SMC & Brake Flush

[Jjonahjamison]

I have done the brake flush procedure several times without too much trouble, including the removal of the SMC and hanging it at a 15 degree angle for the procedure.

I am going to do a brake flush before I trailer the bike south for the winter. I flushed my brakes last fall, so am definitely ahead of the 2 year interval.

However, this has occurred to me: If all we are looking to achieve is to flush old brake fluid and replace with new (not looking to bleed air out of the system) is there a reason to remove the SMC and put it at the 15 degree angle. Won’t the new fluid just push through the SMC piping? I use the Motion Pro one-way bleed valve which should stop any air from being sucked in.

I know its not a big deal to remove it, but hey, why do it if it doesn’t need to be?

Anyone have any thoughts?

Thanks.

 

[Duporth]

I think the 15 deg tilt is to aid removal of sneaky little trapped air bubbles. These can hide in many places in the hydraulic system even after several flushes.
Refer to 'Articles' where there are detailed papers by J Heath on the subject.
D

 

[Igofar]

Do you think air gets in the System just by being sucked in?
Brake fluid not only collects moisture in the system, but heat creates air in the system etc.
You flush the system to remove all the crap in the fluid, not just to remove air.
Short answer, bleed the entire system correctly, and mount the SMC on something firm, hanging it won’t always get all the air/fluid out correctly.

 

[SMSW]

I

Anyone have any thoughts?

I made the same point some years ago - maybe 5 years. I received the same answer. When in doubt, and when all else fails, read the instructions. The Honda Manual makes no distinction between bleeding air out or changing fluid. Rather than admit defeat, I decided bleeding was a good time to lube the SMC bearing/pivot. I always tilted it that 15 deg even though a hard brake meant no air in the system. Yup, I did it by the book, even though I'm not convinced the other argument is correct.

 

[Jjonahjamison]

Thanks experts!

 

[Catmandu2]

you want to flush the clutch as well. The stagnant fluid,trapped in the css turns to goo,,, with all the heat. cheers,, CAt'

 

[Al Gully]

However, this has occurred to me: If all we are looking to achieve is to flush old brake fluid and replace with new (not looking to bleed air out of the system) is there a reason to remove the SMC and put it at the 15 degree angle. Won’t the new fluid just push through the SMC piping? I use the Motion Pro one-way bleed valve which should stop any air from being sucked in.
Anyone have any thoughts?

My thoughts are just like your thoughts, and you're asking for thoughts.
This is my second ST that I picked in in May 22. It looked like it went up to Alaska and back before the PO sold it to me.
Covered in this mud that turned anything that had carbon steel in it and had no zinc, paint or chrome coating on it, was rusting terribly. My bad is I didn't want to have any downtime on it and all I wanted to do was to ride it daily to work and a occasional long trip on weekends.
Long story short, rather than do nothing, I did exactly what you mentioned above until I have enough time to follow the correct procedure.
Out of the 2 bleed nipples on the rear caliper, I was amazed of the slime that came out of both of them even while I wasn't following word for word, the correct procedure mentioned in the ST manual.
Did not bleed the 2 nipples on the front calipers yet either from the rear reservoir.
As we say at work, solution is by dilution
Still have'nt bled the front reservoir, as it is on a separate circuit.
Also, when I get to work or get home, I occasionally touch all 3 rotors and they are all the same temperature.
All 3 rotors feel like a warm mug of coffee.
Brakes feel good and I feel good and the slime has been removed from the rear caliper and SMC.

 

[Jjonahjamison]

you want to flush the clutch as well. The stagnant fluid,trapped in the css turns to goo,,, with all the heat. cheers,, CAt'

Thanks, I did the clutch first during which time I got to thinking about the SMC procedure. Wow, that slave cylinder does look nasty!