ST1300 SMC

[steve wheeler]

I have just completed overhaul on my 2002 ST1300 SMC.

Question.... can anybody confirm if there is a measurement for the piston stroke? I'm unable to move (by hand) in either direction, cant find any info in the workshop manual so was wondering if this was right, any advise would be most welcome.

Thanks Steve.

 

[Tom Mac 04a]

On the center stand, spin the rear wheel... while turning push the SMC in. The brake should stop the wheel and when released the wheel should be free again... If I remember right there is very little play when freshly bleed properly ( or rebuilt ) maybe a couple of mm's to activate the brake by hand.

 

[okmurdog]

Yes, the SMC has very little movement when mounted to the bike and operating correctly (as stated above). If you follow the brake bleed sequence mentioned here, the SMC should have an approximate piston stroke of around 1/2" IIRC.

 

[p3210]

fyi - If your checking the SMC (as identified in post #2) and your doing this by yourself... to spin the rear wheel and simulaneously push the SMC in, simply lay on your back - spin the rear wheel with your feet and push up on the smc with your hands. I just read about this technique earlier this week via this forum - so no credit to me, just passing on info. Thanks and best of luck with your project.

 

[steve wheeler]

Thanks Guys,

Have checked my SMC tonight, only have approx 1/4" inch movement (in) before the rear brake operates, when the SMC is released the rear wheel rotates approx 3 revolutions before completely free. will take the ST out tomorrow for a trial. will keep you posted.....once again THANKS.

 

[p3210]

FYI - my smc doesnt move much either. What distance of movement is too much or too little - I havent figured that one out yet.
From your post it sounds like, once you release the smc it take 3 rotations before the rear wheel will spin freely.
FYi2 - a post about how freely the rear wheel should spin:
https://www.st-owners.com/forums/showthread.php?46064-Clarify-quot-normal-quot-rear-brake-drag-please&

If your rear brake is dragging .... FYI3 is a thread about it:

https://www.st-owners.com/forums/showthread.php?35733-Rear-Brake-Dragging/page7

 

[dduelin]

My SMC has only 2 mm or so movement by hand to apply rear brake, 1/4" (6 mm) would seem to be way too much.

 

[okmurdog]

Yes, you should have very little movement by hand when the SMC is installed. Both my bike and my wife's bike move ~ 2-3 mm.

If you are getting significantly more movement, there may be an air bubble in the SMC circuit. The only time you should get ~ 1/2" piston travel is when the hydraulic circuit is open (ie; bleeding the brakes).


Sent from my iPhone using Tapatalk

 

[steve wheeler]

Update.....Thanks for all your comments/advise have decided to grab the bull by the horns, removed rear wheel and caliper, removed pads cleaned and lubed pistons,and pins, checked rear disc (or as you guys call rotor) 7mm still within spec, copper slip caliper sliders, re grease drive splines and rebuild, removed SMC rubber boot filled with silicon, re bleed brake system (no apparent air bubbles present) took the ST for a ride......have completed some 80 miles this afternoon, (A & B roads.. Motorways) all types of braking from emergency stops to light braking in town, stopped several times during the ride to check rear brake disc, on most occasions the disc was warm to the touch, however, no more than i would expect, on return to the garage with the ST on centre stand the rear wheel rotates freely, however, still have slight drag from the pads. any further developments will keep you posted.

 

[Tom Mac 04a]

however, still have slight drag from the pads

a slight drag and/or noise is ok as pads will not retract off the rotor just have no pressure... the better test is if the wheel spins freely and the temp is not hot on the rotor ( compare to fronts )

 

[steve wheeler]

The rear disc/rotor is slightly warmer than the front's but negligible.

Thanks again.

 

[Tom Mac 04a]

The rear disc/rotor is slightly warmer than the front's but negligible.

I'd say your fine

 

[okmurdog]

I'd say your fine

+1

Sounds normal to me

 

[steve wheeler]

Cheers Guy's

Have a nice day.