SMC and Props to those Here

Joined
Apr 14, 2012
Messages
129
Location
Mississippi
Bike
2007 ST1300
First off, new st owner and new to the Linked Braking system. (steep learning curve)
Want to thank all of those who have posted different smc threads and solutions, mostly Igofar, echo, mellow and all others and st-owners.org in general.
echo, you da man :bow1: when it comes to bleeding hydraulic system. gravity method works awesome!!! did the clutch fluid in 20 min, no vacuum drawing tools.
now i will get to the point.
started off as a brake drag which progressed to almost complete rear brake lock up. after extensive searching, reading, and a service manual, felt i was headed in the right direction. which progressed to this




upon disassembly and complete field stripping of the front brake caliper and SMC, this is what i found. it looked more like a squirrel's nest than a clean functioning hydraulic braking system. clearly, absolutely no grease, lubricant, or rust inhibiting preventive actions were taken on this little jewel...



i'm thinking...houston, we have a problem at this point. probably not a lot of plunging going on here.



hard to see in the photo, but the ball plunger thingy was completely rusted, pitted, and pretty much buggered up beyond repair.


this is what the actual brake cylinder looked like


i did manage to polish and potentially salvage the SMC bore with 00000 steel wool


and now, the waiting game begins. waiting for the UPS man and my parts to arrive.


again, thanks to all who have posted and hope this helps someone down the line.
sd
 

Attachments

Saint Joe

Joe
Joined
Nov 24, 2008
Messages
94
Location
Edmonton, Alberta, Canada
Bike
'12 ST1300A
I took Wednesday off from work to dig into my problem - suspect it will be similar.....we'll see.

Want to thank all of those who have posted different smc threads and solutions, mostly Igofar, echo, mellow and all others and st-owners.org in general.
+1

Joe

PS: Great Pics!
 
Last edited:
OP
OP
scooterdoc
Joined
Apr 14, 2012
Messages
129
Location
Mississippi
Bike
2007 ST1300
I took Wednesday off from work to dig into my problem - suspect it will be similar.....we'll see.


+1

Joe

PS: Great Pics!
thanks joe. hopefully the thorough cleaning, teflon taping, lubing and bleeding and clean new parts will resolve this issue. i guess while i'm waiting, i can do the valves and thermostat.
 
OP
OP
scooterdoc
Joined
Apr 14, 2012
Messages
129
Location
Mississippi
Bike
2007 ST1300
How many miles? What year ST? You have used the same brake fluid over the life of the bike??
Something is not right,,,, Oh I see a 2007 ST,,,, Thats a lot of junk in there....
Would it not be easier to just buy a new SMC and install it
Mike
iride,
it is a 2007, new to me. had it less than 3 weeks or so. it would have been easier to replace SMC but until i got there, wasn't sure of the exact problem. (started with rear caliper). as far as the brake fluid, looked fresh, but after completely disassembling the entire system, i have a strong suspicion that someone incorrectly bled the brake system to solve the problem. i noted teflon tape on only 3 of the many bleeder valves. others had no tape. i have done a couple of calipers over the years on race bikes and found most braking and caliper problems are due to simple inexpensive seals and can be solved pretty easily.

short answer, a SMC replacement would have been easier, and may very well still be required. but i kinda enjoy finding the problem and solving the mystery, and sharing the knowledge so that others may potentially benefit.

cheers
chris
 
Joined
Jan 8, 2011
Messages
7,062
Location
Arizona
Bike
2007 Honda ST1300A
Be on the safe side, order a new unit. With that much corrosion on it, you may have damaged the bore.
I see this alot on bikes that are ridden near the ocean (salt corrosion).
Poor design if you ask me. When you rebuild it, or replace it (better) pack the rubber boot with silicone grease. Also make sure you keep it dry after you wash it, or blow it off after riding in the rain.
It will help them last longer.
Call me on the White Courtesy phone and we'll chat some about it.
Nice job on the photos.
Igofar
 
OP
OP
scooterdoc
Joined
Apr 14, 2012
Messages
129
Location
Mississippi
Bike
2007 ST1300
update on the maintenance marathon.

with the awesome help from Igofar, i was finally able to sort out the brake bleeding and SMC issue. You are obviously the subject matter expert on this and i REALLY appreciate you call and help. I feel relatively certain I would still be screwing up at a high rate of speed if it weren't for your help.

while i was in the garage, other things done included the air filter which looked like this;



so it was out with the old and in with the new


after valve check, i moved on to the radiator and thermostat inspection, replacement and fixes. i found plenty of black overspray in the inlet and outlet ports which cleaned up with a little scotch bright.



lastly after some new ngk iridium cr9ehix-9, i rolled it out, started it up and waited for the bike to self implode. it did not.


anyway, thanks larry, and to those who have posted useful comments and suggestions. they are all read and appreciated. certainly could not have done it without this site and it's great members. once it's cooled off, on goes the plastic and time to scrub some PR3's.

SD
 
Last edited:
Joined
Jun 26, 2014
Messages
15
Location
Devon. UK
Bike
ST1300
Had same problem with my SMC so striped down to service it with new plunger kit. But can anyone tell me what the little white plastic barrel is inside the SMC under the banjo union with two bolts ( you can see it in picture to left of caliper seals) or whats its function is, i'm guessing it's a one way valve or a small filter possibly. Mine popped out along with a O ring and I'm not sure which way up it goes back in as one end is slightly tapered and you can see a little red tab inside it through mesh at one end.

I'm wondering if its a one-way valve and if in upside down this may be the reason rear brake still drags a bit even after fitting new SMC plunger kit (the upgraded one from Honda). if its not allowing brake fluid pressure to return. Any help would be much appreciated.
 
Top Bottom