High-performance enthusiasts are more than willing to find a reason to drive their vehicle anywhere at any given time. Older-style transmissions that don’t have overdrive can make it difficult to drive these cars on the freeway. Gear Vendors has developed a solution for that issue thanks to its overdrive unit for the TH400 transmission.

The idea behind a Gear Vendors overdrive unit is simple, you add it to your vehicle’s driveline to improve the final drive ratio. When you add one of these Gear Vendors’ overdrive units to your vehicle, it’s like adding an overdrive gear without having to change the transmission. These units have become very popular for drag and drive racers who need a stout transmission for racing, and the overdrive gear for journey on the streets to the next track.

Nick Johnson from Gear Vendors talks about how an overdrive unit can help a car equipped with a TH400 transmission.

“This overdrive unit can handle upwards of 4,000 horsepower and is easy to install. The crossmember and tunnel will require no real modifications in most cases to install the unit. A vehicle that’s geared with a 3.73 ratio or deeper will typically turn over 3,000 rpm as it drives down the highway. This unit will knock a 3.73 gear down to a 2.90 when you shift into overdrive. That will lower the RPM by at least 800 rpm.”

The only modification that most people will need to make to their vehicle to install a Gear Vendors overdrive unit is to the driveshaft. Since these units attach to the rear of the transmission, the driveshaft will need to be shortened for the overdrive unit to fit properly.

You can see all of the different gearing options available from Gear Vendors for its overdrive units right here on the company’s website.