HELP! Gear ratio change forthcoming.....

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Oct 27, 2009 | 09:39 PM

#46

krewat

FTE Leadership Emeritus

Joined: Jul 2002

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From: Long Island USA

Quote:

Originally Posted by 1ViciousGSX

Question?

If you have 3:73 gearing and the 4R100, and you turn overdrive off, what rear ratio does that compare to if you were in overdrive with a higher gear rear end?

Divide by .7 which is what the OD ratio is.

So, 3.73 / .7 is 5.32

And that's only if you're running at highway speeds. General all-around acceleration will still be the same.

Oct 27, 2009 | 09:56 PM

#47

1ViciousGSX

Mountain Pass

Joined: Oct 2009

Posts: 114

Likes: 4

Quote:

Originally Posted by Krewat

Divide by .7 which is what the OD ratio is.

So, 3.73 / .7 is 5.32

And that's only if you're running at highway speeds. General all-around acceleration will still be the same.

Thanks. That's what I was wondering. I agree normal acceleration will be slower, but once you're up to speed if you are having trouble with hills and stuff, taking it out of overdrive would do the trick then.

For me where I do need something to move my 37 ft 5th-wheel RV around 600-800 miles at a time, about 4 times a year, the 3:73 will be better for overall mileage when not towing.

Oct 27, 2009 | 10:17 PM

#48

mikefordf550v10

New User

Joined: Oct 2009

Posts: 1

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rear gear

I have 2002 f550 with a538 rear end. It pulls my camper just fine camp wight 13,000.the gas mileage is 7.8 at 68mph in overdrive if outof o.d. the rpm is a3,200 when out 4,300.

Oct 30, 2009 | 10:22 AM

#49

4wheelfurry

Senior User

Joined: Jul 2006

Posts: 209

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From: Deep South Louisiana

I went from stock 3.73 to 4.56 and I wish everyday that I'd went 4.88 or 5.something. Of course I'm running the 20" wheels so my tire dia is larger but these trucks love low gearing! I pull a 35' gooseneck and it is slow to take hills and such, a lower gear would help me. As for fuel mileage my truck gets 14 empty and pulling light and around 11 pulling heavy. I say go with the 4.56 you won't look back I promise!