Question on 2003 st1300 brake problem

[st1300scv]

I was riding out of town yesterday when all of a sudden the rear brakes began to lock up. I pulled off the freeway and they were completely locked up. The front brakes opened and closed without any problem but the back one was not working and the tire would not turn at all. It was completely stuck. I was finally able to move the brake pads a little away from the brake wheel using a screwdriver and let a little brake fluid out the nipple. The tire began to turn again. I rode home very careful only using the front brake but had to stop hard all of a sudden and the rear locked up again. I loosened it again and got home not using brakes but downshifted all the way. I cannot remember if the brake fluid has ever been changed for the rear but there have been times when I have added some to the front reservoir. I saw a video in YouTube on how to change the fluids and will attempt. What I need to know is, is there a difference between the braking system on the st1300 and the st1300A? Because I found a brake bleeding video on the ST1300A. I also wanted to find out can I just replace the rear wheels fluid or must I do the entire system. Also I wanted to find out will the calipers still get stuck if I replace the fluid in the rear? I understand they need to be cleaned and I will use a spray solvent to clean them. Is there a particular solvent to use that will not harm the seals? I need to take a trip in a day or two and wanted to take the bike but I do not want to get stuck again. It appears that the hardest part of the fluid replacement is getting the right side siding off in order to get to the reservoir. My biggest question however is if I replace the fluid which is old, will the calipers loosen so they will not stay extended and keep hard pressure on the rear tire or is there more I need to do to them? I am new to this forum and look forward to everyone's knowledge about ST's. When I got the bike I was told it was the first ST1300 in California received. Its been a wonderful bike. I remember riding it down the street when I first got it and other bikers would stop me and admire it. It was a couple months later I understood where it began to hit the other Honda dealers. Its been a great bike. I will never forget when I was riding up the 405 freeway one day and splitting lanes during rush hour when all of a sudden my left mirror came flying off and fell on the freeway. I must have hit someone's car mirror but did not even know or feel it hit. I could not stop until I pulled over to the right shoulder and began walking back on the side of the freeway. When I got to where the mirror casing was I saw it was in the number one lane right on the dividing line and it was rush hour. Cars were going about maybe 5 to 10 miles an hour and all of a sudden an LAPD motorcycle cop appeared in the lane. He saw the mirror and saw me standing in the shoulder. He stopped his bike and put his arms out for all the traffic to stop. The entire freeway came to a complete stop and he beckoned me to run and get my mirror casing. I ran across the freeway. and as I passed him on the way back. I bowed to him in great appreciation. He saved me the cost of a new mirror and casing! Kuddos for the LAPD motorcycle officers!

 

[paulcb]

TLDR, but sounds like classic symptoms of a stuck Secondary Master Cylinder (SMC), a not uncommon problem with the ST1300. A fluid flush likely won’t solve your problem. Search the articles section for repair options. We also have an SMC expert (Igofar, Larry) who will probably be along shorty with advice. Bottom line is you’ll probably have to replace the SMC.

 

[st1300scv]

TLDR, but sounds like classic symptoms of a stuck Secondary Master Cylinder (SMC), a not uncommon problem with the ST1300. A fluid flush likely won’t solve your problem. Search the articles section for repair options. We also have an SMC expert (Igofar, Larry) who will probably be along shorty with advice. Bottom line is you’ll probably have to replace the SMC.

Thank you, I will do some more searching.

 

[Kevcules]

Yes the ST1300 has a well working, but bizarre braking system and weak point on these bikes. They need more attention than any other bike on the road I think.

The bleeding sequence is very specific and the SMC on the front left brake caliper is a high failure point, which is what causes the symptoms you experienced. (locking up the rear tire) Very likely a new SMC is in your future.

Larry is a great resource for these bikes and has repaired many many SMC problems

Ohhh......I think I hear him coming now!

 

[dduelin]

The ST1300 has enough brake issues that this forum has it's own sub forum titled ST1300 brakes.

Soon you will know more about how to fix them you ever thought possible.

ST1300-Brakes

www.st-owners.com

 

[Limshady88]

That sounds like a SMC problem as described by @Igofar. On the phone, Larry accurately diagnosed my frozen SMC and directed me to order from Ron Ayers in NC also providing me with the part numbers. He does NOT recommend rebuilding the SMC just buy a new replacement. I also bought new pads and with his guidance I was able to change all brake pads, replace SMC, and bled all the brake lines in proper sequence in about 3 hours. I’m sure he will respond shortly.

 

[Igofar]

Here we go again
Just finished replacing an SMC, and flushing and bleeding the brake system on police motor a few minutes ago...
Dinners waiting on me, so I will ask that you private message me your phone number, and I'll call you on the (white courtesy phone) after dinner.
Do NOT attempt to ride your bike further until we have a chance to discuss what's going on.
Igofar

 

[SMSW]

I'm not convinced that the braking system, SMC in particular, on our ST's is a weak point or poorly designed. Based on what I've read here, it seems like a lot of guys do not flush the brake system every two years like Honda recommends, or every year like some of the guys have said they do. I keep reading about members who bought a used bike and flushed dark thick crud out of their brake (or clutch) system. Well, if that stuff comes out, given the size of the holes inside the calipers and master cylinder, what do you think is going to happen? I remember my first Moto Guzzi, which came to me as a semi basket case. I yanked the calipers, popped the pistons and they were rough and rusty. The calipers bores were pitted and corroded. Honing them did nothing - well, I shouldn't say that, it did polish out some of the shallowest pits or beginnings of actual damage, but the calipers were trash. Given the age of many ST's and the fact that most of them are getting long in the tooth, we can probably expect more of these SMC problems - unless we do regular routine maintenance - and that includes popping the rubber boot and adding a bit of silicone grease and lubing the pivot bearing.

 

[Limshady88]

SMSC funny you should say that. Here is a pic of my brake fluid before I flushed it.

 

[Igofar]

Still standing by the white courtesy phone.

 

[jfheath]

A good place to start looking is in the articles section - select ST1300 and look through there. The first one you find that has an 'ST1300 Brakes' tag - click on the tag. It will list all of them.

But to save you the trouble, here are two that I think are worth looking through. (But I am biased).

But first - Do not ride your bike. It will bite you.
2nd - talk with Larry - Igofar.

On the brakes:

Article [13] - ST1300 Maintenance - Brakes- Avoiding the Pitfalls | ST1300 Articles

A close hands-on look at the Honda ST1300 braking system. These are personal observations about the things that can go wrong, why they go wrong and what can be done to keep things working sweetly. Updated April 2020 and to address more recent observations, to include information about the SMC...

www.st-owners.com

And on the bleeding:

Article [13] - ST1300 Maintenance - Getting all the air out of the brake system | ST1300 Articles

A detailed look at the process of getting the air out of the Honda ST1300 brake lines. A sequence of diagrams of the brake circuits, colour coded to show which parts of the system are being accessed when each bleed valve is opened and explanations of where the trouble spots are. These are just...

www.st-owners.com

@Igofar - Larry - I see you have made yourself a cut-away SMC. I cant believe how useful I have found mine to be. The number of times I have taken it out for reference...

Is it a trick of the lens or are some of those retired SMCs distorted ? A bike drop ? Or perhaps the result of having the SMC on the same side as the sidestand - careless parking perhaps ?

 

[Igofar]

Thanks for attaching your links John.
I can always count on you for helping folks.
Just the picture I guess, poor quality cell phone etc.
2 of them had the free play clanking (piston stuck down in the bore)
The other one locked up just outside the bore.
Hope things are ok with you over there.