Should I change gears?
Elder User
Joined: Mar 2006
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From: Greeneville,TN
Another option would be Gear Vendors. I will cost more however. I could certainly be wrong about this, but seems to me that changing to a 3.08 would cause the engine to have to work alot harder to pull that much weight, which in turn would cause a drop in MPG. I will agree that the engine will run at lower RPMs, but at what cost. There are a lot more factors that go into fuel mileage that what the engine rpm is at a given speed. Another more important factor is just how much fuel is required to keep that RPM. I would just be afraid that you couldn't pull a greasy string out of a cat's a_ _ with 3.08's.
http://www.gearvendors.com/
http://www.gearvendors.com/
Posting Guru
Joined: May 2007
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3.08 is made for 3speedautos. having truck run in correct rpm range is key to improved mpg. 1500 to1600 at about 72 to 74 miles per hour. Do the math tire actual rolling dia. gear ratio you want. to see were rpms are at 72mph. Keeping OD off under 55 i would say is no good for MPG. Forgot to say you need to figure in also final tran's drive ratio to, then you would know which gear's to run!
Last edited by jwhitetail; Mar 4, 2008 at 06:50 PM. Reason: add
Gone, but not forgotten
Joined: Oct 2005
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From: Charlotte-Fairbanks-Bflo
Alright, remember I did not even graduate from high school, so I can't do the math. But I sure would like to be able to do 72 mph at 1600 rpm's. What does that take with stock tires. With the higher gear ratio I would be more concerned with transmission damage than I would engine damage. Gear ratio's are probably easier to play with using a 6 speed than an auto. But as far as I'm concerned clutch's belong in Corvette's and race cars.
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Lead Driver
Joined: Dec 2003
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DW is running the 3.08s. Please read the article posted below if you haven't. I have pretty much exhausted all other possibilities. This is why i am looking at gears and possibly the bicycle tires.
http://www.dieselpowermag.com/featur...age/index.html
http://www.dieselpowermag.com/featur...age/index.html
Posting Guru
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Ok he has 3.08 gear's but he changed tires to 225 in rear 28 inch is what they are and 215 in front. he more than likely has Amsoil in everything, Try it change tires and gears, and like i said before, Everything to Synthetic.
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Lead Driver
Joined: Dec 2003
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Originally Posted by UP_There
seems that the $100 in labor your friend quoted you is wayyyyy low! Unless he's just extremely generous! You might find you owe him a LOT of Beer to make up the difference! 
THat is exactly right. C-note at the bar, easy. I was figuring though, while that goes in, might as well add the seals and bearings. So either way, if I take it to my friend or elsewhere, it's going to end up costing $500-$600.
Thinking now I should invest that in my bio setup instead. I am just afraid of doing it, and getting worse mileage.
