Sosa Guitron, S.I. De Silva, S.U. Delayen, J.R. Li, R. Morozov, V.S. Park, H. JACoW Publishing Geneva, Switzerland 978-3-95450-184-7 10.18429/JACoW-IPAC2018-THPAK070 English 3392-3394 THPAK070 Contribution to a conference proceedings 2018 2018-06 https://doi.org/10.18429/JACoW-IPAC2018-THPAK070 http://jacow.org/ipac2018/papers/thpak070.pdf Particle bunches traveling in a ring can excite wakefields inside any radio-frequency element present. These electromagnetic modes can resonate long enough and interact with subsequent passing bunches. A coherent oscillation between bunches can quickly become an instability and needs to be addressed. The Jefferson Lab electron ion collider has a large 50 mrad crossing angle and thus relies on bunch crabbing to achieve high luminosity. Bunch crabbing is done with compact superconducting rf dipole cavities. We study coupled bunch oscillations driven by the higher order modes of multicell RFD crab cavities under study for JLEIC, we calculate the instability growth time assuming a symmetric beam spectrum, identify the HOMs driving the instability and discuss mitigation measures.