The Eaton Truetrac is packed with super-tough gears that can deal with street/strip abuse.
Barney Gwozdz from Eaton expands on why you want to look at a high-quality differential for a vehicle that will see heavy street use.
“Spools cause you to drag the tire every time you turn. The amount of stress that puts on the rest of your rearend depends on the size of tire you’re running. The bigger the tire you have, the more friction there will be between the tire and road, therefore, you can expect more stress on parts. The weight of the car and how sticky the tires are also play a role in how the spool behaves. It will put extra stress on the drivetrain, but a lot of the damage will be done to your tires.”
A spool is nothing more than a solid piece which rigidly connects the axles of the car, where a differential is filled with clutches and/or gears to allow for limited slip as the vehicle is turning. The key to a quality differential is the gears that are inside and how they’re made. To make a highly functioning differential unit, Eaton uses net-forged spider gears inside that add additional durability and torque load carrying capacity to increase its strength.
“All limited-slip units, no matter if they’re cone-driven, helical gear-driven, or clutch-driven, rely on some type of natural gear separation forces. The gears will either separate and wedge clutch disks together like the Truetrac, wedge a cone into a side of the case, or force the gears into the case like a helical gear design,” Gwozdz explains.
What makes a limited-slip differential such an attractive choice for a street/strip car is the efficiency that it can offer. The ultimate goal of a limited slip differential is to get the power generated by the driveline to the ground as quickly as possible.
Setting up the proper relationship between the ring gear and pinion teeth is critical for any application. -Barney Gwozdz
All of that efficiency has to come from somewhere, and according to Gwozdz, it’s based on how the unit is designed.
“The unit is made efficient by the clutch material, the pre-load that’s in the differential, and the tolerances to how the units are assembled. By working with these, that’s how you make the differential more efficient. The more efficient you can make the process happen inside the unit, the better the unit will react.”
Selecting the correct differential is just part of what it takes to make your rearend combination work flawlessly. You also have to make sure everything is set up and maintained properly. Taking the time to ensure the ring and pinion have the correct tolerances and torque specs is the best way to guarantee it can deal with abuse at the track. Equally important is that you observe the prescribed maintenance intervals to eliminate lubrication problems and other issues.