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Lentech's AOD Street Terminator Transmission - An Automatic Plus
Backing Up Our 347 Stroker With Lentech's AOD Street Terminator Plus
Though we normally think of all automatic transmissions as being of planetary-gear architecture, some manufacturers use a hydraulically controlled, manual-type countershaft arrangement.
During the past few years, Lentech Automatics has become practically synonymous with high-performance AOD and AODE transmissions, and boss Len Bertrand is showing no signs of letting up on his goal of overdrive supremacy. Racers themselves, the crew at Lentech seemingly have an AOD or AODE for every power level-from subtle to psycho and for street and/or strip. One of Lentech's more recent AOD offerings is the Street Terminator Plus, a 700hp-capable, street-happy combination that struck Senior Tech Editor Mark Houlahan as the perfect downstream companion to the 347 stroker in his '90 hatchback.
New readers may be questioning why anyone would want an AOD, a transmission that in factory form suffered a bonehead 1-3-OD shift quadrant that inexcusably left Second gear out of the manual-shift scheme. This clearly nonperformance-oriented setup forced people wanting to manually upshift to whack the lever from First up to Third and then immediately back down again-a highly inefficient process that occasionally found Second but, as a side effect, caused all manner of grief within the gearbox.
More grief resulted from the factory's dual concentric input shaft configuration, whereby a hollow outer shaft was splined to the torque converter turbine and drove First, Second, and Reverse with converter torque multiplication, while a comparatively scrawny inner shaft was splined directly to the converter front cover (in effect, the crankshaft) and drove both Third (Drive) and Overdrive in perpetual lockup. A hard upshift into Third commonly bogged the engine when going from that torque-multiplied Second into locked-up Drive and-worse yet-tended to burn out the 3/OD (direct) clutch pack or band, or in extreme cases, even break the inner input shaft.
Well, forget all that stuff, because Mr. Bertrand has engineered changes either within the transmission itself or in the serpentine passages of its valvebody hydraulic brain. These changes morph the AOD from a factory weakling into a brawny and efficient automatic offering quick, precise shifts and the ability to shrug off outrageous power levels. We've documented a number of Lentech's improvements in previous articles, and racers have successfully proven their effectiveness in various drag classes.
As with all Lentech AODs, the Street Terminator Plus benefits from valvebody revisions that provide a correct 1-2-3/OD manual shift pattern for those times when you want to shift for yourself, and that correct factory line-pressure deficiencies. Similar to its newer AODE brothers, it also has an electric Overdrive delete switch, so you can lock OD out when desired. Many of you may be familiar with the features of Lentech's original Street Terminator AOD. Two major changes differentiate the Street Terminator Plus. First is the substitution of a 9.5-inch converter in place of the regular Terminator's 12-inch unit, and second is the fitting of a hardened, one-piece input shaft instead of stock-style concentric shafts. Together, these changes raise the Plus' power-handling capacity from the Terminator's 400 flywheel horsepower to 700.
Len's staff will work with customers to determine the appropriate con-verter properties for their particular applications.
If there's anyone on the planet more committed to AOD and AODE performance and durability than Len-tech, we don't know who it is. Len never fails to impress us with his genuine enthusiasm for the street and strip potential of these underappreciated automatics, and his company stands behind its transmissions with a limited lifetime warranty. Bring on those power adders!
It Came From Another Planet
Hey, racers-even in stock form, the AOD's compound planetary gearset is renowned for its toughness. But for those who just have to have the best of everything, Lentech has introduced its own trick version. With a planet carrier carved from billet aluminum, it is some 3.5 pounds lighter than stock, for reduced rotating mass (and therefore quicker acceleration) as well as unparalleled strength. It's also rebuildable, with a removable billet steel endcap. But perhaps this planetary gearset's biggest advantage is the available selection of gear ratios. In addition to the factory 2.40:1 and 2.84:1 (4R70W) First gears, the Lentech planetary can be had with exclusive First-gear ratios of either 2.18:1 or 2.66:1, so racers can choose the ideal cogs for their particular combination. Call Lentech for more details.