STEP THREE — CHANGE AND RECALCULATE

Before adjusting anything, Steve experimented with the calculator, changing several values to get an idea of how different alterations would affect the final outcome. It’s worth noting that changing one angle will affect the angles of both shafts, as they are connected.

By doing this, Steve discovered that by inserting a higher pinion angle and lowering the driveshaft centre hanger, the figures would become more acceptable.

The process of actually working through adjustments on the car is a tedious and timeconsuming one, even with a rough idea of what needs to be done. Steve replaced the hanger-bearing mounting shims with a pile of flat washers to lower the centre joint, while adjusting the diff-pinion angle. Eventually, he arrived at the figures at right, which yielded a satisfactory outcome.

Knowing that the driveshaft operating angle should be fine, Steve measured the total height of flat washers added to the hanger-bearing mounts and had the shims machined down to suit, safely keeping the centre joint in its optimal position.

This gave the following inertia and torsional effects:Inertia effects (driving member) Degrees: 1.27Rad/sec: 161.9Inertia effects (driven member) Degrees: 0.15Rad/sec: 2.30Torsional effects Degrees: 0.89 Rad/sec: 79.8All in the clear! The final test took place at Meremere Dragway — the only place, other than a dyno, where Steve could safely test for a driveline vibration at over 190kph. All calculations, and their definitions, were sourced through spicerparts.com.Thanks to Steve Gooch and Endeavour Motors for their help in making this article happen.