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Discussion Starter #1
Hello gang,
Prior to buying a rebuild kit for my rear master cylinder, the brakes were hard to push. I bleed the rear with a pump and still no rear brakes. I flushed all brake fluid out since the rebuild and still no fluid is going to the rear brakes. Fluid is making it up to the "manifold" in front of air box but no fluid is coming out of banjo connection to the rear. No matter what I do, no fluid is reaching the back brake caliper. There are no leaks and nothing is melted as others have advised me to check. Can someone please shed some light on this anomaly? Thanks so much.
 

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Hello gang,
Prior to buying a rebuild kit for my rear master cylinder, the brakes were hard to push. I bleed the rear with a pump and still no rear brakes. I flushed all brake fluid out since the rebuild and still no fluid is going to the rear brakes. Fluid is making it up to the "manifold" in front of air box but no fluid is coming out of banjo connection to the rear. No matter what I do, no fluid is reaching the back brake caliper. There are no leaks and nothing is melted as others have advised me to check. Can someone please shed some light on this anomaly? Thanks so much.
Do you have ABS?
If as I suspect yes, then sounds like you're ABS HCU has failed. Really common problem usually caused by not changing the brake fluid frequently enough. No real solution other than changing the HCU which costs around $400 and needs special equipment to bleed it, or bypassing it by piping straight from master cyl to caliper.
 

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Discussion Starter #3
Do you have ABS?
If as I suspect yes, then sounds like you're ABS HCU has failed. Really common problem usually caused by not changing the brake fluid frequently enough. No real solution other than changing the HCU which costs around $400 and needs special equipment to bleed it, or bypassing it by piping straight from master cyl to caliper.
Hi, yes it has ABS and thanks for the information. Is the HCU the part where the 4 brake lines connect to?
 

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Hi, yes it has ABS and thanks for the information. Is the HCU the part where the 4 brake lines connect to?
Correct. Sounds like your HCU has failed. This is generally from not performing the 2 year flushes. This requires to cycle the HCU to get new fluid into it or corrosive old fluid remains in there and the valving will corrode and stick the pintles. Usual symptom is one of the brakes become rock hard and won't work.
Ron
 

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Discussion Starter #5
Correct. Sounds like your HCU has failed. This is generally from not performing the 2 year flushes. This requires to cycle the HCU to get new fluid into it or corrosive old fluid remains in there and the valving will corrode and stick the pintles. Usual symptom is one of the brakes become rock hard and won't work.
Ron
Thanks Ron. I am a tinkerer and hope removing it and cleaning thoroughly might save me some money. If not, then either bite the bullet or plumb a direct line to rear and block ports in HCU if that is remotely possible. Thanks again for your support
Andy
 

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Thanks Ron. I am a tinkerer and hope removing it and cleaning thoroughly might save me some money. If not, then either bite the bullet or plumb a direct line to rear and block ports in HCU if that is remotely possible. Thanks again for your support
Andy
Yes, you can bypass it as the front and rear systems are independant. If you run a direct line for the rear as per non ABS bikes then you will still have ABS on the front brakes. Probably worth getting the front fluid flushed and changed to try and avoid the same happening to the front. You will need to take this to a dealer for this unless you know somebody with either the Twin Scan unit or the ITM system to activate the HCU to bleed it.
 

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Discussion Starter #7
Yes, you can bypass it as the front and rear systems are independant. If you run a direct line for the rear as per non ABS bikes then you will still have ABS on the front brakes. Probably worth getting the front fluid flushed and changed to try and avoid the same happening to the front. You will need to take this to a dealer for this unless you know somebody with either the Twin Scan unit or the ITM system to activate the HCU to bleed it.
Ok thanks but I wonder what a dealer would think seeing the rear bypassed.
 

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Ok thanks but I wonder what a dealer would think seeing the rear bypassed.
Nothing to do with them, it's your bike. The might try and spout BS about it's not correct or safe. Just say to them "that means all bikes without ABS are unsafe?" They will warn you that the HCU could fail on the front when they try to bleed it and it is not their responsibility. Can happen , just depends on the state of the fluid, you have a 50/50 chance.
 
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