It’s a beautiful Saturday afternoon. You’re towing your race car merrily along with your diesel-powered rig, when you suddenly encounter a hilly, winding stretch of highway. You pump the brakes to navigate your way down a steep section of road, but the additional weight of the trailer causes your tow vehicle to pick up speed instead. As momentum rapidly increases, your brakes become overpowered, overmatched, and ineffective.

At this point, you’ve learned what professional truck drivers have known for years: Conventional brakes alone are not sufficient for slowing heavily-weighted vehicles. This is especially true for diesel-powered vehicles, where downshifting is not an option. That’s why big rigs and other large, cargo-style diesel trucks have come equipped with auxiliary brakes for years. Known as engine brakes, or “Jake Brakes,” these auxiliary brakes give diesel-powered vehicles added stopping power whenever and wherever needed.

These days, you don’t have to drive an 18-wheeler-or even a truck with a manual transmission-to get the safety and performance advantages of auxiliary brakes. Thanks to companies like BD Diesel, you can add the benefits of an exhaust brake to your diesel-powered tow vehicle or work truck.

The Basics On Brakes

BD Diesel manufactures a full line of exhaust brakes and accessories for most popular diesel pickups, including GM Duramax, Ford Powerstroke, and Dodge Cummins trucks. Exhaust brakes perform the same function as traditional engine brakes found on 18-wheelers in that they create a mechanical braking effect by retarding horsepower production. While engine brakes accomplish this by altering engine valve timing, exhaust brakes are designed to restrict exhaust flow out of the engine. This yields quick, consistent retarding force throughout the engine rpm range, along with much quieter performance than true engine brakes.

Not Just For Manuals

Exhaust brakes are at their most efficient when the lockup clutch plates in the torque converter are locked together. However, most automatic transmissions simply don’t supply the signal to keep the convertor locked up when you remove your foot from the throttle pedal. When lock up is held in there is not enough pressure to hold the lockup clutch plates together under exhaust brake conditions. In fact, stock automatic transmissions provide lowest hydraulic pressure when your foot is off the accelerator-right at the time exhaust brakes are most likely in use. That means your torque converter is prone to excess slippage, which prevents 100 percentĀ of the retarding force from reaching the ground. In addition, excessive converter slippage in automatic transmissions can cause extreme heat buildup and premature transmission wear.

To make exhaust brakes more efficient in stock automatic transmission applications, BD Diesel offers plug-in accessories such as the PressureLoc. The PressureLoc gives your torque converter the physical ability to remain locked up under intense exhaust brake conditions by increasing the transmission’s hydraulic pressure every time converter lockup engages. This pressure increase holds the converter’s lockup clutch plates together longer, reducing converter slippage during lockup conditions.

Whereas the PressureLoc essentially acts as the muscles for your torque converter by holding the clutch plates together longer, BD Diesel’s AutoLoc computer works as the brains. Designed to work with the PressureLoc, the AutoLoc automatically commands the torque converter to remain locked up when the exhaust brake is applied. Together, the AutoLoc and PressureLoc ensure that the torque converter locks up tightly when deceleration is needed. That allows 100 percentĀ of the retarding force to reach the wheels and eliminates heat buildup and transmission wear due to excessive torque converter slippage.

As an option to the AutoLoc system, BD Diesel offers the TorqLoc computer. The TorqLoc acts much the same way as the AutoLoc computer, but offers added versatility. The TorqLoc takes lockup control away from your stock computer and allows you to operate the convertor in one of three modes. The first mode manually locks up the converter on command. The second mode allows the converter to operate under stock conditions. The third option maintains converter lockup only when the vehicle’s stock computer has established a circuit which is just like the AutoLoc. This option allows you to operate the exhaust brake under throttle and is designed for use in heavy power or extreme load situations.

BD Diesel makes a variety of other accessories to help you get the most from your exhaust brake. Products include the BD TowLoc computer, which allows you to adjust things like disengage speed, fourth-to-third gear downshift, torque converter lockout speed, and many more personal driving requirements with the use of a lap top computer. You can also get transmission valve body upgrades and complete transmission upgrade kits to help bolster your transmission.

The Exhaust Brake Advantage

The safety and performance benefits of BD Diesel exhaust brakes and accessories are no-brainers. An exhaust brake gives you increased vehicle control under heavy load and improved stopping power, particularly on hilly roads.

Exhaust brakes also act as a brake reserve, so you can take some of the stress off of your conventional brakes. Use of an exhaust brake, even in situations where your regular brakes are sufficient, will reduce wear and tear with very minimal effect on your vehicle’s drivability and fuel economy. In the long run, you’ll be less likely to experience overheating, premature wear, and damage to your brake components.

If you tow a trailer, haul large loads, or pull a fifth-wheel with a diesel pickup, you should consider putting an exhaust brake to work for you. It can help prevent your conventional brakes-and your entire truck-from going downhill fast.

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Unlike traditional gasoline engines, which use a throttle valve to control and regulate incoming airflow, diesel engines allow unrestricted airflow to the combustion chambers. As a result, diesel owners are unable to downshift to rapidly reduce power when additional braking force is needed. The butterflies of an exhaust brake are far superior than a throttle valve and are located on the exhaust side of the engine, allowing you to reduce exhaust gas flow of the engine. This creates backpressure in the engine and results in a mechanical braking force. This GM Duramax exhaust brake, for example, provides 300 percent more retarding force than stock brakes alone and can hold your speed down to 15 miles-per-hour.

BD Diesel exhaust brakes--like this Ford Powerstroke brake--come with a heavy-duty air compressor and mounting clamps with electronics to control the engines EGR valve and VNT turbo.. BD Diesel offers the industry's first exhaust brake for the 6.0L Powerstroke.

This BD Diesel PressureLoc system plugs directly into your transmission and increases its hydraulic pressure. This allows the transmission to hold the torque converter's clutch plates together and prevent slippage. Reduced slippage means 100 percent of the retarding force from the exhaust brake reaches your wheels. Plus, it reduces heat buildup in the transmission. BD also has a Pressureloc/Autloc combination for Ford 6.0 equipped with exhaust brakes.

The valve body upgrades will give your stock transmission increased holding capacity to handle a higher horsepower engine or increase retarding force from an exhaust brake. BD Diesel has valve bodies for Ford, Dodge and GM diesel transmission applications.

BD Diesel transmission durability is the result of a custom tuned valve body and internals modified with additional clutches, new oil passages, sun gears and Sprague clutches. All told, it can tame up to 1,400 foot-pounds of torque. Available for Cummins, Powerstroke, and Duramax diesel, a BD Diesel transmission gives you the holding power you need to operate an exhaust brake with maximum efficiency.

Exhaust brakes mount directly on your exhaust system or wastegate turbine. This BD Diesel exhaust brake for the 2005 Dodge Ram Cummins is one of the wastegate-mount versions.

The AutoLoc computer essentially takes control of the converter lockup function away from your vehicle's computer. In doing so, it commands the converter to stay locked up when the exhaust brake is applied so that 100 percent of the retarding force reaches the wheels. The Ford 6.0L application also has BD's PressureLoc built in for additional clutch life.

The BD Diesel TorqLoc works in the same manner as the AutoLoc, removing control of converter lockup from the stock computer. However, it takes converter control a step further by offering three lockup settings: manual lockup, stock lockup, and automatic lockup, which locks up the converter after the stock computer has established a lockup circuit.


BDD-1024119 BD Diesel Exhaust Brake, 2000-2004 GM Duramax 6.6L
BDD-2033143 BD Diesel Exhaust Brake, 1994-97 Ford Powerstroke 7.3L (Turbo Mount)
BDD-1027145 BD Diesel Exhaust Brake, 2003-05 Ford Powerstroke 6.0L
BDD-2033135 BD Diesel Exhaust Brake, 1989-98 Dodge Cummins (Turbo Mount)
BDD-2023138 BD Diesel Exhaust Brake, 2003-04 Dodge Cummins (Turbo Mount)
Author: David Fuller

David Fuller is OnAllCylinders' managing editor. During his 20-year career in the auto industry, he has covered a variety of races, shows, and industry events and has authored articles for multiple magazines. He has also partnered with mainstream and trade publications on a wide range of editorial projects. In 2012, he helped establish OnAllCylinders, where he enjoys covering all facets of hot rodding and racing.