Gear Vendors Under/Overdrive Transmission – Hot Rod Approved
Gear Vendors Under/Overdrive
By: David Freiburger
Photography: Courtesy Gear Vendors
Reprint from


The Gear Vendors unit is a supplemental planetary gearbox that adapts to the output shaft of your existing transmission to provide an extra gear of 0.78:1. The initial benefit is the addition of a 22-percent overdrive in high gear, but because the Gear Vendors can be engaged in any gear, it actually doubles the number of ratios available in any transmission. For example, your TH350 becomes a six-speed (First, First/Over, Second, Second/Over, Third, Third/Over). Likewise, a four-speed manual or automatic becomes an eight-speed, and a five-speed becomes a ten-speed.

Here’s why you care:
First, because most street cars will go quicker down the dragstrip if you can split the gears, since the engine stays closer to where it makes peak power. On the street, the Gear Vendors allows you to always find the right engine rpm for the conditions. Ever climb a hill with your 700-R4? In many cases, Overdrive is too high and Third is too low. With a Gear Vendors, choose Third/Over and you’ll hit the engine’s sweet spot. Finally, on the highway, your engine’s comfortable cruise rpm will result in a mph that’s 28 percent faster with the Gear Vendors engaged in top gear. For example, if you have a non-overdrive trans, 3.50 rear gears, and 27-inch-tall tires, you currently cruise 70 mph at 3,000 rpm. With the Gear Vendors, you can either drop your rpm at 70 to 2,400 or maintain the 3,000 rpm and hit nearly 90 mph.

The Gear Vendors unit is available for nearly any domestic trans, auto or manual, overdrive or not. If you really want to get fancy, you can even stack multiple Gear Vendors units behind the trans. They are also available to mate to most transfer cases for use in 4x4s. In any application, the GV can either be triggered by a simple on/off power button or controlled by the Autodrive computer, which makes the unit shift on its own just like an auto/overdrive transmission.

Gear Vendors Inc.,
Dept. HR01
1717 North Magnolia Ave.
El Cajon, CA 92020

Gear Vendors Under/Overdrive
Overall Ranking: 21 Points
Goes FasterN/A12345
Looks BetterN/A12345
Saves HasslesN/A12345
Bolts Right UpN/A12345
Bang for the BuckN/A12345
Just Plain CoolN/A12345

HOT ROD Approved Official Rankings
Goes Faster: The Gear Vendors can provide the best of all worlds depending on how you use it: It can either improve acceleration, multiply your top speed, or improve your gas mileage. Therefore, it deserves our top honors in this category.

Rating: 5
Looks Better: Sorry, but even those of us who check out a car on our hands and knees might not truly appreciate the beauty of the Gear Vendors. It’s just not an appearance item.

Rating: N/A
Saves Hassles: It’s one of those things you’ll never miss if you’ve never experienced it, but once you drive a GV, you’ll always want one. More tangibly, the GV can save you money if you already invested in a beefy trans and now you want overdrive. Also, it’s the strongest way to have both a trans-brake automatic trans and overdrive.

Rating: 3
Bolts Right Up: For a component as seemingly complex as a supplemental transmission, you’d think it’d be a pain to install. Not. You can physically bolt the GV to your trans in about 15 minutes. Getting the driveshaft shortened is also not a big deal. In some cases, the most hassles will be adding some floorboard clearance, as the GV is “about the size of a 3-pound coffee can” per the company’s literature. See the dimensions on the Web site.

Rating: 4
Bang for the Buck: Frankly, this isn’t cheap. By the time you’ve got the car running with a Gear Vendors, expect to pay about $2,500. But that’s less than the cost of an overdrive auto trans with similar beef, and we think the GV has greater benefits.

Rating: 5
Just Plain Cool: If you’re not really into driving your car, the GV won’t turn you on too much. But if you want to bark the tires five times in a row, or if you love playing with gears, this thing’s for you.

Rating: 4
The Best Thing About It: Being able to split gears for speed and economy.

Things We’d Change: We’d like it a tad less expensive, but we’re not complaining.