I don't have direct experience with the vacuum slider cause mine never
worked since I've owned it, but since I tore it off and and hooked up a
cable, I find that when the engine is either pulling or braking, even
slightly, it's damn near impossible to push the cable to disengage the
axle. I expect the vacuum unit would be similarly ineffective in such
cases. I have to feather the gas so that the inner and outer axles are
freely rotating together in order to slide it off.

I presume you don't resort to the brute force 3000 rpm vacuum method
until after trying to feather the gas to release pressure on the splined
collar.

Steve
http://xjeep.dyndns.org


Mike Romain wrote:
>
> If the vehicle is in 2 wheel drive via the shifter and the slider
> doesn't want to unlock, you need to floor it up to say 3000 rpm, then
> let off the gas fast.