  We present the results of a study with the Swift Burst Alert Telescope in the
14 - 195 keV range of the long-term variability of 5 low mass X-ray binaries
with reported or suspected super-orbital periods -- 4U 1636-536, 4U 1820-303,
4U 1916-053, Cyg X-2 and Sco X-1. No significant periodic modulation was
detected around the previously reported values in the 4U 1916-053, Cyg X-2 or
Sco X-1 light curves. The $\sim$170 d period of 4U 1820-303 was detected up to
24 keV, consistent with the proposed triple system model. The $\sim$46 d period
in 4U 1636-536 was detected up to 100 keV, clearly inconsistent with variable
photoelectric absorption via a warped precessing disc. We speculate that the
appearance of this modulation after 4U 1636-536 entered the low/hard state
indicates that this variability could be linked to jet precession such as
observed in SS 433.
