Bulletproofing a Ring and Pinion Gear

by Mike Kojima

Our friend Pro Drifter Walker Wilkerson was having a problem. As of late he has been plagued by drivetrain failures in his Fatlace Nissan S13. Part of the reason has been that because he competes in Formula D against the big V8’s of other pro teams, with a small displacement boosted SR20DET, Walker must do a lot of clutch kicks to keep the pipey turbo engine in its powerband.

Rookie privateer Walker bringing the fight to seasoned pro Chris Forsberg at The Wall. On his lead run Walker's ring and pinion failed, possibly costing him rookie of the year honors.

This puts a lot of stress on the drivetrain and Walker has had his share of drivetrain issues even with Nissan's normally strong drivetrain. These issues unfortunately probably kept him from winning Rookie of the Year honors in his first season as a pro. After a ring gear failure took him out in the New Jersey Formula D round we decided to help Walker out and prep a ring and pinion gearset for him.

Even though Walker is one of the few 4 cylinders left in Formula D, he can consistently bring the fight to the high powered V8 cars much to the delight of purest drift fans. Here is Walker with Ryan Tuerck.

To reduce stress as part of the root cause of the issue, Walker has recently switched to an Exedy carbon twin plate clutch with softer engagement characteristics. Carbon also resists heat better and can be slipped instead of just being kicked.

Walker's 2.3 liter SR20DET pumps out power in the mid 500 range, equal to some of his V8 competition, however that power is over a much narrower range and Walker must frequently kick the clutch to keep the turbo SR on the boil creating a lot of stress on the drivetrain.

The Nissan R200 is a pretty strong diff. We have seen them used many times on V8 powered swaps, high powered turbo Z’s and raced in IMSA with GTO cars pushing 1000 hp. However due to the unique nature of drifting and the brutal shock of having the clutch kick the engine many times into its powerband, Walker managed to break his. The diff failed at a crucial moment during a run against Chris Forsberg. If Walker had advanced, the end of year points might have played out much differently.

The GT35 twin scroll turbo is fast responding but also has some lag resulting in the need to clutch kick.

Our first step in prepping Walker's spare ring gear set was to send it out to be cryo treated. Cryo treating is really an extension of the heat treating process. It sounds like snake oil but it really does work on most steel and iron alloys. Cryogenic treatment involves cooling the parts to the temperature of liquid nitrogen then warming them to close to the tempering temperature which is around 350 degrees several times over a period of about 72 hours.