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How to Make Your Tranny Live Behind Big Power

Posted in How To: Transmission Drivetrain on July 25, 2017
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All pre-emissions diesel trucks (2006 and older) command a premium these days due to their simplicity and mileage compared to new trucks with Diesel Particulate Filters (DPFs). No truck, though, has held its value quite as well as the 1994-1998 Dodge Ram with the 12-valve Cummins engine. One of the most compelling reasons is that for just a few hundred dollars it is possibly to literally double the power output from these engines. Putting all that torque to the ground, however, isn’t quite so cheap or easy.

BD Diesel, a premier diesel transmission builder, has been building parts and upgrading transmissions for Dodges, Fords, and Chevys for decades now. BD offers a variety of individual components, upgraded kits to rebuild your existing transmission, and fully built automatic transmissions to fit any budget or power level. We recently made a trip to the company’s British Columbia headquarters, where the employees graciously opened the doors to show us all the tricks they use to make the 47RE live behind a modified 12-valve Cummins engine.

We don’t mind getting our hands dirty, but automatic transmissions are voodoo to us, so we didn’t feel comfortable building the transmission ourselves with one of BD’s rebuild kits. Instead we spent our money on a transmission that BD built with its unique parts and years of experience. To offset the expense of the transmission, we pulled the old 47RE ourselves and installed the new unit from BD at home. This ended up costing us about the same amount money as if we had dropped our truck off at a local transmission shop for a rebuilt transmission, except instead we got a billet torque converter and upgraded internals in exchange for some scraped knuckles and dirt under our fingernails. Now our 12-valve is ready for another 100,000 miles of service. We don’t know how much the truck will be worth in another 10 years, but at the rate it is appreciating we think it is definitely worth investing some time and money into our 12-valve.

In BD’s spotless facility, all of the transmissions are torn down and industrially cleaned for inspection prior to assembly. Brad Warren is a second-generation BD employee. He builds several transmissions each day and has been doing so for years.
From bottom to top are the factory clutches, Raybestos GBZ, and Alto Red Eagle frictions. The Alto clutches have more holding power than the Raybestos, but the tradeoff is firmer engagement. BD can build your transmission with whichever frictions you want to fit your needs.
One of the steps that BD performs is machining the transmission pressure plates to accept extra clutches for increased holding power. In our 47RE transmission the forward clutch pack is increased from four to five clutch frictions and the overdrive clutch pack is increased to six frictions.
All of the components that went into our transmission are available as a kit from BD, including the unique components that they manufacture in house. This is a great option if you want to rebuild the transmission yourself or prefer to have your transmission upgraded locally. The process takes longer than having a complete transmission shipped to you, but the tradeoff is saving money on shipping costs.
BD sources the highest-quality parts for the transmission rebuilds. When parts meeting the company’s standards are unavailable, BD designs and builds the parts in house. One example of this is BD’s billet overdrive piston retainer, which in addition to being stronger than the factory cast piece also adds an O-ring for improved sealing.
The Raybestos High Energy Band has more holding power that the stock band, which uses paper friction material. This is important when combined with BD’s valve body, which nearly doubles line pressure at wide-open throttle.
One step that is unique to BD is the replacement of every thrust washer in the transmission with a roller bearing. The roller bearings reduction friction and maintain critical tolerances much better than the factory Babbitt thrust washers.
Brad Warren of BD told us that the pump is not a weak link in the 47RE in his experience. BD focuses on providing the most bang for the buck, and simply adds a brass bushing and new seals to the pump and focuses on the upgraded valve body for performance improvements.
The factory flexplate can crack under hard use, so we added BD’s forged billet flexplate at the same time as the new transmission. It is twice as thick as stock and precision balanced, which results in the ability to handle up to 1,500 lb-ft of torque and an SFI rating for racing use.
BD’s proprietary torque converters are one of the reasons the company’s transmission perform so well. The converters use furnace-brazed fins and a billet cover for greatly improve longevity and reliability compared to the stock converter. BD offers both single-disc and triple-disc converters for Dodge four-speed automatics to fit any budget and power level.
BD recommends that its billet input shaft be used with its triple-disc torque converter. For those looking for maximum strength, BD’s PHAT Shaft is thicker than stock and has an increased spline count, in addition to being made from 300M billet steel. BD also offers billet intermediate shafts and output shafts for racing and other high-horsepower applications.
Twice as much friction material is used on BD’s torque converter piston for increased holding power. BD also designed its own stator for a lower stall speed, which is perfectly matched to the powerband of low-rpm Cummins engines.
The factory pressure transducer can cause shifting issues if it sees too much pressure. BD’s exclusive upgraded transducer eliminates these issues and should be considered a must if you are upgrading your valve body.
Ray Jackson spent 25 years working for Chrysler, and he has been at BD for 11 years. He builds valve bodies all day long, five days a week. He starts each one by laying out all of the clean components; he didn’t just do this for our photo.
The valve body is the brain of the transmission. It controls details such as shift points and line pressure that determine how much holding power and heat are generated. BD tests each valve body prior to installation to ensure that it is functioning properly.
BD caps each of the transmissions it builds with its deep pan. These pans have useful features such as bosses for temp sensors and a drain plug on the bottom. BD’s cast aluminum construction also stiffens the entire transmission assembly and provides cooling through the increased fluid capacity and use of internal and external fins.
Heat is the biggest killer of automatic transmissions, and since we use this truck to tow our wheeling rig, we added a BD auxiliary transmission cooler at the same time as the transmission installation. Since the cooler doesn’t see a lot of airflow, BD fits it with a dedicated electric fan.
BD has assembled transmissions on the shelf ready to ship to you the same day you place your order. It also has a nationwide dealership network than can get you a new transmission in as little as two days. Each transmission is tested on a dyno to ensure proper shifting and line pressure prior to being crated up.
The only special tool we needed for the transmission install was a tranny jack. We borrowed this old jack from a friend and it worked far better than the floor jack and ratchet strap that we have used in the past.
We transferred our existing sensors from our old 47RE to the new BD automatic. BD provided “case saver” brass fittings for the cooler lines that ensure that you won’t crack the transmission case if you get a little overzealous tightening the lines.
The most difficult part of the installation was reinstalling the factory crossmember, which is wedge shaped for a press fit into the frame. We built a “special service tool” from a bottle jack and a piece of tubing to spread the frame enough to get the crossmember in.
We built brackets out of angle iron and welded them inside the frame to mount the auxiliary cooler and filter rather than using the included brackets. This position was safe from harm and still relatively close to the transmission so the lines are not excessively long. An external filter is included with each transmission to catch any debris that may remain from your old damaged transmission.

Sources

BD Diesel Performance
Sumas, WA 98295
800-887-5030
www.dieselperformance.com

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