ring and pinion help
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From: Wyeville
ring and pinion help
i have a question about the gearing on my truck. when i bought the truck it came with 3.23 gears and i put a lift kit and 33's on it which dropped it to 2.83. at the same time it dropped my gas mileage down to 5mpg. my question is would changing the gearing help me to get my gas mileage back with the over sized tires? i want to put 35's back on it after the 33's wear out. what gearing should i run?
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From: Wyeville
not yet but its on the list after i get my ford done the way i want but i just wanted to change the gearing since it seems like the motor is working way too hard to turn them tires. so in theory i was thinking that changing the gearing would make the tires turn easier and the motor not working so hard.
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From: Texas Coast
Reason I said that is I think that the 2.76 is about the best you can do on that set up. But the difference is minimal. Btween it and what you have.
i suggest getting a compresion test done and see where that leads you.
i suggest getting a compresion test done and see where that leads you.
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From: Texas Coast
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It could help a little on the fron end (take off) but not some much after that.
I was suggesting checking out the engine performance to ensure that you narrowed it down to a true torque displacement issue. Or if its a power issue. I always start on the motor end then work into the drive train.
I was suggesting checking out the engine performance to ensure that you narrowed it down to a true torque displacement issue. Or if its a power issue. I always start on the motor end then work into the drive train.
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"it dropped my gas mileage down to 5mpg." What was it getting before ? What height of tires were on it before ? That change shouldn't have made much if any gas milage difference. You may have to put your foot in it a little more to get it rolling but after that it should be like an overdrive. If anything, ever so slight, I'd think it should have went up especially on the highway.
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From: Wyeville
it originally had 235/75/15 (29) on it. i dont know what it was getting before since i bought it and put the lift and tires on it within a week of getting it. ya i had to put my foot into it more to get it rolling but i am only getting 100 miles to the tank. and thats babying the truck everywhere i go weather im in the city or on the highway.
the motor had the bottom end rebuild and new carb, and a tuneup done it too so the motor is in good running order.
the motor had the bottom end rebuild and new carb, and a tuneup done it too so the motor is in good running order.
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OK, forget converting the axle ratio due to tire size changes. The axle ratio is the same.
I take it your AT is a 3 speed, non-OD unit?
If so, with 3.23 gears, a 1:1 high, and 33 inch tires, you should be turning about 30 mph per 1000 rpms. (+/- due to rounding error and add maybe 200 rpm torque converter slip).
That isn't overly tall gearing. Does the truck hold 60 mph without having to keep your foot in it, or having to downshift on slight hills?
A vacuum gauge would be helpful in determining how much load you have at any given speed.
Those trucks were rated 11/13 by the EPA when new, so with bigger tires on it you'll be lucky to run 10 or so. But that's better than 5, so something is wrong there other than the tire change imo.
Sources for gearing and MPH/1000, and EPA:
Novak Conversions - Gearing & Gearing Math for Jeeps
Find a Car
Are you adjusting for the odometer error when calculating MPGs?
Do you have fuel leaks? Recent tune up and carb adjustment?
I take it your AT is a 3 speed, non-OD unit?
If so, with 3.23 gears, a 1:1 high, and 33 inch tires, you should be turning about 30 mph per 1000 rpms. (+/- due to rounding error and add maybe 200 rpm torque converter slip).
That isn't overly tall gearing. Does the truck hold 60 mph without having to keep your foot in it, or having to downshift on slight hills?
A vacuum gauge would be helpful in determining how much load you have at any given speed.
Those trucks were rated 11/13 by the EPA when new, so with bigger tires on it you'll be lucky to run 10 or so. But that's better than 5, so something is wrong there other than the tire change imo.
Sources for gearing and MPH/1000, and EPA:
Novak Conversions - Gearing & Gearing Math for Jeeps
Find a Car
Are you adjusting for the odometer error when calculating MPGs?
Do you have fuel leaks? Recent tune up and carb adjustment?