=Help!= Brake Lock...

617 Views 5 Replies 5 Participants Last post by Drumonster_Dyami, Dec 16, 2006

Drumonster_Dyami

Discussion Starter · Dec 15, 2006

Hi, I'm trying to figure out how to unlock my rear brake. I have a 1999 M750 with brembo four piston calipers. (I think, 2 on each side right?). The screw was comming loose that sets the amount of travel the brake pedal can have. A couple times it unscrewed itself and engaged the rear brake. I pulled over and screwed it back in, no problem (other than I was crusing with my brake clamped, heating up the rotors no doubt). I went out yesterday morning to back it up out of the garage and the brake was engaged. I checked the pedal and it has travel, the brake pad just won't let go. What do I do?

Thanks, drumonster...

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ducman851

· #2 · Dec 15, 2006

Try bleeding off the pressure through the bleeder.

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AKmnstr

· #3 · Dec 15, 2006

Drumonster, I just PMed you but I see that there is more info here. I suggest that you check the specs on you rotor once you get it free and your wheel is once again rotating. You should check it for both warp and thickness. It is possible that serious damage was done to the rotor when your caliper was closing on its own. You'll need a micrometer and a dial indicator. If your not familar with dial indicators here is a web page that descibes them. http://www.mini-lathe.com/Measurement/Dial_indicators/Dial_indicators.htm
Both these tools are not expensive and can be picked up on ebay. The check is simple once you have the tools. You should also check your pads. They may be glazed. The rotor may also be glazed with pad material. Of course you can take your bike to a shop and have it checked. I hope this helps!

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ducpainter

· #4 · Dec 15, 2006

ducman851 said:
Try bleeding off the pressure through the bleeder.

That should release the pressure. Did you make sure the lever is allowing the proper bleed back from the master? If not, it will happen again.

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mitt

· #5 · Dec 16, 2006

If your rear caliper has been subject to alot of dirt or corrosion, it could be that the pistons are not retracting all the way and dragging on the rotor. As they heat up, the fluid expands, clamps the brake harder, etc. I had this happen on my 95 nissan pickup. The only thing that pushes the pistons back in is the runout (wobble) of the rotor (I think it is the same on bikes as cars).

mitt

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Drumonster_Dyami

Discussion Starter · #6 · Dec 16, 2006

Thanks for all the advise... what do I look for when I'm looking for glaze on the brake pads? I'll try to get those tools and check the rotor, but it'll have to wait till I'm back from tour!... Only 10 days now! Ireland, England, Holland, Belgium, Czech. Rep., Slovakia, and Belgium... I'll post some pics when I get back...thanks all!
-Drumonster

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