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Automatic Transmission Tech

Insane Power and Torque Mean Nothing Without The Right Automatic Transmission

Jason Sands
Oct 13, 2015
Contributors: KJ Jones
Photographers: Jason Sands, Courtesy of the Manufacturer
As Ram, Ford, and GM pickup truck diesel engines evolved over the years, so have the automatic transmissions that back these impressive powerplants. The purpose of this report is to give you our insights on the automatics that Dodge/Ram, Ford, and GM have installed in diesel pickups from 1989 to present, and, with respect to their use in high-performance diesel applications, provide details on upgrade options for competition use, operating expectations for modified transmissions, and typical failures…because, as we all know, nothing’s perfect.
Photo 2/16   |   Perhaps the most commonly modified automatic transmissions for diesels are the 47/48-series units found in '94 to '07 Dodge Rams. This unit, built by Brown's Diesel, features an upgraded high-stall torque converter to help spool a large turbo, a Goerend Transmissions valvebody, and billet shafts to handle the rigors of drag racing and sled pulling.
'89 to '93 Dodge Ram
TorqueFlite 727 (three-speed) and A-518 (four-speed)
Found 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. Since TorqueFlites were found in many Mopar muscle cars and they had to handle the 400 lb-ft of torque the 5.9L Cummins engines of the era had to offer, they were pretty stout from the factory. 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 without any major upgrades. Eventually, their non-lockup torque converters and aluminum planetary gears become weak links, but not until much more than 500 rwhp is achieved.
Photo 3/16   |   Even at just 500 rwhp, breakage is still a real possibility. This is a stock 48RE flexplate that had its center ripped completely out thanks to a torquey Cummins engine. Thankfully, no other damage occurred, and it was upgraded to a stronger aftermarket piece.
'94 to '02 Dodge Ram
47RH (four-speed) and 47RE (four-speed)
A lot of the first serious sled 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. This is mainly because their 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. Virtually every part inside these transmissions can be upgraded, from the planetary gears to the pumps, hubs, and bands. It should be noted that early 47RH transmissions employ a hydraulic overdrive instead of an electronic OD. With no dependency on a computer for any of its controls, the 47RH is one of the most popular transmissions for diesel swaps.
Photo 4/16   |   There are a number of parts in a Dodge transmission that need to be upgraded for trucks that will see higher power levels. Shown here are some pieces used by Firepunk Diesel to build its Dodge transmissions, such as upgraded input, output, and intermediate shafts, as well as a stronger drum and apply levers.
'03 to '07 Dodge Ram
48RE (four-speed)
The successor to the 47RH and 47RE transmissions, the 48RE found in '03 to '07 Dodge Rams includes a stronger geartrain featuring steel planetaries and is quite up to the task of holding the common-rail Cummins engine’s 300-plus horsepower and more than 600 lb-ft of torque. For 47- and 48-series transmissions, the most common build involves using a triple-disc torque converter, stronger flywheel, billet input shaft, revised valvebody, and added clutches. There are literally thousands of Dodge transmissions with this exact combination living long and happy lives. If sled pulling or drag racing is on your schedule, then the intermediate and output shafts should be upgraded as well. For extreme horsepower (up to 1,500 hp), larger-diameter input and output shafts made from 300M alloy or AerMet steel alloy are also available.
Photo 5/16   |   For performance levels more than 1,000 hp, Dodge transmissions may need an upgrade to larger shafts. Shown here are oversized input and 29-spline output shafts from Firepunk, which have been tested up to 1,500 hp.
'07 to Current Ram
68RFE (six-speed)
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. While this seemed like a good idea (added speeds), soft shifts and weaker internals had a lot of the performance crowd worried. It turns out the enthusiasts were right. The 68RFE won't handle much more power than stock without major upgrades (in factory form, they often fail at about 150,000 miles). They're also expensive to replace (about $5,000 for a stock transmission from Dodge), and upgraded versions can be insanely pricey. For a 68RFE that can handle 700 to 800 hp, expect to pay in the neighborhood of $9,000 to $11,000! We've seen 68RFEs last in relatively stock trucks with just a tuner and some transmission reprogramming, and we've seen them last in modified trucks as well. So, a strong 68RFE can be assembled, just know what you're getting into when dealing with this transmission.
Photo 6/16   |   On newer transmissions from all the Big Three manufacturers, electronic controls are becoming increasingly important. Products like the Co-Pilot by ATS Diesel Performance are used to revise shift strategies and pressures in order to keep transmissions alive at greater-than-stock power levels.
'07 to '12 Dodge/Ram Chassis Cab
Aisin AS68RC (six-speed)
'13 to Present Ram 3500 H.O. and Ram Chassis Cab
Aisin AS69RC (six-speed)
The new kid on the block for Ram automatic transmissions is the Aisin AS69RC six-speed, and from a performance standpoint, not much is known about this gearbox yet. Physically, it’s comparable to an Allison 1000, and we've already heard stock versions are handling 100hp tunes just fine. It also supports the reported 900 lb-ft of torque of the ’16 Ram 3500. So, it just might have a bright future. For those looking to purchase a brand-new Ram, we'd try and pick one up with the Aisin transmission.
Photo 7/16   |   Physically larger than most of the Ford and Dodge offerings, the Allison 1000 transmissions found in '01-to-present Duramax-powered Chevrolets and GMCs are simple yet extremely strong.
'91 to '01 Chevrolet and GMC
4L80E (four-speed)
Although it’s found primarily in early 6.5L-powered GM trucks, the four-speed, lockup 4L80E automatic wasn't designed specifically for diesels. Despite this, the 4L80E is still a very strong transmission. 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. If your pockets are deep enough, it's possible to build a 4L80E transmission using aftermarket parts exclusively. 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.
Photo 8/16   |   Shown here is a PPE Stage 5 transmission kit, which is all that is needed for street truck applications up to 1,000 rwhp! The kit includes new clutches and steels, a much stronger triple-disc converter, and a valvebody recalibration kit.
'01 to '05 Chevrolet and GMC
Allison 1000 (five-speed)
'06 to Current Chevrolet and GMC
Allison 1000 (six-speed)
When Chevrolet introduced its Duramax diesel powerplant for the ’01 model, it also backed the 6.6L engine with an Allison 1000 five-speed automatic transmission. Long known for its work in the heavy-duty diesel industry, the Allison 1000 is the heavyweight gearbox of the diesel pickup line. Virtually everything on this unit is bigger than comparable Dodge or Ford offerings, from the shafts and clutches to the case itself. While the Allison is bigger and heavier-duty than virtually all the other transmissions used with diesels, its catch-and-release character while shifting and deeply integrated computer controls make the transmission somewhat touchy when modifying it for performance use.
Fortunately, tuners have been tinkering with the 1000 since its inception, and all the electronic kinks have been pretty much ironed out. Still, the Allison has to shift slower and defuel more than similar units, making it a little slow for all-out drag racing efforts. But, for pulling, street driving, and towing, the Allison is a very good choice. Earlier five-speed Allisons (found in '01 to '05 models) can usually handle a good 400 to 450 rwhp with just careful TCM tuning, and later six-speed models can take even more. If the Allison 1000 senses slippage, it can go into "limp mode," which is a single gear at full line pressure. While this can happen with other transmissions, it is most common in the Allison, usually when standing on it in the higher gears. One thing we have to be clear about is that "limp mode" isn't a problem, it's just the computer saying it’s time for an upgrade.
Unless it's an extreme application, drums, shafts, and other hard parts don't need to be replaced in Allisons, as these parts are very strong from the factory. For a normal street driver—even one approaching 1,000 hp—a good triple-disc converter, valvebody modifications, and improved clutches are usually all that is needed to handle big power.
Photo 9/16   |   For extreme racing applications, 300M alloy shafts are available for Allison transmissions. Note the much larger diameter of this input shaft as compared to Ford or Dodge offerings.
'89 to '98 Ford F-Series
E4OD (four-speed)
Much like the other older transmissions from GM and Dodge, the Ford E4OD has many small parts that need to be upgraded to handle decent power. Improved clutches and snap rings, steel planetary gears, and an upgraded torque converter are examples of items that are needed to handle even mild power levels, and we've seen a few E4ODs that have slipped the factory lockup converter even at stock power levels. There is good news, however, as these transmissions are relatively inexpensive and plentiful, and when built properly, they can last for a number of years under heavy use.
Photo 10/16   |   Testing a transmission before it ever leaves a builder’s shop is one way of ensuring years of reliable use. DieselSite performs such extensive checks on its new, “Legendary” Ford transmissions, which are available in both E4OD and 4R100 offerings.
'99 to '02 Ford F-Series
4R100 (four-speed)
With the introduction of the 6.0L Power Stroke engine for 2003, Ford stepped up its transmission game with the 4R100 automatic. This unit would start the trend of extremely reliable and strong transmissions from the Blue Oval boys, which continues to this day. If the 4R100 has a weakness, it's in the input/output/intermediate shafts, much like the Dodge 47/48 units. The smaller shafts must all be upgraded to support big horsepower. If you're only going for mild street performance, only the torque converter, input shaft, and valvebody need to be modified.
Photo 11/16   |   Ford's 5R110 five-speed is one of the strongest transmissions out there. With careful tuning, it's not uncommon for these transmissions to hold 500 to 700 hp for years, with only the stock shafts, clutches, and torque converter.
'03 to '10 Ford F-Series
TorqShift 5R110 (five-speed)
As one of the stoutest transmissions in the Ford lineup, completely stock 5R110 automatics (with tuning) can handle more than 800 hp at the wheels. Similar to other units, these transmissions benefit from upgraded shafts and torque converters for racing use, but 5R110s can also handle an absurd amount of power in stock form. Eventually, though, the clutches will start to prematurely wear and then slip at high power levels. While this can take a number of years, a revised clutch count, converter, and other modifications are needed if a 5R110 is expected to stay together under the rigors of racing, or for a long period of time. Keep in mind, also, that if you're looking at a 300,000-mile 5R110, it might need a rebuild because it's just plain worn out.
Photo 12/16   |   When building any transmission, it's easy to forget to include add-ons, but many are necessary. Seen here is an upgraded flexplate from ATS, which is not only stronger but is also available with an SFI certification for racing use.
'11 to Current Ford F-Series
TorqShift 6R140 (six-speed)
Ford’s 6R140 is one beast of a transmission, and a worthy successor to the 5R110. There are a number of 6R140s out there handling 500 to 600 hp with just electronic tuning, and the aftermarket parts already exist to build a 6R140 capable of supporting more than 1,000 hp.
Photo 13/16   |   Whether you have a Ford, Dodge, or GM automatic, installing an aftermarket transmission pan is a good idea—especially if you tow. This type of pan not only offers greater capacity, it also dissipates heat much better than a factory pan.
Keep It Cool
Because automatic transmissions generate incredible internal heat, which actually tends to be the bane of their existence over time and miles (in both normal and severe-duty driving conditions), ensuring the transmission fluid remains relatively cool is critical. To achieve proper transmission cooling and operating efficiency for stock or modified diesel trucks—especially the older rigs of mid-’90s to mid-’00s vintage that tow or are used for racing—upgrading such transmission accessories as the oil cooler and torque converter is highly recommended. DSLP-151000-TRANS-014_banks_billet_torque_converter
Photo 14/16   |   014 Banks Billet Torque Converter
Banks Power’s Banks Billet Torque Converter, designed for stock trucks pulling heavy loads or rigs with modded oil-burners that make big-time power, features a furnace-brazed turbine, three-friction-element clutch system, and bulletproof billet steel cover, all of which prevent leaks, excessive heating, and abnormal wear. It also allows the converter to triple the torque capacity of most stock 600-lb-ft units. While capable of supporting 1,800 lb-ft of torque, Banks’ converter (available for ’94 to ’07 Dodge, ’94 to ’07 Ford, and ’01 to ’10 GM diesels) is also designed with a slip-resistant lockup clutch that is a major factor in the unit’s ability to help keep transmission fluid temperatures low. DSLP-151000-TRANS-015_bd_xtrude_transmission_cooler DSLP-151000-TRANS-016_bd_xtrude_double_stacked_transmission_cooler_kit
Photo 15/16   |   015 Bd Xtrude Transmission Cooler
Photo 16/16   |   016 Bd Xtrude Double Stacked Transmission Cooler Kit
Micro-Extruded Bar Technology is the highlight of BD Diesel Performance’s single- and dual-core Xtruded Transmission Oil Coolers for Ford, GM, and Ram. The 200 bars inside each unit provide a large surface area for airflow and heat transfer, which promotes nearly 34,000 (single core) or more than 40,000 (two stacked cores) Btu/hr of efficient cooling, a reported 22 percent greater than other designs. Kits for 5/16-inch to 5/8-inch oil lines include all fittings, clamps, hoses, hardware, and a DIY galvanized bracket kit for clean installation. A thermostatically controlled 10-inch 800-cfm electric fan is also available for either cooler.

Sources

ATS Diesel
Arvada, CO 80002
866-490-5573
www.atsdiesel.com
Banks Power
Azusa, CA 91702
866-738-5915
http://www.bankspower.com
BD Diesel Performance
Sumas, WA 98295
800-887-5030
www.dieselperformance.com
Brown's Diesel
Riverdale, CA 93656
559-867-1111
www.brownsdiesel.com
DieselSite
Crystal River, FL 34429
888-414-3454
www.dieselsite.com
Pacific Performance Engineering
Fullerton, CA 92831
714-985-4825
www.pacificp.com

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