Turbo Diesel Register

www.turbodieselregister.com TDR 99 Everything necessary to complete the installation is included in the clutch kit from South Bend. We now have a complete line of single disc clutch kits with solid flywheels that will enable you to add horsepower without fear of overpowering the clutch. For the extreme in holding power and competition, we also offer the Dual Disc clutches for the G56 transmission. Dual disc clutches will exhibit noise at neutral (idle clatter). If you have any questions or concerns, feel free to e-mail or call me at any time. For pricing, you may contact us or one of our many distributors nationwide and in Canada. Peter Pyfer South Bend Clutch Driving Impressions I have had the opportunity to spend a little over 26,000 miles with my G56-equipped Turbo Diesel. Approximately 17,500 of those miles were towing an enclosed car trailer, that when fully loaded, tipped the scales a little over 22,000 pounds GCVW. Having driven more than 200,000 cumulative miles (over several years) with the NV4500 and NV5600-equipped Turbo Diesels, I have a good basis for comparison of the three different model manual transmissions. From day one, the G56 has shifted smoother and with less effort than either of the two previous model offerings. The NV5600 was always "notchy" and you needed to be exact when negotiating up and down-shifts through its gates. Not the G56. Additionally, because the G56 features three-piece synchronizers throughout the transmission, up and down-shifts are much more forgiving should the operator be a little lazy in matching engine speed with road speed and the gear desired. The use of three-piece synchronizers in the NV4500 and NV5600 was limited to first and second gears. This is not to be confused with having the ability to shift "like a hot knife through butter" found in some car manual transmissions. After all, it is a medium duty truck transmission. I have found the shift pattern to be much more efficient. Since first and reverse gears are located directly up and down from one another, it is much easier to move across these gears to "rock" the Ram or move more rapidly between forward and reverse. The G56 transmission is noticeably quieter than NV4500 or NV 5600. This includes full throttle, fully loaded, trailer pulling, and driving up six-percent grade applications. One of the biggest changes is the change in gearing. The chart below shows the differences between G56 and the NV 5600. Gear Ratio's G56 vs. NV5600 Transmission First Second Third Fourth Fifth Sixth Rev. G56 6:29:1 3.48 2.10 1.38 1.00 0.79 5.74 NV5600 5.63:1 3.38 2.04 1.39 1.00 0.73 5.63 Generally speaking the G56 is geared lower in first, second, third, sixth and reverse gears. The lower first and reverse gears provide excellent stump-pulling power for launching heavy loads. Fifth gear is the same in both transmissions (direct drive). Sixth gear (overdrive) is a different story. The G56 has a .79:1 ratio while NV5600 a slightly higher .73. The net result of this difference is that a G56 combined with a 3.73:1 rear axle ratio ends up having almost the same final drive ratio as a NV5600 combined with a 4.10:1 rear axle ratio. G56 with 3.73 rear end gear NV5600 with 4.10 rear end gear Sixth gear = .79 X 3.73=2.94 Sixth gear = .73 X 4.10 = 2.99 I would welcome a higher axle ratio offering for the G56. With engine speeds nearing 2,100 rpm at 65 mph, it is no wonder the fuel economy suffers with this transmission and rear end combination. The Cummins HPCR engine provides plenty of torque to launch most loads, especially with the lower first and reverse gears found in the G56. It would be nice to have the option of selecting an axle ratio that provides a final drive ratio similar to that found in the automatics equipped with 3.73:1 rear end and an overdrive of .69 equating to a final ratio of approximately 2.57. Having that ratio would put the engine speed at approximately 1,750 rpm to 1,800 rpm, which has been shown to provide much better fuel economy. There have been some discussions regarding lubricants and fill levels in the G56. ATF+4 is the recommended lubricant (Amsoil makes an excellent synthetic that meets this specification) and six-quarts is the recommended amount for the G56 in a Turbo Diesel. When I changed the fluid in my '05 3500 truck with the G56 I encountered a small problem. If you fill the G56 to the "bottom of the fill plug" as the shop manual states, it will only accept four quarts. I chased this discrepancy down through Chrysler Group Engineering and verified what the service manual says. ATF+4 is correct; fill to the bottom of the fill hole is correct and, for a diesel transmission, six quarts is correct. What gives? I could not get an answer to this discrepancy. However, we found a sure solution for refilling the transmission to be to remove the floor console, boot and shifter and fill the transmission with six quarts from the top. It is a little more work, but fortunately the drain interval occurs only every 60,000 miles according to the Owners Manual (schedule B) in our 2005. BACK IN THE SADDLE . . . . Continued

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