Article [13] ST1300 - Secondary Master Cylinder Rebuild- SMC

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Due to the high volume of calls on the white courtesy phone, you may experience extended call times.
Please be patient, your call is important, and will be answered in the order it was received.....
:WCP1:
 

SupraSabre

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Due to the high volume of calls on the white courtesy phone, you may experience extended call times.
Please be patient, your call is important, and will be answered in the order it was received.....
:WCP1:
Sounds like Larry needs one of those professional answering companies to screen his calls! :work1:

:rofl1:
 

jfheath

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The only one you need to get at that isn't exposed is the one near the Proportional Control Valve. That is just below the bottom edge of the fuel tank on the right hand side.

if you undo the main right hand fairing bolt, undo the two bolts in the right fairing pocket and release the right hand inner cowl, you can ease the middle fairing away enough to access the bleed valve.

Personally, i prefer to take off the middle cowl. My hands are too big to go fiddling around in small places.

But you need to go round the sequence as described. Ignore the bits that are fed from the front master cylinder reservoir - ie the front top bleed valves on both front calipers. They are a separate circuit. But in replacing the SMC, air will have got into the other lines, so you must bleed that complete circuit in the correct order. You may have to go round a couple of times

This may help - already posted earlier, but here it is again.

 

jfheath

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Due to the high volume of calls on the white courtesy phone, you may experience extended call times.
Please be patient, your call is important, and will be answered in the order it was received.....
:WCP1:
Sounds like you need a break young man. I think I'll put in an emergency call from the Uk and say nothing for an hour - just to give you some time off.
 
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Sounds like you need a break young man. I think I'll put in an emergency call from the Uk and say nothing for an hour - just to give you some time off.
With great power, comes great responsibility :rofl1:
Glad I've been able to help so many folks in the past few months.
 

Suraj

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Received a call from Igofar the same evening. He suggested a couple of checks. After performing those, the rear brakes are still dragging. Seems like the time to change the part 06454-MCS-G03 based on the suggestion. Then bleed the whole system again.


 
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Hi guys.
Having just found my rear brake is seized on I have been reading your posts with great interest. I am hoping the perhaps my problem could be a sticking rear calliper piston(s) or perhaps the sliders and a fairly easy fix. But fearing the worst it could be the SMC. (had to google what SMC meant).
I have a couple of questions regarding fluid loss during the overhaul of the SMC and replacing the brake fluid.
1. Can I clamp off the flexible lines to the SMC to reduce fluid loss and and lessen the amount of air getting air into the system or will that damage the lines?
2. Can I get away with pumping new fluid through the system without taking out the old fluid 1st as the Honda manual suggests so not to have bleed the proportional control valve? My theory being that with minimal fluid loss air (hopefully) wont get in to the Proportional Control Valve.
Thanks in advance.
Bob.
 
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Bob
Dollars to doughnuts, your problem is going to be your SMC.
Pick up a new one and you"ll be grand.
Answering your questions:
1. I'm not a big fan of crimping lines, there are a lot of internal braided layers in brake lines and you don't want to damage any of them.
Also, use a wire or string to hang you calipers, don't let them kink and hang by the brake lines.
2. Another little secret is don't skimp on brake fluid. Brake fluid is hydroscopic, so it absorbs water. So the more old fluid you remove, the better it is for the internals of your brake system. Have lots of paper towels or cloths to mop up what spills.
I take an empty 500ml 16oz water bottle and drill a hole in the cap the same size of the tube to put my spent brake fluid into while bleeding. It also lets you see the color and crap that was in you brake system. Keep bleeding till your satisfied you have removed all the air and the fluid is same color as your putting in your reservoir.
Also, if you don't have a motion pro one way bleeder, now is the time to pick one up.
By using it, it turns into a one man job rather than a 2 man job bleeding brakes on any of your vehicles.
 

jfheath

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Point 1. No. Well you can, but don't expect to be around too long.

Can I get away with pumping new fluid through the system without taking out the old fluid 1st as the Honda manual suggests so not to have bleed the proportional control valve? My theory being that with minimal fluid loss air (hopefully) wont get in to the Proportional Control Valve.
Point 2. That's what I do if I don't want to take anything apart. I get through a lot of fluid though about 2 litres - sucking it through with a vaccum pump while exercising the SMC, front lever and rear pedal. Also sluicing out the fluid behind the pistons. You still get a little air in the system though, but it is easily bled.
I've never had to bleed the proportional control valve. That is the device up near the radiator cap that reduces excess pressure to the rear outer pistons. If you mean the bleed valve near to the PCV ( near the ight hand ignition coil) - it's always a good idea to bleed at that point. It is a very long circuit to be pumping old dirty fluid - it goes all the way from the rear reservoir to the front calipers through the SMC up to the PCV and the bleed valve near there and then to the rea outer pistons. Get it out of the system at every bleed valve possible. (Front lower bleed valves, PCV bleed valve and rear rearward bleed valve).
You also still need to tilt and exercise the Secondary Master Cylinder on the front left fork leg - its not juts about getting air out - its about sluicing out all of the old fluid as well.
 
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Further to the rear brake problem I managed to get the pads out and push the front piston of the rear calliper back in which moved the rear piston forward and when I pushed in the rear piston in the front piston moved forward so those two are not seized. I checked to see if the piston of the SMC moves when moving the bike forward and applying the front brake but the piston does not move. Have pulled back the rubber cover of the SMC and it appears to be bone dry, no sign of any protective grease, and there is rust on the piston linkage under the boot so perhaps seized?
The centre piston of the rear calliper seems fully retracted which is supposed to be operated by the brake pedal. There also seems to be excess travel in the brake pedal compared to before the problem started so perhaps the rear master cylinder also has issues unless a modulator is at fault. Hope not.
One thing I did notice is that giving the SMC a mild tap with a rubber mallet frees off the the rear calliper so perhaps the seized SMC is preventing the front and rear pistons of the rear calliper retracting as intended and a jolt relieves the pressure.

Noted on not crimping the flexible lines, sluicing and tilting. You used to be able get away with on the older rubber types flexible lines but modern ones look some form of plastic. Thought it best to check with those in the know. I still have a brake hose clamp from when I was a car mechanic (many years ago in the days of coils, condensers and contact breakers). I'd never never hang the callipers by the brake lines though.
Fully agree with using new (branded) brake fluid, false economy not to.
Looks like i'm going to be pulling off the fairing to be able to bleed everything that can be bled, after draining everything that can be drained.
Will definitely get a hand operated vacuum pump to pull the fluid through. Will wrap the bleed valve threads with PTFE tape as well if the threads draw in air.

Thanks for the advice all. This place is a wealth of information not found in manuals.

Bob.

Bob.
 

Kevcules

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You can also use a one way valve bleeder shown below. It works by pressing and pulling the brake levers slowly and pushing the fluid out and it can't return because of the internal valve and no need to open and close the bleeder screws.
Good luck....
1621731459607.png
 
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I would suggest against using a vacuum pump on your ST, and purchase one of the Motion Pro check valve bleeders that Kevcules was so kind to attach a picture of.
They work better, there is nothing to clean up afterwards, and they cost much less etc.
Also, you do not need to remove the body panels to flush or bleed the brake system.
To flush and bleed the PCV Bleeder #3, simply remove the seat, place the seat adjustment in the service position (rearward) loosen the one bolt at the rear of the fuel tank, and remove the 2 bolts that secure the front, and lift the tank up (as in changing the air filter).
You'll find your now looking down on the PCV ;)
The bleeder tubing is routed through the side panel, above the cylinder head cover, and a 8mm spanner will reach it from the top opening.
 

jfheath

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See link in post #64 above.
Larry is right, the vacuum pump is messy. Personally, I find it useful to keep fluid flowing while I tap joints and flex lines to release the trapped air bubbles. But he has far more experience than me. For example, the only times that the tube ever detaches from the bleed valve is when I have left the middle cowl on. I then have to remove the cowl to clear up the mess. Its amateur hour.

Check the movement and feel of the SMC once you have no air in the system and the bleeder tube connected to the PCV bleed valve or to the rear rearmost bleed valve (outer pistons). It should push in all the way by hand and should return by itself all of the way, and should it should feel smooth.

At some point you may feel the need to replace the SMC if it is suspect - the part won't be available forever.
 
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The SMC is stuck fast so definitely seized, unless the pivot arm is seized but doubt it. I have a Gunson's bleeding kit which has a non-return valve in the plastic tube so I could use that instead of the vacuum bleeder.
Accessing the PCV from above is a good call to save pulling off the plastic. I'll place some old microfibre towels below it where I can in case of any leaks and keep a close eye on it.
I'm assuming (hoping) the centre piston on the rear calliper isn't coming out when the pedal is depressed is due to the SMC being stuck on/blocked and as a result the rear modulator thinks the front brake is still applied, hence the front and rear pistons being stuck and not returning as a pair. My logic could be completely unfounded although the rear brake was working fine up until yesterday when the SMC seized.
John, have you any advice as to where to source a repair kit for the SMC in the UK, if available and assuming the housing is recoverable that is.
I imagine the complete part from Honda won't be cheap, nothing from them ever is.
 
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I would urge you to NOT purchase a rebuild kit, as they will only provide a piston, boot, seal, and yoke.
They rebuild kits are almost as much as the entire unit.
The fly in the ointment is, the bore is what you'll find damaged, and/or the screen cartridge behind the SMC (inlet port) will be clogged and jammed up, and Honda does not sell parts for this area, so you'll be sitting there with a new rebuild kit, that you won't be able to use.
Honda also states that you should NOT open up the SMC as they are measured/adjusted at the factory, and you could cause your brakes to not work correctly.

BRACKET SUB-ASSY., L. FR. (1ea.)
06454-MCS-R02
Retail Price: $233.34
Your Price: $169.41

BOOT B (1ea.)
45133-MA3-006
Retail Price: $5.05
Your Price: $3.74

WASHER, OIL BOLT (4 ea.)
90545-300-000
Retail Price: $3.81
Your Price: $3.09

These were just taken off Ronayers.com to provide you with the correct part numbers you'll need, and give you an idea of what they cost.
Hoping you'll be able to source one cheaper over there.


SMC R02 Side.jpg
SMC Cutout Assembled 25pc.JPGsmc02 (1).JPG
smc_08c.jpg
 

jfheath

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Ditto what Larry said. Don't buy a rebuild kit. Buy the full SMC assembly. The second photo above - the cutaway - contains a rebuild kit that I had in stock. I gave it to a friend who was having trouble with his SMC. It didn't cure the problem that he had (I had just bought a 2009 model so I couldn't use it), and he gave me the entire assembly less than 2 years later. The problem was with the SMC bore not the piston assembly.
I cut it down the length of the bore as you can see.

I checked if you were in the UK - by looking up Basingstoke in the USA. Yes - there is one there as well, so I wasn't sure.

All suppliers of Honda motorcycle parts seem to be tied to the same controls - and every single outlet quotes the same price. Don't bother looking for cheaper, the websites show prices within pence of each other. Some will have more postage and packing. Some will not show VAT.

The biggest outlet that I know of in the UK is Fowlers Parts
Fowlers Parts | Genuine Motorcycle Parts & Spares
They are no cheaper or dearer than anywhere else, but they carry a huge stock and are very fast.

The model changed in 2008. Make sure when you order that you use the model year of your bike - not the registration year.
The model year is on the white label under the pillion seat. It will say ST1300A6 or ST1300A8 or ST1300-4 or something similar. The ST1300A6 is a 2006 model with ABS. The ST1300-4 is a 2004 model without ABS.

So what year model is your bike ? This may be different from the registration plate.

If there is no white label, look at the Vehicle ID on the right hand side of the headstock. That will probably start with JH2SC5 - or something similar. The 10th character is the model year. It is the same coding 6=2006, 8=2008, E=2014. (There wasn't a 2005 model or a 2007 model in the UK, and there were no new models between 2009 and 2014).

Just glanced on Fowlers website for two types. You would need to check these numbers for yourself. You need to specify the make, model and year of the bike.

Example.
If it is a 2007 registered bike, with ABS and the model year is 2006, then you would specify
Model ST1300A / Year 2006 (not 2007).

They are shown in the L. Front Brake Caliper Fiche.

Just checked fowlers site.

Pre 2008 is 06454-MCS-G03 - in stock. £215.72
2008 and later is 06454-MCS-R02 - not in stock £215.72

Another one that I have used is https://www.lingshondaparts.com
For that, you need the bike serial number to choose the correct fiche - although all versions of bikes use one of the two types above.

Lings don't list in stock or out of stock, so you'd have to phone.
 
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Thanks for the info and advice. It seems the complete part can be purchased in England for just over £200 which I think is about 280 dollars.
I won’t be ordering anything until stripped down and seeing what is/isn’t recoverable. It seems they do sell the kit so any reassembly using a kit if viable would need to be to noted existing settings to ensure tolerances are maintained. I won’t be giving Honda £200 of my cash with out good reason but well end up doing that anyway if that is the only do-able and safest option.
During my car mechanic days we used to rebuild master cylinders and proportion valves for cars and vans using aftermarket parts when the likes of Ford, Nissan, etc didn’t recommend it. Was that because of liability issues and they wanted the customer to buy the overpriced full part from them as opposed to a customer having a serviceable part repaired using parts from others. Likewise BWM and Audi don’t recommend repairing damaged alloy wheels for the same reasons but they can be repaired safely and powder coated for under £200. Cost of the manufactures new wheel, in some cases near a grand. Brakes are life savers so I won’t be doing anything without due consideration. I suspect Honda may well be getting £200 from me but there is always hope.
 
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