While out on a track day a few weeks back, my fun was cut short due to a failure of the front diff. Quite a spectacular failure as it turns out, as the crown wheel and pinion parted company with such force it smashed the diff casing to bits in the process. I suppose asking the original unit to deal with all that torque was just too much for it to handle, so it was time for an upgrade. Something stronger that could take the abuse lap after lap.

So, the first thing on my shopping list was a new diff casing. And with the original part showing it’s clearly not up to the job, my search saw my speaking to Oppliger Motorsport over in Italy. Head honcho, Romain Oppliger, is well known in Cosworth circles for his high-power Escort Cosworth builds, and in particular they beefy transmissions they use. So, when it came to upgrading my front diff I ordered one of Oppliger’s thick wall casing. As you can see from the photo, the new item is much more robust than the original casing.

At the same time as replacing the casing I took the opportunity to upgrade the differential itself too. I was previously running a Quaife ATB, so I was keen to replace with the same to keep the balance of the car the same as before. But obviously I didn’t want a repeat of the crown wheel and pinion failure, so I had the new items shot-peened and super-finished. This is a process that basically smooths the surface of the metal and removes any areas where stress fractures are likely to start from. The result, is a diff that that has the same great handling and power delivery characteristics as before, but hopefully is much less likely to break despite repeated abuse on track. I can’t wait to get back out on track and see what’s like.