front brakes locking up

Yes, I know, very lucky I wasn't thrown ass over tea kettle on this one. Decided to take my xj550 out for a spin down to the river on this lovely day before heading to the bike shop to buy new handle bars and grips.

Would'nt you know it, my bike starts doing the weird dip dance and acting all grabby as I clip along in town at about 40mph. This dip gets worse in a few seconds and just as I am pulling it over the front wheel completely siezes and the brakes clamp down on leaving me to wait until the sysem has cooled down and I can get the wheel to move again. before limping back to the garage at a very low speed and stopping every few block to make sure the brakes don't lock again.

So my guess is that the calipers on the front disc are shot somehow. I rebuilt the master cyclinder a few months ago (with moral and technical help from you all online!) and had very good results. The caliper though is pretty worn looking and I wouldn't be surprised if the pins inside are sprung and locking those pads down against the rotor. Am I right in guessing this is the problem? Should I build a caliper rebuild kit and truck the caliper over to my favorite bike mechanic and have him do this pretty important component on the bike for me?

Chacal, you have a rebuild kit?? : )

Thanks all for any clues, hints or words of sympathy for this sunny day lost to a needy brake system that just won't let go


Chris

 

Yes it IS possible that the calipers can get sticky, Or that the Brake hose can detewriorate into a one way valve. BUT usually it's the wee (hard to even see) Hole in the bottom of the Master Cyl Reservoir that once plugged locks up the calipers the wee hole is the pressure relief hole. Get a fine piece of wire a strand from elecrtical wire often fits. Then find and clear that hole.

 

Definitly the relief hole from the sound of the symptoms, but a complete brake overhaul is probably long overdue.

 

Cool, I will definitely clean the small return port again. I remember it being pretty plugged up when doing the master cylinder rebuild so I will do that again. You think using one of the those dental style automotive scrapers to poke in the hole would be harmful to anything?

Thanks for ideas, I definitely hope its the return port clogging that much less expensive and gets me back ont he road!

Anyone here have experience with rebuilding the caliper? Something best left to the mechanic with more experience and a full shop or would you tackle it yourself?

 

I'd take it on if you have access to small tools and/or a bead blaster to clean up the parts. A Dremel will work (buy a few of the brass and steel wheels). You should be able to do this in a few hours (and that is being liberal with the time).
Good luck and get a good rebuild kit (I hear factory is best).

 

NO.. use the suggested piece of copper wire to clear the hole.
Enlarging the hole intentionally or not is.. Not Clever.
As is 'in my opinion' using Power tools around and Brake parts.
IF your fluid is so deteriorated as to be leaving deposits then the ENTIRE brake system (if mine) would be dismantled and carefully cleaned. of the deposits.
I'm no fan of Fred Flintstone braking techinques.