Fioroni's Tractive IV torque reactive differentials are the most advanced differentials ever made for 1/8th off road vehicles and can be effectively used on buggies, truggies, oval cars, and rally (IGT) cars. An innovator in high end upgrade parts for radio control models, Fioroni's Tractive IV differentials are the fourth installment of 'torque sensing' differentials, following the international title winning Japan, Hyper, and Storm Traction differentials.
Tractive IV differentials are a type of limited slip/torque sensing differentials. They operate much the same as full scale Salisbury differentials, but on a smaller scale, and perhaps arguably in more severe conditions. The locking is enabled by internal ramps which act like a wedge, with the throttle and brake torque being applied to it. The rate of lock is in direct reaction and in direct proportion to the torque input- the more torque, the harder it locks. The angles of the ramps can be changed with optional parts to achieve various handling characteristics.
Compared to an 'open' or standard bevel gear differential commonly found in off road buggies and trucks, Fioroni's differentials work quite differently, both on and off throttle. While an open differential sends power to the tire(s) with the least amount of resistance (think front inside truggy tire ballooning coming out of a corner), the Tractive IV differentials balance the power output more evenly. Instead of thickening differential fluids or changing suspension settings to compensate for the loss of power, which often results in an equally negative effect elsewhere on the track, you can send more power to the wheels without a drastic change in overall handling. By adding lock, the wheel with the least resistance is less likely to spin, which means more power is being put down, resulting in faster acceleration.
Off throttle, the Tractive IV differential will act somewhat like an ABS system (Anti Lock Brakes). Your car will be more stable under braking and if you choose, you can increase the rear brake bias, often shortening brake distance. With today's improved suspension geometry and constantly improving tires, these differentials can be used effectively to lower your lap times. Another direct result is longer tire life. The less your tires spin, the longer they will last.
Fioroni's Tractive IV differentials are a powerful tuning option, not a savior to a poorly assembled and incorrectly setup vehicle. It is recommended to use the front differential first, followed by both the center and rear. By using all 3 there will be a noticeable change to the handling of the car as well as an obvious decrease in tire wear. The differentials can be used on a variety of surfaces from loose dirt to clean pavement. Make sure to try them in practice first and make chassis adjustments as needed before using them in racing conditions.
The standard ramp angles are 120 for Front differentials, 80 for center differentials, and 40 for rear differentials. Optional 60 and 100 degree ramps are available for your tuning pleasure. For optimum performance, it is recommended to clean and re-grease the differential after each weekend of racing, with a maximum of 3 races in between cleaning and re-greasing. Although not necessary, it is suggested to re-install the internal components in the exact position, and allow a short break-in time for new or freshly rebuilt differentials. Do not use any grease or oil except for the one included with your differential and available as a spare part (TRC-020). The differentials can be fully rebuilt and a full line of spare parts is available. You can further complement your car's drivetrain with Fioroni LIC range of lightweight axles, hubs, and gears, available for most popular racing buggies and truggies.
Fioroni Tractive IV differentials, like all Fioroni product, are designed and made in Italy using only the highest quality materials and process. Beware of knockoff 'torsen' differentials. They often work poorly and are made of sub par materials. Fioroni Option Team parts are tested and used by IFMAR World Championship winning drivers. Tractive IV differentials are available for the following cars and their compatibles: Associated RC8, GS Cl-1, Kyosho 777, Losi 8, Mugen MBX5R, and XRAY 808 (available June 2008).