NJL breaking of supersymmetric GUTs

We analyze the breakdown of SUSY GUTs driven by Nambu--Jona--Lasinio condensates. Starting with the most general gauge invariant and pure K\"ahlerian Lagrangian up to quartic order we solve the one loop gap equation and determine the breaking direction. This is done for various classes of groups and spectra of fundamental particles which especially cover the most promising unifying groups $SU(5)$, $SO(10)$ and $E_6$. Heavy masses for the fundamental as well as for the composite particles are calculated. The results are used to single out candidates which may lead to an acceptable low energy theory. In these models we discuss some phenomenological aspects and point out the difficulties in constructing phenomenological viable theories in our scenario.