SMC Rebuild

Mountainbmike said:

I would like to unlink the brakes since a weak brake pedal and way powerful front brake lever reminds me of a Buell lol.

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• The front lever operates 6 pistons: Two on each caliper. The front 4 are applied directly, the rear outers are pplied by the action of the SMC.
• The rear pedal operates 5 pistons. All 3 of the centre pistons directly. The two rear outer pistons indirectly by the action of the SMC.
• There is a delay valve which will not allow the front right caliper to be operated by the brake pdeal until a certain pressure at the pedal is reached.
• The propertional control valve prevents the SMC from applying too much pressure to the rear outer pistons.

jfheath said:

There's nothing like bringing a 9 year old thread back to life ! But if it is addressing the issues that you are looking at, then why not ?

A quick run down on the STs. The ST1100 and 1300 have the same behaviour if they have 3 pistons per caliper. I don't know which model you have, but it has an SMC, so the following applies anyway.

The bike has 9 pistons, 3 on each caliper

• The front lever operates 6 pistons: Two on each caliper. The front 4 are applied directly, the rear outers are pplied by the action of the SMC.
• The rear pedal operates 5 pistons. All 3 of the centre pistons directly. The two rear outer pistons indirectly by the action of the SMC.
• There is a delay valve which will not allow the front right caliper to be operated by the brake pdeal until a certain pressure at the pedal is reached.
• The propertional control valve prevents the SMC from applying too much pressure to the rear outer pistons.

It just works, and is very effectively at stopping a motorcycle weighing half a ton at 70+ mph. And all you need to do is find out how to look after the brake system properly.

Welcome to the forum - I see you have been around for a while, but it is good to see you posting !

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Mountainbmike said:

I think you're saying you have no experience to share in decoupling the linked brakes . But thanks anyway. I guess.

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Mountainbmike said:

I think you're saying you have no experience to share in decoupling the linked brakes . But thanks anyway. I guess.

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Delinked Brakes | ST1300-Brakes

—- as I get questions I am adding, editing and clarifying this post to keep the information in one place—- I delinked to simplify the system I delinked my VFR to reduce potential problems, and because I had some braided lines laying around that happened to fit. So when I bought the 2006...

www.st-owners.com

How to de-Link without caliper modification | ST1300-Brakes

I will add detail in the coming days with hose length and fitting orientation. I'll be editing it for organization and readability. Also, there are some pictures that will help. I removed the linked aspect of my braking system. The legal and safety risks for which you accept if you choose to...

www.st-owners.com

Anna'sDad said:

Yes, and no. The plastic bit does contain a check valve, but also contains an incredibility small passage that bypasses the check valve. When I disassembled my secondary master cylinder, the plastic bit with the end cap (looks a bit like the 60's 'peace symbol') was the end inserted into the SMC, with the O-ring next, it just sits on the plastic bit, and lastly the threaded flange assembly.

When the plastic bit is installed in this manner the check valve allows brake fluid to enter the SMC with minimal restrictions, while brake fluid is still permitted to flow out of the SMC, it's rate of flow is restricted by the incredibility tiny passage. I imagine the intent of the design was to keep a ready supply of brake fluid at the SMC (remember the SMC does not have a brake fluid reservoir of it's own), so that the rear brake caliper always has a supply of brake fluid. That incredibility small passage should allow enough brake fluid to return (to the rear brake master cylinder reservoir) due to expansion of the brake fluid when needed.

The above description of operation is only my interpretation of the brake system. As I've worked on the brakes on my ST1300A, I've disassembled most of the components in an effort to understand the designer's intention of operation.

Here is a link to a drawing I made of the linked brake system used on the Honda ST1300.
As well as a drawing/cartoon of the secondary master cylinder used on the Honda ST1300.

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FlyingScot said:

BOTH LINKS DEAD NOW ;-(

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FlyingScot said:

BOTH LINKS DEAD NOW ;-(

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jfheath said:

There's nothing like bringing a 9 year old thread back to life ! But if it is addressing the issues that you are looking at, then why not ?

Click to expand...

Mountainbmike said:

I think you're saying you have no experience to share in decoupling the linked brakes . But thanks anyway. I guess.

Click to expand...