I figured that it was time to document my own findings to help other ST owners. First off I have see so many post complaining about the same symptoms but saying it in 14,000 different ways.
To summarize, the rear brake will drag either partially or fully, it may or may NOT sing while it is dragging. This is a VERY SERIOUS failure and could be deadly occurring at the wrong time. The culpritt and the cause of this situation is the SMC (Secondary Master Cylinder) which is activated when using the front brake. What actually is happening is that when you are applying the front brake there is a little bit of nose diving which actuates the SMC which applies the back brakes. Moisture gets into the SMC and causes the SMC plunger to corrode and when this happens and the SMC is activated it will very often NOT deactivate.
1) How do I know if my SMC is acting up ?
If your bike is hard to puch or your driving along and oull in the clutch and the bike brakes on its own, your SMC needs immediate attention.
2) How can I check if it truly is my SMC ?
Put it up on the center stand and spin the back wheel, If it spins freely your OK, If it doesnt your SMC is probably bad, To check it further disconnect the brake line at the very rear of the motorcycle. If you can now spin your wheel 'freely your SMC is bad.
3) How do I repair my SMC ?'
First off buy a SMC repair kit. Put the bike up on the center stand. Remove the SMC. 2 bolts holding the caliper and the SMC to the front fork. Remove the rubber boot at the SMC, dont br graceful just tear the sucker out and the spring that is inside of the boot. Next get a pair of spring clip pliers with semi-fine tips and remove the C-clip in the SMC. I found that squeezing the C-Ckip together with the spring clip pliers can get it out of the groove that it in I then used a screw driver carefully and got up underneath the spring clip and removed it from the barrel of the SMC. The plunger actuator can now be removed. You NOT done yet. Now comes the hard part. If you lucky and the sun is shinning on you and its your lucky day the plunger assembly will pop out at which point you can put the new one in and reverse the procedure and your done. I wasn't that lucky. I had to take about a 1/8" drill and drill into the plunger assembly about 3/8" (NOT CRITICAL) just dont go beyond 1/2" you want enough meet to screw a long drywall screw or sheet metal screw into the plunger to pull it out. I found that I had to screw it in as far as I could go to get the plunger to spin, I then began pulling and pulling and pulling until it finally gave way. Clean out the SMC thoroughly with a good clean paper towel and remove all brake fluid and filings. Put in the new plunger assembly and then install the plunger actuator, then put in the new C-CLIP with the Spring Clip pliers. Seat the boot as far in as you can with your fingers ONLY !
Bleed the brakes in accordance with the service manual.
You may need to add some brake fluid so be sure to have some handy ! I
Reassemble everything and then GO do what the ST was meant to do ! ! !
BE RIDDEN !
Any questions I'll be glad to help. it should take NO MORE than 1 1/2 hours from beginning to end !
I hope this post will help someone ! Tomorrow I will post pictures !
Kevin
I have to give credit to Dave (Username: Sennister) for his assistance and guidance. Without him this would NOT have been possible without excessive hair loss and another divorce !
To summarize, the rear brake will drag either partially or fully, it may or may NOT sing while it is dragging. This is a VERY SERIOUS failure and could be deadly occurring at the wrong time. The culpritt and the cause of this situation is the SMC (Secondary Master Cylinder) which is activated when using the front brake. What actually is happening is that when you are applying the front brake there is a little bit of nose diving which actuates the SMC which applies the back brakes. Moisture gets into the SMC and causes the SMC plunger to corrode and when this happens and the SMC is activated it will very often NOT deactivate.
1) How do I know if my SMC is acting up ?
If your bike is hard to puch or your driving along and oull in the clutch and the bike brakes on its own, your SMC needs immediate attention.
2) How can I check if it truly is my SMC ?
Put it up on the center stand and spin the back wheel, If it spins freely your OK, If it doesnt your SMC is probably bad, To check it further disconnect the brake line at the very rear of the motorcycle. If you can now spin your wheel 'freely your SMC is bad.
3) How do I repair my SMC ?'
First off buy a SMC repair kit. Put the bike up on the center stand. Remove the SMC. 2 bolts holding the caliper and the SMC to the front fork. Remove the rubber boot at the SMC, dont br graceful just tear the sucker out and the spring that is inside of the boot. Next get a pair of spring clip pliers with semi-fine tips and remove the C-clip in the SMC. I found that squeezing the C-Ckip together with the spring clip pliers can get it out of the groove that it in I then used a screw driver carefully and got up underneath the spring clip and removed it from the barrel of the SMC. The plunger actuator can now be removed. You NOT done yet. Now comes the hard part. If you lucky and the sun is shinning on you and its your lucky day the plunger assembly will pop out at which point you can put the new one in and reverse the procedure and your done. I wasn't that lucky. I had to take about a 1/8" drill and drill into the plunger assembly about 3/8" (NOT CRITICAL) just dont go beyond 1/2" you want enough meet to screw a long drywall screw or sheet metal screw into the plunger to pull it out. I found that I had to screw it in as far as I could go to get the plunger to spin, I then began pulling and pulling and pulling until it finally gave way. Clean out the SMC thoroughly with a good clean paper towel and remove all brake fluid and filings. Put in the new plunger assembly and then install the plunger actuator, then put in the new C-CLIP with the Spring Clip pliers. Seat the boot as far in as you can with your fingers ONLY !
Bleed the brakes in accordance with the service manual.
You may need to add some brake fluid so be sure to have some handy ! I
Reassemble everything and then GO do what the ST was meant to do ! ! !
BE RIDDEN !
Any questions I'll be glad to help. it should take NO MORE than 1 1/2 hours from beginning to end !
I hope this post will help someone ! Tomorrow I will post pictures !
Kevin
I have to give credit to Dave (Username: Sennister) for his assistance and guidance. Without him this would NOT have been possible without excessive hair loss and another divorce !
