ST1300 Rear Brake Problems

[Igofar]

I'd like to ask a couple questions...
Are the Brake pads that you replaced OEM or Aftermarket?
Did you Bleed the system in the correct order? TL, TR, PCV, Center, LR, LL, OR, (and did you tilt the left caliper during the bleed?)
Were the pads the correct part number for you bike? Did you trust the parts counter guy or the person who packed and shipped them?
Do the rear pads have the white spacer behind the metal plate?
Try this; Lower the mufflers out of the way again, remove the 14mm head caliper stop bolt, pull the axle part way out to clear the caliper, then lift the caliper up and verify that the end of the pad is indeed in the space it is supposed to be. Pull the pin and drop the pads, If they are OEM pads, align the metal plate with the hole the pin goes through, sometimes these can be offset and scrape. Pull the alloy braket off the caliper and clean the (2) pins that slide into the rubber grommets, place silicone grease on them and make sure they are moving freely. If this area gets dry or dirty, it can cause the caliper to bind, etc.
If you bled it manually and did it slowly (a couple seconds between strokes ) and did it until you got no air bubbles, or no sqeaking, creaking, barking, or chirping noises out of the rear pedal,
I'm gonna have to go back and re-read all the posts to get a better understanding of what you've done so far. Have you had the pistons & or seals out of the calipers? Or did you just clean them with brake fluid and a tooth brush? If you just cleaned them, did you operate the brake a small bit, to extend them to expose the dirt ring that rides up next to the seal? You may have dirt behind the seals from pushing the pistons into the calipers without proper cleaning.
Also, You Have NOT used arisol brake cleaner on the pistons did you? This will cause damage to the rubber seals and cause them to swell.
Just trying to think outside the box for you.
The last thing I'd try is to clamp the levers in the open position over night, then walk away for a while and check it in the morning.
Hope something in here may help.
Let us know how the progress goes.
We're here for ya friend.
Igofar

 

[Rick77]

Stupid question. Did you check the brake pads for the correct parts #?
The rear pads if I remember, have a notch in them for placement in the calipers.

 

[Mellow]

Sometimes, new pads will make the rear wheel stick and not free up after releasing the brakes. The wheel doesn't lock up, it just has some extra friction until the bike is ridden a few miles. Just adding that to the mix.

 

[alienskydiver]

After carefully reviewing the many entries in this thread, I think I've managed to distill the pertinent data down to this:

1. Brake system was working fine until rear brake pads needed replacement.
2. After replacing rear brake pads, rear brake would not release fully, prohibiting rear wheel from spinning freely.
3. First effort:
   • Rebuild rear brake caliper with new seals, due to possible contamination during brake pad installation.
   • Bleeding air from rear brake caliper, yielded less than idea results:
   • The front bleed screw (single center piston circuit) when opened, released pressurized fluid, and air.
   • The rear bleed screw (two non-center pistons circuit) when opened, released nothing, no fluid, no air, nothing.
   • Pumping the brake pedal applies the brake pads, though when the pedal is released, the brake pads do not release. Opening the front bleed screw allows the brake pads to partially release.
4. Second effort:
   • Bleed the brake system in correct order with a vacuum pump:
   • Front brakes are fine.
   • Rear brake continues to drag when the pedal is released (though no longer locks up).
   • Noticed that the center piston appears to operate correctly (extending & retracting), however when the two non-center pistons extend to the brake pads, they do not retract.
5. Third effort:
   • Manually operated the SMC, it appears to operate correctly (extending & retracting).
6. Fourth effort:
   • Replaced the SMC, and bled the brake system. Pumping the brake pedal applies the brakes, releasing the brake pedal does not release the brakes preventing the wheel from turning, at a later time (seconds?) the wheel will turn, though with resistance.

I have a few thoughts on what may (or may not) be going on here:

1. Bleed the brakes until brake fluid is present at both bleed screws (rear brake caliper) and all the air has been purged. This will take more than one filling of the rear master cylinder (I recently ran a liter of brake fluid through the rear master cylinder trying to get the last bit of air to purge).
2. As the brake system was in working order before replacing the rear brake pads, it may well be that some action occurred during the brake pad replacement with unintentional results. I can think of two mechanical actions that are worth investigating:
   • Check that the brake pads are installed correctly, specifically that the brake pad tab at the front edge of each brake pad is properly located in the steel retainer (part no. 6, parts fiche). I have had difficulty in the past with fitting the inside brake pad into the retainer, apparently at some time I may have bent one of the tabs on the spring pad (part no. 5, same fiche), which greatly hampered installing the brake pads.
   • Check that the SMC bracket pivots (one at the base of the SMC bracket, and another where the SMC brake rod attaches to the front fork), are both clean of debris, and corrosion. Both pivots need to be well lubricated to ensure free and easy motion, not an easy accomplishment given their location, and minimal weather protection.
3. In the event that the problem is not mechanical, then it may well be hydraulic. As has been discussed (indeed highjacking this thread), if a master cylinder piston is prevented from retracting far enough to clear the compensating port of the master cylinder, then brake fluid cannot return to the master cylinder reservoir. Brake fluid (perhaps already pressurized by the master cylinder) unable to return to the reservoir will not allow the brake caliper pistons to retract. Indeed the brake fluid need not have been initially pressurized (brake pedal use) to cause a problem, brake fluid expands as it absorbs heat, and with no place to go, pressure builds, and the brake pistons extend causing the brakes to drag.
5. The Honda ST1300 rear brake circuit is unconventional in that it utilizes two master cylinders (the rear pedal master cylinder, and the secondary master cylinder). If either of these two master cylinders has a blocked compensating port, I can imagine the effect would be that of a rear brake that doesn't release.
7. Whilst diagnosing and resolving brake issues on this motorcycle can be frustrating (and driving the automobile is a drag), imagine how frustrating it will be every morning when you drive your automobile past the charred hulk that once was a motorcycle.

For the moment I suggest putting the matches and petrol away.
Take a look at the rear brake pads; with a bit of contortion, a strong lamp, and a mirror the inside brake pad and retainer can be seen.
Also see to it that the SMC pivots are lubricated.

Hi thanks for your reply . The smc pivots are all correctly lubed the pads are oem and are all sitting as they should ????

 

[alienskydiver]

Sometimes, new pads will make the rear wheel stick and not free up after releasing the brakes. The wheel doesn't lock up, it just has some extra friction until the bike is ridden a few miles. Just adding that to the mix.

Thanks but believe me the amont of dragging these pads did after I fitted them they are well bedded in . Im surprised there is anything left . Also im not sure of time zones with you guys and here in the uk I work night shifts so we may seem to have a big delay in replying . Just to let you know im not being ignorant .
Plus the nights limits my time I spend down the garage hitting said motorcycle

 

[alienskydiver]

Stupid question. Did you check the brake pads for the correct parts #?
The rear pads if I remember, have a notch in them for placement in the calipers.

Not a silly question at all sir but yes they have the notch

 

[Mellow]

I suppose it's possible you have a bad PCV on the bike.

 

[Igofar]

John, I'm beginning to think we were twins separated at birth
I just PM'd him every single question you just asked.
Including Mellow's possiblity of a bad PVC vavle (recall?)
Lets keep trying to help him folks, keep those ideas coming.
Igofar

 

[alienskydiver]

Well folks today I have done a bit of elimination. jacked the front end up , front wheel is turning on applying front brake wheel does not turn, release lever wheel turns , all good there.
Release pads of rear wheel and spin the wheel whilst operating SMC after pushing the outer two pistons out again and making contact with the disc it stops the rear wheel, upon releasing the SMC the wheel continues to turn, all good there.
The retaining clip in the top of the caliper is in the right way round and sitting correctly, the caliper slides freely on the two sliders and the retaining pin slips throught the two holes on the pads easily.
The rear spindle is in correctly and the spacers all in their correct place , the 14mm retaining bolt is in the oval shaped hole and the pads are seated properly in the tab end also.
So back to the rear pedal now. Jacked the front end up again and spun the front wheel and even though the rear wheel will not turn , on applying the pedal it stops the front wheel and on releasing the pedal the front wheel is free.
So based on this I think I have isolated the problem to the rear of the bike as everything else seems all fine and dandy.
The problem arises when the rear pedal is applied . This is what happens , I push all three pistons in then apply pressure to the rear pedal until the middle piston pushes the pads out , this stops the wheel turning and on releasing the pedal the wheel continues to turn. Further pumps on the pedal continue to push out the outer two pistons and on full extension stop the rear wheel but on releasing the pedal the wheel now drags badly to the point where im pushing the wheel to move it.
After a very short period of seconds maybe the drag decreases but to no point where the wheel spins it will probably move 2-3 inches at best.

Now why is this happening on these two pistons because when they are applied by the SMC they release fine.
Damn my head hurts
Also I thought I might note the pistons are suprisingly awkward to push back in after pushing them out on the pedal especially the outer two as thet seem to fight against each other one in one out scenario but very hard both together??

Hope this sheds some light for ya folks

 

[Igofar]

Unless the PCV is Bad, still sounds like you've got air trapped in the system. Since you've replaced the SMC and had the "lines" open, May I suggest that you take a large plastic syringe (animal feeding type) or brake bleeding specialty one, and "Inject" the fluid from the bleeder nipples upward to the master cylinder to flood the lines more completely just in case. You may want to "crack" the fittings at the joints to "burp" air out as well.
I would also check the Level of the fluid inside each mastercylinder, to make sure you don't have too much creating a problem. The last little thing no body has mentioned is, open the handlebar mastercylinder, remove the plastic piece and lift the diaphram out and look to see the the little return deflector is sitting correctly. If this is bent or pushed down (while cleaning) it may have blocked the return flow hole causing pressure problems.
Keep looking, you'll find something.

 

[Anna'sDad]

That's an excellent, and orderly list of observations. From these observations it appears that the components of the brake system are functioning well.

After a very short period of seconds maybe the drag decreases but to no point where the wheel spins it will probably move 2-3 inches at best.

I think this is a very telling observation that indicates trapped air remaining in the brake system. I imagine if Mr Igofar where visiting in your neighbourhood, he would have had the brake system bled of all air in no time (he is the man!), and all of this would be but a fond memory.

Now why is this happening on these two pistons because when they are applied by the SMC they release fine.

I think this is a function not only of air trapped in the hydraulic brake system, but where in the system the air is trapped:

• When the SMC is working (as when the front brakes are applied) the brake fluid pressure is confined between the SMC and the rear brake caliper, and since the brake piston extends and retracts (as observed), it's reasonable to believe that this section of the rear brake circuit (SMC to rear brake caliper) has been purged of trapped air.
• However trapped air elsewhere in the rear brake circuit may produce different results. I can imagine a scenario (with air trapped somewhere between the SMC and the rear master cylinder) that allows the rear brakes (two non-center pistons) to be applied with the rear pedal (compressing the trapped air), yet inhibiting the immediate release of the rear brake when the rear pedal is released (the air expanding rather than the fluid quickly returning to the master cylinder).
• I think that, unfortunately another bout of bleeding air from the system is in order.

My experiences with bleeding the brakes on my ST1300 have never been as satisfactory as I think they should be. When the brake system is in excellent working condition, I think the brakes are top notch. I also think that the braking system is finicky (due to the varied range of experiences of other owners), with a high degree of maintenance required to keep the brake system in excellent working condition.

 

[alienskydiver]

A very well documented and systematic set of observations sir. It starts to look like any issue is between the rear brake pedal and the rear brakes - but of course there is the line from the rear master cylinder to the front which may be interfering with observations.

As well as Igofar's and AnnasDad's detailed bits - which all make sound sense to me - I have a couple of straws which may be worth clutching at.

i) I read through everything again, and although it has been mentioned a few times, I can see nowhere that you have acknowledged bleeding the proportional control valve. To get at it properly you have to take off the right hand fairing (although it is just about possible without). It is to the rear of the right hand ignition coil. It is at the highest point of the system apart from the Lever master cylinder and a prime spot for any trapped air. Have you been able to bleed the system at this point ?

ii) Check the fuses for the front and rear modulators. It's a very tiny straw to clutch at, but past experience ......

iii) Yesterday, trying to find a rattle, I took the opportunity to have the front calipers off, and while they were tied up, I was able to watch the pistons squeezing the pads together (with a metal plate sandwiched between). I hadn't realised how much they move and how much they spring back when they are realeased. It is an easily visible amount.

iv) Check the reservoirs are not over-full.

v) When you push the outer piston in, yes the other pops out. Put something there to stop it. It is harder to push one piston in, but it should slowly respond. Question to think about - where does the fluid go, and is it getting there ?

Keep at it - I think with that detailed summary you have made a great deal of progress - you know exactly what is working and what isn't.

Yes I did bleed the pcv on both occasions.
Are the fuses for the modulators to do with ABS as mine doesnt have it
From the rear master cylinder to the front brakes seems fine it stops the front wheel turning and releases also.
I think I shall have another bleeding session (pardon the pun ) as soon as I get the chance .
Thanks for your assistance again guys I appreciate it
If it carries on much longer I shall be looking for a GTR 1400

 

[alienskydiver]

Well folks this morning I went down the garage with a fresh head on my shoulders and a good nights sleep behind me. I haven't had the time to do anything till today.
I completely bled the whole system again I used nearly a litre and a half of brake fluid and I did it all manually with a one way valve bleed mate . I don't know whether anybody else has done this also but as well as following the bleeding procedure I also pumped the SMC which produced a healthy amount of air bubbles.
Also on each of the procedures I tapped all lines close to as well as the caliper with the wooden end of a hammer to help dislodge any of those pesky air bubbles that may be hanging around in any nooks and crannies, and believe it or not just when you thought there was no more air ,out popped another bubble.
Suffice to say my rear caliper is no longer dragging to the point of no wheel movement.
I have been out this afternoon just to scrub everything back in and the wheel spins at least a full turn and I can put my fingers on the disc without taking the skin off my finger tips ha ha.

Can I take this opportunity to thank all who have helped and advised it has been incredibly helpful and gratefully received........ thank you all.:bow1:

P.S if it comes back be warned I shall be back ha ha

 

[Mellow]

Very good to hear.

 

[ST Gui]

It must be a huge relief to get all that sorted out. And think of all the money you saved by not getting that GTR1400! That will buy a lot of gas for the ST.