:

Quote:

Originally Posted by Mezo (Post 353072)
May seem a silly question but have you done it before? do you know how to bleed brakes?

No silly question: I have never done it and have no idea (I said I was pretending!:blushing:), except for what I've read on a couple of XT Manuals I got and what I found in the internet. I said “there is always a first time and front brakes still remain there (although working poorly) if I cannot do it properly (to take the XT to a mechanic)”. But I just want to learn to do it by myself.

Some perspective: REAR brake needs new pads, new rotor and new fluid. Front brake needs (only) new pads and fluid. So I thought: I’ll start with rear pads and fluid, to see if it works and then will go with the rotor, before I do anything just too wrong (is it logical or just stupid to start with a worn rotor?)

Bought latex gloves (SOCKS), checked the hose (TED) and followed literally MEZO’s indications till fluid was just crystal clear (refilling, since the 1st I forgot it and messed it all with plenty of air inside).

Finished and tried it. Stopped, it brakes. Running, it really doesn’t. It could be that it needs a time to adapt to the (worn!) rotor, BUT it makes something new and weird: when I push the lever, it doesn't feel like stopping, feeling the pressure on the brake, but like going farther down and it makes a peculiar (and new) “click” sound. Could it be it is actually “compressing” the air inside? Or apart from clumsy I am becoming paranoid?

Esteban

PS: My girlfriend has a 6 hours course on Saturday and rented the bike for the weekend (Spanish lesson: “cuesta un huevo y parte del otro”, “it cost a testicle and part of the other one”) and would love to ride with her, and will have to solve it by Saturday at lunch! Can be done... I hope!:D
PS2: I cannot bleed the brakes, but at least there is one thing I can do reasonably ok: I can cook PAELLA for 40 people, no one around Geneva??? I exchange services: brake bleeding for paella birthday party cooking!

estebangc 20 Oct 2011 21:33

Quote:

Originally Posted by Pboko2388 (Post 353188)
mezo has the right idea but slightly off. you should push pedal, open and close bleeder quickly, than release so you do not suck air back into the line. pump a few times to build pressure and repeat. some brakes are tricky ive spent up to 45 minutes on a front caliper but i tend to be a bit meticulous with my brakes as they are life savers.

I'll check all available systems then!

Mezo's sequence:
1) Loosen bleeder
2) Push pedal and hold it
3) Tighten bleeder
4) Release pedal and again 1) and so on.
And checking fluid reservoir level, refilling when necessary. This one looks really appropriate when I did it.

Your sequence, to try is as well:
1) Push pedal (and hold it, I assume)
2) Loosen bleeder
3) Very quickly tighten it
4) Release pedal... and again 1) and so on.

Is that right? Reservoir cap always out, since we'll be refilling, I assume.

Question: no syringes at all? Because stupide me I forgot to control fluid level and let lots of air to get in the 1st time!:oops2:

Socks 20 Oct 2011 22:58

Quote:

Originally Posted by estebangc (Post 353199)
I'll check all available systems then!

Mezo's sequence:
1) Loosen bleeder. at the same time do 2
2) Push pedal and hold it. when and as peddle reaches end of play (bottoms out) do 3
3) Tighten bleeder to prevent return of oil and air
4) Release pedal and again 1) and so on.
And checking fluid reservoir level, refilling when necessary. This one looks really appropriate when I did it. Spot on!

Your sequence, to try is as well:
1) Push pedal (and hold it, I assume)
2) Loosen bleeder
3) Very quickly tighten it
4) Release pedal... and again 1) and so on.

Gosh! Esteban I hope the two above don't mind me butting in and adding to the instructions above coz they are both correct!

Is that right? Reservoir cap always out, since we'll be refilling, I assume. yes

Question: no syringes at all? Because stupide me I forgot to control fluid level and let lots of air to get in the 1st time!:oops2:

Gosh, dont know how but went into "qoute" and changed original posting (not my original intention) yet I hope it helps.

Best to understand the princibles of bleeding first.

You nearly there, dont go to the mechanic thing when you need this knowledge yourself.:mchappy:

Some one correct me if I'm not right in saying this for the brake disk, but it is often recommended to replace the mounting bolts when replacing the disc, is it not?

estebangc 20 Oct 2011 23:22

If I am able to: a) push the pedal and loosen the bleeder at the same time and, b) then tighten the bleeder when the pedal reaches its end, c) repeat this for 45 min (as Pboko did once), then d) I'm sure I could work in the Chinese circus or become a Shaolin Master!:welcome:

Understood, I'll try tomorrow and Saturday morning.

Those rotor screws are damn expensive!!!! Confirmation, pls?

THX again, Socks (getting to Switzerland next spring? Don't forget you won a "worth a Paella" coupon!):D

PS: I guess I rushed a little and did not do my homework well before getting to the bike (touching all over I read: beware of asbestos in old brake pads! Nice. Clymer Manual talks about rear drum, printed (scanned) Workshop manual has crappy photos and the 3rd manual is in German! So got totally lost in the garage!)

Socks 21 Oct 2011 01:09

Quote:

Originally Posted by estebangc (Post 353210)
If I am able to: a) push the pedal and loosen the bleeder at the same time and, b) then tighten the bleeder when the pedal reaches its end, c) repeat this for 45 min (as Pboko did once), then d) I'm sure I could work in the Chinese circus or become a Shaolin Master!:welcome:

Understood, I'll try tomorrow and Saturday morning.

Those rotor screws are damn expensive!!!! Confirmation, pls?

THX again, Socks (getting to Switzerland next spring? Don't forget you won a "worth a Paella" coupon!):D

PS: I guess I rushed a little and did not do my homework well before getting to the bike (touching all over I read: beware of asbestos in old brake pads! Nice. Clymer Manual talks about rear drum, printed (scanned) Workshop manual has crappy photos and the 3rd manual is in German! So got totally lost in the garage!)

It is possible do do this on your own, simply a lot easier when done with a second person, it goes something like = you (or she) say "in" (pull brake lever in) as one of you says "in" the other opens the bleed nipple, when and as soon as the oil (with bubbles) is let out , close bleed nipple, as you (or she) says "closed" (cerca) once closed you or she lets lever return to relaxed position and so it goes untill no air bubbles and all the old oil is replenished.
Wow! No spongy brakes, and the click may well be the valve in the resevoir opening and closing.

So Estaban, I looked it out and its not nessasary on the xt to replace those rotor screws,(unless damaged)thats another story) sorry about the fright on that! but do loctite (just one small drop goes a long way) them back in. If indeed this needs replacing? IE; badly scored and therefore minimum contact to brake pads or warped disc. If this is so, why? Wear limit for my xt 600 3aj, acording to W/shop is 3.5mm. check this out for your model.

Good luck for you both over the week end.

Jens Eskildsen 21 Oct 2011 17:55

Quote:

Originally Posted by estebangc (Post 353199)
Your sequence, to try is as well:
1) Push pedal (and hold it, I assume)
2) Loosen bleeder
3) Very quickly tighten it
4) Release pedal... and again 1) and so on.

Is that right? Reservoir cap always out, since we'll be refilling, I assume.

Question: no syringes at all? Because stupide me I forgot to control fluid level and let lots of air to get in the 1st time!:oops2:

Yeb, thats how I do it aswell. Between step 3 and 4, I usually pump the pedal a few times, before i go to no. 1. Not sure if it makes a real difference, but thats my thing :D

Pboko2388 22 Oct 2011 01:43

yes jens it does help, it builds pressue in the system. i didnt realize that i didnt mention it as i ment to

Mezo 22 Oct 2011 05:45

Quote:

Originally Posted by Jens Eskildsen (Post 353269)
Yeb, thats how I do it aswell. Between step 3 and 4, I usually pump the pedal a few times, before i go to no. 1. Not sure if it makes a real difference, but thats my thing :D

Nope your dead right there Jens i forgot to mention that, it does help to build up the pressure.

Mezo.

estebangc 24 Oct 2011 14:45

Thanks to all. I will try the perfectionned procedure with more pumping!

My girlfriend could not handle the 215kgs (more than 4 times her weight!) turning around cones and dropped the CBF a couple of times on Friday night already, so postponed the course and I (we) cheated the XT and went for a short trip with me riding gf as a pillion.

Conclusion: sorry, but I still love much more the XT thumping and will get back to her today again! No rush, so probably rotor change inmediately.

oothef 24 Oct 2011 15:12

If the rotor is worn it makes sense to renew it at the same time as the pads then they bed in together rather than bedding the pads to the old disc making them less efficient when you put a new rotor on. Make sure the pads and disc are clean, not contaminated with fluid or oil.
Sometimes it helps to keep the system pressurised overnight, wedge the peddle down or tie the lever back,
Try altering the routing of the flexible pipe whilst you're bleeding the system, if it loops up tie it so it loops down or vice versa.
Be very careful opening the bleed screw whilst the system is under pressure, you could get brake fluid spraying in your face/eyes.
Good luck (a friend has renovated his RD 500 but can't get a good back brake, even having the calliper off and in different positions)

estebangc 2 Nov 2011 23:47

Quote:

Originally Posted by oothef (Post 353526)
If the rotor is worn it makes sense to renew it at the same time

New rear brake disc/rotor installed with (almost) new pads!:D(I tried a moment the pads with the old disc and they got a little worn with the grooves/lines in the old rotor, reason to follow the "change all" advice).

But before I keep on with your wise (clumsy-proof) advice about the bleeding…

With the bike stopped on the center stand, I pushed the wheel for a couple of turns… and the brakes pads are touching/chafing the disc (the previous brake pads were at the end also touching it all the time, so it got worn…). "What keeps them separated?", I thought. Looked around and pulled out the sort of tabs of the "springs" (see photo) that support the brake pads, in case they should be pushing out the pads when not braking (those tiny things cost 32€ new in Yamaha France!:oops2:). They pull more now, but the pads are still touching.

It is very hard to push the piston back (probably normal), so I put WD40 around the rubber joint, since I was told so once. Same scratching. I don’t have those shims (what is that?) they mention in the workshop manual, nor have I cooper grease, could that be, do they stick the pads to the caliper??? I am reading 2'5 manuals (in German way toooo hard) and I'm still lost with those details. I understand the basics of the way the brake works, but not more than that, I guess.

What is wrong / what am I doing wrong? Or am I just too impatient and once properly bled it won’t touch (does it make sort of a vacuum with the piston to pull it out; how do you stick the pads then to use that force)?
I read and run fast … but ignorance is quicker than me and catches me soon and easily!!!! :blushing::blushing::blushing:

http://i.imgur.com/XzqLP.jpg

http://i.imgur.com/VfFzT.jpg

http://i.imgur.com/IwPqu.jpg

oothef 3 Nov 2011 00:32

Calipers depend on the rubber seal around the piston to pull the piston back once you have released the pressure(taken your foot off the pedal). If the piston/caliper are corroded the piston does not pull back properly so some pressure/drag remains.
You can use pressure to pump the piston out to inspect it and the bore of the caliper, if it isn't too badly corroded clean it up with fine wet and dry paper, use brake fluid to lubricate it when you put it back in not oil or WD40 as they could cause the rubber seals to swell.If badly corroded replace the piston and seals and clean the bore with wet and dry.
The shims and springs stop the pads rattling about.
If the piston isn't pulling back(it only takes a fraction) then you'll get rapid wear, heat build up and an effect on the power and fuel economy.

Socks 4 Nov 2011 02:03

Quote:

Originally Posted by oothef (Post 354601)
Calipers depend on the rubber seal around the piston to pull the piston back once you have released the pressure(taken your foot off the pedal). If the piston/caliper are corroded the piston does not pull back properly so some pressure/drag remains.
You can use pressure to pump the piston out to inspect it and the bore of the caliper, if it isn't too badly corroded clean it up with fine wet and dry paper, use brake fluid to lubricate it when you put it back in not oil or WD40 as they could cause the rubber seals to swell.If badly corroded replace the piston and seals and clean the bore with wet and dry.
The shims and springs stop the pads rattling about.
If the piston isn't pulling back(it only takes a fraction) then you'll get rapid wear, heat build up and an effect on the power and fuel economy.


Estaban, as oothef says above plus my added coments below.

New rear brake disc/rotor installed with (almost) new pads!:D(I tried a moment the pads with the old disc and they got a little worn with the grooves/lines in the old rotor, reason to follow the "change all" advice).

But before I keep on with your wise (clumsy-proof) advice about the bleeding…

With the bike stopped on the center stand, I pushed the wheel for a couple of turns… and the brakes pads are touching/chafing the disc (the previous brake pads were at the end also touching it all the time, so it got worn…). "What keeps them separated?", I thought. Looked around and pulled out the sort of tabs of the "springs" (see photo) that support the brake pads, in case they should be pushing out the pads when not braking (those tiny things cost 32€ new in Yamaha France!:oops2:). They pull more now, but the pads are still touching.

It is very hard to push the piston back (probably normal), so I put WD40 (never do this again, I fear you may have contaminated your brake pads, this is the last place you need any wd40 or the likes of :nono: ) around the rubber joint, since I was told so once. Same scratching. I don’t have those shims (what is that?) ( the shims are to prevent the pads from rattleing/chattering) they mention in the workshop manual, nor have I cooper grease,( my opinion, is use a very small (smear) amount of Red grease, not copper grease onto the back/rear of the pads, it helps stop that rattle/chatter of the pads where they make contact with the piston) could that be, do they stick the pads to the caliper??? I am reading 2'5 manuals (in German way toooo hard) and I'm still lost with those details. I understand the basics of the way the brake works, but not more than that, I guess.

What is wrong / what am I doing wrong? Or am I just too impatient and once properly bled it won’t touch (does it make sort of a vacuum with the piston to pull it out; how do you stick the pads then to use that force)?
I read and run fast … but ignorance is quicker than me and catches me soon and easily!!!! :blushing::blushing::blushing:
Again as oothef mentions, the rubber seal on the piston appears to have degraded and no longer doing the job of keeping dust and dirt out of the piston along with the repositioning of the piston back into the calliper. Buy a seal kit with red grease and replace. You can PM me and I will send you in English the instructions.
Other wise doing fine! and we will get you running faster and with ease.

:mchappy:

*Touring Ted* 5 Nov 2011 07:13

If you're still having bleeding problems, here's a few tricks..



1) Bleed your unions. Bleed the brake as normal but loosen off any connecting banjo bolts instead of the bleed bolt on the calliper. Just enough so fluid weeps out of them. Air can be trapped around here and this just might let it out.


2) Back bleeding. Keep pumping your pistons out as far as you can but being VERY careful not to pump them out of their seals. Use a screwdriver or old brake pads to jam in the calliper so this doesn't happen. Make sure you are filling the reservoir too..

Then put an old towel around the reservoir and then force the pistons back into the calliper as far as you can. This will force all the fluid back through the lines 'backwards' and hopefully any force out trapped air too. It will also make a mess and get brake fluid everywhere.

The bubbles you mention could just be that you are loosening your bleed bolt too much or you don't have a good seal on your bleed pipe.

Buying a mityvac should be at the top of anyones list if they're going to work on their own brakes. It makes life 1000000% easier.

Mityvac MV8020 Hand Brake Bleeding Kit. | eBay

A.L.F 10 Nov 2011 10:19

If you're still messing with your brakes now is a good time to solve the drag problem. Brakes work on a basic push pull system, imagine that the master cylinder is like a syringe. Push down and the calliper piston moves out, Pull back and the piston should return. As the pads wear more piston is exposed to the nasty outside world of grime and corrosion which can then build up on it. This in turn hinders smooth operation as you've found out.The shims that are there are basically used to stop the pads grooving the alloy body of the calliper allowing smooth operation and as an anti squeal thing.

With the calliper removed, pump out the piston enough to clean. Brake fluid on a cloth is good for this though I have known people to use brake cleaner/ carb cleaner. Connect a bleed tube to the nipple, open and Compress back into the body with a g clamp (and flat piece of wood to save the body from marking.). Repeat this a few times or until you get decent ease of movement.

A good tip to makesure that the piston does come all the way out is to have the g clamp loose around the piston/housing and use this to regulate how far it can move out.

However if you do pop it out it allows you to clean both the inside of the housing and the piston properly. Its actually a really simple gadget inside consisting of the piston,a o-ring and 'barrel '.Thats all theres really inside. Once you've done one you never need to be unsure about them again, I know I was for years until I was forced to 'operate'.

Once you've overhauled it to a smooth degree. Bleed the unit with the piston fully in (held in a clamp~~) and elevated above the master cylinder. this means that any air trapped in the system automatically pops up to the top of the bleed nipple of its own volition rather being caught in line.

Try any or all of these combinations and you'll get a result.:thumbup1:

Jens Eskildsen 10 Nov 2011 21:38

+1 for a complete thorough disassembly.

You wont believe how much crab can fill up in the brake caliper. You'll get corrosion behind the seals, and the seals will "push" more on the piston, making it go "rougher" in the bore.

Ebay have rep kits, for fairly cheap money.

*EDIT* Like theese: http://www.ebay.co.uk/itm/2206604375...84.m1438.l2649

estebangc 12 Nov 2011 00:04

BIG THANKS... but not being able to do my homework :-(
 
Hi all,

Thank you SO MUCH to all of you. I wanted to answer and thank oothef:thumbup1:, socks:thumbup1:, ted:thumbup1: and now a.l.f.:thumbup1: and Jens:thumbup1: once I had made some progress, but I am way too busy these days and do not get to go to the (not mine, but borrowed) garage to work on the bike :-(

And then later won't be here for a while (I'll try to escape to check the piston as you all said tomorrow after I try the "ring" in my finger... :-) ). Apart from the piston issue, 1 thing I don't get. Let's say one piston is working perfectly ok, I understand the piston pushes the pads when I press the brake pedal, ok. Once I release the pedal, the piston comes back/retreats since there is sort of a vacuum in the brake hydraulic system (hose and reservoir) pulling it. But, what pushes/pulls the pads away from touching the disc? There is no suction effect from the piston to the pads; it'd be logical if piston and pads were "glued" and moved together, but it's not the case; should the "springs" (and only the springs) push them away? Because they are old and the manual says "to be replaced every time. Or what does it do it?

Esteban

PS1: I miss riding, even if cold, but it's nice to remove pieces of the bike and understand it a little better, even if sometimes it's a pain and temporarily I just feel too stupid for not nailing it... :thumbup1:
PS2: I will get those rings to mess around with peace of mind.
PS3: It was a Honda dealer who told me about the WD40 in the piston, no kidding, promised! (we rented 1 weekend a Honda for my gf and I asked)

Martynbiker 12 Nov 2011 09:40

still getting bubbles or not bleeding right?
 
try wrapping a little PTFE tape round the bleed nipple thread, it will seal the threads so no air is sucked back in to the syaten, 3 or 4 wraps should do it, as its really thin and conyours to the thread easily, just dont go past the threads to the tapered part at the bottom.

works for me, never had a bleed thread suck air in on the return using this method.

estebangc 30 Jan 2012 21:29

Quote:

Originally Posted by Martynbiker (Post 355716)
try wrapping a little PTFE tape round the bleed nipple thread, it will seal the threads so no air is sucked back in to the syaten, 3 or 4 wraps should do it, as its really thin and conyours to the thread easily, just dont go past the threads to the tapered part at the bottom.

works for me, never had a bleed thread suck air in on the return using this method.

Sorry Martyn, did not receive notification and didn't read your mail. I was exactly thinking about this today (teflon, something to seal it), I was writing this in Word.

Being away from the bike for a long while, I am back with the same issues:

Got a Mytivac, so have better control over the vacuum and amount of air coming out. Put a cable tie around the hose to be 100% is tight around the bleeder. Anway, the vacuum sucks and seals the hose. BUT, with both the bleeder screw tightened and loosen, I have the same “neverending” flow of bubbles coming out from the hole itself when I use the Mytivac.

So I order a new bleeder screw. I am told it probably has rust on the cone and it is not fitting well anymore. One option would be to “scratch” the rust. Anyway, I don’t really find any, everything looks ok inside. Try the new bleeder. SAME, I loosen, plenty of bubbles. I tighten the screw, less bubbles, but non-stop when I bleed.

The reference of the screw has changed, but it is supposed to be the same. Is the thread or cone gone wrong? Any ideas? Can I use teflon tape to wrap it, will it stand the brake fluid? Or do I have to change the whole thing???!!!!

Thanks in advance.

oothef 30 Jan 2012 22:49

Have you had the brake pipe off, if you have, did you make sure that there was a copper washer on each side of the banjo and the bolts are tight? I can't see where all the air can be coming from.
You can get automatic bleed screws, with a one way valve built in, Goodridge have them, but that doesn't solve the air problem.
Do you keep the fluid topped up in the reservoir? That's my favourite trick, having the system bled, just one last pump to make sure, emptying the reservoir, dragging air in, start all over again......

estebangc 31 Jan 2012 12:42

Yes, OOTHEF, I removed the calliper from the hose and there were two cooper rings/washers, one on each side (down, b/w the calliper and the hose and up, b/w the hose and the head of the screw). So that’s ok. And I keep the reservoir topped up.

If I understood the mechanism… The bleeder has a conical shape at its lower/inner end. Upwards, on top this cone, but before the thread, there’s a hole on one side that connects to the central cavity that goes up all along the screw till the top end of the bleeder, where is located the hole that we use to bleed the brakes. So, when you loosen the bleeder (1/4 turn), you leave some space at the very bottom of it, between the conical end of the bleeder and its seat and that way, the fluid (and air, if any) can go up and through the holes/circuit and then you can bleed the brakes. But the thread should still be "sealed"/tight enough to prevent any outside air to get in!

Example pics (not the actual screw, don’t have any now, but look basically the same):

http://i.ebayimg.com/17/!BqIwc1Q!Wk~...i6(VQ~~_35.JPG

http://img.jpcycles.com/zoom/240-797_A.jpg

So, the cone should seat well and be totally sealed when you tighten the screw, so that brake fluid does not leak/air does not get it the circuit itself. And the thread should also seat well sealed, so that air that does not get in while you bleed the brakes, otherwise you would have new air entering the system.

Am I right in my understanding?

Conclusions, considering that I can pump out bubbles with both the screw loose and tightened: a) the bleeder/screw (particularly the old one; less the new spare) happens to have some slight free play when not tighten. So, that’s wrong to bleed, since new air could probably come in through the thread when bleeding. b) Then, I still can “suck” air with the Mytivac with the screw tightened, and I assume there could be two reasons: b1) the cone does not seat well and somewhere else in the circuit there is air coming in, or b2) the cone actually seats well and that air comes from the slight free play from the thread (which I cannot notice when the screw is tightened, but which is still there).

I tend to think that the cone seats well, that the whole brake circuit is actually sealed, but that it is not possible to bleed it properly since air comes in through the thread.

Solutions I can think of: since that happens with the new spare bleeder as well, that would mean that the thread in the calliper is “gone”, so that would imply 1) changing the whole calliper (expensive option) or 2) seal somehow the thread of the screw so that I can bleed it and then tighten it and seat the cone properly (cheap solution). I guess that is Martynbiker proposal, with plumbers tape (Teflon). I’m going to try it, any alternative method?

Sorry for the loooong post, I hope there is anything in it that can help anyone (as ignorant as me:blushing:)! Thanks again to all of you.:thumbup1::thumbup1::thumbup1:

PS: It's very difficult for a non-native to explain precise parts/movements, etc, so I repeat and repeat to be sure it's comprehensible for the reader... and still there will be plenty of mistakes. Hope at least you get it!

oothef 1 Feb 2012 19:25

The thread doesn't seal, it just allows you to tighten down on the taper/cone which seals the system, I've not used a vacuum bleeder but I think it would pull air through the threads when the screw is tight.
Because the thread isn't sealed is why when bleeding in the old way you slacken the screw, press/pull lever and hold down/in, tighten screw, release lever, pump a few times, and repeat........
http://www.horizonsunlimited.com/hub...BJRU5ErkJggg==Look up the Goodridge speed bleeder, it has a plastic coating on the threads and a one way valve built in so you can leave it slack and just pump the lever.(I've never used one of these either, but it struck me as a good idea).(I've tried posting a picture but it keeps dissapearing!)
Because you can't get all the air out you can't really test the bleed screw seal by pressing very hard on the lever (when the screw is tight) checking to see if any fluid seeps out.
It looks like the caliper is a single piston type, this depends on the caliper sliding across to pull the other brake pad on, if the caliper doesn't slide the piston distorts the disc making the brake feels spongey and very inefficient.
Again, the threads don't seal, the taper/cone seals when the screw is tight

estebangc 1 Feb 2012 19:35

Solved.-
 
:DSOLVED!:D

1st try: 4 wraps of teflon tape around the thread of the bleeder. Not enough, still bubbles coming out.

2nd try: 8 wraps around and IT WORKED.

Took way too long... getting married in the meantime also took some time off (working on) the bike.:innocent:

bierThanks to everyone for your advice. bier Hopefully this also helps to someone.

estebangc 1 Feb 2012 19:53

Quote:

Originally Posted by oothef (Post 365533)
The thread doesn't seal, it just allows you to tighten down on the taper/cone which seals the system, I've not used a vacuum bleeder but I think it would pull air through the threads when the screw is tight.
Because the thread isn't sealed is why when bleeding in the old way you slacken the screw, press/pull lever and hold down/in, tighten screw, release lever, pump a few times, and repeat........
http://www.horizonsunlimited.com/hub...BJRU5ErkJggg==Look up the Goodridge speed bleeder, it has a plastic coating on the threads and a one way valve built in so you can leave it slack and just pump the lever.(I've never used one of these either, but it struck me as a good idea).(I've tried posting a picture but it keeps dissapearing!)
Because you can't get all the air out you can't really test the bleed screw seal by pressing very hard on the lever (when the screw is tight) checking to see if any fluid seeps out.
It looks like the caliper is a single piston type, this depends on the caliper sliding across to pull the other brake pad on, if the caliper doesn't slide the piston distorts the disc making the brake feels spongey and very inefficient.
Again, the threads don't seal, the taper/cone seals when the screw is tight

My post crossed with yours.

I get your point. The vacuum bleeder may get air forcing it through the thread. But the instructions for similar model (on line, I got only instructions in German) say "pump a few times to create vacuum and then crack the bleeder with a wrench", so I assume it should not be the case. With (enough) teflon, it definitely suck any. So the taper/cone seat does not seal well (not with old nor new bleeders), and therefore it's all because of the teflon tape. Man, I'm getting confused, IT WORKS!:D I'll mess with the front next!:smartass:

btw, I tested the brake in an underground parking: snow in the streets, new disc and new pads. But it brakes.

Here is the Goodrich Bleeder, I looked at it. Brilliant.

http://www.fastech-racing.com/images...0ef318e33f.gif

oothef 1 Feb 2012 22:25

Glad it's good to go!

estebangc 6 Feb 2012 19:11

Front Brake Master Cylinder Screws: metal or CHEESE?????????
 
My Goodness, I applied very little strengh! doh (wtf!) Maybe due to cold temperatures..?

I plan to buy an impact driver tomorrow, but will it damage the mecanism? (emptying fluid, removing it from its place and putting it over a wooden block, for a softer impact). What about heating with a BIC lighter (know them better than with oxy-acetilene torches people recommend for studs)

Any other options in such delicate place? Drilling seems pretty tricky.

Does the cover has an inside "lid" or can I rotate it if I remove 1 of the screws?

Already postponed MOT twice... what's going wrong with these damn f**king brakes???

http://i.imgur.com/Ex5L7.jpg

oothef 6 Feb 2012 20:12

Try the impact driver, press down really hard and give it a firm tap, you could try a sharp punch and drive the screws round with that, or drill, I think the screws are M4, drill a shallow pilot hole 2-3mm (take care not to break the bit!) then use a 4mm bit,(don't break it!) this should take the head of the screw off, lift the top off and use pliers or grips to take the screw out of the master cylinder.
Replace them with "allen" screws
Impact driver will be a good investment, as is a hot air gun

grumpy 6 Feb 2012 20:37

How about a slot with a dremel then screwdriver.

Socks 6 Feb 2012 21:45

Your not the first and you will not be the last to do this to those screw in paticular. I understand that the eastern fiends have a slightly different slot to the drivers you/we have and so the driver head is wrong shape.

Have a look here http://www.motorcycle.in.th/article....ps-Screwdriver or

JIS Screwdrivers - webBikeWorld

Best ensure slot is clean and then apply direct and firm presure whilst turning driver.

But for now as mentioned above Try the sharp punch or a bradle on the flat outside of the head first. If you drill dont go to far just enough to remove the head of the screw.

Good luck

estebangc 6 Feb 2012 22:03

Quote:

Originally Posted by oothef (Post 366261)
Try the impact driver, press down really hard and give it a firm tap, you could try a sharp punch and drive the screws round with that, or drill, I think the screws are M4, drill a shallow pilot hole 2-3mm (take care not to break the bit!) then use a 4mm bit,(don't break it!) this should take the head of the screw off, lift the top off and use pliers or grips to take the screw out of the master cylinder.
Replace them with "allen" screws
Impact driver will be a good investment, as is a hot air gun

Thx (again), I'll try the impact screwdriver. Plastic head hammer rather than fully iron? I should get many tools, but I do not plan to stay here forever, so not good to move out/leave behind (and I have borrowed the garage, so not really my place to work):(

Quote:

Originally Posted by grumpy (Post 366268)
How about a slot with a dremel then screwdriver.

Same for the dremel, but I'd love it!

Quote:

Originally Posted by Socks (Post 366276)
Your not the first and you will not be the last to do this to those screw in paticular. I understand that the eastern fiends have a slightly different slot to the drivers you/we have and so the driver head is wrong shape.

Have a look here http://www.motorcycle.in.th/article....ps-Screwdriver or

JIS Screwdrivers - webBikeWorld

Best ensure slot is clean and then apply direct and firm presure whilst turning driver.

But for now as mentioned above Try the sharp punch or a bradle on the flat outside of the head first. If you drill dont go to far just enough to remove the head of the screw.

Good luck

At least I did this right: I tried several (exchangeable) screwdrivers till I got the perfect fit. I guess it was too cold and I applied not so perfect strength... But I'll write with interest the whole article.

Thanks again to all. Maybe one day I'll give those advices to a novice hubber-mechanic-wanabee as myself! :smartass:

estebangc 7 Feb 2012 16:44

For those considering drilling any other screw, I just saw this and was told it works well (although cost more than 60€ here!). It seems pretty interesting (I think about snapped header pipes bolts):

Amazon.com: Alden 8530P Grabit Damaged Screw Remover 3 Piece Kit: Home Improvement

Amazon.com: Alden 3719P X-out Damaged Screw Remover Kit with Case, 3-Piece: Home Improvement

http://ecx.images-amazon.com/images/...gL._AA300_.jpg

http://ecx.images-amazon.com/images/...500_AA300_.jpg


http://ecx.images-amazon.com/images/...500_AA300_.jpg


In the meantime, I got this impact screw that I also expect to use more often (20€)... but have to wait until tomorrow to try it out:

http://www.kraftwerk-hosendorfer.at/...mages/2035.jpg


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