Rear Brakes Now Dragging

[MarkJ]

Good Morning Everyone;

I took the St to the dealer yesterday afternoon as i need to replace both tires, well after getting the bike back, i proceded home and within a mile the rear brake acted as if in was dragging , well it was too late as the dealer was closed so i babied it home for 20 miles stopping every few miles to check rear rotor, way too hot too touch. got home, took the caliper off and cleaned the pistons with brake fluid and pushed on the pistons, both moved very freely so i thought this was the problem, nope, took the bike to work this morning and rear brake is still dragging, front brakes appear to be working ok, smc problem? the brake were fine for the last 9,000 miles, is it just coincidence after a tire change? or could the mechanic have screwed up? i prefer to fix this my self as i dont trust any of these dealers, what might i start with and any idea on possiable cost? thank you for your help guys. also, if this is a smc problem, who can i report it to?

 

[dduelin]

Did you leave the brake pads in the caliper when you removed it? The front end of the pads have a tab that fits in a notch in the caliper. It is possible to not install the pads properly then force the retaining pin in place. The pads look as if they are OK but they are not unless the retaining pin easily fits through the holes in both pads and into the threaded hole on the inside of the caliper. The pad(s) not installed properly will not slide on the pin when the pistons retract and the brake will drag.

The SM has the tech remove the pads and the caliper to pull the wheel. I would double check the pad installation. I would not expect the secondary master cylinder on the LF caliper to contribute to this if it worked OK before going to the dealer. Always check the last thing worked on.

 

[Mellow]

I would not expect the secondary master cylinder on the LF caliper to contribute to this if it worked OK before going to the dealer. Always check the last thing worked on.

+1

I don't believe in coincidences. Even though the rear is dragging, it's the front area that is probably the issue as the SMC 'sounds' like it's being activated for some reason. It could very well be bad but as, stated above, make sure the front is installed correctly 1st. Make sure the wheel spacers are on the correct side of the wheel. The thinner one goes on the left / SMC side of the wheel.

 

[MarkJ]

thanks for replying, when i got home, i removed the mufflers on both sides, pushed the axle out far enough to pull the entire brake caliper off, pulled the pads off, cleaned the pistons with toothbrush and brake fluid, wiped down with clean rag, greased all the pins and put the pads back on along with greasing the retaining pin, reasembled everything, pumped the rear brake pedal until it felt pressure, then spun the wheel a few times and applied the rear brake, it appeared to work correctly , got up and rode the bike to work this morning, all was fine until i applied the rear brake, went a few miles tsaying off the brakes then stopped at a gas station and felt the rea rotoe, too hot to touch but the fronts were cold to touch. any ideas?

 

[Firstpeke]

Sounds far too like that front caliper has moved and/or the smc is sticking.....

On returning after riding, when it is dragging, if you put a clear pipe on the rear outer pistons bleed nipple and into a container, crack open the bleeder, does it spit out some fluid under pressure? If so, it's the SMC.

 

[Igofar]

Sounds far too like that front caliper has moved and/or the smc is sticking.....

On returning after riding, when it is dragging, if you put a clear pipe on the rear outer pistons bleed nipple and into a container, crack open the bleeder, does it spit out some fluid under pressure? If so, it's the SMC.

The SMC would be my guess. You can check it by laying on the ground on the left side of the bike, and briskly spin the rear wheel with your foot. While the wheel is turning, grasp or press the SMC/Caliper forward towards the fork. It only moves about 2mm, but when pressure is applied, it should lock up the rear wheel solid! When released, it should completely release the rear wheel again, so you can spin it freely.
When you remove the pads to clean the pistons with brake fluid, rather than just cleaning what you see, apply a little bit of pressure on the brake lever, to push the pistons out a little farther. Sometimes you get built up rings of dirt on them, and simply brushing them, then pushing them back in, forces the dirt into the seals.
Hope this helps, good luck.
IGOFAR

 

[MarkJ]

dropped the bike off at the dealer during lunch, 2 hours later, they still can't figure out why rear brake is sticking, mechanic said it wasn't smc and he bled the rear brakes, they said they will fix it, well see how well that goes.

 

[dduelin]

The OP posted that one of the symptoms was after riding the front rotors were cold and the rear was hot. If the SMC was causing the rear to drag the left front rotor would be warm or hot to the touch. That is why I did not go there.

 

[MidLife]

The OP posted that one of the symptoms was after riding the front rotors were cold and the rear was hot. If the SMC was causing the rear to drag the left front rotor would be warm or hot to the touch. That is why I did not go there.

Could you expand on why the front would be hot?

 

[Firstpeke]

An interesting idea that you wouldn't go to the front left disc.... it may be cold to the touch so are you assuming that this means the SMC is okay????

Granted it "could" be the rear master cylinder that has a fault preventing the pressure dropping back to zero after rear brake application...... but I have never heard of that.

I have heard of quite a few SMC's sticking......

 

[dduelin]

The SMC is often the first thought but he said the brakes were fine prior to the dealer replacing the tires. The SMC might be the problem but I would focus on the rear caliper and rule out sticking pads.

Igofar posted the way to test the SMC for sticking. If the SMC releases in this test and the rear brake continues to drag the LF caliper would be dragging enough to apply rear brake thus heating up the LF rotor.

 

[Igofar]

dropped the bike off at the dealer during lunch, 2 hours later, they still can't figure out why rear brake is sticking, mechanic said it wasn't smc and he bled the rear brakes, they said they will fix it, well see how well that goes.

***Ask the shop/mechanic how the REAR brakes were bled???
We have several shops that either A. don't know the correct method, or B. Do it incorrectly because they don't want to remove the body work because it takes too much time and costs them money
You can't just bleed the REAR brakes!! You must follow the correct method in the service manual, which will mean, tilt the SMC (I'll bet they didn't do that) bleed the PCV valve (I'll bet they didn't do that either) then bleed the forward rear bleeder, then the right lower front bleeder, the left lower front bleeder, then the last bleeder in the rear. If they only attempted to add fluid to the rear mastercylinder, and open up the rear bleeders, You've now got air in your system.
Remember its a linked system.
Simply ask him how it was done...if he won't give you a direct answer, with the correct procedures, take your bike to a different shop.
Just my .02

 

[MidLife]

The SMC is often the first thought but he said the brakes were fine prior to the dealer replacing the tires. The SMC might be the problem but I would focus on the rear caliper and rule out sticking pads.

Igofar posted the way to test the SMC for sticking. If the SMC releases in this test and the rear brake continues to drag the LF caliper would be dragging enough to apply rear brake thus heating up the LF rotor.

Am trying to understand how pressure trapped between the SMC and the rear caliper could affect the left front?

 

[dduelin]

Am trying to understand how pressure trapped between the SMC and the rear caliper could affect the left front?

Forget that idea for now.

In order to activate the SMC, the front or rear brake lever has to be applied so the LF caliper applies friction to the rotor. When this happens the LF caliper pivots forward and applies pressure to the SMC thus sending fluid pressure to the rear caliper. If you test the SMC for function and freedom and it passes this test, the only way for the SMC to continue applying rear brake is for the LF caliper to be dragging on it's rotor when riding which would build up heat. If the rotor was cold and the SMC is not sticking we rule out that part of the system for the malfunction. Was I more clear in my thoughts?

 

[MidLife]

Forget that idea for now.

In order to activate the SMC, the front or rear brake lever has to be applied so the LF caliper applies friction to the rotor. When this happens the LF caliper pivots forward and applies pressure to the SMC thus sending fluid pressure to the rear caliper. If you test the SMC for function and freedom and it passes this test, the only way for the SMC to continue applying rear brake is for the LF caliper to be dragging on it's rotor when riding which would build up heat. If the rotor was cold and the SMC is not sticking we rule out that part of the system for the malfunction. Was I more clear in my thoughts?

Makes sense. Did MarkJ observe if the rear was still dragging when stopped to check if hot?

 

[Igofar]

Forget that idea for now.

In order to activate the SMC, the front or rear brake lever has to be applied so the LF caliper applies friction to the rotor. When this happens the LF caliper pivots forward and applies pressure to the SMC thus sending fluid pressure to the rear caliper. If you test the SMC for function and freedom and it passes this test, the only way for the SMC to continue applying rear brake is for the LF caliper to be dragging on it's rotor when riding which would build up heat. If the rotor was cold and the SMC is not sticking we rule out that part of the system for the malfunction. Was I more clear in my thoughts?

Well said Double D!

 

[MarkJ]

when i realized it was the brakes , i would stop about every 2 miles, remove the hard bag and try to jar the caliper to make it loose, after starting the bike back up and having to apply brakes because of traficc, light, etc, the brake would immediately start dragging and the pads wouls start howling pretty loud, each time i stopped, took a glove off to check heat of rotor, you could tap and know it was way too hot, this was at night, but the rotor never turned red hot so i did my best to get it home without causing any real damage, but i expect not to pay a dime to anyone as this is not my resposibility, i brought them a bike that worked fine for the last 10k miles and a simple tire change renders it useless, i bought the bike from this dealer and even had them change the tires at 8k...honda better get its act together, i cant imagine going 70 or 80 mph and having these brakes lock up..not sure if i will keep thisbike, i pretty much have lost faith even if they do manage to fix everything by replacing all the parts, would you trust this bike to not lock up again at that speed?

 

[Diamond Dave]

i pretty much have lost faith even if they do manage to fix everything by replacing all the parts, would you trust this bike to not lock up again at that speed?

I feel the same way you do about my bike and with mother honda out in califonia.These rear brakes can really be a problem and they don't want to admit to it.

 

[Firstpeke]

Perhaps a local techSToc will get it sorted quicker and with more confidence than at the dealers....... better someone working on it that knows the bike than someone that is paid to do it but rarely ever does an ST.....

Even if it is under warranty, will the dealer get it fixed, or will they just keep "trying".....

 

[Igofar]

when i realized it was the brakes , i would stop about every 2 miles, remove the hard bag and try to jar the caliper to make it loose, after starting the bike back up and having to apply brakes because of traficc, light, etc, the brake would immediately start dragging and the pads wouls start howling pretty loud, each time i stopped, took a glove off to check heat of rotor, you could tap and know it was way too hot, this was at night, but the rotor never turned red hot so i did my best to get it home without causing any real damage, but i expect not to pay a dime to anyone as this is not my resposibility, i brought them a bike that worked fine for the last 10k miles and a simple tire change renders it useless, i bought the bike from this dealer and even had them change the tires at 8k...honda better get its act together, i cant imagine going 70 or 80 mph and having these brakes lock up..not sure if i will keep thisbike, i pretty much have lost faith even if they do manage to fix everything by replacing all the parts, would you trust this bike to not lock up again at that speed?

I'm betting the dealership didn't bleed the system correctly, by the book.
I'd start from scratch.
Remove and clean ALL the pads, mounting contact points, pins, pistons, etc. Then bleed the entire system from A to B.
With all the SMC failures with both the ST's and now the GL1800 goldwings, I'm betting it might be that.
Another thing that could be contributing that nobody has talked about, and I'm sure the shops never check,
is when you remove the front left caliper, to tilt it durning the bleed process, the lower mounting point goes through a
spacer that rides on needle bearings. Push this out with your fingers and have a look at it.
I've found several other members spacers damaged and galded due to no grease on the needle bearings.
If there are wear marks, sometimes they can be polished out with scotchbrite pads, greased and replaced.
If the wear can be felt with your fingers, I'd replace the spacer because it is showing signs of binding on the bearings,
which would cause the SMC to stick, thus causing the rear brakes to drag.
If you get stuck on the road, you can do a couple things to get home...
Call a tow truck (safest method)
Crack open the rear bleeder for a second to remove the pressure, then only use the foot pedal on the way home.
I would not operate ANY vehicle, no matter how short the distance, when the brakes are showing signs of locking up.
The can lock up at any time without warning.
Did you contact the dealer and ask how it was bled?
Good luck.
IGF