gear ratios
#11
07-23-2011, 04:45 AM
3.46 ratio? Not ever seen that one. I got 3.42 in my truck and am turning about 1500 at 70mph on low pro rubber.
Seen 3.21, 3.36, 3.42, 3.55, 3.58, and 3.70 but never a 3.46. Guess one can learn something new every day. Either way, if you want to run 70-75 mph and "try" to get mpg you can live with, I would consider going to 3.36 or even 3.21. Most engines (at least emissions equipped ones) seem to get their best mpg with the engine operating around 1300-1400. The DDEC 3 liked it higher, but the DDEC 4 and 5 do pretty decent between 1300 and 1400. Can't really comment on the new DD15. I would agree also, with others, that having an ECM tune could be helpful overall. If one was going to change gearing, an option worth considering is going to one drive axle with a pusher or tag axle. You could put lockers in the drive axle for added traction. A shop would give you credit for the drive axle and power divider you take off and you will reduce your overall weight by 400 lbs, more or less. Add to that you will decrease your rolling resistance and pick up a tenth or two mpg minimum. I can get this done at a shop near me for not much more cost than redoing the gears and keeping the same setup.
__________________
Freedom does not mean the choice to do whatever you want. It means the choice to do what you ought. Last edited by Copperhead; 07-23-2011 at 05:08 AM.
#12
07-24-2011, 05:02 AM
And tracer changes them once every 6 months lol
__________________
Truck Driving an occupation consisting of hours of boredom interrupted by sheer terror!! "All the coolie carriers suck. Log 70, work 80-100, paid for 50." - the Great ColdFrostyMug 
#14
07-28-2011, 12:35 PM
well, it's a business. you try something, if it doesn't work - you try something else. I thought 3.73 was too slow, so I got a 3.42 and turned out to be too fast FOR MY PARTICULAR OPERATION. I compromised by taking a step back and getting a 3.58. I drive at 57 MPH now and my 15 L CAT spins at 1,270 RPM and I'm laughing all the way to the bank. Don't listen to people who tell you it costs 4 grand to change the gears. The gear shop where I did my axle ratio job charged me $2,500 first time and the second time I think it cost me 50% less. All you have to do is find the right shop. By the way when I park my truck and get into the Cobalt Sport 2.4 I mostly drive at 75 MPH
 I like driving fast especially when the PASSENGER vehicle I"m driving gets 34 MPG!
__________________
Watch my YouTube videos |
