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XB12XT rear brake bleed
https://ukbeg.com/forum/viewtopic.php?f=8&t=25549		 Page 1 of 1
Author:  RevM [ 24 Sep 2024 16:13 ]
Post subject:  XB12XT rear brake bleed
I just can't seem to get the air out of the system on my rear brake (Ulysses XB12XT). I have bled and bled but no joy. The system must be leaking somewhere I guess? All hoses and connections look good and clean (no leakage). The only place that looks wet with fluid is the beed nipple on the caliper. Could this be the source of my frustration? I'd like to replace the bleed screw to be sure. However, as it's a Buell branded caliper I guess the bleed screw is an imperial size? Can anyone advise what size I need to get?

Thanks for your help.
Author:  Nutah [ 24 Sep 2024 20:06 ]
Post subject:  Re: XB12XT rear brake bleed
not 100% sure but i think they are re branded Nissin calipers
so a good chance it will be metric
Author:  Nutah [ 24 Sep 2024 20:09 ]
Post subject:  Re: XB12XT rear brake bleed
viewtopic.php?f=8&t=23641&p=310534&hilit=rear+caliper#p310534
Author:  barney [ 24 Sep 2024 20:14 ]
Post subject:  Re: XB12XT rear brake bleed
do a google/ youtube search , have a look at, reverse bleeding.
or if you have put plenty of fluid through the system . leave the cap off the reservoir and just gently operate the brake only need a few mm of travel and watch for bubbles rising in reservoir repeat until bubbles stop , might need to leave it a few hours or over night and do same again ( air is always going to try to get to the highest point )
Author:  Stot [ 25 Sep 2024 13:47 ]
Post subject:  Re: XB12XT rear brake bleed
:yt:

Had the same problem with my M2. The master cylinder moves so little fluid it cant push the air through the pipes fast enough to beat bouyancy and it just floats back to the highest point.

I used a Gunson Eazibleed to push fluid through from the caliper nipple back and it did it first time. A big syringe can do it too if you can keep the tube on the end of it and make sure you dont push air in. Brake fluid can make it too slippery to stay on the end of the syringe, especially DOT 5 like on the M2. :evil:

Cheers
Stot
Author:  rik [ 25 Sep 2024 14:01 ]
Post subject:  Re: XB12XT rear brake bleed
Stot wrote:
:yt:

Had the same problem with my M2. The master cylinder moves so little fluid it cant push the air through the pipes fast enough to beat bouyancy and it just floats back to the highest point.

I used a Gunson Eazibleed to push fluid through from the caliper nipple back and it did it first time. A big syringe can do it too if you can keep the tube on the end of it and make sure you dont push air in. Brake fluid can make it too slippery to stay on the end of the syringe, especially DOT 5 like on the M2. :evil:

Cheers
Stot


...don't forget to keep an eye on the level in the reservoir, it will be rising not dropping! A second syringe comes in handy for sucking the excess out.
Author:  barney [ 26 Sep 2024 08:15 ]
Post subject:  Re: XB12XT rear brake bleed
rik wrote:
Stot wrote:
:yt:

Had the same problem with my M2. The master cylinder moves so little fluid it cant push the air through the pipes fast enough to beat bouyancy and it just floats back to the highest point.

I used a Gunson Eazibleed to push fluid through from the caliper nipple back and it did it first time. A big syringe can do it too if you can keep the tube on the end of it and make sure you dont push air in. Brake fluid can make it too slippery to stay on the end of the syringe, especially DOT 5 like on the M2. :evil:

Cheers
Stot


...don't forget to keep an eye on the level in the reservoir, it will be rising not dropping! A second syringe comes in handy for sucking the excess out.

:yup:
Author:  RevM [ 23 Oct 2024 14:56 ]
Post subject:  Re: XB12XT rear brake bleed
Thanks for all the help and advice.
For the record the rear brake on my 2010 XB12XT uses a single piston Nissin caliper (metric). The piston itself is 38mm in diameter. I was able to get oil seals quite easily once I had this information.
Author:  Nutah [ 24 Oct 2024 13:06 ]
Post subject:  Re: XB12XT rear brake bleed
:yup: :sun:
Author:  RevM [ 03 Nov 2024 17:27 ]
Post subject:  Re: XB12XT rear brake bleed
OK, I've think I've jut about got there. Here's what I have learned (for what it's worth):
1. Bleeding the rear brake on an XB12 is a delicate operation!
2. 'Standard bleeding using the brake pedal fails. It simply leaves air pockets in the system.
3. Sucking fluid throught the caliper bleed nipple is problematic, it seems to draw air in with it. I gues this is throught he master celinder and brake piston seals which, of course, are designed to work only one way.
3. I couldn't get reverse bleeding to work. I simply couldn't force fluid into the system. I probably missed something here.

Ss here's I finally got there:
1. Suck fluid through the system from the caliper nipple.
2. When fluid starts apprearing reduce the suction to an absolute minimum then continue to draw until the bubles stop.
3. Finish the process with the tradional method using the brate lever until all the bubbles stop.
4. Leave overnight then bleed again the next day using the traditional method.

I guess you would be succesful if you pushed fluid through from the resevoir. I didn;t have the tools to do this.

Hope this helps alleviate frustration.
Author:  rik [ 04 Nov 2024 23:02 ]
Post subject:  Re: XB12XT rear brake bleed
Did you put any sort of grease on/around the nipple thread? ...that's most likely where your air was being drawn in.
Author:  RevM [ 05 Nov 2024 09:36 ]
Post subject:  Re: XB12XT rear brake bleed
Thanks. Good thought, I didn't!
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