Everything posted by connercop
Moses, Thanks for the info. I have counted the teeth on ring and pinion sets many times to determine ratios. Mostly for race car applications when the gear set is on the bench and not yet installed in the vehicle. I will attempt the drive shaft rotation procedure you described. I will also use a stopwatch and the mile markers to ensure the speedometer is accurate. My tires are Cooper brand and what is printed on the door sticker matches what is printed on the tire. Since I use this vehicle almost exclusively for towing, I suppose that 4.10 gears may not be the worst thing for my particular application. I considered taller tires the next time I replace them, but that may not be the best choice. I have yet to watch the video, but it sounds like that "tune" may be the way to go. I was just curious after reading your information regarding RPM and fuel mileage. I'll keep you posted. P.S. I plan to tow the trailer at 65 MPH, which, as you noted above, puts me in the 2100 RPM range.
To clarify, Moses, I have the 6 speed manual transmission. My truck is a 2WD and a short bed. I would guess with all of the combinations out there, mine would net just about the best fuel mileage possible. I probably tow the 11,000 Lb. trailer more than I drive the truck empty as I don't use this vehicle much unless I am towing the trailer. Where exactly is the tag on the differential that indicates the gear ratio? Also, I read on a forum (somewhere) that a 2006 with a six speed manual transmission ONLY came with 3.73 gears, however, I am sure about the RPM range as when I attempted to set the cruise by the tachometer at 2000 RPM I was closer to 60 than 65 MPH.
Moses, I have been reading your thread for a while now. I have a 2006 5.9 Cummins with a 6 speed. I had to do the tachometer repair because it is (was) one of the 2006 models with the tachometer issue. Now that I have repaired the tachometer, I noted that 65 MPH for me is between 2000 and 2100 RPM. I ran the truck empty for 400 miles on one tank at 65 and was able to achieve 21 MPG. It is a short bed, 2WD 4 door. It would appear I have .411 gears? Is there a simple way to check using the VIN or similar? The tires are 26570R17. The door label says the tires should be 26570R17 and an "E" added at the end. I pull an 11000 LB trailer most of the time when I drive the truck and am wondering if a taller tire would help (or hurt) the mileage. Your thoughts? EDIT: I found a PDF here http://www.dodge.com/bodybuilder/2006/docs/intro/vin.pdf that tells you about the VIN. Apparently the VIN does not change when the rear ratio changes. In fact, I could not see where the transmission type was included in the VIN either.