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Rear brake blead

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Aarong View Drop Down
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    Posted: 09 Mar 2019 at 16:33
Has anyone one got any tips for bleeding a rear brake on a 07 rsv? 
I've changed the fluid as the old fluid was pretty black and now I can't keep a solid pedal, I'm pretty sure it's air in the system and not a leak.
I've tried hanging the caliper higher than the master cylinder and resivour with the bleed nipple at the top bit still no joy.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote redratbike Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2019 at 17:19
Reverse bleed it from caliper to m/c or use a power bleeder


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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tifa Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2019 at 17:45
Put a little ptfe tape on the thread part of the nipple.
Will help stop air getting drawn back in.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote IanG Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2019 at 19:59
Best tip for any bleed nipple on the bike Clap

Did you not bleed the old fluid out and replace it that way then?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aarong Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2019 at 20:37
That's something I haven't tried but I will give it a go thank you
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aarong Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2019 at 20:39
Sorry I meant the ptfe on the thread I haven't tried, yes I did bleed the old stuff out but I had the caliper in the normal position which is where I think I went wrong.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote IanG Quote  Post ReplyReply Direct Link To This Post Posted: 09 Mar 2019 at 23:37
In that case as long as the res didn't run dry the only way air could have got in is round the nipple threads.

As with a lot of other makes the threads on bleed nipples seem to be very loose,possibly to hopefully stop dissimilar metals corroding together?

What ever,I always wrap nipples with PTFE tape  ( My Mrs sometimes wonders about it LOL)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote 426hemi Quote  Post ReplyReply Direct Link To This Post Posted: 10 Mar 2019 at 00:22
I've been looking at getting some of these to help with the bleeding.
http://www.stahlbus.com/info/en/service/faq-s/bleeder-valves/64-stahlbus-compared-to-other-products
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Post Options Post Options   Thanks (0) Thanks(0)   Quote legend88 Quote  Post ReplyReply Direct Link To This Post Posted: 10 Mar 2019 at 07:42
Originally posted by IanG IanG wrote:

with a lot of other makes the threads on bleed nipples seem to be very loose,possibly to hopefully stop dissimilar metals corroding together?


I've heard this suggestion before but never actually used the idea. Of course the nipple is not supposed to rely on the threads for sealing. It's the taper that closes against the seat in the caliper that produces the seal.

Sometimes it is suggested that air is drawn in p0ast the threads during the actual bleeding process. However whenever you have been able to achieve a solid brake lever then clearly that has not happened so I am not sure that this often happens?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote IanG Quote  Post ReplyReply Direct Link To This Post Posted: 10 Mar 2019 at 10:16
You wouldn't think so but it does help,I've needed to do it on several cars in the past and it's just second nature now.

Another possible benefit is that it stops any brake fluid bypassing the nipple and finding it's way up the threads during bleeding which can get messy.

It certainly helps with preventing the nipple ever corroding in place which I've had happen on some vehicles I've bought over the years so it's worth it just for that.

Just make sure the tape doesn't go past the thread and foul the shank and mating taper and all should be good
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aarong Quote  Post ReplyReply Direct Link To This Post Posted: 15 Mar 2019 at 13:27
Well I've now got a back brake, I took the caliper off and hung it from the rear passenger foot rest and re bled the system.
I still didn't have much of a pedal though so I placed the caliper on some rag on the floor at an angle so the bleed nipple was the lowest point, then pressed the brake pedal down and cable tied it down and left for a few days.
Now I have a good pedal which seems to be holding.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowman Quote  Post ReplyReply Direct Link To This Post Posted: 18 Mar 2019 at 19:29
Years ago on brothers Harley tried bleeding front brakes to no avail, so just cable tied front lever in at handles bars overnight and hey presto when cable tie was released the brake was nice and firm 😮
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aarong Quote  Post ReplyReply Direct Link To This Post Posted: 18 Mar 2019 at 20:29
Originally posted by snowman snowman wrote:

Years ago on brothers Harley tried bleeding front brakes to no avail, so just cable tied front lever in at handles bars overnight and hey presto when cable tie was released the brake was nice and firm 😮

It's something I got told to do with my mountain bike disc brakes by a cycle shop, I thought I'd give it a go and bingo Thumbs Up
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Post Options Post Options   Thanks (0) Thanks(0)   Quote legend88 Quote  Post ReplyReply Direct Link To This Post Posted: 18 Mar 2019 at 20:47
I've never got how that can work. If you have air in the system, how can clamping the lever on resolve that?

The only thing I can think is that it's not about air but more to do with sticking pistons and the constant pressure helps to free them off?

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Aarong Quote  Post ReplyReply Direct Link To This Post Posted: 18 Mar 2019 at 21:23
Originally posted by legend88 legend88 wrote:

I've never got how that can work. If you have air in the system, how can clamping the lever on resolve that?

The only thing I can think is that it's not about air but more to do with sticking pistons and the constant pressure helps to free them off?


 On some bicycle disc brakes there are tiny holes in the master cylinder so I got told to put a cable tie around the handle bar and brake lever, stick it on the back wheel and leave it over night, apparently it leaves the system open and with the caliper at the lowest point and master cylinder at the highest point it gives it time for the air to get to the top.
Don't ask me how it works but it seems to for me, I also used the method on my front brake and it firmed the lever up more as well. 
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tifa Quote  Post ReplyReply Direct Link To This Post Posted: 19 Mar 2019 at 19:51
It allows any air in the lines to rise and escape naturally.
Pulling in the lever allows the air to pass by the m/c piston.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote legend88 Quote  Post ReplyReply Direct Link To This Post Posted: 19 Mar 2019 at 21:48
Originally posted by Tifa Tifa wrote:

It allows any air in the lines to rise and escape naturally.
Pulling in the lever allows the air to pass by the m/c piston.

I still don't see how. The pressure in the system increases the effectiveness of the seal in the master cylinder so the air may rise to the top but it can't escape past the seal or the fluid would too.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tifa Quote  Post ReplyReply Direct Link To This Post Posted: 20 Mar 2019 at 13:59
Originally posted by legend88 legend88 wrote:

I still don't see how.


It's science dude.
Not 100% sure myself...just my theory.

Recon it's one of those crazy unexplainable hydraulic things, like hanging a weight on your rear brake pedal overnight will restore it and give a firm pedal.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Tifa Quote  Post ReplyReply Direct Link To This Post Posted: 20 Mar 2019 at 14:00
Originally posted by Tifa Tifa wrote:

Originally posted by legend88 legend88 wrote:

I still don't see how.


It's science dude.
Not 100% sure myself...just my theory.

Recon it's one of those crazy unexplainable hydraulic things, like hanging a weight on a spongy rear brake pedal overnight will restore it and give a firm pedal.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote snowman Quote  Post ReplyReply Direct Link To This Post Posted: 20 Mar 2019 at 18:14
I don’t care how it just does ?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote MorathB Quote  Post ReplyReply Direct Link To This Post Posted: 21 Mar 2019 at 22:50
Originally posted by legend88 legend88 wrote:

Originally posted by Tifa Tifa wrote:

It allows any air in the lines to rise and escape naturally.
Pulling in the lever allows the air to pass by the m/c piston.

I still don't see how. The pressure in the system increases the effectiveness of the seal in the master cylinder so the air may rise to the top but it can't escape past the seal or the fluid would too.

I think the pressure makes the small/micro air bubbles even smaller so they can rise up to the lever more easily and after releasung the lever they're going into the reservoir
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Post Options Post Options   Thanks (0) Thanks(0)   Quote badapple Quote  Post ReplyReply Direct Link To This Post Posted: 22 Mar 2019 at 00:51
I've used this method before and it did work, I hung a tin of paint and a couple of weights on top of the tin off the rear brake pedal  only trouble was for some reason it knackered the rear brake light switch I wouldn't do it again because of that never had a problem with regular bleeding on the clutch or front brake. 
I started out with nothing and I've still got most of it left
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Post Options Post Options   Thanks (0) Thanks(0)   Quote IanG Quote  Post ReplyReply Direct Link To This Post Posted: 22 Mar 2019 at 08:35
I think the weight on the pedal or tie round the lever thing works in the same sort of way as cleaning the disc bobbins until they're free to spin.

In as much as logic and reason fly in the face of proven results

With the bobbins I think although it's not needed or probably even desirable for them to be freely rotating it's actually beneficial as if they are that clean then it means you've flushed out any foreign matter which could make the swept area run out of true.

Like the can/tie practice which I'm guessing pressurizes any trapped air as small bubbles which will naturally try and flow upwards and find their way to the res in time.

However these are very simple circuits and if in serviceable condition and bled properly they are quick and easy to get done with minimal fluid use.

Now I've always had a serviceable rear brake with the standard cylinder arrangement, and I bleed the slave in situ every year ( or two Embarrassed)  to change the fluid and I usually manage to only use a couple of reservoirs worth of fluid. 

It just depends on how you go about it I suppose,a lifetime of working on old bikes and cars certainly helps Wink
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