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Apologies in advance for repeating what you have already suggested Duck. The rear brake pedal pressurises the entire system front and rear through the DV, SMC and PCV. The front brakes release, so the DV and Rear Master Cylinder are ok. Pressure is not being released by either the PCV or SMC. Try cracking the lines in the correct sequence to determine if it's the PCV or SMC, e.g. press then release the pedal to make the rear drag then crack the relevent line. When you crack the line, pressure will be released and the rear wheel will/should be easy to turn instantly. Crack the line between the PCV and SMC first and if the brake releases, then the SMC is faulty and the PCV is ok. Yes you'll have to bleed the system again,,, argh!! The PCV should be fine unless it has been blocked by crud. But as The Duck said, it has to be the SMC. Either the check valve is blocked or the compensating port is covered by the piston cup. The below links relate to the Goldwing but they may be applicable, for a clue. I still think it's crud, but this is what I meant by making sure the ports aren't being blocked by a poorly adjusted SMC. There are no specs for the Blackbird. Hopefully someone can measure a factory set one? It's getting late here so I hope what I typed makes sense. The system is very basic and it's all about fluid transfer. Where does the fluid flow and what could restrict or block the flow. GL1800 Secondary Master Cylinder Photo by BobUSNA71 | Photobucket http://m7.i.pbase.com/g4/41/9841/2/140126307.ZJzHejVG.jpg
 

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I had a think about this and I believe the outer rear pistons should move with just the pedal and then be assisted by the SMC further in to the braking.

When the SMC is in it's fully retracted position - the small port in the side allows fluid from the pedal line - straight through the SMC and out to the rear caliper (outer pistons )
Only when the delay valve has allowed the activation of the front centre pistons will the SMC activate and increase the pressure further on the outer rear pistons.


I think the SMC is not returning fully OR the tiny return hole in the side valve is blocked.
I could have gone to bed much earlier if I had of seen your post!!! Took me ages to type my post :( Good work and he'll get it sorted. He'll be cranky and frustrated but sorted
 

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Discussion Starter #43
OK...i took the secondary master cylinder appart...AGAIN...

I found that in the plastic valve inside, one tiny hole was blocked. It was a pain to clean it. I used a small coper wire like in the pic, but i had to struggle a bit, since the blockage was too strong.

I dont have time right now to re-assemble everything...but later today i`ll see if this was the MISTEREOUS CASE of my rear brake drag.

(the pic shows the hole that was blocked.) va1.jpg va2.jpg
 

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I've got my fingers crossed for you eduardo but assuming that you have got all the brown mess out of the whole system I've got a good feeling ......

Some interesting thoughts CBRDEANO, I suppose the only way to work out exactly how much effect the rear pedal has is to work out the volume of fluid moved to the front and how much is used to push out the central front pistons (indeterminate because it depends on pad to disc clearance). Any excess fluid is then cycled into the SMC to be used when the SMC is activated, it can only be the excess otherwise pressure on the centre pistons would drop..... or perhaps it does!
Testing in the garage/workshop makes the system work in an unnatural way (does anybody stamp on the rear and not touch the front when out riding?) so to me it is no surprise that we see some strange effects.
 

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OK...i took the secondary master cylinder appart...AGAIN...

I found that in the plastic valve inside, one tiny hole was blocked. It was a pain to clean it. I used a small coper wire like in the pic, but i had to struggle a bit, since the blockage was too strong.

I dont have time right now to re-assemble everything...but later today i`ll see if this was the MISTEREOUS CASE of my rear brake drag.

(the pic shows the hole that was blocked.) View attachment 79578 View attachment 79586
That's the one - so many people don't see it when cleaning.
 

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Some interesting thoughts CBRDEANO, I suppose the only way to work out exactly how much effect the rear pedal has is to work out the volume of fluid moved to the front and how much is used to push out the central front pistons (indeterminate because it depends on pad to disc clearance). Any excess fluid is then cycled into the SMC to be used when the SMC is activated, it can only be the excess otherwise pressure on the centre pistons would drop..... or perhaps it does!
Testing in the garage/workshop makes the system work in an unnatural way (does anybody stamp on the rear and not touch the front when out riding?) so to me it is no surprise that we see some strange effects.
As far as I can work it out - the pressure in the front centre pistons won't drop.

You apply the pedal - this pushes the centre rear piston and sends fluid forwards via the delay valve to the front centre pistons.
It also allows fluid to pass through the SMC to activate the outer rear pistons ( this is also how the rear of the system compensates for pad wear )
As the SMC activates - it closes the side port of the SMC so the pedal to front centre pistons is now a sealed system ( and keeps the pressure applied with the pedal )
 

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Discussion Starter #47
UPDATE...
I installed the plastic valve into the secondary master cylinder again.

THE REAR BRAKE KEEPS DRAGGING.

With the help of a flat screw driver, i push the rear pads away from the disc, then pump the secondary master cylinder ONLY.
Rear brake stops the rear wheel as expected. Leave the SMC and the rear caliper lets the rear wheel spin free...as expected.

With the help of a flat screw driver, i push again the rear pads away from the disc. Pump the rear brake ONLY and the rear caliper gets stuck and drag appears again.

I never got so serious about taking the bike to a dealer and trade it for something else.


(3 calipers cleaned, SMC cleaned, plastic valve cleaned, Rear master cylinder cleaned, PCV cleaned, brake fluid flush...about 1.000 times.)
 

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UPDATE...
I installed the plastic valve into the secondary master cylinder again.

THE REAR BRAKE KEEPS DRAGGING.

With the help of a flat screw driver, i push the rear pads away from the disc, then pump the secondary master cylinder ONLY.
Rear brake stops the rear wheel as expected. Leave the SMC and the rear caliper lets the rear wheel spin free...as expected.

With the help of a flat screw driver, i push again the rear pads away from the disc. Pump the rear brake ONLY and the rear caliper gets stuck and drag appears again.

I never got so serious about taking the bike to a dealer and trade it for something else.


(3 calipers cleaned, SMC cleaned, plastic valve cleaned, Rear master cylinder cleaned, PCV cleaned, brake fluid flush...about 1.000 times.)
Wild guessing now - is the plastic valve fitted the correct way ?
P1010764.JPG

Also - another thought - have you tried pulling the pin that attaches the pedal to the rear master to see if it is the pedal not returning fully ?
 

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Discussion Starter #49
Pedal is returning fully. Plastic valve mounted the right way.
By the CBS scheme, if you pump the rear pedal, oil goes directly from the rear master cylinder to the centre caliper piston...but it also flows to the front calipers, secondary master cylinder, PCV and rear outer caliper pistons.
I`m guessing the problem here is a very slow oil return when you leave the pedal.

Only two parts are directly involved into oil return...secundary master and rear master cylinder. Am i right????

If so, the SMC or the RMC is not being capable of dealing with the return from the whole system.

Thats what i am guessing right now...
 

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Only two parts are directly involved into oil return...secundary master and rear master cylinder. Am i right???? And the delay valve
 

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There was another thread ( not sure which forum ) where a guy was having this sort of issue.

The culprit ended up being the brake line running down to the SMC and then on to the caliper.

It was blocked fully with crap. fluid under pressure got through the crap but the return flow was not happening.

he replaced that one brake line and everything was sorted.
 

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Discussion Starter #53
by making sure the ports aren't being blocked by a poorly adjusted SMC. There are no specs for the Blackbird.
I still dont understand this. If you mess with the SMC adjustment, all it does is sitting the left caliper higher or lower. The piston inside takes the same travel lenght allways. Kind a like adjusting the height of the rear brake pedal. Same principle.

Well...at least in my head...
 

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I still dont understand this. If you mess with the SMC adjustment, all it does is sitting the left caliper higher or lower. The piston inside takes the same travel lenght allways. Kind a like adjusting the height of the rear brake pedal. Same principle.

Well...at least in my head...
Not quite.
if you move the pushrod bracket too far down - the caliper is still held up by the brake line and holds the piston in.

The adjustment must allow the pushrod to come out fully whilst the caliper is attached to the brake line.
 

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Yes...the front pistons are operating.
Last night at the garage, with the help of a pressure plier, i cut the brake oil flow at the rubber hose near the rear brake caliper.

If i cut the flow from the hose that brings the oil from the front, the rear brake is fine. No problems. (I am performing this test just by operating the rear pedal with the bike stopped.)

If i cut the flow from the hose that comes directly from the rear master cylinder to the rear caliper and just leave the oil flowing from the rear master cylinder to the front brakes then into the rear caliper...the rear brake gets stuck and the wheel drags.

I did some research on google about CBS rear wheel drag and found some recalls for this problem with the Goldwing models. Honda changed the secundary master cylinder to solve the problem.
Hi eduardo, i have no idea what the inner core of the brake hose is made off or what tool you used to cut the flow of brake fluid, but is there a chance you may have crushed the hose enough to damage the inner core? If the inner core has now collapsed, could that be your flow restriction?
 

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Excellent! Where does it come from? Is there more of this?
Stumbled on it whilst googling. I've done numerous searches but can't locate any more details other than the image I posted. A search did relate to something on the goldwing site Honda Goldwing Discussion Forum, Service Manuals, DIY How-To Articles and Much More ? goldwingdocs.com but I'm not joining it to find out. It's obviously a huge problem on the US goldwings (more liability lawyers per capita I'd say) which resulted in a number of recalls which haven't solved the problem. We'll wait and see what the latest recall solves, or doesn't.
 
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