Rear Brake Dragging

Don Miller

Don Miller

Joined
Feb 19, 2007
Messages
13
Location
Mooresville, NC
Bike
R1200RT
Any known issue with the rear brake pads dragging on the rotor? With 7,000 miles on my '07 ST, it happened the first time on a ride two weeks ago. By the time I pulled off the road, put the side stand down and I got off to feel the rotors to see where the drag was coming from (the rear was hot!), the problem corrected itself. It happed again this morning :( on the short ride to the dealer.
 
Somehow a pebble got lodged between the brake pad and the plunger which caused the pad to contact the rotor at an angle. The top of the pad was toast in less than 3KMi.
 
Have your dealer check and clean the secondary master cylinder on the front. If it does not release properly than the rear will drag. Pay close attention to all the notes in the service manual about servicing the SMC. Not all dealers are competent with the linked breaking system and the SMC. Not all dealer shops read the manual. Take a look at the folks working on the bikes and see if they have the manual with them. Problem could be something else, but most rear break problems have been traced back the the SMC getting dirty or corroded and not releasing properly.
 
rcbst1300


Join Date: Sep 2006
Location: Midland, Tx.
Posts: 5 Re: REAR BRAKE problems on '05 ST1300

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Long story...... I struggled with this problem for several months on my 03' ABS. It reared its ugly head first at approx. 30k locking the rear brakes down tight. So I replaced pads, cleaned and flushed etc. It cleared the problem up. Started out on a cross country trip, and rear brakes started locking down again. Luckily, I was close to a decent dealer that picked my bike and me up for free. The problem was diagnosed as the rear ABS modulator, after much searching and diagnosis. So it was replaced. It turned out as being the wrong diagnosis as it turns out. At 36k it did it again. Only this time I burned the rear rotor and brakes completely. So I replaced these items and started calling local dealers for answers to no avail. I finally found the answer on this board. The SMC was my problem the whole time. It appears to be a design flaw. The angle that it is mounted allows for moisture and dirt to get past the boot and cap. Even though it has a weep hole. Causing the piston rod to stick. Therefore not letting the piston release. I dismantled mine and sure enough there was a lot of corrosion. I cleaned mine up well enough to make the rest of this season. HAPPY HAPPY JOY JOY. Have new parts on order though. Thanks to STowners.com
 
MY non ABS 05 spent 4 months in and out of the shop for the same problem. They changed everything including the kitchen sink.

https://www.st-owners.com/forums/showthread.php?t=7016&highlight=rear+caliper

The last part changed was the SMC and it did the trick. The work was done at 12K miles. Bike now has 43K and I have had no other brake issues.

I am guessing there was something stuck in the return path of the SMC that wouldn't let the pistons release.
 
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Also check how the pads slide on the rear caliper pin. On mine, the first two sets of pads wore through the chrome on the pin and created a rough, rusty spot that caused the pads to hang up. I removed the anti-rattle spring in the top of the caliper, lubed the pin with silicone grease and have been a happy camper since.

--Mark
 
Well Chuck, you were on the money. After just one year and 7,000 miles on the clock, corrosion around the piston in the secondary master cylinder was causing the piston to stick and in turn, causing the rear brake to drag. The forward facing, upward orientation of the recessed piston in the SMC encourages water to enter this area when riding in the rain or when the bike is washed. It doesn't take much encouragement for the teeny tiny drain hole to plug and create a perfect environment for corrosion. It's maybe a bit extreme to call this a design flaw, but is most definitely a design deficiency with expensive consequences outside the warranty. The dealer suggested a shot of compressed air in the pocket after a wash or wet ride. After my experience, I'd say that's a "must".
 
Don Miller said:
Well Chuck, you were on the money. After just one year and 7,000 miles on the clock, corrosion around the piston in the secondary master cylinder was causing the piston to stick and in turn, causing the rear brake to drag. The forward facing, upward orientation of the recessed piston in the SMC encourages water to enter this area when riding in the rain or when the bike is washed. It doesn't take much encouragement for the teeny tiny drain hole to plug and create a perfect environment for corrosion. It's maybe a bit extreme to call this a design flaw, but is most definitely a design deficiency with expensive consequences outside the warranty. The dealer suggested a shot of compressed air in the pocket after a wash or wet ride. After my experience, I'd say that's a "must".
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Glad you got it resolved. Did your dealer come to this conclusion or did you have to tell them where to look. Need to know for future folks.
 
ChucksKLRST said:
Glad you got it resolved. Did your dealer come to this conclusion or did you have to tell them where to look. Need to know for future folks.
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To his credit, the service manager suspected the SMC from the start. And as you suggested in an earlier post, I confirmed that he had the shop manual. In fact, he let me have it for twenty bucks when I picked the bike up earlier this week. He had just received a new one. Talk about good timing!
 
Don Miller said:
Well Chuck, you were on the money. After just one year and 7,000 miles on the clock, corrosion around the piston in the secondary master cylinder was causing the piston to stick and in turn, causing the rear brake to drag. The forward facing, upward orientation of the recessed piston in the SMC encourages water to enter this area when riding in the rain or when the bike is washed. It doesn't take much encouragement for the teeny tiny drain hole to plug and create a perfect environment for corrosion. It's maybe a bit extreme to call this a design flaw, but is most definitely a design deficiency with expensive consequences outside the warranty. The dealer suggested a shot of compressed air in the pocket after a wash or wet ride. After my experience, I'd say that's a "must".
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Since I don't have a convenient source of compressed air, I wonder if a quick shot of contact cleaner or brake parts cleaner would be effective in getting rid of the moisture? It evaporates quickly without leaving any residue.
 
Don B said:
Since I don't have a convenient source of compressed air, I wonder if a quick shot of contact cleaner or brake parts cleaner would be effective in getting rid of the moisture? It evaporates quickly without leaving any residue.
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Careful with the contact cleaner, some of these will damage rubber components. Brake parts cleaner might linger in the confines of the boot, but should eventually dry.

You can get some compressed air in a can at most office supply stores. Used for blowing out computers, camera, etc.

I wonder if filling the boot with some silicone grease would help? Basically leave no place for the water to go and prevent corrosion too.
 
Black Magic said:
Mr. Miller

Does you wash your bike lots? Is that area getting strong spray during rinsing?

I could be trying to learn why some have problem but many do not.
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Bought new almost a year ago, I've washed it 3 or 4 times and got caught in the rain twice. It's kept in a temperature/humidity controlled garage.

I think you're right in saying that this particular problem is not in the mainstream. Given the relative newness of the bike, the service manager was a bit puzzled as to reasons for the premature corrosion. Hopefully, the new SMC will be my ticket to join the ranks of the many that have not had this problem.
 
My original SMC was bad at 8 months 12K miles. The replacement has 2 years and 30K on it and is fine.

I have not changed my washing or riding in bad weather habits. May be they made a design change to the replacments.
 
I wonder if it would make sense to design some kind of guard to keep the crud out of it, or if maybe there's a way to put a boot over the whole assembly.

--Mark
 
Blrfl said:
I wonder if it would make sense to design some kind of guard to keep the crud out of it, or if maybe there's a way to put a boot over the whole assembly.

--Mark
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You would be amazed at what you can do with a piece of old bicycle inner tube!
 
I am going thru this right now. 25k on the 2004 and just took it into the local honda dealer to have it serviced. they call me telling me I need new rear pads, so I ok that repair for a total of $300 something . had it in only for an oil change and a set of new tires. got it back and after a day the rear has an intermittant "humm" in the rear at slow speeds. took the bike back, paid another $300 to rebuild the rear calipers. was told they were dirty and when they pushed them back the dirt got in the pistons so they had to rebuild. took in home and it still has the noise. took the bike back AGAIN and showed them the problem with the bike on the stand and they essentially said it will go away and cleaned the rotor for me. now that I have this info I will take it back yet again and ask for a refund of the money I have already spent.

anyone tried to talk to honda about this problem? when I tried to get this fixed under warranty they denied it.
 
schla said:
they call me telling me I need new rear pads, so I ok that repair for a total of $300 something.
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$300 to do the rear brake pads? Holy markup, Batman! The pad set is $45 and they take about a half hour to install at a leisurely pace. Add 10 minutes if you stop to clean the pistons and disc.

...anyone tried to talk to honda about this problem? when I tried to get this fixed under warranty they denied it.
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The problem in your case is not a result of an engineering or manufacturing defect, which means it isn't covered by the warranty.

What you have there is a defective dealer service department which should be replaced immediately, if not sooner. :rolleyes:

--Mark
 
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