![]() Virtually everything on this unit is bigger than comparable Dodge or Ford offerings, from the shafts and clutches to the case itself. Long known for its work in the heavy-duty diesel industry, the Allison 1000 is the heavyweight gearbox of the diesel pickup line. ![]() When Chevrolet introduced its Duramax diesel power plant for the ’01 model, it also backed the 6.6L engine with an Allison 1000 five-speed automatic transmission. For those who just want something that can handle the power of a hopped-up 6.2L or 6.5L engine (about 200 to 300 hp), a stock rebuild with a shift kit and a performance torque converter is just fine. ![]() If your pockets are deep enough, it’s possible to build a 4L80E transmission using aftermarket parts exclusively. The transmission benefits from a healthy aftermarket thanks to gasoline-powered pickups and can be outfitted with parts and pieces to handle more than 1,000 rwhp – even with the torque of a diesel. Despite this, the 4L80E is still a very strong transmission. They’re also expensive to replace (about $5,000 for a stock transmission from Dodge), and upgraded versions can be almost cost prohibitive.Īlthough it’s found primarily in early 6.5L-powered GM trucks, the four-speed, lockup 4L80E automatic wasn’t designed specifically for diesels. The 68RFE won’t handle much more power than stock without major upgrades (in factory form, it often failed at about 150,000 miles). While this seemed like a good idea (added speeds), soft shifts and weaker internals had a lot of the performance crowd worried. When Dodge upgraded its diesel engine choice to the 6.7L Cummins for the ’07 model year, the company also put a six-speed automatic behind it: the 68RFE. With no dependency on a computer for any of its controls, the 47RH is one of the more popular diesel transmissions to modify. It should be noted that early 47RH transmissions employ a hydraulic overdrive instead of an electronic OD. Virtually every part inside these transmissions can be upgraded, from the planetary gears to the pumps, hubs and bands. This is mainly because the clutches are prone to start slipping as power increases (unless pressure is bumped up), and the stock single-disc torque converters are not capable of supporting much horsepower beyond the factory rating. Eventually, the non-lockup torque converters and aluminum planetary gears become weak links, but not until much more than 500 rwhp is achieved.Ī lot of the first serious truck pullers, drag racers, and street trucks were built from ’94-to-’98 P-pump Dodge Rams, which means the four-speed 47RH and 47RE Dodge transmissions are some of the most commonly modified automatics out there. ![]() If the transmission is in good shape, either the 727 or A-518 can handle about 400 hp, along with about 700 lb.-ft. of torque the 5.9L Cummins engines of the era offered, these transmissions were pretty rugged from the factory. Since TorqueFlites were found in many Mopar muscle cars and had to handle the 400 lb.-ft. TorqueFlite 727 (three-speed) and A-518 (four-speed)įound in first-generation diesel Dodge Ram trucks, the TorqueFlite 727 and A-518 transmissions are the predecessors of the later ’94 to ’07 Dodge transmissions, so they share a lot of the same architecture. Here is a basic review of the automatic transmissions that you are likely to encounter and the known performance traits. There are numerous aftermarket suppliers of upgraded automatic transmission parts along with complete performance upgraded transmissions capable of handling up to 1,000 horsepower.ĭepending on your customer’s application and the engine upgrade you can guide your customer in the right direction. If you’re saying you’re an engine guy and don’t know much about what happens after the flywheel, relax.
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