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:

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:)

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.

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.

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.

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

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!

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:

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?

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.

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

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

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

Mezo.

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.

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)