KJ Jones
Brand Manager, 5.0 Mustang & Super Fords
April 1, 2011
Photos By: KJ Jones

Truetrac VS. Locker Q&A
We've used a limited-slip Detroit Truetrac differential in our ProCharger F-1C-supercharged, '02 Mustang GT, and now have a freshly installed Detroit Locker in the 'Stang's 8.8 rearend. However, before we ever installed either unit, a lot of thought was put into the short- and long-term performance goals that we had for the project car. Remember-the car is street driven, and despite the array of race superchargers we have installed, our intent is to maintain good street manners and driveability.

This project has brought about several questions about Detroit's Truetrac and Locker differentials that we think many of you are asking. Here is a quick Q&A that hopefully will give you good insights about both units, and help you make the right selection for your Pony's rearend when it's time to upgrade.

Detroit Truetrac
Q: When does the Truetrac lock up?
A: The Truetrac is a helical-gear, limited-slip differential and never "locks up." The Truetrac operates by transferring power from the spinning wheel to the wheel with the most traction. If one tire breaks traction, the amount of rotation (or spin) is controlled. The torque is then sent to the other tire that still has traction.

Q: I use my car on the street and on the strip. Will the Truetrac hold up?
A: On the street, the operation of the Truetrac is transparent. You will not know it is there until you need it. In racing situations the unit will apply torque to both tires and consistently launch straight.

Q: How much horsepower and torque will the Truetrac take?
A: There are many factors to consider when determining if a specific differential will last in your 'Stang. Horsepower and torque are important factors. However, the weight of the car, tire height/width, the terrain, and suspension are all important things to take into consideration.

Detroit Locker
Q: When does a Detroit Locker lock?
A: The Detroit Locker is fully locked up when driving in a straight line or if the tires are spinning. The unit unlocks in a turn for the wheel that is turning the fastest.

Q: When I step on and off the gas pedal, I hear the unit make a clunking noise. Why?
A: Detroit Lockers have backlash between the drive and driven teeth, and you will hear clunking usually when going through corners and when going from drive to coast mode. Also, with the 'Stang on the ground and the transmission in neutral you will have 1/4 to 1/3 of a turn of lash in the driveshaft. This is completely normal.

Q: Can I run a Detroit Locker on the street?
A: Many people do use the Detroit Locker during everyday street use. The Detroit Locker is an aggressive differential, so you will hear it and feel it every day on the street.

Q: How much horsepower and torque will the Detroit Locker take?
A: There are many factors to consider when determining if a specific differential will last in your vehicle. Horsepower and torque are important factors. However, the weight of the car, tire height/width, the terrain and suspension are all important things to take into consideration. For example, a setup that uses street tires will live longer because both tires will break loose and spin before any real strain is put on the unit. But as the tire gets wider, the stress on the unit increases because the traction is greater.