Brake piston alignment

[Dana Loomis <dloomis@domain.elided>]

I'm posting this observation because it is safety-related and may be
important to someone in the future.  

Owners of factory service manuals for 105, 115 and 116 series Alfa Romeos
(and possibly other models, but I haven't seen the books) have probably
seen descriptions of how the alignment of the brake caliper pistons in
their bores should be checked with special wedge-shaped tools.  I doubt,
however, that many have gone through the procedure of checking and
correcting the piston position.  I personally went for years without doing
it on any of my Alfas; no-longer-available special tools are required, and
I didn't believe the pistons were likely to have gotten out of alignment.
WRONG!

I just went through this exercise with my 1750 GTV race car and found that
the pistons were misaligned in all four calipers.  Whoever had assembled
those calipers (it wasn't me!) had installed the pistons with the raised
portion oriented toward the opening where the pads fit, rather than toward
the leading edge of rotor travel, as they should be.  The front pads were
worn unevenly as a result.  

Misalignment of the pistons can result in a soft pedal and inconsistent
brake performance.  If you have access to the factory tools, check yours.
If you don't, have your mechanic perform the check. 

Dana Loomis

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