Any thought on gears?

BlackSTX · #1 Wed, November 11th, 2009, 06:38 PM

After having had my tunes for a while now, and having adjusted to the performance of the truck, I now want more acceleration. Sure, like many of you I'd prefer to add some power adders, but a supercharger for a truck with a 4.6L in it isn't easy to find, or really in the budget; so I'm left with the idea of swapping the gears.
I currently have 3.55's and the stock size tires but am considering something in the range of 4.10 to 4.56. Have any of you swapped into this range, and how has it helped?
I don't do much highway driving so any mileage loss isn't really an issue to me; I'm more interested in acceleration and responsiveness.

Give me some ideas, I've posted this elsewhere a while back, but the bench racers there gave me ratios a bit too extreme, and I'm looking to be realistic and streetable. After all, this is my daily driver, not a weekend warrior.

***88Racing*** · #2 Wed, November 11th, 2009, 06:55 PM

This a tough one!
You are not pulling anything big(load wise) or not putting bigger tires on. The bigger the ratio the more the economy is sacrificed.
My gut is telling me 3.73's.
My brain is telling me 4.10's.
Tell you what plug your numbers into the pegasus gear calcultor and see what that comes up with.
Just some thoughts.
JMHO
Lars

BlackSTX · #3 Wed, November 11th, 2009, 07:36 PM

Yeah, it is. I've been trying to think it out for a while. I have gone to a few sites and plugged in some numbers, and it appears 4.30's would likely raise RPM's at 55 mph in overdrive about 300 RPM's, which I don't consider significant for the driving I do. Since my daily commute is about 6 miles round trip, and the majority of driving I do isn't at expressway speeds.
I just want to get the mass moving quickly..... Something a relatively low horsepower 4.6L is a bit challenged in doing.

***88Racing*** · #4 Wed, November 11th, 2009, 08:24 PM

Well general rule is to go a step up. So if the info pointed you to 4.30 then go to 4.56. Or is this toooo radical?

JWBFX4 · #5 Wed, November 11th, 2009, 11:21 PM

I would think 4.10's would be a perfect fit. But IMO i would not go over 4.30's

But you will sacrifice some mileage at the higher speeds (interstate driving)

***Jackpine*** · #6 Thu, November 12th, 2009, 11:10 AM

And, Ford's torque control is going to get in the way if you go too high. Bill posted about this somewhere a long time back and I can't really think of a good "search string" to find it. Maybe if you search on all posts by "Power Hungry" and "gears" you may get lucky?

At any rate, if you put the gearing too high. the PCM won't see the need for power and will limit what you can get (at least that is what I understand).

Bill also published an Excel spreadsheet "RPM vs MPH calculator.xls", recently that you may be able to find pretty quickly if you look for it.

Personally, I would not go above 4.10.

- Jack