My Linked Brakes

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Jun 1, 2020
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606
Location
Oklahoma, USA
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2006 ST1300
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9039
What about the delay valve system?
How many working pistons on rear wheel with your routing?
3 rear brake pistons from the rear brake pedal.

6 front Pistons, 3 each side, operated by the Nissin 5/8" front MC.

Zero connection between front and back brake operation.

Road tested on recent 1,500 mile sport touring ride from Oklahoma to Wichita to Colorado to down near Albuquerque to Amarillo and back to OK.
 

jfheath

John Heath
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I think we'd have issues with the insurance cover if we did that modification in the Uk. They don't like people messing around with performance or safety features.
 

mello dude

Half genius, half dumazz whackjob foole
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No reason for it. All the plumbing between front and back is gone. It is now a conventional non-linked braking system.
If I ever jump out and grab a ST1300, I plan to delink as simular, or do the deed with revised triples and forks.
-I did the fork swap delink thing on my VFR800......No SMC for me!
 
Joined
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Oklahoma, USA
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2006 ST1300
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9039
If I ever jump out and grab a ST1300, I plan to delink as simular, or do the deed with revised triples and forks.
-I did the fork swap delink thing on my VFR800......No SMC for me!
What is the correct fork/triple swap for the ST1300? I don't mind the SMC now that it's basically a lump of aluminum filled with JB. I will keep an eye on it for awhile and make sure the shock is receiving is not damaging the steel linkage that holds the two halves together.

I put a F3 front end on my Hawk.
 

mello dude

Half genius, half dumazz whackjob foole
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Messages
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Dayton Ohio
What is the correct fork/triple swap for the ST1300? I don't mind the SMC now that it's basically a lump of aluminum filled with JB. I will keep an eye on it for awhile and make sure the shock is receiving is not damaging the steel linkage that holds the two halves together.

I put a F3 front end on my Hawk.
It will take some digging around, possibly other OEMs forks too, or even look at some Ohlins..same with the triple, may have to custom machine a solution...its TBD at the moment. I think the ST forks are a bit of a bastard diameter size, so it will be interesting..won't know until a bike is in my garage.

Still though, dunno if I'm going there ....that new Suzuki 1000GT has my eye too....
 
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Houston, Tx
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2003 ST1300
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5952
I'm going take one of my R410A High Side Gauges with a 800 PSI range, pull 29.92" vacuum, prime the bourdon tube solid with DOT4, connect it to the rear caliper bleed port and have my lovely assistant from the studio audience apply a gradual progressive pressure on the brake pedal.

Did you ever get a chance to get readings on the PCV thresholds? Would be good to have for the model below.



A distinct lack of contributions to the forum recently (I blame "other projects"... :well1: ) so here's a dirty "simulation" of the ST13 braking system!!


I've tried to get it as accurate as possible, but don't have actual numbers for the PCV or delay valve threshold pressures. But the defaults seem to be vaguely sensible (but feel free to change them if you disagree -

I think I've captured the intended behaviour... Comments/corrections/etc more than welcome!
 
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Chris09
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No I didn't follow up on that, for a couple of reasons [lazy] first being, okay, second reason, [don't have the contributor's name handy] the [video] demo of the difference in effect on the SMC under isolated moderate application of front and rear brake lever / pedal application kinda changed my whole outlook, combined with my [yet] unsubstantiated belief that there's a hydraulic delay between rear [centre piston] and front left [centre piston] force [via difference in resistance] upon rear MC application. My opinion not withstanding mjc506's elucidation [and excellent work on the subject] is that it remains overall intractable. For my own practical purposes, how comparatively infrequent and never in real world traffic I get out in the near three years I've riden my ST, it's almost academic anyway; I've never engaged the ABS, I've got negligible wear on brakes from initial measurements and not much on tires - good roads, no brine and clean rain for a large part, I'll probably need bearings and moly before tires. As well I'm winding the engine higher more as of late and relying more on the engine / clutch to reduce speed [will see how long that lasts].
 
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No I didn't follow up on that, for a couple of reasons [lazy] first being, okay, second reason, [don't have the contributor's name handy] the [video] demo of the difference in effect on the SMC under isolated moderate application of front and rear brake lever / pedal application kinda changed my whole outlook,
Is this the vid you are referring to?


 
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Chris09
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It was STRrider who posted his own video here on a thread that I was referring to. I think this is the first time I've seen this youtube one.
If I recall correctly STRider goes through a similar routine of moderate front and rear applications from about 50 mph which seem to produce very similar results - about twice as much plunger travel for isolated front vs isolated rear. So it's good to see two separate tests produce close to similar outcomes.
I'm incorrect to suggest it's beyond complete understanding [just because it might be for me]. There are obviously differences between bikes and brake / tire / suspension / rider / loading conditions as well as changes once the PCV spool travels; if, when and to what extent, the whole pressure rise / hold / drop process.
The beauty of it has to be that there are a lot of high milage stories out there which says this stuff works, and not too many scary braking stories [as long as everything is maintained].
 
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.... once the PCV spool travels; if, when and to what extent, the whole pressure rise / hold / drop process.
The P in PCV is kind of misleading, as the valve itself does nothing to control the proportionality/pressure rise, except to remain in pass through mode and let the pressure rise until it shuts off. It is more like a pressure limiter/relief valve.
 
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Chris09
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I have to agree; it's an acrynom that leads you off in a different direction, leaving you first needing to back up and abandon what you might understand of the term; it's the same for the delay valve; these are names that do not apply by any stretch of the imagination nor generally accepted definition of the word and obfuscate the operation and function of these components.
 
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I have to agree; it's an acrynom that leads you off in a different direction, leaving you first needing to back up and abandon what you might understand of the term; it's the same for the delay valve; these are names that do not apply by any stretch of the imagination nor generally accepted definition of the word and obfuscate the operation and function of these components.

I see cut outs posted Any idea what prompted replacing the Valves? External leaks?

If the cut out valves were replaced because of external leaks, chances are good they had internal leaks as well, in which case the valve was just in the way, doing nothing (beside collecting bubbles).
 
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Chris09
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Everyone has their own skill level, experiences and opinions. For my skill level and intended riding conditions [great bike in the rain... hope it comes back...] the design of the braking system was the basis for choosing this bike. I think the systems have contributed substantially to riders remaining upright when physics and fatigue could have caused otherwise.
 
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Everyone has their own skill level, experiences and opinions. For my skill level and intended riding conditions [great bike in the rain... hope it comes back...] the design of the braking system was the basis for choosing this bike. I think the systems have contributed substantially to riders remaining upright when physics and fatigue could have caused otherwise.
Has been good for me as well.

But what I am wondering about, is how do we know when it is time to replace the PCV? How do we find out it is no longer doing its job (no limiting action anymore)?

Given the cut-out pictures posted on the site, some have obviously replaced theirs. What prompted them to replace it?

Thought you might have an idea on that as it looks like you have a used one on hand?

I suppose some could have been overpressured and damaged after a rear lock-up following a stuck SMC?
 
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Chris09
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I don't actually have a used one on hand, a while back I was interested in aquiring some used parts for testing but subsequently learned through the site that it's a well trodden path and there was no point. There's people here that have already done all the heavy lifting. I may have given the wrong impression, I don't have any spare parts but I do have an entire second system. It's attached to a second motorcycle that I bought in January. It's also a little different but utilizes the same components more or less and the same principals if not a bit of an earlier version.
My ST has 40k [Canadian] and the blackbird has 4,150 miles; with the exception of a couple quarts of No 4 that I've used I've had no cause to dig any deeper at this point, dismantle anything on either yet so to put things in perspective, what I really know about these systems wouldn't slosh out of a teaspoon if I was running down a hill in a three legged race.

... in a snow storm... alright, but you get it.
 
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