KX500 Front brake Caliper ceasing up

[dans89kx500]

hey Y'all,

I'm having a problem with my front brake caliper ceasing up. It locks up almost frozen. Will WD40 do the trick? Have anyone else had this problem? Any suggestions would be great.

Thanks,

Dan in Vacaville

[Johnniespeed]

 This is a serious situation, as the power of a KX500 needs the brakes to function perfectly.  You say the front caliper is siezed ?  If you loosen the bleeder and the wheel spins freely, the caliper isnt the problem. However if the caliper is seized with all hydraulic pressure relieved, then disassembly is in order. The caliper piston should move without a great amount of force. The brake pads should not be stuck on the pins.  I think with a little detective work you will figure it out.
   WD 40 is a water dispersant, it will displace any water. I doubt that water on the caliper is causing your problem. I know it can be used as a penetrant or a lubricant, but there are much better penetrants and much better lubricants available.
 Hope you get this sorted out easily. John

[KX500freak]

my 2 cents..


i guess the brake is been hidden behind that cover for ages,
therefore its probably never been checked cleaned or ....till it shuts you down.

i should take the caliper apart ,the piston out ,clean it good
check the rubber rings for shape ,hard area,s or wear.
the piston when cleaned must slide nicely up and down in its cylinder

then assemble it again and bleed it thoroughly,
when your busy ,put in new brakefluid too 


oooww btw ..is your lever not adjusted too tight
 
had it once with my rearbrake ....tooo tight adjusted and its continuing making contact with disk,
due to building up pressure and then heat at the caliper

good luck then

freak

[dans89kx500]

Yes, the caliper has been hidden behind a cover since the beggining of time. Also, when I freed the bleeder it relived the pressure (brake fluid blew all over my face) the wheel did spin and the pistons were able to be pushed back in.
Thursday and today, I had this problem. The heat outside both days was over 100 degrees.

Dan in Vacaville

[KX500freak]

mmm  i do think you should refresh the fluid and clean the caliper ,
because its contaminated with watercondens due to no refreshing for ages too i guess
that means there,s more fluid in the system then ment by the manyfacterer..
that should explain the stuff coming out so hard ,even hits you in the face
even explains why its seizing up ..to much pressure build up

fluid from the bleeder shouldn,t come out that hard ,
only when applying lever

i hope you can work this out

[KX500freak]

Yes, the caliper has been hidden behind a cover since the beggining of time. Also, when I freed the bleeder it relived the pressure (brake fluid blew all over my face) the wheel did spin and the pistons were able to be pushed back in.
Thursday and today, I had this problem. The heat outside both days was over 100 degrees.

Dan in Vacaville

well Dan,


did you solve your issue on that caliper yet
kinda curious what was the problem after all

[demographic]

If the pressure is maintained when theres no lever pressure I would also check out the master cylinder and maybe give it a rebuild.
Sounds like the brake master cylinder piston isn't returning to the point where the fluid can return back into the resevoir.

[tharden]

Something else to check is the brake line. Check for kinks, and if a break line gets to old the inner layers will separate and act like a check valve and cause this problem.

[Mick]

Hey Dan I got an '89 too that had that same problem.  It's already been mentioned once before but I'll through it out there again.  Check the play at the lever.  Maybe the older models are a bit prone to this, but when the lever is too tight the caliper gets hot with use and the fluid expands and pushes against the lever.  When the piston can't push the lever anymore the only other place the fluid can expand is at the pistons in the caliper.  Hence the lock up.  When the front end locked up the lever was completely solid, I could not move the lever a fraction of an inch.  If this sounds familiar just add a little play in the lever and you should be good to go.  That was all I had to do.  Well...and replace a heat warped rotor but you get the idea.