Screw in the speedometer cable...
Screw in the speedometer cable extension included in the kit. If you're doing the install yourself, you will have previously measured your tire diameter, and supplied it to Gear Vendors (along with your rear gear ratio) when ordering your unit. This will guarantee the right speedo gear is inside your overdrive housing.
Yeah, we said "fun." We didn't really expect that an overdrive button could be so cool, but it was a blast to chirp the tires by clicking it on. Likewise, turning it off on the highway, into a non-overdrive passing gear, was a thrill, too. And the icing on the cake: blasting through all the gears, splitting them with the overdrive (that's six in all for our Turbo 400-equipped Chevelle). It was so fun, we almost forgot the initial impetus for going overdrive: better gas mileage.
A careful measure of fuel economy before and after the Gear Vendors installation revealed that even under ideal conditions (55-mph top speed, no full-throttle blasts), the best we could muster on the highway without overdrive was 7.5 mpg. After the install, we easily pulled down 10 mpg, and we were going way faster than 55 mph, more like 65 mph. That's an improvement of 25 percent. Put another way, we could go the same amount of miles from our fill-up for about 20 bucks less-and still have 5 gallons left in the tank. The only question we're asking now is: "Why didn't we do it sooner?"
These two wires energize the...
These two wires energize the overdrive control solenoid, and must be routed to the Gear Vendors electronic control box.
Here's the Gear Vendors electronic...
Here's the Gear Vendors electronic control unit mounted safely under our dash, with connections already made for the solenoid control, speed sensor input, 12-volt power, thumb button control, and indicator lights.
At the terminus of the Gear...
At the terminus of the Gear Vendors speedo cable extension (where your factory speedo cable screws in) is a speed sensor with two wires. These should be run to the Gear Vendors electronic control box, which you'll mount inside the cockpit under the dash.
We're deviating from the standard...
We're deviating from the standard Turbo 400 A-body installation because our Chevelle originally came with a 307 small-block and a Turbo 350. Last year when we swapped over to the Turbo 400, we just reused the Turbo 350 crossmember in different framerail holes. This put the crossmember in a slightly different place than normal, necessitating a boxed notch to clear the sump on the overdrive. Unless you are mixing and matching engines, transmissions, and crossmembers, you won't need to do this.
We elected to mount the two...
We elected to mount the two Gear Vendors indicator lights on our Stewart Warner gauge panel. The red light (left) is the Autostart indicator. When the overdrive button is engaged from a stop or a very slow roll, this light will come on. It lets you know that overdrive will automatically engage once you exceed approximately 15-20 mph (the in-shift threshold). The green light is the overdrive indicator, and tells you that the overdrive is now engaged. Overdrive automatically disengages (the out-shift threshold) when vehicle speed dips below 5 mph.
You can choose a floor-mounted...
You can choose a floor-mounted stomp switch, a dash-mounted slider switch, or a shifter-mounted switch to activate your Gear Vendors overdrive. We chose one on the shifter. This switch from B&M is stocked by Gear Vendors, and fits all B&M Bandit-style shifters. It also happens to fit our TCI Outlaw shifter perfectly. Now it's time to hit the road and try it out.