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| Front brake master cylinder http://ducatipaso.org/forum/viewtopic.php?f=2&t=6641 |
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| Author: | Giscard [ Thu Apr 03, 2014 7:32 am ] |
| Post subject: | Front brake master cylinder |
I think I have a problem with my front brake master cylinder in that I went out for a ride and the brakes locked on at low speed. I could not pry the pads away from the disc to release it. I undid the bleed nipple at one of the calipers to release the pressure which freed it up and manged to limp home only using the back brake. I have tried it again and they have locked up. As before releasing the pressure allows the pads to release the disc. I have read that Ducati do not do rebuild kits but has anyone identified and alternative supplier of seals, or seals for a different model that are suitable. It may just need a good old clean as the fluid was not great but it would be useful to be ready with new seals anyway. |
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| Author: | Derek [ Thu Apr 03, 2014 9:17 am ] |
| Post subject: | Re: Front brake master cylinder |
The screw on the front brake lever is too far in and preventing the piston from returning far enough to uncover the bleed hole that lets the fluid return to the reservoir. Back off the screw until there is just clearance between the lever and the piston. If you know what you are doing you can take it in a little further but's hard to describe how, so just allow a tiny clearance to be on the safe side. |
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| Author: | paso750 [ Thu Apr 03, 2014 9:35 am ] |
| Post subject: | Re: Front brake master cylinder |
Before turning the lever screw I`d remove the brake lines as I guess you`re still using the original ones. If they start to dissolve internally braking can clog the lines completely and lock the brake (often you`d notice that the brake fluid is almost black). If this is the case it`s possible you`ve got dirt also in the calipers. If the caliper seals don`t leak you can split the calipers and clean them also w/o replacing the seals. |
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| Author: | Giscard [ Thu Apr 03, 2014 10:50 am ] |
| Post subject: | Re: Front brake master cylinder |
Thanks for the replies. I have a set of braided lines on order as my intention was to overhaul the brakes as much as I can, when they arrive. Once they are replaced I was going to check the master cylinder out. I will however check out the screw on the brake lever as my view was that something was stopping the fluid returning, thus reducing the pressure and this could be part of the problem. Whether that corrects it or not I will be fitting the braided hoses as soon as they arrive. |
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| Author: | paso750 [ Thu Apr 03, 2014 11:45 am ] |
| Post subject: | Re: Front brake master cylinder |
that screw usually has a bit of paint on it from the factory. Did you ever change the position of the screw ? If you never did and the brakes worked in the past that`s not the problem. |
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| Author: | Giscard [ Thu Apr 03, 2014 2:49 pm ] |
| Post subject: | Re: Front brake master cylinder |
The previous owner fitted new brake shoes and had not used it after that. I have only done a few miles on it before the problem arose. I have just slackened off the screw and I can now rotate the wheel although the pads are still rubbing slightly but that may be because the discs are rusty after hardly being used for several years. The brakes lock the wheel up if I push the bike in the garage, without too much travel on the lever so it all seems reasonable When it stops raining I will try it out - carefully. |
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| Author: | Giscard [ Sat Apr 12, 2014 8:21 am ] |
| Post subject: | Re: Front brake master cylinder |
OK so that did not fix it, as although the brakes worked well they did not release properly. Fortunately I was only 50metres from my house at the time. On examination of the calipers it appears that the pistons are not movng freely on one of them and once on effectively stay on. The small springs on the caliper retaining pins were also both broken, presumably by the previous owner. Does anyone know if these are available in Europe as getting them from the US is likely to be less than cost effective with the postage, but if that is the only source. Hopefully someone will know if they are fitted to a newer bike. |
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| Author: | higgy [ Sat Apr 12, 2014 1:09 pm ] |
| Post subject: | Re: Front brake master cylinder |
Bevel Heaven will have what you need if you can't find it anywhere else |
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| Author: | persempre907 [ Sun Apr 13, 2014 11:09 am ] |
| Post subject: | Re: Front brake master cylinder |
However, since you are fitting the braided lines, I'd replace the master cylinder with a more effective one, too. I have done it (fitted the 999's master cylinder). The braking improvement is impressive, believe me. Ciao |
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| Author: | Mc tool [ Mon Apr 14, 2014 2:21 am ] |
| Post subject: | Re: Front brake master cylinder |
Ah , might be time to disassemble and re furb your calipers ( piece of cake ) , and as presempre907 says may as well do the pump too . You really would be better off doing the whole lot . IF you are fitting braider lines and ( and this could be the decider ) a new pump , you may want to ditch the front brake light switch assy /union thing and fit a pump with a switch already fitted ........tidies up the plumbing How are you anyhow ?  Hamish |
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| Author: | Giscard [ Mon Apr 14, 2014 8:00 am ] |
| Post subject: | Re: Front brake master cylinder |
Thanks for all the advice. The more I read the less I know. I went onto the bevel heaven website and saw the pictures of the the small "springs" on the calipers which are exactly the same as mine. I assumed there was meant to be a loop at both ends and was surprised when I took the second one off and that appeared to be identical to the first. Doh. I want to order all the seals for the pistons and the calipers but am slightly confused (not difficult) as to whether I need the seal kit for F08 which I think may be correct or P108. Thanks for the greeting Hamish. Everything is fine here in France (except my Ducati). You OK ? |
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| Author: | bmw851 [ Mon Apr 14, 2014 9:12 am ] |
| Post subject: | Re: Front brake master cylinder |
| Author: | Giscard [ Mon Apr 14, 2014 1:04 pm ] |
| Post subject: | Re: Front brake master cylinder |
Peter I know what you mean about being mechanically challenged. I certainly am when it comes to getting to grips with the Paso. Do you know whether I would need the F08 seal kit or the P108 seal kit. I struggle to work out the difference as they are both for 38mm pistons. As far as I am aware I have the original disc callipers for a 1989 906 Paso. |
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| Author: | paso750 [ Mon Apr 14, 2014 2:17 pm ] |
| Post subject: | Re: Front brake master cylinder |
Brembo P08 are the front calipers, the rear one is P108 |
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| Author: | higgy [ Mon Apr 14, 2014 11:04 pm ] |
| Post subject: | Re: Front brake master cylinder |
Like G said Steve Allen at Bevel Heaven is a very helpful and knows more and more about the Paso all the time  I throw my biz in his direction every chance I get 
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