Secondary Master Cylinder Information

[Igofar]

Do NOT take the new one apart, it is ready to assemble from the factory.

 

[Andrew Shadow]

Application of some rubber safe grease inside the boot to reduce any possible water ingress is a good idea is it not?

 

[Igofar]

The complete factory assembled units already have silicone grease on the mating surfaces.
Trying to pull the boot back to apply more may only risk tearing or damaging the boot.

 

[Andrew Shadow]

I injected some grease in with a small syringe- barely displaced the boot at all.

 

[jfheath]

The issue with the rubber boot is that it has to be seated correctly if it is removed. The rubber boot is shaped a little like a top hat with a brim. The brim contains a round spring, like a key ring. The bore in which the boot sits narrows just in front of the circlip, and it forms a step. The brim of the top hat is slightly larger than this narrow bit, so it has to be pushed over that step so that the key ring spring is squeezed and it grips the sides, forming the seal and keeping it in place. The step is angled slightly, so pushing it into place will help the circular spring to compress. But you can feel when it pops over that step to seat properly.

This does two things:
1. It forms a proper seal to keep water out of the bore of the SMC
2. It moves the brim of the top hat seal behind the water escape channel.

If that boot is removed and is not put back properly, the brim will block the water escape channel, and water will pool near the brim. The pooled water can then get behind the boot because the brim isn't sealing properly. It is not easy to seat the rubber boot properly - you need to be able to push the brim equally around its circumference in at least 3 different positions. And that risks puncturing the rubber. Really, it needs a tube, but you can't get a tube in without undoing the bracket, and that risks altering the critical length of the SMC push rod.

Best to leave it alone as Larry suggested.

Here is an article that I wrote about this with some illustrations.

Article [13] - ST1300 - SMC Boot Fitting - A Cause of Failure ? | ST1300 Articles

The rubber boot on the ST1300 Secondary Master Cylinder is designed to keep water out. Unfortunately, since you cannot see what you are doing when fitting the rubber boot, it is entirely possible that casual maintenance can result in allowing water to be let in. I made reference to this in the...

www.st-owners.com

 

[alfixit]

Thanks. I'm glad I asked.
I thought it might sound like a dumb question.

 

[jfheath]

Thanks. I'm glad I asked.
I thought it might sound like a dumb question.

I'm glad that you did ask.
Not knowing, or not understanding isn't dumb. How else do you find out? The only dumb questions are the ones that never get asked.

 

[Jay Freddy]

I recently acquired an 09 St1300 ABS that had been rode hard and put away wet.

The rear wheel is starting to bind and the SMC seems seized, it doesn't move at all at the front caliper.

I plan to replace the entire part and have the brake lines flushed and bled. I know that it has been at least two years since the brakes were flushed.

I am a little confused about what part number I need for the 2009 model.

Again, I want to replace the entire assembly, but it's not clear which part number is the correct one for the 2009.

Thanks in advance!

 

[Sadlsor]

I am a little confused about what part number I need for the 2009 model.
Again, I want to replace the entire assembly, but it's not clear which part number is the correct one for the 2009.
Thanks in advance!

Last December I replaced the SMC (thanks @Igofar!) with a whole lotta help from the White Courtesy Phone.
Mine is a 2008, which is after Honda's modification from the earlier-model's SMC. Ordered from Ron Ayers -- use this part number (EDIT: the R02 suffix reflects the newer p/n):

 

[jfheath]

@Sadlsor has provided the correct part for models from 2008 onwards.

Make sure your bike IS the 2009 model that you think it is, and not a pre- 2008 model that was registered late.

The white label on the frame under the pillion seat tells you and the 10th character of your frame VIN should be a 9 for a 2009 model.

Dont forget to buy plenty of crush washers for the banjo bolts. Many of us buy copper from on-line suppliers at not much money per unit.

 

[Jay Freddy]

Last December I replaced the SMC (thanks @Igofar!) with a whole lotta help from the White Courtesy Phone.
Mine is a 2008, which is after Honda's modification from the earlier-model's SMC. Ordered from Ron Ayers -- use this part number (EDIT: the R02 suffix reflects the newer p/n):

Thanks for that. For anyone who may have difficulty reading the above image, the correct part number for 2009+ SMC replacement is:

06454-MCS-R02

Thanks again!

 

[Jay Freddy]

@Sadlsor has provided the correct part for models from 2008 onwards.

Make sure your bike IS the 2009 model that you think it is, and not a pre- 2008 model that was registered late.

The white label on the frame under the pillion seat tells you and the 10th character of your frame VIN should be a 9 for a 2009 model.

Dont forget to buy plenty of crush washers for the banjo bolts. Many of us buy copper from on-line suppliers at not much money per unit.

Thank you. VIN confirmed as 2009.

Is there a specific size for the "crush washers"? Or a Honda part number?

How many would you consider "plenty"? 10-12? Or 50-60?

Also, with the Banjo Bolts, what is the Honda part number or its equivalent?

I want to make sure that I have a complete shopping list before I begin this job.

Thanks again!

 

[Sadlsor]

@Jay Freddy I bet you can find the crush washer Part number on one of the ST1300 Articles about the SMC.
As well as the alternate sources. I can't look right this second, but can later if someone else doesn't chime in before me.
The magnifier / search tool may be of some help, unless SMC is too generic.

 

[Igofar]

You only need 4 oil bolt washers.
You can find them on ronayers parts diagram under brakelines.
I can't get to it from my phone at the moment.
And they are directional....
The sharp flat edge of the washer must be against the banjo fitting for proper seal.

 

[jfheath]

And they are directional....
The sharp flat edge of the washer must be against the banjo fitting for proper seal.

I didn't know that. Is this just the Honda ones, or are all crush washers like that ?

ps I do overkill, so when I bought my banjo crush washers, I bought 100 for £7 - just to have them in stock, and if I am taking hydralics off, I might as well do the lot. But they aren't Honda washers. They are copper and don't seem to leak any. Both sides seem to be polished.

 

[Nanook75]

Whoops-that would be 06454-MCS-G03. I discovered that the 5 was actually an S after I cleaned my glasses.
Thanks for the help.

Appreciate you posting the part number. I'm sure it's in a few dozen spots on the forum, but searching secondary master cylinder yields roughly 4.7 thousand threads. Also worth noting, in case it helps someone else's search:

The secondary master cylinder is part of BRACKET SUB-ASSY., L. FR., 06454-MCS-G03 for the earlier models. Hope this helps other folks search out the right part. Just paid 145 for mine with tax, best price I saw in my quick review.

I'll note that the Adept Powersports site at the link below had some very handy references to model year specific diagrams to make sure you were getting the right part. Props to them for that. I will definitely keep that in my back pocket when I'm trying to figure out which other pieces/parts to order next time.
http://www.adeptpowersports.com/oem-parts/honda-bracket-sub-assy-06454-mcs-g03-part.html?gclid=Cj0KCQjw38-DBhDpARIsADJ3kjlMHLiOo0whGZMCC8jb2ND69ViU6xOBIhxiRlhu99h7BluYajqQefkaAky0EALw_wcB

 

[Ralf_CT]

One potential cause for failure may be the dust seal not having been fitted properly/or being perished. Due to the installation angle of the SMC water will sit in the area above the hydraulic seal between the piston and bore, eventually causing the unit to seize.