FIT NEW DIFF
This is the business end of the upgrade, but you can’t get all giddy and bolt the Quaife ATB straight into the gearbox – there’s a few bits that need doing first.
The crown wheel that was removed from the original diff needs to be installed to the ATB (ensuring the bolts are thread-locked and torqued-up correctly) and the new differential taper bearings need pressing onto both sides of the new ATB unit, while the corresponding bearing cages in the gearbox casing need the old items removing and the new cages securely pressing in place. Then the diff backlash is checked, as per Ford’s ETIS procedure.
The new bolts for the crown wheel and the differential bearings are included in the fitting kit mountune offers – along with the PTU oil seal, new propshaft bolts, and driveshaft oil seals that you will also need to complete the job.
With the diff bearings securely in place and lubed up with a bit of assembly compound, the new ATB unit can be offered up to its new home. Ensure everything’s sitting correctly in the bearing and the crown wheel is meshing as it should with the rest of the gearbox, and then it’s time to start the reassembly process.
A nice even bead of gasket sealer is applied to the gearbox before the bellhousing can be refitted – a gentle tap ensures it sits snugly over the dowels before the series of bolts can re-fitted and torqued accordingly.
The gearbox is nearly ready to be re-fitted to the car now, but before it is the driveshaft oil seal and new PTU oil seal (the one that is notorious for leaking, even on standard cars) need to be fitted, and the clutch slave cylinder re-installed. At the same time, the second driveshaft oil seal should be fitted to the PTU unit, and then everything’s ready to go back together…