The front brake rotors can warp and cause a vibration when braking. The rotors will need to be machined or in cases where they are worn to thin, replaced to correct this issue.
Car Problem Reports
Honda CRX Warped Front Brake Rotors May Cause Vibration When Braking
Honda CRX Problem
Average Mileage: 222,500 mi (215,000 mi - 230,000 mi)
Visitor, 1990 Honda CRX, 215,000 mi
This is a continual issue for this model, I've gone through at least 3 sets of rotors (including aftermarket upgrades) and they have each been machined multiple times. Every time the work is done the brakes work fine for a few thousand miles, but they eventually warp back up again. My mechanic told me that ultimately the rotors need to be larger as the OEM size is just not large enough to properly dissipate heat from hard stops.