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4RT rear brake bleeding


TimDH
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11 hours ago, jonnyc21 said:

One more FYI on my comment about the issue with the master needing to be honed.  The bur is small and cuts a very small scratch into the rubber seal that is only easy to see under a microscope or quality magnifying glass.  Even at that size it is large enough to let in just a touch of air. 

I hope its okay to cross post from another forum, if so here is the thread on the exact issue I am talking about from ADVRider. (almost forgot one was over there)
https://www.advrider.com/f/threads/braktec-master-cylinder-problems-why.1090928/

 

PS. I see the images on the 3rd page are not showing up for me any more, however they looked a lot like post 57. - https://www.advrider.com/f/threads/braktec-master-cylinder-problems-why.1090928/page-3#post-28052194

Is there another MC manufacturer as I can't just keep buying them until one works if that's the cause.

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3 hours ago, TimDH said:

Is there another MC manufacturer as I can't just keep buying them until one works if that's the cause.

I really don’t know other than maybe if you can find an old stock AJP?  The other choice is to find a shop that can inspect it and hone it for you?  I know motobene (my friend) was able to get some seals and the information on the hone size is in that thread so maybe that’s the best option?  
 

sorry I am not of more help.  
 

Edit: I think I just noticed you already have the AJP brakes?  If so then if you can find new stock/lot braktech they did eventually fix the issue with the manufacturing defect.  Though I am not sure how best to check lot/manufacture date on them.  


or maybe the seals could be replaced on the old master?  See if you could order a new set?
 

Wish I could be of more help.  good luck.

Edited by jonnyc21
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26 minutes ago, jonnyc21 said:

I really don’t know other than maybe if you can find an old stock AJP?  The other choice is to find a shop that can inspect it and hone it for you?  I know motobene (my friend) was able to get some seals and the information on the hone size is in that thread so maybe that’s the best option?  
 

sorry I am not of more help.  
 

Edit: I think I just noticed you already have the AJP brakes?  If so then if you can find new stock/lot braktech they did eventually fix the issue with the manufacturing defect.  Though I am not sure how best to check lot/manufacture date on them.  


or maybe the seals could be replaced on the old master?  See if you could order a new set?
 

Wish I could be of more help.  good luck.

Cheers

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14 hours ago, jrsunt said:

Leave the rear end up in the air over night if possible. It’s just air trapped in the system some where. Don’t be tempted to push the caliper pistons back in though or the good work will be undone

I have done this as it's easy enough,which part of the system am I leaving open though.

Edited by TimDH
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Leave it all closed apart from the reservoir cap. Those pesky bubbles should work their way to the highest point.
 

When you come to have a go at it again, keep the system closed and use lots of tiny movements on the brake pedal to tease the bubbles out. (The vibrations should encourage them) You might lose pressure again but you’ll know that they’re on the move

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Everyone with  different opinion. The easiest way to bleed a system thst is being stubborn is to remove the whole thing assembled and just hang it with the caliper at thd top and the m/c at the bottom. Use a clear hose on the nipple straight up. It's all about gravity. Here is an example.

 

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  • 2 weeks later...

I'm back from skiing now so time for an update.

Before I went I tried lifting the front of the bike and bleeding having tried lifting the rear which I never thought would work as there's no logic to it.

As it was I left my bike for a week with the front lifted with an obvious air bubble in the link pipe,that was still there when I got back FFS.

In summary I have tried every method possible together with new parts,but this mornng I took the whole system off and bled it as described in the video by lineaway.

I think the angle of the parts is vital.

Bit of a ball ache getting it out in one piece but this method as shown in the vid worked first time,I'd have taken the ****ing engine out if I'd know it would work.

Thanks to all that have given advice.

 

 

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7 hours ago, TimDH said:

I'm back from skiing now so time for an update.

Before I went I tried lifting the front of the bike and bleeding having tried lifting the rear which I never thought would work as there's no logic to it.

As it was I left my bike for a week with the front lifted with an obvious air bubble in the link pipe,that was still there when I got back FFS.

In summary I have tried every method possible together with new parts,but this mornng I took the whole system off and bled it as described in the video by lineaway.

I think the angle of the parts is vital.

Bit of a ball ache getting it out in one piece but this method as shown in the vid worked first time,I'd have taken the ****ing engine out if I'd know it would work.

Thanks to all that have given advice.

 

 

Really glad to hear you got it working!

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