Symptoms of Your SMC going South!

[Igofar]

"I thought my SMC was good"...."The wheel stopped turning, then released when I sqeezed the SMC like it should"... "My rear rotor always feels warmer than the front"...
"I don't notice anything different"...."Brake pads are just dirty or dusty"...

Any of these sound familar? I flush and bleed my brakes 2 X a year and my SMC still went south on me! I always made sure it was clean and dry under the boot.....I even filled the area up with silicone grease to waterproof it better....

When I pulled mine out at 19K it was TOAST! Corroaded, pitted and jammed in the housing....and yes my I checked my SMC by turning the wheel and pushing it forward to lock the rear wheel almost weekly...

Here are some of the subtle signs I've noticed when these things go bad, or start to go bad...

1. Bike becomes just a little heavier to push into the garage
2. The bike has this strange little WIGGLE just when you start to take off! (heard that before?) its all over the forum, thinking its suspension or tires. Well guess what, its the rear brake rotor grabbing, causing it the WIGGLE. Mine went away the moment I changed the SMC.
3. when you roll your bike BACKWARDS with the engine off, you hear a slight scraping or groaning sound.
4. You hear scraping sounds as you stop.
5. You think you simply have dirt on your brake pads.
6. The rear rotor is hotter to touch than the front rotors.
7. Your rear wheel won't freely turn more than 1 turn when spun by hand.
8. Your brake fluid is dark brown, or has white stuff in it, and has not been changed often.
9. Your brakes have not been bled properly or often enough
10. You pull back the rubber boot and see pitting or corosion on the rod.
11. Pond scum oozes out when you pull the boot back.
12. The bike feels funny as you let off the throttle, rolling into a turn (BIGGIE HERE)
13. You feel a groaning or vibration in the shifter lever against your foot that feels like the transmission or driveshaft issue.
14. Your rear brake pads wear out often (should get at least 20K out of them)
15. Your rear brake pads wear wedged shaped (BIGGIE)
16. The bike starts handling funny or just off enough to feel like somethings not right, but you can't put your finger on it.
17. Slow speed handling is harder than before.
If you have any or several of these symptoms, I would strongly urge you to PLEASE CHECK YOUR SMC.

The test is really simple
Lie on the ground on the left side of the bike and take your foot and spin the rear wheel. While its turning, push the SMC forward and watch the rear wheel lock up.
When you release the SMC the rear wheel should spin FREELY again.
Mine was only spinning about ONE revolution around. I thought that was normal because of the pads and shaft drive. This is not normal.
The wheel should spin TWO to TWO AND A HALF turns around with a single, firm spin.
The SMC should also move FREELY back and forth. You shouldn't have to get a death grip on it to move it forward.
You should simply be able to push it forward with a couple fingers pressure.

My guess is there is a whole lot more dying SMC's out there than we are willing ot admit.

Please be safe and check yours today.
Ride safe.
Igofar

 

[Coucours Grad]

Stupid Question.....


Define SMC....



I'll go sit at the very back of the classroom now.

 

[silverbub]

this is where i am looking for that neat emoticon with the student waving hand in air..."pick me to answer the question"...or in this case: "teacher...SIR!...i have a question"...just where is this SMC on left side of st1300 & does any plastic need to be taken off?...(obviously, asking w/o a service manual)...thanks!

 

[MidLife]

check yours today....and report defect to the NHTSA.

This board should have enough weight to push Honda for a real solution, instead of the tentative patches they have tried so far.

Honda found the real solution: no more SMC on newer bikes! But in the mean time, we are stuck with this dangerous nonsense.

There probably would be more action from Honda if a LEO had experienced a rear wheel Lock Up..........

 

[st1300r]

this is where i am looking for that neat emoticon with the student waving hand in air..."pick me to answer the question"...or in this case: "teacher...SIR!...i have a question"...just where is this SMC on left side of st1300 & does any plastic need to be taken off?...(obviously, asking w/o a service manual)...thanks!

Look at the left caliper. The doodad at the top with the plunger connected to the fork is the SMC. When the front brake is actuated the whole caliper assembly moves and pushes on that piston sending hydraulic force to the rear brake.

The proportion valve is under the tupperware and sends rear brake hydraulic force to the front brakes.


And get yourself a shop manual they are definately worth it

 

[Byron]

. . . I always made sure it was clean and dry under the boot.....I even filled the area up with silicone grease to waterproof it better. . . . Igofar

This may have accelerated it. Some rubbers do not do well with silicone and are only compatable with breakfluid. Don't know how close you are to the ocean or humid salt air but that could also hassen things. Honda drilled a drain hole in the newer units so washing your bike could also put more moisture at the SMC. There are many things that could have contributed to the early demise.

 

[st1300r]

The rubber should be ok with silicone grease since it's being made of material compatible with brake fluid.

Likely regular grease would not be good as that type of rubber isn't compatible with brake fluid.

 

[dduelin]

If the boot is in good shape it seals better than this thread describes. The open end of it fits in a recess let into the bore and if you try to remove it you will see how the press fit works. The boot seal and drain worked OK on my bike so far - but that is only 96,xxx miles.

 

[tempus]

check yours today....and report defect to the NHTSA.

This board should have enough weight to push Honda for a real solution, instead of the tentative patches they have tried so far.

Honda found the real solution: no more SMC on newer bikes! But in the mean time, we are stuck with this dangerous nonsense.

There probably would be more action from Honda if a LEO had experienced a rear wheel Lock Up..........

I went to the NHTSA web site to see where to report something like this. I did not find where to do that. Does anyone know where on the NHTSA web site we can report such a defect?

 

[STU]

Would it be safe to remove the pin from the fork leg to the SMC and ride like that? that way the caliper will still move but the SMC wont operate??

 

[Firstpeke]

Your braking would be less effective, only allowing one piston to operate on the rear disc. The SMC is responsible for operating the two outer pistons of the rear caliper.
This course of action would not be recommended.

 

[dduelin]

Would it be safe to remove the pin from the fork leg to the SMC and ride like that? that way the caliper will still move but the SMC wont operate??

This would not prevent at least some application of the SMC as there is only about 2 mm of clearance between the nut that secures the SMC pushrod in the U-shaped piece the upper pin (caliper bolt) passes through and the fork leg. Under braking with the upper caliper bolt missing the joint pushrod would contact the fork leg and apply SMC pressure then likely bend under the force.

 

[Txrebel]

I went to the NHTSA web site to see where to report something like this. I did not find where to do that. Does anyone know where on the NHTSA web site we can report such a defect?

Your in luck, I filled out a complaint a few weeks ago for the SMC trouble.

https://www-odi.nhtsa.dot.gov/ivoq/

 

[bkra13]

Your braking would be less effective, only allowing one piston to operate on the rear disc. The SMC is responsible for operating the two outer pistons of the rear caliper.
This course of action would not be recommended.

OR.. you could just use the back brake in the normal manner.

 

[Mellow]

OR.. you could just use the back brake in the normal manner.

That won't work either as the foot brake also applies pressure to the front calipers, once they grab, they will push the smc plunger.

 

[dduelin]

OR.. you could just use the back brake in the normal manner.

You couldn't apply any back brake at all without applying front brake - IIRC the center pistons on the front brake calipers are activated by the rear pedal, thus the left front caliper would move forward and then compress the SMC, all by using the back brake alone like Mellow said.

 

[STU]

Thanks for all your replies guys. I should have looked at the bike first, since there really isnt much space between the push rod and the fork anyway...(as one of you said).
Wish I lived in the USA. It seems like you guys over there know much more about the Pan, and that your dealers are more prepared to replace faulty items etc. I'm gonna get my SMC fixed next week hopefully, but not at a Honda dealer. I'm not even going to bother asking a Honda dealer in the UK to do it. Too expensive, and they wont do it as a recall thing Im sure.
Used to live in Hong KOng where the labour charges/mechanics were excellent. Boy, do I miss that!!! Costs an arm and a leg in UK

 

[Pete in PA]

All right! Now I'm paronoid! (I think) I don't have but 2 symptoms. Rear wheel only turns 1 rev by hand (or foot) and the rear rotor is hotter than the front. Not blistering just hotter. Bike pushes fine, I can lay on the left side and do the push up on left front caliper and lock the rear wheel, release and the rear turns again test fine.

I frequently check the freewheeling at stop lights, most times there is a slight hill or bumpy pavement that allows me to ease the clutch out, move forward slightly, pull clutch in and bike rocks back.

I also have a slight burning rubber smell after a ride I still haven't found. I'm not the only one with THIS smell, It's NOT the burned brake (or car clutch) smell I know well, which is the same smell as following a truck downhill and they smoke check their brakes.

Is it easy to pull the boot back without damaging it for inspection?

I am VERY seldom in rain and My wash and wax technique doesn't involve hosing the bike down which would get soap in there causing corrosion.

 

[st1300r]

Rear wheel only turns 1 rev by hand (or foot) and the rear rotor is hotter than the front. Not blistering just hotter.

Normal.
Go ride.

 

[Pete in PA]

Normal.
Go ride.

I like that answer.