front left brake and rear brake drags

[Igofar]

A couple other things that should be inspected, are the pads themselves. Are they OEM Honda? or Aftermarket? EBC etc.
If they are EBC, these could be causing fitment issues, as the EBC front pads are too thick, and will not allow the caliper to back away from the rotor.
Honda uses thick pads on the rear, and thinner ones in the front calipers etc. EBC chose only to use the same thickness on both pads, and this has been known to cause issues with dragging brakes etc.
EBC also chose to leave out the heat shield on the rear pads, causing the fluid to degrade faster etc.
You should also check the rear caliper mounting bracket to make sure the pad retaining pin is firm/square and not worn away at the bottom edge allowing the pads to tilt ever so slightly, causing bind on the guide dowel etc.
Several things must be checked/inspected in the brake system.
If the piston didn't move freely before pushing and pulling on it, but it now moves more, that probably means that the piston is stuck down inside the bore a bit, and was just forcefully moved etc.
The pistons should not move more than 1-2mm. If you've got 3-4 mm of free play, that means the piston is stuck down in the bore etc.
The piston should be under both spring and hydraulic pressure, and should not have any dead space in its stroke, unless something is wrong, such as air in the system, binding, damaged SMC etc.
The needle bearings could be dry and binding...
The spacer on the upper SMC attachment point could be damaged and folded over, causing binding....
The return inlet port and filter/screen cartridge is clogged and not allowing fluid to return, thus building up pressure behind all the pistons, causing things to bind....
The counter sunk head of the the lower SMC pivot bolt (think bearing surface) is dry and binding....
The rubber boots in any of the calibers are swollen and binding....clips dislodged and dragging/binding....bent clips....damaged/dry pad retaining pins...the O-ring on the end of the pad retaining pin(s) could be damaged/torn/missing, causing binding.....
Too much grease/lube on the guide dowel...yup, causing binding...
Rear wheel assembled incorrectly (sequence) stopper bolt needs to be tightened before the axle nut or it will cause binding....
Stopper bolt loose, pinching down on the rear brake line hose....etc.
Someone used spray brake cleaner to clean the calipers, and its causing the seals to swell and drag the pistons....
The seals are dry/dirty binding....
The seals are worn flat....binding.....
Dirt behind the seals etc....binding...
If it were on my table, I would carefully start inspecting EVERYTHING and try and find the cause of the problem, instead of throwing solutions at a problem...
I'd probably be reaching in my parts cabinet for a replacement secondary master cylinder, 4 oil lock washers, and some fresh Dot 4 brake fluid....AFTER, I inspected everything.
But that's just how I roll....or spin...or not drag....

 

[ahope]

Thank you igofar, that was a most impressive list of things to check.

I will start to take off calipers and inspect them for a start. while at it, I will replace the pads. thanks for the tip about ebc pads!

Then i just need to go through item after item until i get to the bottom of this.

 

[jfheath]

I've just come to this thread and confess to having only glanced at previous posts.

If the front left brake is getting hot - then the front brake is probably dragging. In that case you can fully expect the rear to be getting hot. The SMC is designed to apply the rear brake when the brake pads rub against the front left brake disc. It doesn't necessarily follow that the SMC or the rear brake is at fault. On the other hand, anyone that can put in a front wheel and front caliper in such a way that it drags - well they could have messed up other stuff as well.

There are lots of things that could cause this - see Larry's list. One thing not mentioned is the correct position of the front left fork - possibly due to incorrect wheel installation (eg wrong sequence or spacers put on incorrectly). That can move the caliper and pads into the brake disc / rotor and initiate a drag depending on how new the pads are. When checking the front wheel installation, look at this.

Article [13] - ST1300 - Maintenance - Front & Rear Wheel Install and Front Axle Animation | ST1300 Articles | ST-Owners.com

I also spotted a typo in an earlier post. The SMC should move only about 1 or 2mm when working properly !

So glancing up to Larry's sign off - yes I would inspect everything. But personally, I would first check why the front caliper is dragging - and I would start with the front wheel - because it is the probably the last thing that you would think of, and I am a bit weird like that.

 

[ahope]

Another excellent suggestion! The garage just changed the seals on the front forks, so thats a possibility. don’t really trust those guys. last service they dumped almost 5 liters of oil into the engine (should be 3.9 liters). Also said It’s normal for brakes to drag a bit. and some more..

 

[caldercay]

last service they dumped almost 5 liters of oil into the engine (should be 3.9 liters).

I'll bet I know why. They kept the bike on its side stand while filling with oil - the sight glass is on the opposite side, so yea, way more oil ends up being poured in.

Bike needs to be on its centerstand to check and fill.

Also said It’s normal for brakes to drag a bit.

That's because EBC sintered pads were installed ... so as they rest against the spinning discs, they create a slight "metal rubbing" noise. The other issue that Larry pointed out, is the EBC front pads are thicker, so exacerbate the issue.

These are just two examples why I do all work on all our bikes, trucks, and farm equipment (and house plumbing and electrical and ...).
I'd not bring my bike to that shop again.

 

[broc11]

Sounds like that shop hasn't much of a clue about linked brakes anyway, my Vfr800 is doing the same thing, same linked brakes as the ST1100 and probably the ST1300. better start digging to see what's going wrong.

 

[SMSW]

Another excellent suggestion! The garage just changed the seals on the front forks, so thats a possibility. don’t really trust those guys. last service they dumped almost 5 liters of oil into the engine (should be 3.9 liters). Also said It’s normal for brakes to drag a bit. and some more..

If they pulled the forks, well, I should have said if that shop worked on the forks, you should loosen the triple clamp bolts and torque them according to the Honda Service Manual's instructions. That would only take a few minutes more since everything down low is going to be unbolted for inspection.

Normal for brakes to drag? Only if you consider it normal to drag the mechanic down the street because he screwed up your bike.

 

[ahope]

Latest update:
I pushed the pistons back in the calipers to free up the brakes. I then rode a while using only the front hand brake. No problems whatsoever, and the bike rolled really freely when I pulled the clutch. Going for a highway run, and then rolling out to a stop the rotors all around were normal (cool to the touch).

As soon as I touched the rear brake, the brakes came on - and stayed. Both rear and left front brakes were dragging and heating up the rotors.

This also happen when the bike is standing still, so there is no movement on the front wheel. So the SMC does not move at all in this case.

I checked brake fluid reservoirs both front and rear, not overly full. pads are 7.5-8mm thick and seems used, but not worn (I only had the bike for a couple of months).

Reading through the forum and searching around, there seems to be 4 schools of thought:

• The SMC. Answer to life, universe and ST1300 brakes
• The rear master cylinder compensation/relieve valve or holes blocked so fluid can't return
• Air in the system
• Brake pads wrong/mounted wrong/calipers

From what I can understand, the rear brake pedal will send fluid forward to the center piston on both sides of the front wheel. But only the left caliper/pads are dragging? Why?
Also, rear brake pedal creates pressure and moving the pads, but pressure does not go away when pedal is released. Seems some relief valve / hole somewhere being clogged?

Since the brake system is so complex and time-consuming to completely overhaul, I hope it's worth it to spend some time analyzing probable cause of fault before tearing down everything and overhaul the lot. That would be $$$ and time-consuming, so hoping to narrow this down before ordering parts and have a go at it.

 

[Sadlsor]

Since the brake system is so complex and time-consuming to completely overhaul, I hope it's worth it to spend some time analyzing probable cause of fault before tearing down everything and overhaul the lot.

Ahhh, Grasshoppa.
You learn well.

The sig line for @Igofar, in each of his posts:
"Find the cause of failure, instead of throwing solutions at a problem."

 

[mjc506]

Good fault finding! Regarding your final comment - it certainly wouldn't hurt to do a complete overhaul, but hopefully we can find the root cause of this issue and at least delay that until winter

As you've gathered, while the SMC is a fairly common issue, it's not to blame for all brake problems

So if you managed to push the front caliper pads back, the caliper and seals etc are probably ok. That you can use the front brake with no problems at all supports this, and implies that the SMC is ok too (and all the spacers/pads/etc are in the right place).

Pressing the rear brake pedal makes front and rear bind, even at a standstill... so that rules out it just being a front caliper problem activating the SMC and rear caliper.

Have you seen this article? https://www.st-owners.com/forums/th...g-all-the-air-out-of-the-brake-system.156754/ It contains some excellent diagrams of the brake system. The only thing I can see that could make a rear master cylinder issue only affect the front left caliper is the 'delay valve' on the right have fork leg. My understanding is that this isn't actually a true delay valve, but allows fluid to the left caliper first, and then the right caliper once pressure builds sufficiently (allows gently rear braking for low speed manoevers and more braking with more rear brake pressure). Entirely possible, quite likely in fact, that a problem in the rear master cylinder could build sufficient pressure for the brakes to bind slightly, but not enough for all the brakes to bind.

How does the rear brake pedal 'feel'? Nice and smooth and firm? Stiff and notchy? A stiff pedal pivot could hold the master cylinder slightly activated, preventing fluid return. Something worth checking.

My first inclination in your position would be (subject to what I found during the process) to flush the brake system - you'll probably need a litre of Dot4 (get two, just in case...). You may get away without flushing the front circuit (front master cylinder, outer pistons on the front calipers) but it would be sensible to do it anyway. Follow the steps in that article and you won't go far wrong. Some don't like the vacuum flush tools, but I've had good success, perhaps followed by a quick 'manual' bleed. If the fluid hasn't been changed recently (when was it last done?), it would be good to get fresh fluid in the lines, and hopefully it may dislodge any debris that may be blocking ports. It'll also exercise front and rear levers, SMC (which will move much more while you're bleeding the system!) and valving which is probably a good thing.

Hopefully, that'll sort your problem for now and get you until winter when you can do a full overhaul. But it is entirely possible that you may find another/the problem along the way. Frustrating perhaps, but better to find in the garage than out on the road. Do keep an eye out for damaged brake hoses - one failure mode is the internal lining braking up, and a 'flap' acting as a one way valve, potentially allowing fluid into a caliper, but preventing it leaving for example. Not always visible from the outside, but pushing each piston in each caliper back fully (after cleaning) should highlight issues like that.

Good luck!

But yes, scheduling a full investigation along the lines of Igofar's list would be a good idea

 

[Igofar]

Your statement about using only the front brake lever points out that you really don't quite understand how the brake system works on these bikes.
Lets back up a bit, before your bike pitches you off while your experimenting with using only one lever etc.
Have you performed the secondary master cylinder inspection?
How many rotations does the rear wheel turn when spun with a single push with your foot?
Does the rear brake instantly lock up when you apply forward pressure to the SMC?
Does it release completely when the pressure is released?
When did this issue start happening? Were either of the wheels removed?
What may help us to help you, would be if you could post some up close pictures of a few things....
I would like to see pictures of the following areas:
1. Left front wheel spacer
2. Rear caliper as viewed from the rear, so I can see the pads/rotor/caliper
3. The stopper bolt (rear swingarm)
4. The guide dowels on all 3 calipers
5. Both sides of the rear brake caliper bracket, where the front pad retaining clip sits (from right and left side)
6. Inside the hole where the stopper bolt rides (rear caliper bracket)
7. Picture of the front wheel pointing straight while on the center stand from the front view etc.
8. Clips in the roof(s) of all three calipers
If the stopper bolt (rear wheel) was not tightened before the axle nut was tightened, this alone could be causing your binding issue, as well as worn surfaces on your bracket, misalignment issues, or damage to parts etc.
If the stopper bolt is loose, it could be pinching down on the rear brake line (check for witness marks).
* the fact that the front brake lever works the brakes, does not rule out that there is not a problem with the SMC*

 

[ahope]

Your statement about using only the front brake lever points out that you really don't quite understand how the brake system works on these bikes.
Lets back up a bit, before your bike pitches you off while your experimenting with using only one lever etc.
Have you performed the secondary master cylinder inspection?
How many rotations does the rear wheel turn when spun with a single push with your foot?
Does the rear brake instantly lock up when you apply forward pressure to the SMC?
Does it release completely when the pressure is released?
When did this issue start happening? Were either of the wheels removed?
What may help us to help you, would be if you could post some up close pictures of a few things....
I would like to see pictures of the following areas:
1. Left front wheel spacer
2. Rear caliper as viewed from the rear, so I can see the pads/rotor/caliper
3. The stopper bolt (rear swingarm)
4. The guide dowels on all 3 calipers
5. Both sides of the rear brake caliper bracket, where the front pad retaining clip sits (from right and left side)
6. Inside the hole where the stopper bolt rides (rear caliper bracket)
7. Picture of the front wheel pointing straight while on the center stand from the front view etc.
8. Clips in the roof(s) of all three calipers
If the stopper bolt (rear wheel) was not tightened before the axle nut was tightened, this alone could be causing your binding issue, as well as worn surfaces on your bracket, misalignment issues, or damage to parts etc.
If the stopper bolt is loose, it could be pinching down on the rear brake line (check for witness marks).
* the fact that the front brake lever works the brakes, does not rule out that there is not a problem with the SMC*

Ok, i can do pics. since it involves taking out the calipers (for pictures of bolts and clips etc) i will do it next week when my new pads arrive. if lucky, i can fit those while i am at it.

 

[ahope]

Ok, i can do pics. since it involves taking out the calipers (for pictures of bolts and clips etc) i will do it next week when my new pads arrive. if lucky, i can fit those while i am at it.

Well, I could not wait, so here are some of the pica you requested.
View attachment 275846
Left front wheel spacer

below rear caliper:

 

[ahope]

Frontfrontccalipers:

 

[Sadlsor]

I am no @Igofar and I am no @jfheath -- but is it just me, or do those slider pins look a bit crusty?
While I doubt this is the root of your sticky problem, at the same time, I don't see how it can help the situation.
EDIT: now that you've posted the next set of photos, I was referring to the previous set / the first batch.
The second group of pics, the slider doesn't look "as" bad.

 

[ahope]

I agree 100%. I am just starting to dig into this, and I do not like what I see on those pins. pistons also look lokecthey can use a good clean, socthey go for cleaning when my pads come next week. cant do much harm.

 

[Igofar]

Sitting in doctors office at the moment, and can't see pictures very well on my phone etc.
Rear pistons and caliper filthy etc.
But please tell me your front brake pad is not in backwards, and the pad material is facing the pistons ....
I will enlarge pictures when I get home.

 

[ahope]

Sitting in doctors office at the moment, and can't see pictures very well on my phone etc.
Rear pistons and caliper filthy etc.
But please tell me your front brake pad is not in backwards, and the pad material is facing the pistons ....
I will enlarge pictures when I get home.

You almost scared me there!

No, pad marerial is at least facing the rotor. I know because i have checked how much material is left all around.
But wrong way round? Is that even possible? I need to check.

 

[Igofar]

Please take a picture of the left front wheel spacer and post it.
They can be put in backwards.
10mm side goes into wheel, 5mm side outside of wheel.

 

[Igofar]

Those also do not look like oem honda pads either, as they are missing the white heat shield on the rear.
The rubber bits look swollen and or crooked as well.
Check the O ring on pad retaining pin, if torn or missing, it will bind due to angle.