gear change / fuel mileage

[ironscott]

I am planning on putting 3.73 gears in my TB / 4X4. I have 3.42's right now, my question is how much loss of fuel mileage will is see, and what range will I be at on rpm at 70 mph in OD? I sit around 2000 rpm's at 70 in OD w/ my 3.42's

[TrailBlazzin]

i just switched out my 3.42 for 3.73's and originally i was at 72mph at 2k rpm's and now with the switch to 3.73's am at 66mph at 2k rpm's, haven't had the chance to have the pcm recalibrated for the changes but the dic shows over a 2 mpg increase, so after the change i'm guessing it will be the same. I drive a lot of hilly terrain.

[onewheeldeal]

I average 20mpg in mixed city/hwy driving with my 3.73 gearing. That includes about dozen full throttle stabs at pedal too, per tankful. At 70mph, in OD I run at 2100 rpm. I don't think you'll notice much differance, if any change in fuel economy, just snappier off the line and overall performance. I would recommend recailibrating your pcm though. Unless your installing larger tires that make up the difference.

[ironscott]

Thank for your input. I do plan to put larger tires on my TB.
I'm ordering my new 3.73 gears in next week and plan to have the shop install them within a week after I get them in.