6L80
| (Above) Literally everything is packaged within the 4L80 transmission case, so it has a lower and more pronounced midsection than its 4L60 predecessor/contemporary. Weight is 209 pounds, wet. |
Obviously, most of this is in regards to avoiding a gas guzzler tax and promoting excellent highway mileage. If it is in anticipation of the ever-circling fuel gouge, is it strong enough for high performance application? According to Hydra-Matic specs, there will be four distinct variants (covering FWD, RWD, and AWD) launched in 25 different models this model year. Torque capacity ranges from 258lb-ft to a fat 520lb-ft. Shift speeds are up to 7,000rpm, driven by a 32-bit controller. Remember that torque ratings are measured in 24-hour constant cycles at WOT, so there’s plenty of capacity here for a high-performance engine.
Though the trucks use a button on the shifter, the C6 employs paddle shifters, located just above the center of the steering wheel that can be up- or downshifted with a thumb or forefinger at least as quickly as a full-on power shift with the T56. Gear changes happen right now. And your arm won’t get sore. Keep it mind.
So what’s the subtext? While this configuration might be misconstrued as a fuel economy-only ploy, it was also created to enable premium shift quality and drivability, and therefore make the engine more flexible and add to the performance factor. It features new technologies as found in clutch-to-clutch operation, automatic grade braking, driver shift control (DSC), and enhanced performance algorithm shifting (PAS). What the gobbledygook boils down to is a tough transmission that fits the hot rod case so well that it’s scary. Yes, it’s electronically controlled. Yes, it will bolt to any Gen-III or Gen-IV LS engine.
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| A 4-pinion input carrier gearset (left) and a compound 3-pinion output gearset uses three sets of pinion gear pairs; one set meshes with the sun gear and the other set with the ring gear. |
Although it’s rosy on the surface, in the short term there are some rather tall hurdles that make this proposition impractical for the hot rod nation. The 6L80, along with the rest of the car’s major functions (HVAC, stability control, ABS, etc.) are integral to the whole. When they “talk” to one another, they must all be present for the conversation, so if you installed a 6L80 in your LS-powered hot rod right now, it flat wouldn’t work. According to GM Powertrain Engineer Jim La Fontaine, the transmission might be able to engage Low gear, but that’s all. By SEMA ’07, there will be better news. Facilitation for the swap might better come from the aftermarket. To giant GM, it doesn’t even blip the radar screen—yet. So for the immediate present, the carrot dangles, but we suggest that you do not bite.
