Final drive assembly process

Starting point

We’re ready to start building the final drive unit. The Blackline limited slip differential contains helical spiral gears that lock under high torque loads, like the Torsen differentials fitted to some performance cars.

Fitting bearings

Outer tracks for the pinion’s two tapered roller bearings are pressed in. Shimming and adjusting pinion pre-load comes later.

Tooth mesh & backlash

The pinion is now in place but its shims need adjustment. Paul makes small changes to pinion and diff shims until engagement between the gear teeth is correct, revealed by tell-tale yellow paint. Backlash is measured with a dial gauge.

Finish

The back of the final drive casing is bolted over the diff then the output shafts with their bearings and seals are inserted from either side then their retaining plates are bolted up, finishing the build.

Shimming the diff

As the bearings are pressed onto the diff, shims must be included to precisely adjust the crown wheel’s position.

Oil seal for pinion flange

The pinion flange is tightened without an oil seal and the bearing pre-load checked with torque wrench. Once correct, the oil seal is fitted and the flange nut is finally torqued and secured with a split pin.