Kawasaki Motorcycle Forums banner
1 - 15 of 15 Posts

·
Registered
Joined
·
192 Posts
Discussion Starter · #1 ·
So a couple weeks ago i was involved in a minor accident. Upper cowl was cracked, and the brake lever snapped off at the fail point - I replaced the lever.

I've had the bike on a swing arm stand since and have been able to roll it around.

I'll just try to get out the facts without so much of the story. I went for gas, station was unusually closed. As i came home the bike chugged, i pulled the clutch and the bike came to a stop (i figured i ran out of gas) But really the front brakes was locked as i discovered by trying to roll the bike.

After sitting for about 15 minutes the front brakes moved relatively freely again, i rode home, pulled clutch in front of house.. and same thing. Again i waited about 15 - 20 min and then was able to power the bike into the garage.

I don't think air got into the lines.. as that would cause the brake to feel mushy wouldn't it? and the pads can't be totally seized because they release the rotors, i assume as they all cool down again..

Ideas??? i am puzzled for now.
 

·
Registered
Joined
·
1,640 Posts
sounds more like damage to the brakes. Check the rotors aren't ever-so-slightly bent. This will cause rubbing on the caliper and brake, cause it to heat, then the fluid expands and locks on. Get the front wheel up while it's all cold, and spin it looking carefully at each rotor. If they're bent, not many places will bend them back into shape, so you could be lookin for another one to replace it.

And yes, air will cause it to be mushy, if there was air in there.
 

·
Registered
Joined
·
59 Posts
Sounds like you have too much fluid in the master cylinder; such as if it's filled up to the top.

When you ride for awhile, the brake pads heat up simply due to drag. Some of this heat transfers to the fluid. The fluid expands. If your brake fluid is filled to the top, the fluid has nowhere to go and that force is transferred to the brake pads. They close more, create more heat, and the issue gets worse and worse. You stop riding and everything cools down.

Fitz
 

·
Registered
Joined
·
192 Posts
Discussion Starter · #4 ·
Sure enough...

Right side rotor is warped...

I did some simple tests by partially bleeding out some of the brake fluid.. ran the bike around the neighborhood for a minute... the right rotor was notably warmer.

Would one rotor being warped cause both sides to grip and lock since they are linked? Or would just the bad rotor lock it up? (obviously its going to be strong enough)

I hope replacing the rotors will cure this problem.. I'm missing out on the nice weather and its depressing.
 

·
The Indifference Engine
Joined
·
6,150 Posts
Both will lock up.

If you want a "cheap" way to check the rotor then get the front end off the ground and find a spray can that has a straw (usually WD40 or chain wax will have one). Set the can on the ground and position it so it just barely touches the rotor, now slowly spin the wheel. If the rotor moves away or towards the straw then you're warped. If it stays the same distance it isn't warped.

It's also possible that you have a seized piston in the caliper.
 
  • Like
Reactions: hoser

·
Registered
Joined
·
192 Posts
Discussion Starter · #8 · (Edited)
Neveda, I've ruled out the master cylinder.. After the initial lock on the main road i did not touch the front brake at all, only used rear to get home. Yet they locked up right in front of my house... So i believed it had to be an issue with the calipers/discs.

In my test i bled out a lot of the fluid from the brake lines so that they would not have enough to grip very hard on their own, it takes several pumps from the brake lever to engage the brakes strong enough, and they release easily afterwards.. again helping to rule out lever/mc issues. Also I think this rules out having a seized pad or piston because they release easily?

Today i only had time to take off one caliper housing the check the pads and piston, the left side appeared fine. I rode the bike without the front hugger in order to see the discs by looking down the fork. The right side has significant wobble, i would say .5cm or a quarter inch from what i can visually see. Its bad. Left side is perfectly fine disc wise. Thoughts?

I imagine it is best.. as well as correct to replace both rotors at the same time. Having one differ from the other in any way would likely cause some issue, small or larger down the line I guess.

Ideas on new rotors guys? I am thinking about upgrading now that they have to be replaced...

edit: and thanks for the help so far guys. Its reassuring to have minds pointed in the same direction.
 

·
The Indifference Engine
Joined
·
6,150 Posts
Just replace the damaged one with a stock one it'll be fine. Hydrolic system will account for any differences. But I would replace both sets of brake pads.
 

·
Kawi for Life!
Joined
·
1,610 Posts
I just had this on my 97'500. Although theres only one brake up front it sized on me cause of warping. Not sur ehow it warped but it did. i just replaced the rotor and pads, checked the piston and was away. I kind of air on the side of caution with my bikes and cars and their brakes. I ALWAYS replace both pads at the same time, and always replace the rotors at the same time. So I know how long they've been on there and such. Good luck man.
 

·
Registered
Joined
·
1,640 Posts
if it was an older bike, I'd say replace both rotors.
But since it's hardly worn, you'd be fine replacing that one rotor imo, with a new or 'as new' used one, but check you aren't buying another warped one first!

And yeah, some new pads for the new rotor, so might as well do both calipers. This is cos the pads score in line with the rotor, like finger print stuff. The new rotor that's replacing the damaged one will have a different face. The pads wear to the face. And by replacing both sides, that just means they'll wear at the same rate, instead of just one side being worn
 

·
Registered
Joined
·
192 Posts
Discussion Starter · #12 ·
Alright, i may just do the single rotor then.. with new pads.

I have 3300 miles on mine.. A think a new one from babbits or bikebandit ( i forget) was 250 bucks?

and currently on ebay there is a set of rotors with about 2000 miles for $200.. I asked and they are said to be in perfect condition, other than the mileage, no warping or bends, but i am uneasy about buying anything used off ebay that is performance oriented.

Or i could just go for a new set of something nice, haha.
 

·
Registered
Joined
·
192 Posts
Discussion Starter · #14 · (Edited)
Nevada.. that may be the exact problem.

Although i will have to replace one rotor anyway because it wobbles about a quarter inch, which is real bad...

The replacement lever I bought was off of ebay, it looks 100% identical to the OEM on the bike, other than the housing for the pin/pivot on the lever being brass instead of aluminum. Not nissin stamped on the bottom.. so it must just be a look a-like. I'll have to see if there is a way to fix this...


Thanks
 

·
Registered
Joined
·
192 Posts
Discussion Starter · #15 · (Edited)
Just took off the replacement lever. Nevada thank you so much for that link.

When you install the replacement from ebay, a slight amount of pressure is required to get the pivot housing to line up with the holes on the MC assembly. I did not think anything of this when i first installed, i figured it was the force needed to push the lever back out... its actually compressing the MC a small amount.

Thank you very much nevada, I owe you.

Edit: Actually, now that I am going down into the garage and playing around with both the OEM and the replacement.. they do the same thing. You have to slide the brake lever in a certain way to get the pin on the MC to sink into the slot for in on the lever just right. Then it lines up perfectly on both levers.

I Think I may have done this incorrectly when i installed the brake lever. But.. because of how and when my brakes locked up.. I am guessing the disc is the real isssue. Because I rode the bike without using the front brakes at all, and they still locked up after riding for a shorter period of time than described in the other thread. and we all know friction on brakes causes A LOT of heat.. so that must be the culprit. My MC/lever combo cannot gradually apply more pressure if they are not being used at all.

warped disc to be replaced.

Thanks again Nevada, i jumped the gun on concluding, but its a very real possibility.
 
1 - 15 of 15 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top