Here a failsafe i found on ebay $5 works well i got one wait is long price is cheap!!
http://cgi.ebay.com/Nitro-RC-Fail-Safe-for-All-Car-Truck-Tank-Boat-Failsafe_W0QQitemZ270518267404QQcmdZViewItemQQptZRadio_Control_Parts_Accessories?hash=item3efc252e0c
http://cgi.ebay.com/Nitro-RC-Fail-Safe-for-All-Car-Truck-Tank-Boat-Failsafe_W0QQitemZ270518267404QQcmdZViewItemQQptZRadio_Control_Parts_Accessories?hash=item3efc252e0c