Mitochondrial intermembrane chaperone that participates in the import and insertion of some multi-pass transmembrane proteins into the mitochondrial inner membrane. Also required for the transfer of beta-barrel precursors from the TOM complex to the sorting and assembly machinery (SAM complex) of the outer membrane. Acts as a chaperone-like protein that protects the hydrophobic precursors from aggregation and guide them through the mitochondrial intermembrane space. The TIM8-TIM13 complex mediates the import of some proteins while the predominant TIM9-TIM10 70 kDa complex mediates the import of much more proteins (By similarity). Heterohexamer; composed of 3 copies of TIM8 and 3 copies of TIM13, named soluble 70 kDa complex. Associates with the TIM22 complex, whose core is composed of TIM22 (By similarity). Expressed in roots, flowers, young cotyledons and leaves. The twin CX3C motif contains 4 conserved Cys residues that form 2 disulfide bonds in the mitochondrial intermembrane space. However, during the transit of TIM13 from cytoplasm into mitochondrion, the Cys residues probably coordinate zinc, thereby preventing folding and allowing its transfer across mitochondrial outer membrane (By similarity). Belongs to the small Tim family.