  We study the time variability (over $\le$7.3 yrs) of ultra-fast outflows
(UFOs) detected in a sample of 64 C IV broad absorption line (BAL) quasars
(with 80 distinct BAL components) monitored using the Southern African Large
Telescope. By comparing the properties of the quasar in our sample with those
of a control sample of non-BAL quasars we show that the distributions of black
hole mass are different and the bolometric luminosities and optical photometric
variations of UFO BAL quasars are slightly smaller compared to that of non-BAL
quasars. The detection fraction of C IV equivalent width (W) variability
($\sim$95%), the fractional variability amplitude ($\frac{\Delta W}{W}$) and
the fraction of ``highly variable" BAL (i.e., |$\frac{\Delta W}{W}$| $>$0.67)
components ($\sim$ 33%) are higher in our sample compared to the general BAL
population. The scatter in $\frac{\Delta W}{W}$ and the fraction of ``highly
variable" BALs increase with the time-scale probed. The $\frac{\Delta W}{W}$
distribution is asymmetric at large time scales. We attribute this to the BAL
strengthening time scales being shorter than the weakening time scales. The BAL
variability amplitude correlates strongly with the BAL properties compared to
the quasar properties. BALs with low W, high-velocity, shallow profiles, and
low-velocity width tend to show more variability. When multiple BAL components
are present a correlated variability is seen between low- and high-velocity
components with the latter showing larger amplitude variations. We find an
anti-correlation between the fractional variations in the continuum flux and W.
While this suggests photoionization-induced variability, the scatter in
continuum flux is much smaller than that of W.
