Changing gear ratio

[mohead1]

I have a 08 F-450, 4wd w 4.88 gears. I want to change the gearing front and back to something more isable like a 4.10 or 4.30 gearset. How much approx. is this gonna set me back....i know not cheap but tired of being wound out at 75 mph unloaded on the interstate.

 

[mikeeg02]

On your rear axle, are the axle tubes round or square? (Round axle tubes are a dana 80, square is a s110 or s130)

Also where are you located? That way if someone knows a reputable shop around you we can suggest it.

 

[mohead1]

Thanks for response, it has the heavy axle, square tube....i believe its the 110 Dana

 

[mikeeg02]

I looked up the s110's, and they do have gears available down to 3.73s. At least Yukon gear has them. Your front should be a variance of a dana 60, though having 4.88 gears you may need to get a different carrier, because I am pretty certain the split is at 4.10s.

Lets look at the ratio break down.

A$$uming ~33" tires,

4.88 gears
.71 for Overdrive
75 mph
~2645 rpm Seem right?

4.30 gears
.71 for Overdrive
75 mph
~2330 rpm

4.10 gears
.71 for Overdrive
75 mph
~2225 rpm.

3.73 gears
.71 for Overdrive
75 mph
~2025 rpm.

Where do you want to be?

In my experience, gear swaps cost about 1k per axle. That varies based off of shop time, price and price\quality of gear set.

 

[scparrish]

http://www.grimmjeeper.com/gears.html

That calculator will help you find exactly where you want to be.

Just swapping the gears yourself you are at 500 per axle in parts.

 

[mikeeg02]

I like this one, for just calculating highway speed.

http://www.crawlpedia.com/rpm_gear_calculator.htm

 

[Leftthenleft]

I end up around $1800 swapping gears thru a buddy of mine. Ithat included adding a rear Detroit locker. I went from 3:73s to 4.88s on my last 250. I don't remember having to change the carrier and I went with motive ring and pinion. Motive is a little louder than factory gears unless you spend the time to have them polished.

Something to think about. Instead of a crush sleeve, machine a spacer to set your lash. It takes more time, but you won't ever collapse it if you wheel hop. Ask me how I know. Haha

 

[mikeeg02]

When you bought a detroit for the rear, you bought a new carrier. And in the front, I believe on D60's you can buy a "thick" gearset that will bolt in place of the numerically lower carrier to allow for numerically higher gears. Unless I have that backwards. Its been a while since I looked into ratio swaps.

And I havent looked at the breakdown of the s110 rear axles but I would be surprised if they had a crush collar, as big as they are. But if they do I agree, one of the best things you can do is eliminate it. Just takes a little longer to shim it properly. I forgot to add that, so props to you!

 

[mohead1]

I checked some gear companies, and hell, its running in the $2200 range by the time all is said and done. Im now thinking an overdrive unit is the way to go, like a gear vendors. Then i have the gearing for loaded truck-trailer grunt, but reduction for unloaded highway running. Gotta check to see if they have one to fit my transfer case.

 

[mikeeg02]

I would watch putting one of those on a 450+ application. I remember some failures from people continuously towing large 5th wheel campers if I remember right. I also don't think they are much if any cheaper. 1st gear in the 6r140 is pretty low for take off. I guess at some point you'll have to determine if you'll drive it enough to save enough fuel to cover the ~$2500 in changes.

 

[mohead1]

Thanks for the tip "mikeeg02". I remember reading about that, but i thot it was just heavy towing that the unit cant take, it mentions it on the website too. I wud only go into overdrive in high gear, and be unloaded, or not towing

 

[cbf9703]

The last time I did a regear I went through Randy's ring and pinion. They were great to work with, but I would definitely go with the name brands like yukon and not an off-brand for a DD. I did a cheaper option in an off-road truck and there is more noise out of them.

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