LEARNING CURVES LEARNING CURVES
QUESTION: I’ve always wanted a diesel, and now I have my first one: an ’08 Dodge Ram 2500 with a six-speed manual transmission. I’m 23 years old and have only driven pickups with automatics, and I’m having a little bit of a challenge shifting smoothly. Sometimes I get a little gear grind. Could there be a problem with the transmission that is making it so difficult—or is it the “young gun” behind the wheel? ANSWER: Congratulations on your first diesel! Stepping away from an automatic and moving to a manual six-speed also deserves credit. Many Dodge Ram owners have found replacing the G56 transmission’s synthetic ATF with a synthetic SAE 50 lubricant and over-filling by 1 quart helps improve shifting. (Beware that over-filling a transmission, differential, transfer case, or other component that runs gearsets can cause aeration of the oil, and, as a result, cause degradation of cooling). Others have found combining a quart of Amsoil 5-30 Synchromesh with a synthetic 50-weight engine oil is a good combination. However, the lubricant inside the manual transmission is just a small part of achieving smooth shifts with a Cummins/G56 six-speed package. It’s the driver that really makes the difference. Seasoned owners of manual-equipped diesel pickups (and most race car drivers) know the secret to making smooth, slick shifts: double-clutching. It’s a very basic concept—letting the transmission gears match the speed of the engine before making that shift up or down. When you want to shift up, say from Third to Fourth, push the clutch in, lift off the throttle for a second, shift to neutral, let the clutch out, wait a brief
moment, then push the clutch back in, and slide shifter into Fourth. That brief clutch in/out/in period allows the engine and transmission gears to be closer to the same rpm they would by just trying to slam the shifter home in one motion, which usually results in a little gear grinding. The same principle applies to downshifting: clutch in, shift to neutral, clutch out, blip the throttle so engine rpm comes up a couple hundred, then clutch in and make the downshift. Once you get the hang of it, making smooth shifts becomes second nature—and fun. Drivers that are really good at it can shift up and down through the gears without touching the clutch once the truck is rolling, just like professional big-rig drivers. One other item of note to consider when driving diesels with manual transmissions: Keep your foot off the clutch pedal when you aren’t shifting. “Riding” the pedal tears up throw-out bearings. Keep your left foot on the floor until it’s time to shift, double-clutch while making the shifts, and you’ll be good to go.