Fwd: ST 1300 - Rear break can only be released with the bleeder nut.

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ST1300 Pan European
ST 1300 - Rear break can only be released with the bleeder nut.

The dealer is currently trying to figure out why the rear brake is not releasing (at all). The first time I brake with the rear brake pedal it breaks normally to stop. Then the problem, it won't release. The only way is to loosen up on the air bleeding screw on the rear caliper. Then everything goes back to normal. ( out of the two bleeding screws it is the most rear one where the pressure in the brake hose won't release). The dealer has replaced the valve on the front fork. Replaced the brake fluid and made sure everything is checked, but still it doesn't work. Now they are lost and have contacted the Honda distributor to Norway to seek technical assistance. Currently the bike has been with the dealer for two weeks and still no progress.


Forgot to tell that the problem started on a shorter trip, and after breaking down normally it was stock. No earlier indications of any problems.
 

SteveST1300

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SMC you say they checked the SMC? Sounds like that is your problem though we have had quite a few instances of the same problem over here.
 
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Jon Erik
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The dealer told me it is replaced, but it didn't help ?????
 

SteveST1300

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Thats what my SMC did. Well I hope that the Honda Tech guys can get you back on the road please let us know the outcome.
 

Mellow

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Might be a PCV issue as well or maybe they haven't bled the system correctly. A PCV issue is pretty rare. Sure sounds like SMC to me.
 

SteveST1300

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I thought about improper bleed but wasn't sure it would create that symptom. I would think air in the system would make for a soft brake not a stuck one.
 
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OP says first time braking with rear brake.? is that with just the rear brake pedal or are both brakes being applied?
If just rear brake pedal would that still be SMC?
Dang, I'm confusing myself here...
 

Mellow

Joe
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OP says first time braking with rear brake.? is that with just the rear brake pedal or are both brakes being applied?
If just rear brake pedal would that still be SMC?
Dang, I'm confusing myself here...
doesn't matter, they are linked so pressing the rear activates the fronts as well and as soon as the fronts are applied the smc plunger gets pushed.
 
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Jon Erik
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Hi everyone. I have made a couple of new observations of the problem:

1) if I let the engine idle and heat up, the rear brake will slowly stick, most likely because the braking fluid is being heated in the pipe from the engine heat. That is to me an indication that the problem must be in front of the engine somewhere.
2) if I use the front brake only it still seems to be a problem, but to a much less degree.

Then:

SMC - Secondary Master Cylinder - where is it located on the bike?
PCV - ?? - And where is it located on the bike?
 
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Pull the rear wheel and caliper and check the copper colored spring clip to see if they bent one of the little tabs...this would tilt the pads enough to cause your issues..and...make sure they do a complete and correct bleed procedure that includes tilting the caliper and bleeding the pcv valve...believe it or not alot of our dealerships either don't know the correct procedure or take shortcuts and do not follow it.
 

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Joe
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May also want to make sure they replaced the black pivot bolt for the caliper. Without that the rear caliper will push forward and pinch the brake line. I would think that's an obvious thing a dealer would notice first but you never know.
 
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Jon Erik
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Hi guys and thanks for all your advices. I confronted the dealer with your advices and they agreed with your conclusions. Another SMC unit is ordered and will arrive next week. I'll give an update when I get more info from the dealer. It turned out that had replaced the wrong piece and not the SMC in the firstplace.
 
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Make sure the pinch bolt on the front left brake caliper is not too tight. You should be able to grab the caliper and rock it forward and backwards. If not, the bolt is too tight. The Honda torque value for that bolt is too tight for my bike. Others on the ST-sight may have a different experience.
 
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Make sure the pinch bolt on the front left brake caliper is not too tight. You should be able to grab the caliper and rock it forward and backwards. If not, the bolt is too tight. The Honda torque value for that bolt is too tight for my bike. Others on the ST-sight may have a different experience.
The torque should not be wrong, I would guess the needle bearings and bushing need to be cleaned up and repacked with waterproof grease. Also apply some to the machined head of the lower bolt as it is a bearing surface that can also bind.
 
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It sounds like the fluid it not being released. thus opening bleeder releases the brake . I have had this situations in cars. Crack open the brake line before the hose (when locked) if it releases then crack the line at the smc. I have seen aneurisms in brake hoses that blocks the fluid from releasing , not often but it does happen. if cracking open the line at the smc releases the brake its a bad smc..
 
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Jon Erik
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Last update. Got mail from the dealer yesterday. After replacing the SMC, cleaning the calipers and bleeding the brake lines the bike is ready to go. Will pick it up next week when returning home to Norway from New York.

Again thank you to all of you for the advices. It really helped me solve the problem and in addition gave me a lot of knowledge on this issue. THANKS!
 

RONST1300

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Make sure the dealer knows the correct procedure for bleeding the breaks as Larry mentioned. It's tricky and will not work if it is not done properly. There are articles on it here under SMC.
 
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I'm sure most of us on here thought it was the secondary master cylinder sticking.

What was the first part that they replaced.

Was this work done on warranty.

If it was done on warranty and the brakes still feel a bit spongy, get them to bleed them again. Get them to point out all the bleeding ports to you. The PVC one is the hardest and the most important one to bleed.
You will know where all the bleed points are in the article that I posted for you below.

If you ever bleed your brakes yourself, here is the most used brake procedure on this forum.
You will go though about 2 litres of brake fluid doing it properly.

Best of Luck

https://www.st-owners.com/forums/showthread.php?68913-ST1300-Brake-Fluid-Replacement
 
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