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Double The Gears

Installing The Gear Vendors Under/Overdrive In A Tri-Five

By Grant Peterson

In the pursuit of building a cool car today, there are many avenues to consider taking. Why not go down whichever path you pick with three more gears to choose from? Unless you have been in the far reaches of our solar system, you have probably heard of Gear Vendors. By now, and as far as I can tell, they have turned the way we think of transmissions upside down. Mark Newberry, the owner of this '55, wanted to explore Gear Vendors' ideas in the pursuit of some quick numbers at the track as well as reliability and economy on the road. Mark's car has a small-block GM crate motor and a TH400 tranny and as we found out, everything is pretty much a bolt-in job for the Tri-Fives except for drilling the holes in the dash for the indicator lights. You may also need to put a kink in an E-brake bracket, even if the tranny crossmember/ mount stays in the same place. Other than that, all you need to worry about is wiring.

Once you have an idea of what Gear Vendors can do for your car, you may be in a state of euphoria. Rick Johnson, owner of Gear Vendors, believes the strongest transmissions for performance cars in our range of the hobby are the TH400, TH350, Powerglide, and M21 or M22 Muncies. I am told that the reason the early trannies are stronger is that GM cared about strength then, and today's gearboxes are all about things like fuel costs and EPA legislation. Gear Vendors says "Why not take out your musclecar-era three-speed auto or four-speed manual and replace it with a late-model overdrive trans that is inherently weaker when you can keep the superior strength and add a superior overdrive to it." GM did exactly that with the Callaway Twin Turbo Corvettes, which only came as automatics with a Gear Vendors/TH400 combination instead of the factories own 700-R4 or 4L80E. Ratio is the big key to the success that Gear Vendors enjoys. Gear Vendors has the same ratio spread as a 2-3 or 3-4 shift of a Muncie close-ratio manual, which is also the same ratio that many performance gearboxes have used (i.e. Porsche, Ferrari, BMW, etc).

With this ratio, Gear Vendors provides the automatic in your Chevy with twice as many gears and you guys with three pedals get some cool features like clutchless shifts, for example; check the Gear Vendors Web site for full details. Virtually all three-speed automatics have the same ratios within a few hundredths (2.5 First, 1.5 Second, 1.0 High). This means your transmission takes 2.5 engine revs to turn the driveshaft once in First gear, 1.5 in Second, and is direct drive 1:1 in High gear. Gears are multipliers of torque. Putting a 2.0 gear between First and Second is going to keep both torque multiplication and engine rpm high which means more hp getting to the rear wheels. If they can then put a 1.2 gear between Second and Third, and an overdrive gear beyond Third. Then we have a close ratio six-speed overdrive trans with four nderdrive power gears, a direct-drive High gear, and an overdrive Cruise gear, hence the under/overdrive moniker. Let's top all this off with the improved economy, expect 25 percent thereabouts cruising with a normal aspirated engine, thanks to 22-percent lower rpm. With the overdrive, a 3.73 rear gear will feel just like 2.91 when cruising! With the way gas prices are headed, the money saved on gas will pay for the unit and beyond. That's the layman's explanation of the Gear Vendors principals, or you can just call it the best of both worlds!

There are two styles of electronics you can get from Gear Vendors: the standard Auto Drive package and the optional, new AutoShift sequencer. Late last year at the SEMA show, Gear Vendors debuted their new AutoShift electronics, which garnered quite of bit of press. Since it was something new, we thought we would try them out on this install just before they are being made available to the public.

The difference to the standard package is that the AutoShift takes those shifts where you are moving the shift lever and clicking the Gear Vendors and automates the process. So, launch in First and immediately press the button for First-over (like the standard electronics the overdrive will shift to First-over at the appropriate speed--when you are tached up and ready for Second, move the shift lever and when the trans grabs Second-gear the AutoShift sequencer will take out the overdrive without you having to click the button. When you are ready for Second-over just click the button, and when you move to Third the sequencer takes out the overdrive. When you are cruising and click in the overdrive, it will turn itself off at low speed/rpm and when you want it back on just click it in. So you always tell it when you want to shift in to overdrive in any gear which preserves the fun interactive part and still allows you to decide on 1/2 steps in gearing or full steps depending on what mood, acceleration, or who's watching. The sequencer just automates the deactivation of the overdrive. Well, that's a good amount to absorb for now, stay tuned for more on Gear Vendors in the future.

Let's take a trip to Firehouse Fabrication in Placentia, California, and follow owner Brett Maxwell as he walks us through the Gear Vendors install on this '55 that is nearing the first stages of completion.

SOURCES
Firehouse Fabrication
704 Monroe Way, Dept. CRM
Placentia
CA  92870
Inland Empire Driveline
4035 E. Guasti Rd., Ste. 301
Ontario
CA  91767
8-00/-800-0109
www.iedls.com
Gear Vendors
8-00/-999-9555
gearvendors.com
Lokar Performance Products
10924 Murdock Dr.
Knoxville
TN  37932
8-65/-966-2269
www.lokar.com
By Grant Peterson
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