OP
OP
Looking back at your #24 post, I agree. The clip recess is damaged and I've got striations on the stopper bolt hole. I ordered a new bracket earlier this afternoon.
2006 ST1300 w/61K miles - should I rebuild the brakes?
- Thread starter SirSquid1300
- Start date
OP
OP
Not yet, but tonight I kind of had a breakthrough moment... maybe. While following the second bleed "cycle" things improved when I was bleeding the PCV. I pumped both the rear brake pedal and the SMC. I only pumped the SMC four times, but it appears to have helped. For how many steps in the bleeding process do you need to keep the SMC tilted btw? How many times should the SMC be pumped?
I'm getting 2 turns out of the rear wheel, but the front still drags.
Finally, I also noticed some chattering from around the glove compartment area near the PCV. I know there is another brake-related hydraulic component in that area. It would happen while applying pressure on the brake pedal and cracking the PCV open.
The last thing I wanted to add is that I followed the "Avoiding the pitfalls of bleeding brakes" guide bleeding procedure. I guess I just need more guidance regarding bleeding the SMC.
I'm getting 2 turns out of the rear wheel, but the front still drags.
Finally, I also noticed some chattering from around the glove compartment area near the PCV. I know there is another brake-related hydraulic component in that area. It would happen while applying pressure on the brake pedal and cracking the PCV open.
The last thing I wanted to add is that I followed the "Avoiding the pitfalls of bleeding brakes" guide bleeding procedure. I guess I just need more guidance regarding bleeding the SMC.
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jfheath
John Heath
The reason for tilting the SMC is to make sure that air bubbles float towards the outlet port. You are not bleeding just the SMC - you are bleeding the entire system. Any bubbles between the master cylinder the SMC will pass through the SMC before it can be bled at the PCV bleed valve. You will not want them to hang around in the SMC
Fluid passes the primary seal quite easily when pumped by the brake pedal. It only seals in one direction - like the washer in a bicycle pump.
Regarding the noise from the PCV itself....I have not experienced that but you can bleed and exercise the PCV it in a similar way to the way you should bleed the clutch, once you have got some solid feel in the system:
This can be done from the right hand side of the bike. Keep the SMC tilted.
Close all bleed valves, but have a bleed tube on the PCV bleed valve.
Pump the brake pedal hard a few times. The idea is to provide enough pressure to overcome the spring in the PCV. If you increase the pressure gradually, you should feel the pedal dip as the valve is opened. So you get a sense of where it happens. ***
On the last stroke, hold the pedal down and keep it down.
Open the bleed valve. The fluid should be pushed out under the pressure of the returning piston in the PCV.
Just before the fluid stops flowing, close the PCV bleed valve.
Release the brake pedal. Repeat.
Check your fluid level regularly.
Doing it this way is possibly better than not, because it forces the PCV spool/piston to move, so part of the bore is exposed to fresh fluid, which helps clean the bore. If you do it 'normally' that spool/piston will not budge.
*** Actually, you may sense TWO dips as you press the brake pedal harder. The first will be the delay valve allowing fluid pressure to the front right centre piston. The second will be the pressure relief piston in the proportional control valve.
Fluid passes the primary seal quite easily when pumped by the brake pedal. It only seals in one direction - like the washer in a bicycle pump.
Regarding the noise from the PCV itself....I have not experienced that but you can bleed and exercise the PCV it in a similar way to the way you should bleed the clutch, once you have got some solid feel in the system:
This can be done from the right hand side of the bike. Keep the SMC tilted.
Close all bleed valves, but have a bleed tube on the PCV bleed valve.
Pump the brake pedal hard a few times. The idea is to provide enough pressure to overcome the spring in the PCV. If you increase the pressure gradually, you should feel the pedal dip as the valve is opened. So you get a sense of where it happens. ***
On the last stroke, hold the pedal down and keep it down.
Open the bleed valve. The fluid should be pushed out under the pressure of the returning piston in the PCV.
Just before the fluid stops flowing, close the PCV bleed valve.
Release the brake pedal. Repeat.
Check your fluid level regularly.
Doing it this way is possibly better than not, because it forces the PCV spool/piston to move, so part of the bore is exposed to fresh fluid, which helps clean the bore. If you do it 'normally' that spool/piston will not budge.
*** Actually, you may sense TWO dips as you press the brake pedal harder. The first will be the delay valve allowing fluid pressure to the front right centre piston. The second will be the pressure relief piston in the proportional control valve.
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OP
OP
Thanks for your insights @jfheath. I used your technique in tonight's attempt to get the front wheel to stop dragging. No chattering this time around; last time, it felt like a "water hammer" if you've ever heard that expression. I can get 1.25 rotations on the front wheel when it's lifted off the ground. The rear spins up to 2 or three times - it's doing great back there.
I also followed the procedure outlined in this article: https://www.st-owners.com/forums/threads/st1300-brake-fluid-replacement.68913/
When it came to bleeding the PCV, I used the rear pedal first, to pump fluid out of the PCV. I then attempted to pump the SMC and it would barely budge. I've felt the full stroke of the SMC on previous failed attempts to bleed the system. Would I be ale to pump the SMC if I dealt with the SMC first and the PCV valve right after?
I also followed the procedure outlined in this article: https://www.st-owners.com/forums/threads/st1300-brake-fluid-replacement.68913/
When it came to bleeding the PCV, I used the rear pedal first, to pump fluid out of the PCV. I then attempted to pump the SMC and it would barely budge. I've felt the full stroke of the SMC on previous failed attempts to bleed the system. Would I be ale to pump the SMC if I dealt with the SMC first and the PCV valve right after?
jfheath
John Heath
Fluid goes from the rear master via
1. The delay valve (nothing to worry about there) where the line splits
1a. The front right centre piston (and ends there)
1b. Front left centre piston and bleed valve, and continues to
2. The SMC inlet, through the SMC and on to...
3 The Proportional Control Valve
4. The PCV bleed valve
5. The rear outer pistons (rearmost bleed valve)
Are you are saying that when you press the rear pedal, fluid comes out of the PCV bleed valve (4)? If so, then it has gone through most of that sequence including the SMC.
If the PCV valve is closed then the SMC will move but only by about 1-2mm. If you pusht he rear wheel with your foot, you should be able to feel the wheel lock up as you push the MSC and release when you let go of the SMC.
But if you can barely move the SMC when the PCV bleed valve is open, it has nothing to do with fluid flow. You should be able to get a full stroke of movement - 1cm or more ( never measured it ) - simply by pushing the SMC onto its plunger.
If you can move it by that much, then stop reading here ! The rest is to do with what might be wrong if you cannot move the SMC with the PCV bleed valve open.
If you can't mov the SMC when the PCV bleed valve is open then that would suggest to me that the piston is jammed in the bore. OR if the SMC is on its 2 mounts, then maybe the bottom mount is seized. It sits in a needle roller bearing in lower bracket of the left fork leg. That may be dry and gunged up - or someone has been rather careless with liquid loctite and it has locked up the pivoting bush in the bearing. The chromed cylindrical sleeve in the lower left mounting bolt - through which the lower bolt passes - should push out easily.
It is possible that there is a blockage in the line to the PCV bleed point - possible to push fluid past with the brake pedal, but not with the restricted force that you can apply with the hand with the SMC. With the pcv valve open, the brake pedal should depress easily - little resistance. If you think that a blocked line is an option then you can try removing the bleed nipple.
That is going to be messy. Secure some plastic sheet / bin liner over your engine. Stuff rag under the valve to stop it sneaking down the back. Fashion an empty plastic container cut to shape under where the bleed valve is screwed in, in order to catch as much fluid as you can. Fill your rear reservoir. When you're ready, carefully remove the bleed valve DO NOT DROP IT. Put it safe. Give the pedal a few pumps. Anything that is stuck will be near the hole and should fly out like a champagne cork - th ehole is now much larger.
Catch the remaining fluid spill as best you can. The Valve is almost at the highest point, so fluid will stop coming out before long.
Check the the hole in the bleed valve is clear. Clean it up. Blow through it when it is clean. I have used soapy water for this in the past, rinse and dry throughly. Then just blow with lips. Make sure it is bone dry, then rinse in fresh brake fluid. Then screw it back into the hole. With things like this, I always start by turning the screw slowly backwards and feel where the thread 'drops off the end', then start turning forward - clockwise, with just my fingers knowing that i have found the start of the thread. It helps to prevent cross threading. But before you do, wrap some plumbers teflon tape around the thread - keeping clear of the side hole and the lower threads.
To answer your question about bleeding the SMC before the PCV. When you bleed the SMC - the only place that you can bleed it effectively is at the PCV bleed valve.
If you are referring to 'exercising' the PCV - that is the cast mechanism that is attached to the fram just in front of the ignition coil - then you need to be able to apply pressure in the fluid so that the PCV piston moves - and for that you need to have no air in the system, so that would have to be done last of all. Normally there is no need to do anything with the PCV when bleeding - but you mentioned a noise. This is how to get it to move and a chance to expose it to some new fluid around the bore. Not an issue normally as it is doing that every time you apply the brakes. But if the bike has been sat for a long time without fluid change ........
Dont confuse the PCV with the Delay Valve. The delay valve (which only has any effect on the front right brake caliper centre piston) is bolted behind the top of the lower fork leg
1. The delay valve (nothing to worry about there) where the line splits
1a. The front right centre piston (and ends there)
1b. Front left centre piston and bleed valve, and continues to
2. The SMC inlet, through the SMC and on to...
3 The Proportional Control Valve
4. The PCV bleed valve
5. The rear outer pistons (rearmost bleed valve)
Are you are saying that when you press the rear pedal, fluid comes out of the PCV bleed valve (4)? If so, then it has gone through most of that sequence including the SMC.
If the PCV valve is closed then the SMC will move but only by about 1-2mm. If you pusht he rear wheel with your foot, you should be able to feel the wheel lock up as you push the MSC and release when you let go of the SMC.
But if you can barely move the SMC when the PCV bleed valve is open, it has nothing to do with fluid flow. You should be able to get a full stroke of movement - 1cm or more ( never measured it ) - simply by pushing the SMC onto its plunger.
If you can move it by that much, then stop reading here ! The rest is to do with what might be wrong if you cannot move the SMC with the PCV bleed valve open.
If you can't mov the SMC when the PCV bleed valve is open then that would suggest to me that the piston is jammed in the bore. OR if the SMC is on its 2 mounts, then maybe the bottom mount is seized. It sits in a needle roller bearing in lower bracket of the left fork leg. That may be dry and gunged up - or someone has been rather careless with liquid loctite and it has locked up the pivoting bush in the bearing. The chromed cylindrical sleeve in the lower left mounting bolt - through which the lower bolt passes - should push out easily.
It is possible that there is a blockage in the line to the PCV bleed point - possible to push fluid past with the brake pedal, but not with the restricted force that you can apply with the hand with the SMC. With the pcv valve open, the brake pedal should depress easily - little resistance. If you think that a blocked line is an option then you can try removing the bleed nipple.
That is going to be messy. Secure some plastic sheet / bin liner over your engine. Stuff rag under the valve to stop it sneaking down the back. Fashion an empty plastic container cut to shape under where the bleed valve is screwed in, in order to catch as much fluid as you can. Fill your rear reservoir. When you're ready, carefully remove the bleed valve DO NOT DROP IT. Put it safe. Give the pedal a few pumps. Anything that is stuck will be near the hole and should fly out like a champagne cork - th ehole is now much larger.
Catch the remaining fluid spill as best you can. The Valve is almost at the highest point, so fluid will stop coming out before long.
Check the the hole in the bleed valve is clear. Clean it up. Blow through it when it is clean. I have used soapy water for this in the past, rinse and dry throughly. Then just blow with lips. Make sure it is bone dry, then rinse in fresh brake fluid. Then screw it back into the hole. With things like this, I always start by turning the screw slowly backwards and feel where the thread 'drops off the end', then start turning forward - clockwise, with just my fingers knowing that i have found the start of the thread. It helps to prevent cross threading. But before you do, wrap some plumbers teflon tape around the thread - keeping clear of the side hole and the lower threads.
To answer your question about bleeding the SMC before the PCV. When you bleed the SMC - the only place that you can bleed it effectively is at the PCV bleed valve.
If you are referring to 'exercising' the PCV - that is the cast mechanism that is attached to the fram just in front of the ignition coil - then you need to be able to apply pressure in the fluid so that the PCV piston moves - and for that you need to have no air in the system, so that would have to be done last of all. Normally there is no need to do anything with the PCV when bleeding - but you mentioned a noise. This is how to get it to move and a chance to expose it to some new fluid around the bore. Not an issue normally as it is doing that every time you apply the brakes. But if the bike has been sat for a long time without fluid change ........
Dont confuse the PCV with the Delay Valve. The delay valve (which only has any effect on the front right brake caliper centre piston) is bolted behind the top of the lower fork leg
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OP
OP
@Kevcules @jfheath thank you both for your input. Luckily there was no blockage and the needle bearing unencumbered. It seems that I simply didnt have the PCV valve open when attempting to bleed the SMC.
Last night, I used a combination of a vacuum pump and pedal actuation which turned out to be very effective. It allowed me to push 24 ounces of brake fluid through the system in a fraction of the time.
I managed to get "most" of the air out of the SMC by tapping it with a rubber malet and moving the SMC around in random directions; kind of like calibrating your smartphone compass. When I went to crack the PCV open, three or four large air bubbles emerged.
The rear wheel now rotates close to 2.5 to 3 rotations when elevated while the front wheel gets 1.5 to 2 rotations. Both brake levers were also noticeably firmer.
I would like to think that this is the end of this saga, but I won't really know until the end of the month, when I get cleared by my surgeon to start wearing shoes again (so I can test ride the ST).
Finally, I thought I would share a technique to easily access the PCV without removing the right side fairing (see picture). You can buy the air bladder at Harbor Freight for about $15. Makes for a great wedge to give you direct access to the bleed screw.
Last night, I used a combination of a vacuum pump and pedal actuation which turned out to be very effective. It allowed me to push 24 ounces of brake fluid through the system in a fraction of the time.
I managed to get "most" of the air out of the SMC by tapping it with a rubber malet and moving the SMC around in random directions; kind of like calibrating your smartphone compass. When I went to crack the PCV open, three or four large air bubbles emerged.
The rear wheel now rotates close to 2.5 to 3 rotations when elevated while the front wheel gets 1.5 to 2 rotations. Both brake levers were also noticeably firmer.
I would like to think that this is the end of this saga, but I won't really know until the end of the month, when I get cleared by my surgeon to start wearing shoes again (so I can test ride the ST).
Finally, I thought I would share a technique to easily access the PCV without removing the right side fairing (see picture). You can buy the air bladder at Harbor Freight for about $15. Makes for a great wedge to give you direct access to the bleed screw.
Attachments
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Sadlsor
Site Supporter
Good news!
As clumsy as I am, I still just remove the right fairing / cowl during this operation.
Glad you got it to submit to your will!
As clumsy as I am, I still just remove the right fairing / cowl during this operation.
Glad you got it to submit to your will!
That is a pretty risky way to get to the PCV bleeder. I'm surprised you didn't crack the very expensive side/middle fairing 
You can get to that bleeder many different ways without risking breaking stuff, or prying on stuff with your air bladder.
Lift the tank and your looking down on it.
Remove the lower black cowl, tip over cover, (2) bolts under the tip over cover, (1) bolt above the cylinder head cover, and two screws in the glove box, then the fairing pulls away easily without stress or possible damage.
If you want to know how to get more air out of the system, and where it hides, give me a call later today.
You can get to that bleeder many different ways without risking breaking stuff, or prying on stuff with your air bladder.
Lift the tank and your looking down on it.
Remove the lower black cowl, tip over cover, (2) bolts under the tip over cover, (1) bolt above the cylinder head cover, and two screws in the glove box, then the fairing pulls away easily without stress or possible damage.
If you want to know how to get more air out of the system, and where it hides, give me a call later today.
OP
OP
@Sadlsor Thanks! This was a lot harder than it should have been, but that's on me lol.
@Igofar Yeah, it looks bad because I didn't unscrew the glove box screws for the picture. Prior to that, I would unscrew all the points you listed above and the "bowing" of the fairing is not so pronounced. Thanks for extending the olive branch, but I'm going to take a brake from working on the ST until the end of the month. I've been fiddling around with the ST, after work, for the past four days lol. I'll probably give you a ring after I get cleared to ride, closer to the end of the month, if you have availability.
@Igofar Yeah, it looks bad because I didn't unscrew the glove box screws for the picture. Prior to that, I would unscrew all the points you listed above and the "bowing" of the fairing is not so pronounced. Thanks for extending the olive branch, but I'm going to take a brake from working on the ST until the end of the month. I've been fiddling around with the ST, after work, for the past four days lol. I'll probably give you a ring after I get cleared to ride, closer to the end of the month, if you have availability.
jfheath
John Heath
Glad it was just the unopened PCV bleed valve !
Dont forget that if you don't get more than 2 turns from the front wheels when the pads are not touching the disc, you are not going to get any more by bleeding the brake lines. That may be down to incorrect bearing fitment years ago.
As for bleeding the PCV bleed valve - I work on the principle that if it is possible for anything to go wrong it will. So I always do my brakes when I have the fairing off anyway. That way when the bleed tube comes off without my invitation, I can clean up the mess fairly easily !
Dont forget that if you don't get more than 2 turns from the front wheels when the pads are not touching the disc, you are not going to get any more by bleeding the brake lines. That may be down to incorrect bearing fitment years ago.
As for bleeding the PCV bleed valve - I work on the principle that if it is possible for anything to go wrong it will. So I always do my brakes when I have the fairing off anyway. That way when the bleed tube comes off without my invitation, I can clean up the mess fairly easily !