Help! Rear Rotor Getting Hot. Not The SMC.

[amv606]

I have a 2008 ST1300 with 22,000 miles.

On a trip down to Kentucky at the beginning of September the rear brake was getting so hot you could smell it. I rode most of the trip using engine braking by gearing down as much as possible.

Once home I changed the rear pads and took the bike in for the brake recall. I said to the dealer that the rear brake was getting hot, and that it must be the SMC. He changed the SMC and bled the brake system.

It made no difference. The rear rotor is still getting very hot. On the center stand I can only get about half a turn out of the rear wheel, spinning it by hand.

 

[970mike]

Sounds like you may have a bad caliper that is not releasing if they have replaced the secondary master cylinder. Take it back to the dealer and have them take a look at it as it is not repaired.

 

[Firstpeke]

Brake piston seals and crud on the pistons and caliper plus pad mounting pin and sliding pin that aren't..... sliding..... strip, fully clean and protect, then re-assemble using appropriate grease on pins etc.....

I clean and re-protect my brake calipers at any opportunity when doing tyres or servicing, some feel it unnecessary, I thinks it is vital to good brake operation, especially on such a heavy bike...... who knows, we may need to use our brakes in anger one day........

 

[Rick Gibson]

The caliper isn't releasing for some reason.

 

[Mellow]

It's possible the dealer didn't do a good job with the brake fluid change, if they don't follow the procedure it's easy to miss the part where you tilt the SMC. Not sure but the ST may be the only bike that has that added and requiring that step.

 

[hortok]

I have to agree with FirstPeke. Brakes get really nasty between tire changes and lubing that pin is the only thing that can ensure that the caliper CAN slide enough to release. Brakes are so simple at first glance and it's easy to overlook how important the right maintenance is. It isn't really all that hard to do right so I'd take a shot at it and see if that works. I'd be very disappointed that the dealer didn't do all this when you had it in though. Disappointed enough that I'd say something if you fix it. 80

 

[wjbertrand]

Check that the caliper stopper bolt is properly installed. If it misses the hole in the bracket it can push the bracket inward creating binding.

 

[Shadowfax-ST]

Check that the caliper stopper bolt is properly installed. If it misses the hole in the bracket it can push the bracket inward creating binding.

To prevent hijacking this thread for my own needs I've started a question here (LINKY) but could you explain that one again, please? It's striking a chord.

Currently have the brake retaining pin wearing on the disk edge. Just found it; been blaming the rubbing noise on the spring, then once worn 20% the noise goes away

 

[treemuncher]

I had similar problems last year at this time. It sort of ruined the BRG for me. I went through every caliper and master cylinder, control valves, flushed, cleaned, lubed, new fluid and bleeding. I still had the same problem with the rear brake drag, heated disc and other associated problems.

My problem was finally solved when I bled out the system with a combination of conventional bleeding (pump to pressure, hold & bleed) and vacuum bleeding over and over again until the controls felt hard and felt right. There was more air in there than I would have thought. The SMC and the proportional valves were likely the major causes. I likely went through 2 pints of fluid to get it bled properly.

Now, I have no rear brake drag. If I grab and hold the brake lever and then depress the foot pedal at the same time, you can feel the effects of one on the other via the proportional control valve. When the bleeding was not 100% air free, one control would not have any effect on the other.

 

[amv606]

Thanks to everyone for their help. I find it annoying that such a new bike has let me down. In my 35 years of biking I have never had that before.
I?ve got my Suzuki 500 loaded on my son?s pickup and we are headed for Daytona Beach tomorrow. When I get back, I will put an honest effort into figuring this out.

 

[treemuncher]

I just went through all of this again. (what the frank, Joe, are we not allowed to say sCRAP on the board? Isn't that just a little too prissy and squeaky clean? H to the double L's, just delete this whole reply like you do with the rest of them.) After changing my front tire, the front brakes started dragging way too heavy. Last year, it was the rear brake before and during the BRG.

I tried bleeding but that did not stop the drag. The only thing that did was to relieve pressure at the caliper hose connections. I pulled the valve on the right fork and did my best to clean and work that over with compressed air. There is no way to get it apart without destroying it. You can tell with light air pressure whether or not the mechanism is moving around inside as it should.

I found the SMC to be hanging up, again. That was cleaned and worked over pretty well with a file on the lathe. The seal closest to the ball socket seems to stick and the shaft under that seal had some corrosion. I think I may need new seals for that MC eventually. I've got it cleaned up enough that it was working freely, again. Lousy design. Makes me wish for a simplified system.

Both front calipers were disassembled, cleaned, lubed and verified to be working freely with air pressure.

The system was re-assembled and bled. If I had taken the right side plastic off, I would have taken the PCV off and tried to clean that as well.

The system was refilled and rebled about 3 times until the controls became firm. It seems to be working better with only a light drag. It's nearly 2 AM and the BRG trip is in the AM. I think that I will wait to road test in the daylight morning hours.

Note: you can bleed the PCV without completely removing the right side tupperware. Remove the right mirror cover, front and glovebox screws and the one upper 5mm allen head bolt and you can pry the plastic back enough to attach a bleeder hose and an 8mm wrench. It is not easy but it is much faster than removing all of the plastic.

Note 2: combining vacuum bleeding methods with conventional pump&hold techniques is the only way that I have been able to properly bleed this complex system.

 

[RONST1300]

I am with Mellow and Treemucher. I am currently going through brake problems after a system bleed. I am finally understanding how these systems work, with the guidance of Igofar. I would bet the shop did not bleed the SMC properly. It is not a job that can be done quickly or half a. Garages, well.... That portioning valve CAN NOT BE SKIPPED. You probably did need the SMC and now you need a good bleed, tilting the caliper and going through the entire procedure from the top.

If you, laying by your bike, hold the SMC closed with your hand and rear wheel does not lock up as you spin it with your foot, you either have a bad SMC again, or air in your system. It's probably the air. That SMC has to work to prevent the rear brakes from locking.
Ron

 

[rossilvr]

Please do let me know whether you fixed this. I have a very similar problem to yours that I havent been able to fix for a long long time.

I have a 2008 ST1300 with 22,000 miles.

On a trip down to Kentucky at the beginning of September the rear brake was getting so hot you could smell it. I rode most of the trip using engine braking by gearing down as much as possible.

Once home I changed the rear pads and took the bike in for the brake recall. I said to the dealer that the rear brake was getting hot, and that it must be the SMC. He changed the SMC and bled the brake system.

It made no difference. The rear rotor is still getting very hot. On the center stand I can only get about half a turn out of the rear wheel, spinning it by hand.