Diesel Pick-up Truck Transmissions

So you have your 150hp tuner, your AFE stage 2 intake system, the 5" exhaust and larger injectors. But what is all this doing to your transmission? Here we’re not only going to discuss what causes transmission failure, but also what you can do to prevent it.
Heat is one of the biggest causes of transmission failure. The fluid in your trans. can reach in excess of 250E. That kind of heat can damage your transmission in a short amount of time due to fluid breakdown. Normal operating temperature should be about 175E to 200E and will get well over 100,000mi out of your stock trans. Many high performance upgrades designed for towing and racing create large amounts of heat. Stock transmissions will usually start to slip around double the stock horsepower and torque rating.

Your stock torque converter and valve body is another weak point of your transmission. Stock components will not provide enough pressure to the clutches, bands, and other pressure components in modified and some stock applications. As the torque is increased above 550-600 lbs, the stock single disc converter will continue to slip until the fluid (between the clutch and lid) either overheats, or is gone. When this happens, the clutch material burns off and lodges itself in the trans and cooling lines. Over time this will shorten the life of your transmission. Companies like ATS, BD Power and Banks have greatly improved on stock design flaws by designing products that help your truck run more efficiently. For example, the five star torque converter designed by ATS houses a patented five-disc clutch that eliminates slippage without raising line pressure. Also, the valve bodies are redesigned with larger solenoids, 1st and 2nd gear lock ups, and increased line pressure to maximize load capacity. Companies such as ATS and BD offer units known as Trans-Command and Lockup Controller. These are designed with push button controls that allow the driver to select the speed at which the converter clutch will engage and disengage; this gives you total control over your transmission. Such products also offer better acceleration and cooler running, as well as allowing the user to brake or holdback (even without an exhaust brake). If an exhaust brake is in place, the ATS "Trans-Command" has the ability to automatically control the brake and converter clutch so power is not over-applied.

One of the smallest, yet most important improvements you can make to your transmission is changing to synthetic fluid. Simply by changing to synthetic you will not only lower your transmission temperatures, but also help find lost horsepower and torque. Synthetic fluids such as Royal Purple also help avoid cold temperature thickening, sludge and varnish formation, poor friction stability, and premature maintenance. A synthetic fluid will extend lubricant life up to six times and provide protection well beyond non-synthetics. Also, upgrading to a larger transmission pan such as a Mag-Hytech will help. These pans are designed to hold more fluid; this results in the transmission running cooler and lasting longer. Aftermarket trans pans are great for towing applications where high heat is a factor. Another advantage to an aftermarket pan is that it is already tapped for a temperature probe for vehicles that don’t have a trans temp gauge already.

Now lets talk monitoring. Keeping a watchful eye on your engine, transmission, EGT (exhaust gas temperature), and turbo can be most useful in not only short term, but also long term vehicle life. Choosing a chip/tuner that monitors your engine parameters is very important. You don’t want to choose a chip that just gives you tons of horsepower and torque. Although it might seem cool to tell your buddies that your chip/tuner gave you 220hp and 400 ft lbs, it’s not so cool to be stuck on the side of the road with a 30ft trailer because the system you chose didn’t de-fuel or warn you when your EGT was through the roof. Systems such as an Edge Juice w/Attitude or a Bully Dog Outlook monitor will not only notify you when a problem occurs, it will allow you to visually see where the problem is occurring.

Though your stock transmission will work great for some applications, improvements can always be made to ensure the safety of you and your vehicle. Remember to choose carefully when purchasing new parts. You may want to look for the unit with more monitoring features. It will prove to be the smarter decision in the long run for you and your truck.