Page 1 of 3 123 LastLast
Results 1 to 10 of 29

Thread: ST1300 - Photos of dismantled SMC

  1. #1
    John Heath jfheath's Avatar
    Bike
    ST1300A9 (2013)
    Join Date
    Mar 2006
    Location
    Ilkley, West Yorkshire, UK
    Posts
    2,190
    Tip Overs
    2
    2017 Miles
    005856

    My Gallery

    ST1300 - Photos of dismantled SMC

    A while ago I posted a query concerning some off behaviour on a friends braking system. The symptoms were that in spite of getting rid of the air in his brakes and the brakes feeling absolutely fine, over a period of miles, his left SMC calliper would start to chatter and his rear pedal would go soft. A few pumps of the pedal and his rear brake would return to normal. I spent a long time with him over the phone to make sure that this wasn't an air issue and produced the article that I posted here 'Getting all of the air out of the Brake System'. He worked on the brakes with a friendly mechanic - always ending up with the same result. Brakes initially OK, and would get worse over a few miles.

    In the meantime, he did some tests for me and we decided that in spite of the SMC service kit having been replaced in the last couple of years, that the full SMC bracket would be required. Last week, he fitted the new bracket and everything is working properly and better than they have ever done. Yesterday, I received a parcel in the post. His old SMC ! So naturally, I took it apart and took some photos - which I thought I would share. Click the thumbnails to see a larger 800x600 image.

    First - various views of the SMC taken from an ST1300A4 bike. Note the little drain hole at the left end of the master cylinder in the first pic - modified in the last photo which is from my ST1300A9

    Click image for larger version. 

Name:	SMC-ST1300A4-01.jpg 
Views:	148 
Size:	42.1 KB 
ID:	180879 Click image for larger version. 

Name:	SMC-ST1300A4-02.jpg 
Views:	121 
Size:	47.2 KB 
ID:	180880 Click image for larger version. 

Name:	SMC-ST1300A4-03.jpg 
Views:	126 
Size:	70.1 KB 
ID:	180881 Click image for larger version. 

Name:	SMC-ST1300A4-04.jpg 
Views:	108 
Size:	63.6 KB 
ID:	180882 Click image for larger version. 

Name:	SMC-ST1300A4-05.jpg 
Views:	113 
Size:	46.2 KB 
ID:	180883 ....... ST1300A9 --> Click image for larger version. 

Name:	SMC - ST1300A9.jpg 
Views:	139 
Size:	73.3 KB 
ID:	180901

    --

    Prior to removing the circlip to release the piston from the cylinder bore. The circlip is particularly difficult to access - even with the unit off the bike on the work bench. The lack of light and rubber boot and the plunger being in the way hinder things considerably. Note that in the last photo, I gave up and removed the bracket and the boot in order to get a better view. This should not be done unless a new piston service kit is to be fitted. The securing bolt is set to the correct length at the factory, and the correct length is critical.

    Click image for larger version. 

Name:	SMC-ST1300A4-06.jpg 
Views:	119 
Size:	77.8 KB 
ID:	180884 Click image for larger version. 

Name:	SMC-ST1300A4-07.jpg 
Views:	112 
Size:	74.4 KB 
ID:	180885 Click image for larger version. 

Name:	SMC-ST1300A4-08.jpg 
Views:	108 
Size:	69.4 KB 
ID:	180886 Click image for larger version. 

Name:	SMC-ST1300A4-09.jpg 
Views:	129 
Size:	79.0 KB 
ID:	180887

    ---

    In the next sequence, the piston has been removed. The photos show the amount of crud that has built up behind the boot. This unit was greased behind the boot and the drain hole was kept clear. Nevertheless, this is a mess.

    Click image for larger version. 

Name:	SMC-ST1300A4-10.jpg 
Views:	135 
Size:	45.3 KB 
ID:	180888 Click image for larger version. 

Name:	SMC-ST1300A4-11.jpg 
Views:	100 
Size:	28.5 KB 
ID:	180889 Click image for larger version. 

Name:	SMC-ST1300A4-12.jpg 
Views:	103 
Size:	67.2 KB 
ID:	180890 Click image for larger version. 

Name:	SMC-ST1300A4-13.jpg 
Views:	100 
Size:	27.5 KB 
ID:	180891 Click image for larger version. 

Name:	SMC-ST1300A4-14.jpg 
Views:	91 
Size:	34.5 KB 
ID:	180892 Click image for larger version. 

Name:	SMC-ST1300A4-15.jpg 
Views:	93 
Size:	101.4 KB 
ID:	180893

    ---

    Here I have turned the bracket over and removed the inlet port cover plate, which is retained with 2 small bolts, which have thread lock applied. Underneath is a rubber ring and a small white cylindrical cartridge - the SMC inlet port valve and the relief port

    Click image for larger version. 

Name:	SMC-ST1300A4-03.jpg 
Views:	126 
Size:	70.1 KB 
ID:	180881 Click image for larger version. 

Name:	SMC-ST1300A4-16.jpg 
Views:	81 
Size:	24.6 KB 
ID:	180894 Click image for larger version. 

Name:	SMC-ST1300A4-17.jpg 
Views:	89 
Size:	78.1 KB 
ID:	180895 Click image for larger version. 

Name:	SMC-ST1300A4-18.jpg 
Views:	87 
Size:	72.0 KB 
ID:	180896

    ---

    The Inlet port valve and relief port cartridge. both sides have a very fine mesh gauze. I haven't yet dismantled it. The last two photos show the inside view of the inlet port and the tiny relief port.

    Click image for larger version. 

Name:	SMC-ST1300A4-19.jpg 
Views:	74 
Size:	55.2 KB 
ID:	180897 Click image for larger version. 

Name:	SMC-ST1300A4-20.jpg 
Views:	74 
Size:	65.0 KB 
ID:	180898 Click image for larger version. 

Name:	SMC-ST1300A4-21.jpg 
Views:	77 
Size:	80.7 KB 
ID:	180899 Click image for larger version. 

Name:	SMC-ST1300A4-22.jpg 
Views:	77 
Size:	117.5 KB 
ID:	180900

    These photos are just for info for anyone who is interested and may find them useful.

    The fault ? Well the metal 'cup' at the end of the piston which is closest to SMC plunger was a very tight fit inside the cylinder bore. There was no build up of crud just inside the bore - in spite of the amount on the outside, and the metal cup didn't feel rough. When the piston was pushed inside the bore, it met with resistance once the secondary seal was inside - the metal cup was tight against the sides. When it was pushed in further, it eased up and would return part way under spring pressure.

    This sounds like the classic situation which often results in the SMC not returning and causing the back brake to lock, but this wasn't the case - on the contrary, the pedal lost pressure.

    As it stands at the moment, I reckon that the cylinder has had a slight knock and has become slightly oval. Although the secondary seal was doing its job the fluid was able to move back past the primary seal, resulting in the long pedal and chattering SMC bracket. My diagnosis might be wrong but its a working theory.

    [Edit]A separate link here shows pictures of a brand new SMC unit for a 2008-onward ST1300, including a measurement for the plunger.[/Edit]
    Last edited by jfheath; 10-20-2017 at 12:18 AM. Reason: Added link to Images of a New SMC

  2. #2
    AdminiSTrator Mellow's Avatar
    Bike
    ST-1200
    Join Date
    Dec 2004
    Location
    Carrollton, TX
    Age
    53
    Posts
    26,746
    Tip Overs
    2
    2017 Miles
    012235

    My Gallery

    Re: Photos of dismantled SMC

    Very nice! Thanks John!

  3. #3
    Site Supporter Ashley's Avatar
    Bike
    2004 ST1300
    Join Date
    Aug 2009
    Location
    Jacksonville, Florida USA
    Age
    54
    Posts
    962
    Tip Overs
    3
    2017 Miles
    013459

    My SPOT
    My Gallery

    ST1300 - Photos of dismantled SMC

    I seem to remember someone having the same issue a while back and discovered the bore was not perfectly round as well. Maybe V8-Stan.


    Sent from my iPhone using Tapatalk
    Ashley Horn
    2004 ST1300
    STOC# 4906
    IBA# 62013
    Ok, the AZ trip was a fly and rent a Goldwing trip...

  4. #4

    Re: ST1300 - Photos of dismantled SMC

    I had an out-of-round piston by about .25mm that was enough to bind the piston in the bore.

    http://www.st-owners.com/forums/show...air&highlight=

    Now have about 50K miles on the repair with no problems.

    Also if you need to remove the bracket and boot ( quote: " removed the bracket and the boot in order to get a better view. This should not be done unless a new piston service kit is to be fitted. The securing bolt is set to the correct length at the factory, and the correct length is critical.")
    measure the protruding end of the bolt or count the turns to remove the nut, so you can reset it to the original length .

  5. #5
    John Heath
    (Threadstarter)
    jfheath's Avatar
    Bike
    ST1300A9 (2013)
    Join Date
    Mar 2006
    Location
    Ilkley, West Yorkshire, UK
    Posts
    2,190
    Tip Overs
    2
    2017 Miles
    005856

    My Gallery

    Re: ST1300 - Photos of dismantled SMC

    Thanks for including that link V8-7. As i was taking this one apart, it reminded me a post i had read ages back a piston being 'skimmed' . Good to re- read it and compare the pics.

    Good suggestion about measuring or counting - it helps to emphasise the importance of the correct length. In my case it was 9 half turns ! The movement in the Smc is so small when operating, that even a fraction too long and the piston will not clear the relief port when it returns - potentially resulting in the dreaded rear brake lock. I didn't want to inclue a photo with the bracket removed without referring to what Honda say about it.

  6. #6
    Dave.David's Avatar
    Bike
    2004 ST1300A
    Join Date
    Dec 2016
    Location
    LA California USA
    Posts
    570
    2017 Miles
    003000

    My Gallery

    Re: ST1300 - Photos of dismantled SMC

    Great info, any idea how to prevent this? Can we keep the "drain hole" clear? Which hole is the drain hole? Lol. No really, which hole

  7. #7
    John Heath
    (Threadstarter)
    jfheath's Avatar
    Bike
    ST1300A9 (2013)
    Join Date
    Mar 2006
    Location
    Ilkley, West Yorkshire, UK
    Posts
    2,190
    Tip Overs
    2
    2017 Miles
    005856

    My Gallery

    Re: ST1300 - Photos of dismantled SMC

    Quote Originally Posted by Dave.David View Post
    Great info, any idea how to prevent this? Can we keep the "drain hole" clear? Which hole is the drain hole? Lol. No really, which hole
    The A4 had this hole which just leads to a channel behind the boot.

    Click image for larger version. 

Name:	ST1300A4 Drain Hole.jpg 
Views:	61 
Size:	16.7 KB 
ID:	180910


    The A9 has this channel which drains from the front.

    Click image for larger version. 

Name:	ST1300A9 Drain Hole.jpg 
Views:	61 
Size:	41.1 KB 
ID:	180911

    Suggestions include putting silicon grease behind the boot to stop water getting in. Problem is - If it does get in, then it can't get out. Heavy rain at 70mph.

    I rode my first A6 for 70,000 miles in all weathers - including Yorkshire winters when the roads are heavily gritted and salted. I started getting the sign of problems at 70,000 - I bought the service kit and never used it - I traded in for a new bike. So the kit went to my friend. The same service kit is the one that has just been taken out in the photos - so that didn't last long - possibly due to problems with the cylinder bore ?

    What would cause this deformation, I don't know - but it is quite an exposed component when manoeuvring the bike in tight spaces - like the garage for example. I wonder if small knocks against the SMC bracket would cause this ? I really don't know. I'm speculating.
    Last edited by jfheath; 03-24-2017 at 04:49 AM.

  8. #8
    Still above the sod ibike2havefun's Avatar
    Bike
    2004 ST1300
    Join Date
    Jan 2015
    Location
    Rockville, MD, USA
    Posts
    776
    Tip Overs
    6
    2017 Miles
    007876

    My SPOT
    My Gallery

    Re: ST1300 - Photos of dismantled SMC

    Thanks for the very detailed info. I hope never to have to put that information to use, but if I do... I know where to look.
    -= Keith Adams =-
    Rockville, MD, USA
    STOC # 8824 -- Embarrassingly high but it's mine


  9. #9
    Catmandu2's Avatar
    Bike
    '04 ST1300 Blue STar
    Join Date
    Sep 2015
    Location
    Wasaga Beach, Ont. Canada
    Posts
    516
    2017 Miles
    012400

    My Gallery

    Re: ST1300 - Photos of dismantled SMC

    Great photo report, John. One thought occurred about your friends smc,, is that it had been repaired/serviced prior, as indicated by the presence of the silicon grease. I think brake dust and moisture combine to create this oxidized muck that then dries out somewhat on sunny days. Better shielding, in addition to the oem rubber boot might help keep more contamination from being caught up in the rather open cupped upper end of the smc. Might be worthy of some thought, given your typically rainy rides,,, Cat'

  10. #10

    Re: ST1300 - Photos of dismantled SMC

    John, thanks for posting the pictures. Looking at the picture of the piston, it appears that the rubber bits have worn down to allow the metal piston body to come in contact with the bore (see shiny wear spots on the fins) several things to be at work here, the grime and crap on the push rod head and around the end of the assembly, air in the system, the rubber not keeping the piston centered perfectly in the bore, the spring getting weak and taking a set, also would allow the piston to not be centered in the bore, and could cause it to cant or bind etc.
    Every bad SMC I have taken apart, I have always found wear on the top inside of the bore. It may only appear as a dark shadow or ring just inside the bore, but once measured, it revealed that the bore was no longer true.
    Once again, thank you for posting such great pictures, and going the extra mile to help the other members, you are a true gentleman.
    Larry
    Last edited by Igofar; 03-24-2017 at 04:12 PM.

+ New Posts
Page 1 of 3 123 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •