[Fot] Restrictor Valve

[Randall]

> Does anyone know the purpose, function, or reason for this valve.

It's more accurately called a residual pressure valve; it basically keeps
the front brake pistons from being knocked back into the caliper when the
spindle flexes.  If you simply disable it as many do, the brake pedal may be
low after a hard turn.

A better solution IMO is the spacers and uprated spindles developed by uncle
jack.
http://www.zeni.net/trf/TR6-250GC/119.php?s_wt=1680&s_ht=1050

These address the root of the problem, rather than band-aiding the symptom.

Randall