Abstract: A window balance system includes a tilt lock carrier connected to a balance for a tilt sash so that the carrier and other components of the balance can be inserted laterally through a slot in a front wall of a balance channel, rather than requiring assembly length wise from an open end of the channel. The preferred way of accomplishing this is by configuring the carrier in a channel shape with spaced apart side walls bearing locking elements and a pivot allowing the carrier to be folded up to straddle a connector or balance in a compact configuration that is laterally insertable.