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question about gearing and mpg

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Old 06-03-2012, 08:40 PM
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Lightbulb question about gearing and mpg

I have a 2000 4runner and in running 35 inch tires. I changed out the stock 373 gears for 529s but my mpg has actually Decresed a little bit. Just wanting a little insight on some reasons this could have happend. Everything i have read said that 529s with 35 inch tires on my year 4runner would take it back to stock mpg. What am i overlooking here?
Old 06-03-2012, 08:47 PM
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Changing the gears and/or tires changes the formula for calculating the MPG because the odometer will be out of calibration.

Did you make any adjustments?
Old 06-03-2012, 08:49 PM
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No, but im only getting around 9mpg so im guessing something is way off on my 4runner.
Old 06-03-2012, 09:55 PM
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Your speedo is about 20-30% higher than stock. Use a gps with a trip meter and odometer to get your true readings.

No way you're getting 9mpg.

Also, forget "getting back to stock."
That ain't happening. You added a load of weight and pushed your brick at least a few inches taller which in turn kills all aerodynamics.

My guess is you're getting 14-17.

Old 06-05-2012, 05:38 PM
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That makes since bavause when i put it in 4 low my speedometer is way off
Old 06-06-2012, 04:52 AM
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Getting the right gears to match your tire size will bring the RPM's at a given speed back to stock at a given speed, but once you put on 35's nothing will bring your MPG's back to stock
Old 06-06-2012, 06:00 AM
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529 gears are kinda steep for 35's for running the hwy. 4.56 would have been a Lil better choice. But 5.29 gears are the better of the two when it comes to running trails and playing on the rocks. Like I was told years ago, are u building the rig for the hwy, or building it for the trails? Can't have the best of both worlds!!!!
Old 06-06-2012, 06:29 PM
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Originally Posted by kcpanages
529 gears are kinda steep for 35's for running the hwy. 4.56 would have been a Lil better choice.
I run 529's and 35's and put about 30K miles on my truck per year.
They are not too low for highway use. I do 80 and get 16 on a straight highway tank.

Old 06-06-2012, 06:41 PM
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Originally Posted by scuba
Also, forget "getting back to stock."
That ain't happening. You added a load of weight and pushed your brick at least a few inches taller which in turn kills all aerodynamics.
This. Imagine how bad it'd been without a gear change. I'll bet you are doing fine on mpg, for 35s.
Old 06-06-2012, 07:32 PM
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529 gears are kinda steep for 35's for running the hwy. 4.56 would have been a Lil better choice. But 5.29 gears are the better of the two when it comes to running trails and playing on the rocks. Like I was told years ago, are u building the rig for the hwy, or building it for the trails? Can't have the best of both worlds!!!!
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Hope you mean 4.88's and 35's ,,, 4.56 is a good gear for 33's, but is to high for 35's even with a 5VZ.
Old 06-06-2012, 08:07 PM
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on road performance + off road performance = dual cases, 35's 4.88's - 5.29's (depending on motor)
Old 06-06-2012, 08:47 PM
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Originally Posted by ThatGuy1295
on road performance + off road performance = dual cases, 35's 4.88's - 5.29's (depending on motor)
winner winner chicken dinner... however, not everyone is willing to go that route. Not only $$$ but you don't see a lot of 3rd gen'rs going where they'd need dual cases. Me on the other hand, I need duals bad
Old 06-06-2012, 11:41 PM
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Originally Posted by ThatGuy1295
Hope you mean 4.88's and 35's ,,, 4.56 is a good gear for 33's, but is to high for 35's even with a 5VZ.
No, I meant 4.56, but ur right on ur gearing for tires!!!! Every yota I've built I went straight to 5.29 gears, but all my builds where trailer queens! They weren't built to run on the hwy! I don't run smaller than 38's on any of my builds

Last edited by kcpanages; 06-06-2012 at 11:43 PM.
Old 06-07-2012, 08:44 AM
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Originally Posted by scuba
I run 529's and 35's and put about 30K miles on my truck per year.
They are not too low for highway use. I do 80 and get 16 on a straight highway tank.

I got 16mpg doing 75 towing a uhaul with 5.29s....
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