Bleeding the brakes
Discussion
I'm in the process of fitting a riser kit to the SV to give me a bit more comfort, when bimbling around town in the traffic. As part of the deal, I've replaced the original top hose for the front brake with a braided item supplied with the kit. This obvious means I have a load of air in the new hose to clear. So folks, do you have any tips on how to do this?
Ta,
Steve.
Ta,
Steve.
Steve,
This is easiest done with a mate, but you can do it on your own. Here goes. Before we start, you need to remember to keep the master resevoir filled up at all times so as to avoid sucking air through your newly bled system!
1. take the top off the fluid resevoir
2. remove the bleed nipple covers from the calipers
3. find a ring spanner (not an open ender, you may damage the nipple (fnar fnar)) to fit the bleed nipple
4. gently undo the bleed nipple about 1/4 turn (until the resistance goes)
5. attach a lenth of rubber hose to the bleed nipple of the side you intend to do first and pass this from the caliper into an old coffee pot or something similar
6. whilst GENTLY squeezing the brake lever, simultaneously slowly release the bleed nipple. As you do this you should notice that i) fluid starts coming out of the attached hose and ii) the lever should offer less resistance and make its' way towards the bar
7. without releasing the lever, nip up uthe bleed nipple again and slowly release the brake lever
8. repeat 6-7 until all the air bubbles have been bled out of the side you're doing (you will notice that the residual fluid you've bled out int he bottom of the collecting container lets you see if there are any bubbles left).
9. you may want to tap the caliper and the actual master cylinder with a large screwdriver to dislodge any trapped bubbles - not guaranteed, but sems to work OK.
10. make sure the bleed nipple on the caliper you've just beld is tight (but don't overtighten it, otherwise you'll either strip the threads in the caliper of round off the top of your nipple (woof woof).
11. repeat for the other side
12. you should then have a firm brake lever which doesn't feel spongy at all.
13. a neat trick is to tie the brake lever as far back to the bar as it'll go overnight (use a zip tie or something) then in the morning, hold the brake lever whilst snipping the zip tie and SLOWLY release the brake lever. This often forces the minute air bubbles out of the system to the top of the resevoir.
Remember to check your brake lever a few times for resistance and roll the bike fwd to check the brakes themselves work, as you really don't want to check the brake coming up tot he lights!
Good luck.
This is easiest done with a mate, but you can do it on your own. Here goes. Before we start, you need to remember to keep the master resevoir filled up at all times so as to avoid sucking air through your newly bled system!
1. take the top off the fluid resevoir
2. remove the bleed nipple covers from the calipers
3. find a ring spanner (not an open ender, you may damage the nipple (fnar fnar)) to fit the bleed nipple
4. gently undo the bleed nipple about 1/4 turn (until the resistance goes)
5. attach a lenth of rubber hose to the bleed nipple of the side you intend to do first and pass this from the caliper into an old coffee pot or something similar
6. whilst GENTLY squeezing the brake lever, simultaneously slowly release the bleed nipple. As you do this you should notice that i) fluid starts coming out of the attached hose and ii) the lever should offer less resistance and make its' way towards the bar
7. without releasing the lever, nip up uthe bleed nipple again and slowly release the brake lever
8. repeat 6-7 until all the air bubbles have been bled out of the side you're doing (you will notice that the residual fluid you've bled out int he bottom of the collecting container lets you see if there are any bubbles left).
9. you may want to tap the caliper and the actual master cylinder with a large screwdriver to dislodge any trapped bubbles - not guaranteed, but sems to work OK.
10. make sure the bleed nipple on the caliper you've just beld is tight (but don't overtighten it, otherwise you'll either strip the threads in the caliper of round off the top of your nipple (woof woof).
11. repeat for the other side
12. you should then have a firm brake lever which doesn't feel spongy at all.
13. a neat trick is to tie the brake lever as far back to the bar as it'll go overnight (use a zip tie or something) then in the morning, hold the brake lever whilst snipping the zip tie and SLOWLY release the brake lever. This often forces the minute air bubbles out of the system to the top of the resevoir.
Remember to check your brake lever a few times for resistance and roll the bike fwd to check the brakes themselves work, as you really don't want to check the brake coming up tot he lights!
Good luck.
Couple of other points,it is surprising just how much air there is in the system after a hose change,maybe even repeat the bleeding procedure a couple of times(i had to with my SP1)also if your setup is that the hose goes down to front right caliper,then another hose loops across to other caliper,bleed the one furthest away first(the one being fed from the hose from the right hand or double banjoed caliper)
>> Edited by rumpelstiltskin on Monday 18th October 20:55
>> Edited by rumpelstiltskin on Monday 18th October 20:55
It's not something that affects me as my bike has a cable-operated front brake and rod-operated rear brake, but I have heard people speak well of "reverse bleeding" for systems where it's a bugger to get all the air out. This basically involves connecting a squeezy bottle full of brake fluid to the nipple with a bit of rubber tube and forcing brake fluid back from the caliper up to the master cylinder, using another squeezy bottle to suck the extra fluid out of the reservoir as you go.
Thanks to all for the helpful comments. Got the bars in position for a basic comfort test and all is looking good so far. Am wondering if I'll have the time to get the job finished before I go on hols tomorrow afternoon. Will it do any harm to leave the system half filled for a week and address it when I return?
Thanks,
Steve
Thanks,
Steve
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