Rear master cylinder failure?

Nortenere

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My Super Tenere i a 2012 with km 62.000. When I did a hill start a few weeks ago the rear brake had no resistance. Since then I have bleeded the rear brake and cycled the ABS pump. I get pressure when I pump the brake pedal and hold it. When I Iet the pedal up and press it down again, there are no pressure. I could feel the ABS working front and rear when I cycled the ABS pump. I hope the seals in the master cylinder i leaking. My plan is to change the seals first. If still no rear brake I have to contact the dealer. I have read a lot about rear brake failures in this forum and it is often a symptom of ABS pump failure. Has anybody replaced the seals in master cylinder and solved the problem?

Thanks Nortenere
 

Squibb

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When you bleed the rear system again, are you getting air bubbles appearing in the spent fluid? .....or does it flow clean.

Seems like this has happened suddenly, so it's worth checking out the lines/caliper as Steve suggests - could be physical damage somewhere; it only needs a tiny nick in a brake line to admit air, yet it will only leak a minute amount of fluid.
 

patrickg450

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the part is cheap compared to the time it will take you to repair it (IMO). I replaced mine, took 15 to 20 mins........you could have an ABS issue.
 

Nortenere

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I did get a lot of air bubbles whwn I bleed the rear system first time. No air bubbles when I bleed after I cycled the ABS pump. Yesterday I ordered a seal kit for the rear master cylinder from my Yamaha dealer. I hope new seals will fix my problem. A new ABS pump will be too expensive here in Norway. Thanks for Your replies.
 

2daMax

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What I have encountered is that the air is somewhat trapped inside the ABS unit. If you feel no resistance, it means there is still air inside the ABS unit. The only way to get the air out is to cycle the ABS pump, bleed the rear completely, refill, and then repeat the Cycling.....until no more bubbles is seen exiting out from the pump. I am talking about up to 20 or more times of cycling the ABS pump/bleeding.
 

Nortenere

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I bought a Yamaha rear master cylinder repair kit. I replaced it today. I have not cycled the ABS pump yet, I will tomorrow. I now have resistance again. If I still have rear brake the next weeks I hope I have cured the problem.
 

MikeinNZ

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I bought a Yamaha rear master cylinder repair kit. I replaced it today. I have not cycled the ABS pump yet, I will tomorrow. I now have resistance again. If I still have rear brake the next weeks I hope I have cured the problem.
Hi , did you cure the problem as I have just bought a 2010 with the same problem
 

Nortenere

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Yes, I now have rear brake again. I could not see damage at the original master cylinder parts but I changed them anyway. I did not use the rear brake very often, now I use it every day. The dealer will do 60.000 km service next week. I guess they will tell me if the rear brake is not working properly.
 
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Nortenere

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I have driven 500 km since I got my bike back from the dealer after its winter sleep. I still have front and rear brakes. It seems that a rear master cylinder repair kit and a lot of ABS cycling cured my problem. Now I will use rear brake every day. And cycle the ABS at least every 6 months.
 

Squibb

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BTW, the brakes are linked, or should I say 'unified', so the rear gets a little exercise, when the system decides - page 3-27 in the owner's manual.

Still good riding practise to use that rear pedal though; it helps settle the bike better IMO if you are carrying a load/pillion passenger.
 

Checkswrecks

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