Yet another SMC question/theory

Igofar said:

just had surgery on both hands

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Heal well !!

It turns out the snap ring was probably worn because I used a new one and it fit tightly and never popped out. But, after talking to Larry this afternoon we came to the conclusion the SMC is actually bad because the piston won't slide in the bore like it should. I had a hard time getting it out when I initially took it apart and after reinstalling it, if you push it down, the return spring doesn't return it to the neutral position.

After I got off the phone with Larry, I had my daughter spin the rear wheel and I lifted up very slightly on the left caliper to see if the SMC was working correctly. The rear wheel stops when I do this but it also drags when I release the pressure on the caliper. This means that piston is sticking, keeping the pressure on the rear pads. If I hit the rear brake pedal though, the rear frees up because the SMC piston is forced back to the neutral position.

Either way, the bike is out of service and a new SMC has been ordered. Hopefully it arrives before my SS100 in 2 weeks. A great big thanks to Larry for taking the time to go over the brakes with me. As soon as I find that picture on my phone, I'll send it to you.

Brian

I had a very hard time getting the piston out when I first took it apart and I guess in hindsight, I should have just ordered a new SMC right then and there. Even when putting the piston back in it was very difficult and never returned when bottomed out. The piston, yoke, snap ring and everything inside was pristine, not a spec of rust anywhere. I did go through a set of rear pads in as little as 5,000 miles though, that's why I initially took it apart, to see if it was all crudded up inside.

Brian

Brian, there are a couple more things you should do while you are waiting for the parts to arrive...
Remove both front calipers and slide them apart, the clean and lubricate the dowels they slide on.
If ANY of the calipers bind they cause the rear brakes to drag and wear pads quickly and unevenly.
Also remove the rear caliper and pull it apart and lube both pins there too. The unit should move easily without pads in when pushed directly against the center of the caliper.
Also check all clips and make sure none are bent.

I did all of that on Sunday, while I was depressed because I can't ride. Everything is completely free of gunk, salt, rust, scale, and whatever else was growing on the slides and calipers.

Again, thanks for the help. I still need to send you that pic but I keep forgetting.

Brian

Ugh.... looks like I'll be going through all of this as my rear brake locked up today during a ride. I rode about 70 miles, stopped at the post office, when I came out the rear brake was frozen stiff.... pumped the pedal hard a couple times and it seemed free enough to roll but completely locked again within a mile, after 30 min it was free again and I limped home 3 miles without touching the rear brakes and only gently using the front....

First... I consider myself lucky that the issue didn't occur until the last 4 miles of a 150 mile ride...

Second... my extended warranty expired on the 18th of this month... (I didn't buy it but was left over from the previous owner...

If I understand the issue/test correctly I should be able to pivot the entire front left caliper assembly on the lower bolt connected to the fork and the will activate the rear brake.... I cannot move this assembly at all and I assume this means the SMC is shot and I need to rebuild it... or at least clean it well and order the rebuild for the near future...

Question 1 - any way to test this further without having to open the fluid system and bleed it?

Question 2 - is there a way to disable the SMC and limp home, what if I had been 75 miles from home not 4....

OK being a person with no brake experiece, little mechanical experience, should I even consider doing this myself? The bleeding process I understand is a pain. Getting a friend to help isn't easy... is it possibly solo?

Waiting by the white courtesy phone.
PM me a contact number and I will call and answer your questions.
Igofar

Thank you for the call today! Above and beyond! I hope some of those simple/cheap/easy possibilities work out for me, I'll be taking a look at her when I get home from work in the morning, but won't have the chance to really tear into it until Sunday....

Ok... I pulled the rear caliper cleaned it and replaced the pads... checked and cleaned the fronts, made sure all the pins were lubed and sliding properly then bleed the entire system... unfortunately this didn't resolve my sticking rear brake... only one thing left to do... ordering a new SMC assembly...

This was all done with the incredible help of fellow forum member Igofar! Larry talked me through the entire bleeding process step by step over the course of 3 hours! It took this long due to my nearly nonexistent mechanical skills ( first time I've bleed any brake system) but Larry was a great teacher and everything went smoothly. Thank you so much for the help!

Ordered a replacement SMC bracket today from HondaPartsDirect.com today $146 plus shipping $20 was the cheapest I could find but the delivery is going to take a week +.... I might have been better served to order it from someone else... but hard to say if anyone would have gotten it to me earlier... well apparently I'll be down 2-3 weeks with this issue, I'm already going through motorcycling withdraw...

Jethro77 said:

Ordered a replacement SMC bracket today from HondaPartsDirect.com today $146 plus shipping $20 was the cheapest I could find but the delivery is going to take a week +.... I might have been better served to order it from someone else... but hard to say if anyone would have gotten it to me earlier... well apparently I'll be down 2-3 weeks with this issue, I'm already going through motorcycling withdraw...

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The next time you need parts, try Service Honda or Ron Ayers. Just looked at the price of an SMC for my old '05 ST1300 and Service Honda shows $122.

Dang.... Apparently I should have looked harder, the best I could get on Ron Ayers was $160 or full retail of $200 depending on which side of the site I was on, but I didn't try Service Honda.... wish I had!

Do what I do.....just sit on your bike and make varoom noises.

Igofar said:

Do what I do.....just sit on your bike and make varoom noises.

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Yeah, that's what I've been doing but my wife is starting to question my sanity.... I have no idea what took her so long to do so...

Update on my original sticking rear brake and SMC...

I called and ordered a new SMC from Ron Ayers about 2 weeks ago. I got a confirmation email saying I would receive the part on the 7th of April. Well that's not going to work because I'm doing the Curt Gran SS to Moonshine in the 6th. So I came up with a plan to figure out how to stop the SMC from rotating forward, thus preventing the piston from sticking in the bore. Well, my idea worked flawlessly, but if you want to know how you can P.M. me as I'm not going to be responsible for others bypassing the SMC.

Anyway, I took a few short 50 mile rides and continously checked my rotor temps with a infrared gun. None of them were ever more than 5 degree difference but I just didn't feel 100 percent confident that the snap ring was not going to pop out again, especially with the new SMC on its way. So I postponed the trip by a day, and when UPS delayed my package, I delayed it another day.

I finally got the new SMC this afternoon and since it was too late to do the SS, I put off installing it until a few hours ago. While I'm kind of pissed I missed the SS for the first time in 5 years, I'm glad I waited until it was fixed right.

I'll be heading down to Moonshine tomorrow, in 35 degree weather. I guess that's better than the white out snow squalls we were having this afternoon though!

A big tip of my helmet to Larry for the help. Honestly, of it wasn't for talking to you, I would have just left on the SS with my invention in place and who knows what would have happened.

Brian

A few tips for you, Jethro. 1) when it comes time to bleed the brakes, you can do it by yourself if you have long arms and good coordination. I did mine several times by pumping the hand brake or foot brake and holding it, then cracking the bleeder open. Just make sure you don't let go of the brake before you close the bleeder screw back up. Yes, it does make it easier with a helper but it isn't necessary. 2) You do not need to remove the right side body work. You can fit the 8mm wrench on the proportioning valve with no problems if you remove the little access cover and the plastic valve cover decorative piece. Again, use your clear tubing and connect it to the bleeder screw but pump the brakes with the foot pedal. Use the pump foot pedal, hold, crack open bleeder, close bleeder, release foot pedal technique. This alone will save you an hour in removing plastic bits. I did it this way about 5 different times and never once had a drop of brake fluid on the body work. 3) After I got done with everything, I had a great, firm pedal. I still went back through the entire sequence one more time just to make sure you get any remaining air that may be trapped. 4) Larry suggested to place a weight on the foot brake and tie the hand brake closed over night, do this...their are microscopic bubbles that will find their way back through the system and out the master cylinders. 5) Ditch the vacuum bleeder and do it old school. Pump and hold baby, pump and hold.

Brian

I have an upcoming SMC rebuild and brake/clutch flush on a friend's ST..... good info here. I'm not a vacuum bleeder fan, but would think Speedbleeders would help. Also, if you can find silicone tubing (from Speedbleeder), it will stay on your bleeder screws very well.

I have installed speed breeders in the past with mixed results...downside is cost! As you have to order more than half a dozen of them...after a couple bleeds you must purchase their goop and bake it on the threads...and...I have seen more than a couple fail by sticking either open or closed...
The motion pro is a single unit, cheaper, and can be used on ANY vehicle.
.02

RaYzerman said:

I have an upcoming SMC rebuild and brake/clutch flush on a friend's ST..... good info here. I'm not a vacuum bleeder fan, but would think Speedbleeders would help. Also, if you can find silicone tubing (from Speedbleeder), it will stay on your bleeder screws very well.

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Ray, I changed out my hydraulic fluids this winter with a motion pro one way bleeder valve. Very simple and worked well.

https://www.amazon.ca/Motion-Pro-Hydraulic-Brake-Bleeder/dp/B000MXW2EM/ref=sr_1_fkmr0_1?ie=UTF8&qid=1460230312&sr=8-1-fkmr0&keywords=motion+pro+mini+bleeder

You are certainly welcome to use it if you like.

Dennis

My Mityvac has bled my ST about 14 times and I never have any help on levers or pedals. I do use a three foot long piece of broom stick to pump the foot brake from the left side of the bike. Just saying more than one way to skin a cat.