The early Cleveland master cylinders had an external spring but it was too weak from the factory so they issued a Service Bulletin to change them. They provided the parts free at the time. I changed mine but I don't think I had a problem to begin with.
When you set up the brake pedal linkage it is essential to make sure there is no binding as that will cause dragging brakes with any stock master cylinder springs, internal or external. There's nothing wrong with adding external springs but make sure your linkage is set up correctly first.
RV-6 N207AM w/G3X, 1,500 hours +
South St. Paul, MN (KSGS)
Manager - Panel Design, SteinAir, Inc.
A&P, EAA Tech Counselor
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