Sounds like your using a Talon SRX over CAN bus.
Be sure to update to latest FRC legal firmware 2.0. (Section 2.3).
Please read section 16.9 and section 20 for tweaking the update rates the Talon reports it's signals over CAN bus.
setExpiration() and SetSafetyEnabled() is a totally different feature available for all motor controllers (has to do with auto-zero-ing your motors if software does not call set often enough). Also is explained in section 19.
Is there any reason why you are not letting the Talon SRX perform the close-loop for you (section 10.3 Velocity closed loop)?
Sections are in the Talon SRX Software Reference Manual...
http://www.ctr-electronics.com/talon...ical_resources