So, for those of you located in the Northeast, you know we have had beautiful weather the past few days, but today, snow and frigid cold again.

So riding my bike today I noticed something that I noticed in the past, but did not mention until now.

When the temperature is really cold in the morning, I have noticed that since flushing and bleeding my front brake (did this at the end of February 2014), that when the bike is super cold (air temp 20-30 degrees) my front brake pads are applied without me even having to squeeze the brake. So today my 1 mile ride in to work, the brakes slightly applied on their own the entire ride because of the cold weather. When I got to work, I felt my disc, and it was scalding hot, so the brake was definitely applied slightly the entire ride (not good, I know)

However, on a warm day, the brake behaves like normal, and the brake is not applied at all on my ride in to work. The other day when it was warmer out, I rode the entire way without applying the front brake at all. Used the rear brake the entire time. When I got to work, I felt the front disc, and it was cold, implying that there was no rubbing of the pads to the disc.

In short:

When its freezing out, front brake pads are constantly applied to disc, and rubs the entire way to work.

When warm out, front brake pads are not applied to disc, and the brake behaves as normal, not rubbing at all unless I apply the brake by hand.

So, does anyone have any idea why this is happening? Perhaps there is air in the line? I know that when cold, air shrinks, so when it is cold out I figure it would be the opposite and retract the brake pads, and when it is hot, the air in the line would expand, therefore creating pressure in the line and applying the breaks. However, that can not be happening since my observations are the complete opposite...

When was the last time the fluid was flushed? Perhaps you have moisture in your brake fluid which is causing it to stick somehow. I honestly am not sure what could cause it but I would try flushing your brakes with new fluid.

When was the last time the fluid was flushed? Perhaps you have moisture in your brake fluid which is causing it to stick somehow. I honestly am not sure what could cause it but I would try flushing your brakes with new fluid.

I just flushed and bleeded the brakes on a warm day at the end of February 2014. Used a brand new container of dot4 brake fluid.

Why would it stick in cold weather in the mornings, but when its a warm morning, it does not stick?

Yes it's rather odd. Have you pulled the piston out of the caliper slightly and cleaned it or see if is dirty or rusted? Perhaps your brake master piston is sticking and not releasing/returning and still applying pressure. As to why temperature affects it is still beyond my morning thinking capabilities. How was the color and clarity of the brake fluid when you flushed it? Did you notice any rust?

Yes it's rather odd. Have you pulled the piston out of the caliper slightly and cleaned it or see if is dirty or rusted? Perhaps your brake master piston is sticking and not releasing/returning and still applying pressure. As to why temperature affects it is still beyond my morning thinking capabilities. How was the color and clarity of the brake fluid when you flushed it? Did you notice any rust?

I did not do anything with the piston or clean it. I just did a complete flush and then replaced with new fluid and bleeded the brakes to get all the air bubbles out.

The old brake fluid was really brown and dark. It definitely was old. Did not notice any rust or debris in the old fluid when I flushed it.

Only reason I flushed it to begin with is because the previous owner could not tell me when it was last done, so for all I know it could have been years. I just wanted the assurance of knowing I have good new fluid in there now, since I know when I last did it and I track all of my maintenance.

I rode the 1 mile to work today with the brakes slightly applied because of the cold weather. When I got to work, I felt my disc, and it was scalding hot, so the brake was definitely applied slightly the entire ride (not good, I know)


I guess I'm not understanding what the problem is. :confused:

moisture/water is the only thing that makes sense.

Water/ice expands as it gets colder down to a certain temperature, everything else that could be in the line would do the opposite, air would become more dense, along with the brake fluid, but the water/ice would expand possibly increasing pressure.

^other than this IDK? Was it below freezing at your place today? it was here for sure

Either way, i would completely clean and reflush

^^^ Water must still be in the caliper. How did you flush the system?

I guess I'm not understanding what the problem is. :confused:

He has brake drag on cold days. It kills your pad life, mpg, speed and could also overheat the brakes to the point of fading badly.

He has brake drag on cold days. It kills your pad life, mpg, speed and could also overheat the brakes to the point of fading badly.

Yeah I get that, but if you read the part i quoted it sounds like he was braking for the entire ride.

Yeah I get that, but if you read the part i quoted it sounds like he was braking for the entire ride.

Yeah, he was just referring to his current observation of how the cold weather was applying the brakes on its own.

I'm not sure how often they salt the roads up north or the proximity of the salty air to you is, but rust and moisture can get past the seals of the brake caliper and contaminate the fluid. Also, rubber is slightly porous so it can absorb moisture.

sounds like its time for a caliper rebuild

:werd: I had to read it twice to put it into context. But yea, it could read as if Ken lightly pulled the lever to drag the brake on purpose. I don't think that is what Ken meant though.

Maybe it's a built in safety feature to keep riders from going to fast in the cold weather because of the reduced traction. :p

I guess I'm not understanding what the problem is. :confused:

What I mean is that the brake was applied on its own. I did not apply the break.

I had no other way to get to work, and I did not have time to fix it prior to my ride in. So I had to just go the 1 mile with the brake applied on its own.

I can see how you misunderstood my wording. I will edit.

Maybe it's a built in safety feature to keep riders from going to fast in the cold weather because of the reduced traction. :p

hahaha. yeah and at the risk of completely overheating the breakpads. no big deal

.....Why would it stick in cold weather in the mornings, but when its a warm morning, it does not stick?

Rubber hoses freeze and become very stiff when it's below freezing. They can also alter pressures in a pressurized system.

Is your bike stored outside? What is the condition of your brake hoses?

Another interesting fact about brake fluid-
"One of brake fluids most important characteristics is in fact its ability to absorb water! It is designed to absorb water! Diffusion allows moisture in the air to permeate microscopic pores in the rubber brake hoses and the various seals in the hydraulic brake system. This moisture would then rot out the internals of our brake system if it wasn’t absorbed by the brake fluid. In extremely cold weather it also stops this water/moisture from freezing in the brake system. This feature comes at a cost, which is, that water contaminated brake fluid reduces its performance. But brake fluid composition and therefore its effectiveness can also be altered by its working environment, because the brake system generates extreme temperatures, some of this is transferred off the disc pad and rotor into the brake caliper holding the disc pad and this heats up the brake fluid that flows within the brake caliper. To give you some idea of this in action, should your brake system have 3.7% of water trapped within its brake fluid, the boiling point level of your standard brake fluid is reduced from 205 degrees Celsius to 140 degrees Celsius a thirty percent reduction! So we now know that moisture will reduce the effective boiling point by almost 1/3. There are many different types of brake fluids with many differing effective temperature ratings to handle this event. "

^^^ Water must still be in the caliper. How did you flush the system?

I flushed it the normal way. Opened up the reservoir cover, then pumped all of the old fluid out by constantly pumping the front brake to build up pressure, then opened the bleeder valve to release the old fluid. Closed bleeder valve. Repumped the brake to build up pressure, then opened bleeder valve again. Continued this process until all of the old brake fluid was out. I then cleaned the inside of the reservoir, and then put new fluid in, and bleeded the system just like the wiki says. Continued to bleed until I saw no bubbles. Then filled the reservoir to the fill line, and was done.

moisture/water is the only thing that makes sense.

Water/ice expands as it gets colder down to a certain temperature, everything else that could be in the line would do the opposite, air would become more dense, along with the brake fluid, but the water/ice would expand possibly increasing pressure.

^other than this IDK? Was it below freezing at your place today? it was here for sure

Either way, i would completely clean and reflush

Yeah it was definitely below freezing overnight last night. Slightly above freezing at 9am when I rode in to work.

I think that is what I am going to do, do a clean and reflush and start over. Cant hurt, and only took a few minutes.

Rubber hoses freeze and become very stiff when it's below freezing. They can also alter pressures in a pressurized system.

Is your bike stored outside? What is the condition of your brake hoses?

[/I]

Yes, I store it outside year round. I do not winterize it in the winter because I ride it everyday, regardless of the temperature. Between my girlfriend and I, we only have one car, and she works 10 miles away from our condo, and I only work 1 mile away. So I have to man up and take the bike, so she can take the car.

The brake hoses appear to be fine. No cracks or anything from what I can see.

Another interesting fact about brake fluid-
"One of brake fluids most important characteristics is in fact its ability to absorb water! It is designed to absorb water! Diffusion allows moisture in the air to permeate microscopic pores in the rubber brake hoses and the various seals in the hydraulic brake system. This moisture would then rot out the internals of our brake system if it wasn’t absorbed by the brake fluid. In extremely cold weather it also stops this water/moisture from freezing in the brake system. This feature comes at a cost, which is, that water contaminated brake fluid reduces its performance. But brake fluid composition and therefore its effectiveness can also be altered by its working environment, because the brake system generates extreme temperatures, some of this is transferred off the disc pad and rotor into the brake caliper holding the disc pad and this heats up the brake fluid that flows within the brake caliper. To give you some idea of this in action, should your brake system have 3.7% of water trapped within its brake fluid, the boiling point level of your standard brake fluid is reduced from 205 degrees Celsius to 140 degrees Celsius a thirty percent reduction! So we now know that moisture will reduce the effective boiling point by almost 1/3. There are many different types of brake fluids with many differing effective temperature ratings to handle this event. "

Wouldnt water in the line have the opposite effect tough? Meaning that I would have to apply much more pressure to the brake lever to get braking power? Why would the brake pads be compressed by themselves in cold, but in warm weather they act just fine?

He has brake drag on cold days. It kills your pad life, mpg, speed and could also overheat the brakes to the point of fading badly.

Exactly. I felt bad having to ride in today with it, but I had no other option. Luckily my commute is only a mile long. Any longer than that and I would have been in trouble

I flushed it the normal way.

I guess I am old school, I take the calipers off and turn it upside down to drain it. Harder, takes longer but I know for sure it's flushed completely.

its a floating caliper with 2 bolts. its easy to take off

if it is moisture i am thinking it is a problem more up top in the master than down low at the caliper. The heat from braking would have warmed up any fluid lower in the system. Since the braking did not get better as things warmed up and remained the same it is logical to think that this section would not be the issue as you do not have the same issue on warmer days.

However the master cylinder will not see the same heat as caliper ect... which could explain why you did not see an improvement after things heated up at the caliper.

^is any of this making sense?

But on warmer days everything including the master are at a more reasonable starting temp and things are all fine and dandy or so it would seem.

if it is moisture i am thinking it is a problem more up top in the master than down low at the caliper. The heat from braking would have warmed up any fluid lower in the system. Since the braking did not get better as things warmed up and remained the same it is logical to think that this section would not be the issue as you do not have the same issue on warmer days.

However the master cylinder will not see the same heat as caliper ect... which could explain why you did not see an improvement after things heated up at the caliper.

^is any of this making sense?

But on warmer days everything including the master are at a more reasonable starting temp and things are all fine and dandy or so it would seem.

http://2.bp.blogspot.com/-Ppd0JABlbVw/UiZgnfQw1vI/AAAAAAAAEis/KNxTDc0C580/s1600/Logical.gif

....Yes, I store it outside year round.

...The brake hoses appear to be fine. No cracks or anything from what I can see.

While signs of deterioration, such as cracked, hardened or weak hoses can often be seen from the outside, damage to brake hoses on the inside can go undetected. Brake lines deteriorate from the outside as well as the inside. Extreme weather conditions is one reason, contaminants in brake fluid is another.

Although Kawasaki recommends replacement of brake lines @ 4 years or 48K miles, it can also depend on the overall condition of the bike. Rubber exposed to the elements (sun, dust, heat, cold, snow, salt, etc..) will deteriorate faster than rubber that is shielded from the elements. So actual replacement intervals can vary.


Wouldn't water in the line have the opposite effect tough? Meaning that I would have to apply much more pressure to the brake lever to get braking power? Why would the brake pads be compressed by themselves in cold, but in warm weather they act just fine?


Water makes brake fluid expand, combine that with compressed rubber hoses and you have a system under higher than normal pressure. Guess where that pressure goes?

lol

Probably need a rebuild of the caliper or master cylinder. The bore in the caliper could be bad, or the piston seals may be old and hard.

You could remove the caliper and clean around the piston seals for starters. There may be a build-up of fluid and brake dust that's restricting the movement of the piston when cold.

what i find odd though is that i never had this problem prior to bleeding the brakes with new fluid. the old brake fluid functioned fine.

however, after the brake bleed the brake lever had to be squeezed much more than prior to the bleed to apply the brakes, so i did the wire tie method to fix that. after 48 hours of doing the wire tie method with the tie on there compressing the brakes, it solved the problem of the brake lever, but shortly after that, that is when i noticed the brake drag.

i started this thread back right after i bleeded and changed the fluid.

https://www.ninjette.org/forums/showthread.php?t=169260

so perhaps the problem was with the wire tie method. perhaps i did it too tightly and caused it to apply too much pressure in the system.

what i think i need to do is relieve a little bit of pressure in the line by draining a little bit of fluid. and see if that fixes it.

take a look at these posts from that thread linked above:

That is actually exactly how I did it this weekend.

I just found the wiki and read this section:

If you can't get all the air out
If all else has failed, and you still can't get the brake lever to be firm, air may have collected at the top banjo bolt. You have two options:

Option 3: Zip-tie the brake lever to the bar overnight. This opens the bleed valve at the master cylinder and can let air escape. For the rear, connect the lever to the horizontal bar on the center stand using two zip ties while standing partially on the rear brake. Take the zip tie(s) off in the morning and check to see if it helped.
http://faq.ninja250.org/images/thumb/3/31/123-22.jpg/150px-123-22.jpg

I think I am going to give the wire tie option a try.

So I gave the wiretie method a shot, and let it sit for the last 48 hours (since we had a snowstorm).

Took the wiretie off this morning to ride to work, and walah! It worked.

Only problem, it worked too well. haha. The break pads are slighly applied, even with no squeeze of the brake. So, I am going to relieve a little bit of the pressure by letting out a little bit of brake fluid, and then we should be good to go.

***UPDATE***

Didnt even have to relieve any pressure by opening the bleeder valve.

I just went outside to ride home for lunch, and it seems like the pressure relieved itself as it sat there for the past few hours with the wiretie off.

So I'm back to normal!

Just from that, it sounds like you have a dirty brake master. Bleed valve or piston is sticking and not relieving pressure. Perhaps, having the lever closed case it to stick or scratch the piston bore? Just the caliper and brake master off and clean them.

Just from that, it sounds like you have a dirty brake master. Bleed valve or piston is sticking and not relieving pressure. Perhaps, having the lever closed case it to stick or scratch the piston bore? Just the caliper and brake master off and clean them.

so what you think i need to do is just take the caliper off, and clean it all up. clean around the pistons and make sure to get rid of all grime and dirt. hopefully that fixes it.

only issue i have now is that i do all my maintenance 5 miles away at my dads house. he could probably come here, but hed have to bring all the tools here to do it... is there a way to alleviate the pressure in the caliper temporarily to allow me to get home without the brake pads constantly applied? you think hand forcing the pads away from the disc will free up some space?

Probably need a rebuild of the caliper or master cylinder. The bore in the caliper could be bad, or the piston seals may be old and hard.

You could remove the caliper and clean around the piston seals for starters. There may be a build-up of fluid and brake dust that's restricting the movement of the piston when cold.

i am going to do just that. thanks for the recommendation.

so what you think i need to do is just take the caliper off, and clean it all up. clean around the pistons and make sure to get rid of all grime and dirt. hopefully that fixes it.

only issue i have now is that i do all my maintenance 5 miles away at my dads house. he could probably come here, but hed have to bring all the tools here to do it... is there a way to alleviate the pressure in the caliper temporarily to allow me to get home without the brake pads constantly applied? you think hand forcing the pads away from the disc will free up some space?

Cleaning the caliper piston rules it out leaving the brake master as the culprit.

Crack the bleeder on the caliper. (8mm)
Install a clear tubing over the bleeder nipple. Put the other end in a bottle/container.
Unlock the steering and turn the handle bar so that the brake fluid reservoir on the front brake master is level with ground.
Open the reservoir cover with a Philips screwdriver.
Remove the cover and the rubber diaphragm.
Looking inside, you will see a bleed hole and the piston in the larger hole.
Squeeze on the brake lever and you should see the piston move and return back when you release the lever. You will notice that brake fluid squirt out of the bleed hole. When you squeeze the lever pay attention to the piston and see if it's moving as you squeeze and let go. If it sticks when you let go, then there's your problem.

Cleaning the caliper piston rules it out leaving the brake master as the culprit.

Crack the bleeder on the caliper. (8mm)
Install a clear tubing over the bleeder nipple. Put the other end in a bottle/container.
Unlock the steering and turn the handle bar so that the brake fluid reservoir on the front brake master is level with ground.
Open the reservoir cover with a Philips screwdriver.
Remove the cover and the rubber diaphragm.
Looking inside, you will see a bleed hole and the piston in the larger hole.
Squeeze on the brake lever and you should see the piston move and return back when you release the lever. You will notice that brake fluid squirt out of the bleed hole. When you squeeze the lever pay attention to the piston and see if it's moving as you squeeze and let go. If it sticks when you let go, then there's your problem.

So I am doing all of that with the brake caliper removed first correct? Remove the caliper and the brake pads, so that way I can see the piston on the caliper?

I am confused, there are two pistons? One at the top inside of the reservoir, as well as the piston that pushes the brake pad out to make contact with the disc. When I bled the brakes previously, I did not take too good of notice at to what is inside the reservoir. I guess I will see what you are talking about when I do this.

It's easiest to check the brake master piston first otherwise with the caliper odd you would be pushing the piston out with each pump of the brake.

Yes, a piston inside the master and one in the caliper.

So I am doing all of that with the brake caliper removed first correct? Remove the caliper and the brake pads, so that way I can see the piston on the caliper?

If you squeeze the lever with the caliper removed you may push the pistons completely out.

Clean-up the caliper and seal area first, then re-install it before doing the fluid flush.

I would take a good look at the pads when you have the caliper off. They may be toast if they have been dragging a while, or they may be glazed. If they still have a decent amount of material left I would sand them with sandpaper to de-glaze them before putting them back in.

Lay the sandpaper (220 might be about right) on a flat surface and slide the pad over it until the surface is evenly dull - then clean with brake cleaner.

It's easiest to check the brake master piston first otherwise with the caliper odd you would be pushing the piston out with each pump of the brake.

Yes, a piston inside the master and one in the caliper.

thanks, I will be sure to check that first, prior to cleaning the caliper.

If you squeeze the lever with the caliper removed you may push the pistons completely out.

Clean-up the caliper and seal area first, then re-install it before doing the fluid flush.

I would take a good look at the pads when you have the caliper off. They may be toast if they have been dragging a while, or they may be glazed. If they still have a decent amount of material left I would sand them with sandpaper to de-glaze them before putting them back in.

Lay the sandpaper (220 might be about right) on a flat surface and slide the pad over it until the surface is evenly dull - then clean with brake cleaner.

To confirm, the seal area is the area between the caliper and the piston?

ive been watching videos on youtube of people cleaning their calipers, and I think this is the best video.

Is this what I should do?

https://www.youtube.com/watch?v=FNz00OTRLzM

At 13:27 in the video I think is exactly what my problem may be.

Yes, there's a rubber seal in between the caliper and pistons. When you remove the caliper off the fork, remove the brake pads, inspect them for even wear. Also, inspect your slide pin. Crud may have gotten under the rubber boot and rusted the pin. Use a good grease for the pins after you clean them.

Pump on the brake lever to push the piston out enough to get to the crud and clean it off. You may need a scotch pad or steel wool depending on how bad it is. Brake cleaner is your friend. When pushing the piston back in, I'll crack the bleeder screw to relieve the pressure and then top of the brake fluid.

The EX500 is known for having problems if you just slap new pads on without doing a full caliper service. As the pads wear, the pistons stick out further and further past the seals, so you end up with crud on the pistons. If you just push them back in when put on the new (thicker) pads, you end up with issues. Instead, you need to remove and clean the pistons so they mate nicely with the seals. http://www.ex-500.com/wiki/index.php?title=Brake_Caliper_Service is a detailed guide to a complete brake service on the 500 (though the 250 should be quite similar).

The EX500 is known for having problems if you just slap new pads on without doing a full caliper service. As the pads wear, the pistons stick out further and further past the seals, so you end up with crud on the pistons. If you just push them back in when put on the new (thicker) pads, you end up with issues. Instead, you need to remove and clean the pistons so they mate nicely with the seals. http://www.ex-500.com/wiki/index.php?title=Brake_Caliper_Service is a detailed guide to a complete brake service on the 500 (though the 250 should be quite similar).

thanks for the info! I appreciate it.

Prior to purchasing the bike, the previous owner put new pads on for me the day before I purchased it, and I highly doubt that he did a full caliper service. He did not take too much care of the bike.

I will take a look at the wiki and see what I feel comfortable doing. Perhaps this is something I should have my local shop do for me...

This past winter i had put on new brake pads from magnum and ran into all kinds of problems with them leading up to having to replace both rotors on the bike, they both kept applying pressure to the pads and not releasing with the brake levers. Once i changed to a set of sumo pads from ebay along with new rotors i have not had a single problem since.
As a precaution i would change the pads and make certain that the retaining holes are large enough to not cause it to bind on the pins after release of the brake lever.

This past winter i had put on new brake pads from magnum and ran into all kinds of problems with them leading up to having to replace both rotors on the bike, they both kept applying pressure to the pads and not releasing with the brake levers. Once i changed to a set of sumo pads from ebay along with new rotors i have not had a single problem since.
As a precaution i would change the pads and make certain that the retaining holes are large enough to not cause it to bind on the pins after release of the brake lever.

Thanks for the input. I will definitely take a look at that. I plan to do all of this tomorrow, so hopefully I can get it all done in one day. We'll see. I am hoping that I do not have to replace the pads or rotors.