Horizontal gauge symmetries between fermion families and their spontaneous breaking can be at the origin of the inter-family mass hierarchies. The corresponding gauge bosons must have flavor changing couplings to fermions and generically the very stringent limits on their masses arise from flavour changing phenomena and CP-violation. However, in the special cases of chiral horizontal symmetries separately acting on left and right species, manifesting suppression effects due to custodial symmetry, the flavor-changing bosons acting between first two families are allowed to be as light as few TeV, without contradiction with the existing experimental limits and thus they can be detectable as new resonances at the LHC.