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Hi guys!

There’s another issue with my monster(( For some reason rear brakes not working. I went to service and had it bleed few times, but after 1 week all the same. The brakes gradually disappears.
I’ve already changed master cylinder (62540201A). Nothing changed though.

To make it clear the caliper was positioned upwards during bleed and brakes were working fine right after the service.

I’ve been in 4 different services nobody knows the reason. Even official Ducati dealers says they have no idea what is the cause of problem. Everyone says it’s normal for Ducati. I would agree with it and don’t care much if they work for at least a couple of months. But brakes disappeared 1 week after bleeding.


PS
I’ve duplicated this post to another Ducati forum as well.


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Let’s talk basics here: Air Leak. You have one. You bleed the air out of the system. Everything is fine , the brakes work. But air then gets back into the system.
ive taken the complete brake system off the bike and rebuilt it all before. You may cure the problem doing that, but you still won’t know what the problem is. That’s not a good solution.
Start at the Start: Rebuild the master cylinder. Carefully check the bore for flaws . Even with new seals, if the bore isn’t perfect there will be some amount of air getting in. If it were me, I would use something other than stock seals because they may be the problem in the first place for all we know. Do not refinish the bore with power tools. Only hand turn a hone if you have one, or emery cloth. Just enough to verify that the bore has no low spots that might not seal air out even with a new seal.
Replace the brake line. Use a different brand. Not stock. Seal the threads with something.
If any area of the system is near a heat source , insulate it.
Rebuild the caliper. Inspect the bores. There can’t be any flaws. Once again, a light resurface of the bore with emery cloth, enough to check for low spots. Don’t use parts with pits or flaws in the bores, they may introduce air into the system.
Bleeders: Get some with Teflon coating on the threads if you can. I think speed bleeders have this. If not, use Teflon tape to avoid an air leak.
Use quality brake fluid recommended for higher temperatures.
I hope this helps.
 

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Discussion Starter #3
Let’s talk basics here: Air Leak. You have one. You bleed the air out of the system. Everything is fine , the brakes work. But air then gets back into the system.
ive taken the complete brake system off the bike and rebuilt it all before. You may cure the problem doing that, but you still won’t know what the problem is. That’s not a good solution.
Start at the Start: Rebuild the master cylinder. Carefully check the bore for flaws . Even with new seals, if the bore isn’t perfect there will be some amount of air getting in. If it were me, I would use something other than stock seals because they may be the problem in the first place for all we know. Do not refinish the bore with power tools. Only hand turn a hone if you have one, or emery cloth. Just enough to verify that the bore has no low spots that might not seal air out even with a new seal.
Replace the brake line. Use a different brand. Not stock. Seal the threads with something.
If any area of the system is near a heat source , insulate it.
Rebuild the caliper. Inspect the bores. There can’t be any flaws. Once again, a light resurface of the bore with emery cloth, enough to check for low spots. Don’t use parts with pits or flaws in the bores, they may introduce air into the system.
Bleeders: Get some with Teflon coating on the threads if you can. I think speed bleeders have this. If not, use Teflon tape to avoid an air leak.
Use quality brake fluid recommended for higher temperatures.
I hope this helps.
Thank you for your reply! Planning to visit service this week. Will ask them to rebuilt all break system. Hopefully don’t need to purchase new caliper(( You can’t even get it in Russia have to order one and wait for a weeks.


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Thank you for your reply! Planning to visit service this week. Will ask them to rebuilt all break system. Hopefully don’t need to purchase new caliper(( You can’t even get it in Russia have to order one and wait for a weeks.


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Thank you for your reply! Planning to visit service this week. Will ask them to rebuilt all break system. Hopefully don’t need to purchase new caliper(( You can’t even get it in Russia have to order one and wait for a weeks.


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There is a recall on the brake lines of some Monster models because the fittings on the lines cause air leakage. Both my rear and front lines on my 18 M821 have been replaced under warranty. Fixed the issue!
 
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