About Spec-R Gear Diff
When it comes to on-road touring cars, racers have a choice of running with Ball Diff; Gear Diff or Spool(Locked Diff). In the early days, open bevel gear diff was popular. In the early 1/12th pan car for example, the open diff worked fine because the inside rear wheel rarely lifted off the ground. However, racers soon realized that their 4WD touring cars loses forward momentum when the inside wheels lifted off the ground while and the outer wheels got zero power.
Starting in late 1980s to early 1990s, the ball diffs started appearing on the scene. An adjustable ball diff could also serve as a slipper clutch to reduce gearbox damage and with proper adjustment, it prevented inside wheels from getting 100% power during cornering and thus drastically improved touring car performance on the track. However, a ball diff only works well when it is built and adjusted properly; and it requires far too much maintenance and rebuilds. Then somewhere along the way, drivers started to realize that a front spool in a 4WD touring car was the quicker way to go and it kept the front end very stable under braking but with reduced turn-in. However, with a spool there is a lot more additional stress and wear on the front outdrives and driveshafts and many racers paid the price. Until recently, racers at Spec-R invented the revolutionary Sealed Gear Diffs with a compromise among durability; tunability; maintenance and optimal performance. Our patented gear diffs are race proven and gained popularity worldwide. Gear diff tension is adjusted by using different oil weight; and it goes a long time without needing a rebuilid. With proper sealing, Diff setting is maintained and is recorded by oil weight rather than by "feel" compared to a ball diff. Racers now can build a Spec-R gear diff to mimic a Spool too by using heavy oil in the differential. Unlike a spool, you have much better protection upon impact and tire chattering and scrubbing can be minimized.