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Page 9
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(Photo showing the O.D. control panel mounted):
Our driver control panel for the Gear Vendors overdrive was cleverly mounted by Performance Unlimited in the stock dashboard knock-out location resulting in a clean factory look. Both the overdrive indicator lamps and control switch are within easy reach and clearly visible by the driver. With the switch in the MAN position, the overdrive is only actuated when depressing the manual over/under drive button. In the AUTO position, the overdrive automatically upshifts upon reaching approximately 47 m.p.h., and automatically downshifts at around 20 or so.

(Photo showing the O.D. manual actuator button next to the installed unit): Even though our overdrive kit came complete with a thoughtful mounting bracket and housing for our control switches and buttons, half the fun of a "do-it-yourselfer' project is customizing it to your own personal tastes. Since we planned on using our overdrive more as a gear splitter, we wanted easy and immediate access to the actuator button. Here we neatly substituted an on/off button from our local Radio Shack in place of the manufacturer supplied floor mount foot switch.

(Photo showing the O.D. button wiring into steering column): We drilled a hole in the OEM shifter lever and discretely ran the wires down the inside of the steering column. The final product looks neat and tidy just like the factory… had they ever offered such a cool product in the first place.

(Photo showing the O.D. computer installed):   This is the brain of the system. The central processor for the overdrive which oversees all shifting operations by automatically engaging and disengaging the overdrive, as well as preventing the system from being accidentally engaged while in four wheel drive, reverse or at too low of a speed. All the sensors and controls provided with the kit plug directly into this one box. There's even a diagnostic readout to trouble shoot in the event of a problem. We conveniently attached ours securely to the underside of the steering column.

(Photo of stock tailshaft housing and d-shaft next to overdrive assbly): Gear Vendors changed the factory slip yoke driveshaft system over to a stronger and solid slip shaft system, with their included bolt-on yoke. Rick Johnson from Gear Vendors told us that the driveshaft length needed to be shortened by only  14". The small but super-tough ear Vendor unit uses a tough planetary design which they claim is much stronger, longer lasting, quieter and more reliable than the "Mainshaft-Countershaft" design. This unit is rated to handle up to 30,000lbs. gcvw, up to 1,200 horsepower and a 4,500 ft/lbs. torque spike. They back up their claims with a 2 year unlimited mileage warranty, and give a life expectancy of a minimum of 250,000 miles.

(Photo of both driveshafts): Rich Wegener at A-1 Driveshaft set us up with a brute of a driveshaft in place of our rusty old inadequate piece. Rich tells us that with less tubing used due to the shorter shaft needed, as well as the additional section taken up by the newly added slip-spline, any resonating frequencies will be moved up to a higher RPM level and therefore nearly eliminating all probabilities of any future driveshaft vibrations. We had none. The new shaft sported big beefy Spicer 1350 joints along with a nearly bullet proof .095" Wall tubing. The new shaft's tubing diameter was also upsized from 3" to a formidable 3.5" as well.

(Photo of O.D unit and kit laid out): The Gear Vendors well thought out kit had everything you could possibly imagine for a successful install. All the wiring looms were packaged and labeled along with the connectors attached and all ready to go. This was probably one of the nicest installation packages and most thought out kit of any kind we've ever experienced. Certainly a joy to work with.

(Photo of speedometer adapter): One of the many smart solutions provided in the kit was a unique speedometer coupler adapting the original cable to the Gear Vendors extension cable in only a few minutes. The Gear Vendors unit installed with such ease is it only took two relaxing hours to accomplish the under side installation, leaving only the control box to be connected and the driveshaft modifications to be done at the local driveline specialist.   

(Photo of speedometer cable with insulating wrap on it): As a precaution, we used DEI's insulating tape to protect the speedometer cable from the nearby hot exhaust tubing. Yep, the same stuff we used on the air box and the brake lines, earlier.

(Photo of  pouring in special fluid into overdrive): Gear Vendors adamantly demands that only GM 80w-90 gear oil
(pt#1052271) be used in their overdrive unit. We were told this particular oil contains no extreme pressure or limited slip additives which can be harmful to brass or bronze internal components. Gear Vendors say that there is no advantage in using any kind of synthetic lubricants or additives, since they claim their hi-efficiency planetary design requires only 1 hp per 400 hp to operate, anyway. That's only a one quarter of a percent overall loss!

(Photo of Installed overdrive): The Gear Vendors Under/Overdrive auxiliary transmission unit is a planetary design similar to those found in current factory automatic overdrive transmissions. The sophisticated and stout design is packaged in a relatively small and lightweight unit, which is easily installed and operated. We actually installed the overdrive prior to the new exhaust system being placed so we could bend around it. Since the presence of the overdrive has no affect on the vehicle's operation when not engaged, it did not interfere with any of the subsequent tests.