BOTH front calipers stuck ?

[urq]

The dual diagonal system went away with the advent of ABS.  The front brakes
are fed from one circuit and the rears from the other.  ABS doesn't replace
the functionality the dual diagonal system provided, that being if you have
a failure in the circuit that drives the front wheels you have lost the
majority of your braking capability.  I remember reading that it was
difficult to make ABS work in a dual diagonal system.  Those were the early
days, I'm surprised that there has been no effort to revive some method of
redundancy.  The newer BMW motorcycles link the rear and front hydraulic
systems to allow each to have some effect on both brakes.  BMW motorcycles
have had ABS since the 1990 k1 (I have a '92 in my garage).  

The situation you describe is usually due to two issues, one that you have
gotten some water in the hydraulic system, and the other that the piston in
the brake M/C is not returning to the fully released position.  When the
brakes are fully released a port is opened which allows the pressure in the
brake system to be balanced.  This may be due to a failure in the M/C or the
brake booster.  It may be that the rest position of the brake pedal is not
set correctly.  Try bleeding the front brakes; if the M/C piston isn't fully
releasing you won't be able to get fluid through the system.  

Steve Buchholz

-----Original Message-----

Well, the issues keep piling up. I got to work this morning and BOTH front
calipers were smoking - seems that BOTH are stuck. I am wondering if its the
master cylinder because a: I replace both calipers less than a year ago
(rebuilt, not new) and b: no reason BOTH should go at the same time.
However, to verify, does anyone know offhand if the 200 has diagonal brake
plumbing off the MC? If so, that would blow my diagnosis.  Also, if it IS
the MC, can someone explain how an MC fails in such a way to not release
just one of the circuits?

Sheech, I really don't want to work on the car any more, but it seems that I
will be jack the car up and removing some wheels tonight

Dave
90200QA that is now running like a freight train. Stopping is the
problem.......
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