AT LAST….. 5th gear has arrived…. in the shape of the Canadian Rock Mountain Overdrive. It used to be called the “Roverdrive” but Land Rover didn’t like that, so the name was changed to the “Global Roamer Overdrive”.

The overdrive is a Power Take Off (PTO) unit. A variety of devices can be run from the PTO on the back of the transfer box, (winch, compressor, hydraulic pump, welding generator, lawn mower, under drive, over drive, additional prop shaft to run a belt drive from the rear cross member, further extending the ability of the vehicle… corn thresher, circular saw etc. You can’t do that with a Pius… sorry… Prius) and one of these devices will allow you to have a 5th gear.

The overdrive is a gear totally independent of the rest of the 4 speed gearbox and operated by a separate gear lever. In normal driving conditions, one would drive sequentially through the main box (1st, 2nd, 3rd ,4th) then engage the overdrive (5th).  It can also be used as a splitter gear between all 4 gears (and reverse) in the main gearbox… for example1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5.

The overdrive increases gearing by 28% which makes motorway driving far more comfortable and also (in theory) improves fuel economy and reduces stress on the major mechanical components.

PLUS…. it means theres a 4th gear lever in the cab 🙂

But installation was not without issue. I cannot, for the life of me, get the overdrive to go all the way onto the coupling…. and I know exactly why. It’s easy enough to slide the coupling together on the bench but once you’re under the vehicle…. its a different kettle of fish. I’ll leave it for a couple of days and have another tinker with a fresh pair of arms… The overdrive is not the lightest of units.

When was the last time you has something delivered in a crate? This crate was packed by Ben
Rocky Mountain Overdrive and sundry hardware
Register plate
The Overdrive comes with a dip stick for the transfer box
A few wraps of PTFE tape will reduce likelihood of oil drips
The dip sticks fits into the fill plug aperture
Elbow fitted
Shaft and dip stick fitted. When the tip of the dip stick is wet, you know you have enough lubrication
New inspection cover with convenient filler plug. Replaces the one in the next picture
Out with the old and in with the new
Original pick off gear ready to be removed
New overdrive coupling fixed in place behind the oil finger
Lucking nut is torqued up to 135 Nm
Overdrive, new gasket and fixings ready to go
Gasket offered up over the old studs (these will be removed)
Gasket sealant applied to the opposite face
Studs removed. Next step fit the overdrive
Fitting the overdrive…. except the last 30mm. Hmm.