ST1300 Rear Brake Problems

[alienskydiver]

Hi folks, been having a problem with my rear brakes binding and after checking everything out proceeded to rebuilding the rear caliper and replacing the seals.
Upon trying to bleed the caliper back up I can only get the bleed nipple closest to the front of the bike to expel air and fluid.
Nothing comes out of the other nipple. But if I close the one I can get fluid out of and pump the pedal up the brake becomes locked on....... open the nipple the wheel moves but pads are still binding.
The combined braking ststem drives me mad it says the rear brake operates the middle piston but it must operate all three as all three have come out upon bleeding throurh the front nipple. Im losing patience now and I am getting very confused as my rear brakes were fine until I changed my pads and pushed the pistons back in which is why i changed the seals as I guessed I ust have dragged some muck back in. I hope you can help as I need my bike for work.
Hope Ive not been to confusing. Mylesconfused:

 

[BruceP]

believe it or not 90% it is the equalizer on the left front botton fork.

 

[nokesy]

check the secondary master cylinder on the lower left fork for corrosion

 

[Indian Express]

check the secondary master cylinder on the lower left fork for corrosion

+1, Been there done that! There are a few threads here that deal with the Secondary Master Failure, failrly common on these bikes. Once you rebuild/replace the SMC you need to follow the very specific brake bleeding procedure. There is a thread under the brake tech forum on how to do this. Once you do this chances are all will be well.

 

[Tom Mac 04a]

this will help you fiq out what does what..... follow with a full bleed as above and it should be fine

 

[alienskydiver]

When you pushed the pistons back in, did you check if there was any space in the fluid reservoir ? It might be that the system is full to overflowing.

But you need to go through the entire sequence with the bleeding - which includes tilting the front secondary master cylinder to raise the back end a little above horizontal, and also bleeding the proportional control valve which is below the petrol tank on the right hand side of the frame. It is possible to get at it without removing the fairing, but it is very fiddly.

Do I remember you saying that you are in Derbyshire at some point ? Its not really close enough to West Yorkshire - especially with dodgy brakes. Unlikley that you have dragged muck back in once the new seals were inserted and the pistons were in place - theres a very good dust seal there which prevents that from happening.

When you open the rearward nipple and nothing comes out - are you able to depress the brake pedal ? If so, then it sounds as though there is a lot of air and a lot of bleeding to do in that line. If not, and you say that all 3 pistons have come out whilst bleeding, then perhaps the nipple is clogged up ?

There are lots of threads on here - this one is worth a look though

The pedal can be pushed when the rear nipple is open but nothing comes out. Bleeding with the other nipple open I have taken about a cylinder full of fluid . All three pistons are out but brakes dragging . Yeah I am in Derbyshire

 

[Honda-st-team]

this will help you fiq out what does what..... follow with a full bleed as above and it should be fine

Great color schematic

 

[Blrfl]

The pedal can be pushed when the rear nipple is open but nothing comes out.

This is a big red flag that you're trying to bleed the brakes as if they were a conventional, un-linked system, which isn't the case on the ST. With linked brakes, the entire system has to be bled at once and it has to be done in a certain order or it isn't going to work. The rear bleeder on the rear caliper is on a circuit fed by the secondary master cylinder on the front wheel and is bled as part of the front system.

If you have access to a service manual, the procedure is detailed in Chapter 17; if not there's an article with a couple of videos that cover the right order.

I've just put together a quick guide to the procedure: CLICKY

Great color schematic

The original is here: CLICKY

--Mark

 

[Anna'sDad]

Here is a diagram of the ST1300 brake system, with a bit of explanation of the braking circuits.

 

[alienskydiver]

Ive ordered a vacuum bleeder so hopefully by the weekend I will be able to do the bleeding sequence and I shall let you know what happens . Touch wood . Thanks for your help so far

 

[alienskydiver]

Well folks the saga continues . Bled the brakes today using my newly acquired vacuum pump . Did the correct sequence finished most of with the pump method....to be honest once you have fluid in the lines I think it works better.
Front brake is fine rear one is still dragging but at least its not locking on anymore.
I pushed all the rear pistons in to free up the wheel and whilst my other half pumped the pedal I watched until the middle piston (the one operated directly by the rear pedal ) ) pushed on the pads and stopped her .
At this point the wheel is fine . It was only when all three pistons were out did it drag !!!!!!.
I have two questions.
1/ how does the brake pedal push the outside two pistons out if they are operated by the smc .
2/can anybody shed any light on this before matches and petroleum get involved .

Thanks myles

 

[Mellow]

Sounds like the SMC is the issue and sticking.. you should be able to move it a few millimeters forward and it should move back.

I would replace the smc assembly or get a rebuild kit... it's a little more $$ for the whole assembly but not much and everything is put together so it's easier.

 

[Anna'sDad]

1/ how does the brake pedal push the outside two pistons out if they are operated by the smc .

That's an excellent question, perhaps this sketch will be of assistance in your comprehension of the ST1300 Dual Combined Brake System.

That sketch can be downloaded and kept on your computer, where you can view (as well as zoom in, zoom out, and print) it with any PDF viewer.

 

[Igofar]

Sounds like a failing SMC (common). Replace the entire unit as Mellow suggested, then bleed the system manually or with a check valve type tool like the Motion Pro or Stockton tool company bleeder.
Clamp levers down over night to help bleed air out of system.
Follow the correct procedure for BLEEDING the system that your service manual indicates, however, you DON'T have to drain the system first, simply remove the fluid from the master cylinders and replace with fresh fluid and bleed as indicated. Make sure your tilting the SMC bracket as directed.
You should also remove the bushing from the SMC PIVOT point and check for scoring, and polish it with a scotch bright pad, then PACK THE BEARINGS with good waterproof grease, also put grease on the head of the lower mounting bolt (bearing surface). If these bearings are DRY, or the bushing is scorred, it can cause the SMC not to pivot as it should and cause the (2) outer pistons to drag on the rear wheell.
Hope this helps.
Good luck
Igofar

 

[970mike]

I had the same problem with my 07 ST1300. Honda replaced the Secondary master cylinder and the brakes are working as they should.

 

[alienskydiver]

That's an excellent question, perhaps this sketch will be of assistance in your comprehension of the ST1300 Dual Combined Brake System.

That sketch can be downloaded and kept on your computer, where you can view (as well as zoom in, zoom out, and print) it with any PDF viewer.

Your sketch although very good and it explains completely how the linked braking system works it still dont answer the question how does the rear pedal push all three pistons on the rear caliper out when the bike is at a standstill and the SMC is not being utilised, I have splinters in my fingers from scratching my head ha ha.

 

[alienskydiver]

Sounds like the SMC is the issue and sticking.. you should be able to move it a few millimeters forward and it should move back.

I would replace the smc assembly or get a rebuild kit... it's a little more $$ for the whole assembly but not much and everything is put together so it's easier.

Well I ve just been down the garage and checked the SMC operation with my other half spinning the rear wheel ( well spinning is a little overkill lets say turning) and on pushing the caliper upwards it moves a few millimetres stops the back wheel and returns allowing the wheel to be turned as before, so this seems ok . I am thinking do I need to do another bleed on the system with a manual bleed as Igofar has mentioned.
Just one question after tilting the Smc during the bleed sequence do I leave it at that angle for the rest of the bleed like I did or return it to its mounts at some point.

Thanks again Myles sorry to be a pain

 

[Mellow]

Well I ve just been down the garage and checked the SMC operation with my other half spinning the rear wheel ( well spinning is a little overkill lets say turning) and on pushing the caliper upwards it moves a few millimetres stops the back wheel and returns allowing the wheel to be turned as before, so this seems ok . I am thinking do I need to do another bleed on the system with a manual bleed as Igofar has mentioned.
Just one question after tilting the Smc during the bleed sequence do I leave it at that angle for the rest of the bleed like I did or return it to its mounts at some point.

Thanks again Myles sorry to be a pain

It sounds like it's working... so yes, another brake bleed can't hurt. Have you pulled the rear wheel and looked at the pistons and given them a good cleaning w/brake fluid? Could be they have some surface corrosion that's keeping them from working correctly.

 

[alienskydiver]

It sounds like it's working... so yes, another brake bleed can't hurt. Have you pulled the rear wheel and looked at the pistons and given them a good cleaning w/brake fluid? Could be they have some surface corrosion that's keeping them from working correctly.

Yeah Ive replaced all the seals with new ones and cleaned all the pistons up, there isnt anything fancy about the seals is there they all looked the same with flat faces no fancy angles or a paticular way round they go in . the pistons slid in and out nice and easy with my fingers. Do I still leave the smc angled for the remaining bleed sequence do you know. Thanks Myles

 

[Mellow]

Yeah Ive replaced all the seals with new ones and cleaned all the pistons up, there isnt anything fancy about the seals is there they all looked the same with flat faces no fancy angles or a paticular way round they go in . the pistons slid in and out nice and easy with my fingers. Do I still leave the smc angled for the remaining bleed sequence do you know. Thanks Myles

I don't. I put it back after I bleed the PCV. Then I continue with the rest of the rear brake bleed.