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1 24th May 03:25
bccubed
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Posts: 1
Default Axle ratios: what does it mean?


Hello all,

I have been bit by the new truck bug. I really like the new F-150 and am
currently driving a 2002 Black Sport 4x2, 4.6. I do like this truck but am
fascinated by the new one with the console in the FX4 trim package. You only
live once why not have a nice truck? The financing is so good now anyway.

I want to build this truck, no more take what we have on the lot only. The
last time I took what was there and I don't want to do that this time. Can
someone explain to me the logic behind 3.55, 3.73, or 4.10 axle ratios?
Regular or Limited slip?. This truck will not be used for heavy work. I will
put racks and work with it but only small trailers etc.... Which should I
choose?

I like the FX4 trim package nicer than the Lariat, I am not fond of leather.


Thanks
neil
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2 24th May 03:25
hattmakr
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Default Axle ratios: what does it mean?


bccubed@aol.com (BCcubed) writes:

3.73 should work well for your intended use.

AW
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3 24th May 03:25
spdloader
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Posts: 1
Default Axle ratios: what does it mean?


I'm sure someone else will give you a much more in depth answer, but simply
put:

3.55 Ratio:
When the driveshaft (pinion gear) turns 3.55 times, the rear axle (ring
gear) turns once.
3.73 Ratio:
When the driveshaft (pinion gear) turns 3.73 times, the rear axle (ring
gear) turns once, you can see where this is going.

The more times the drive shaft turns to complete a single rotation of the
rear axle, the "lower" the gearing is, and the better suited the truck is
for pulling.

The less times the drive shaft turns to complete a single rotation of the
rear axle, the "higher" the gearing is, and the better suited the truck for
highway, and more speed.

Regular, or "open" differential, is when the rear axles turn independent of
each other, one at a time receiving power from the engine, at a loss of
traction, but a gain in economy.

Limited slip, is when the rear axles turn in unison, both receiving power
from the engine, giving vastly better traction, at a slight loss of economy.

Not a scientific answer, but pretty much it.

Spdloader
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4 24th May 03:25
steve barker
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Default Axle ratios: what does it mean?


3:55 , you won't need the lower ratios for what you describe. No need to
waste the gas. Of course perhaps we should qualify what you call a "small"
trailer. Where I work, the small trailers weigh 4000 lbs empty. On the
other hand, our dodges have 3:55's and pull these 4000 - 10000 lb trailers
fine.

--
Steve
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5 24th May 03:25
tyrone
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Posts: 1
Default Axle ratios: what does it mean?


And my Ford has a 3.55 and pulls 10000 - 12000 lb trailers easily to.
The fact that it is a PSD, might also have something to do with that.
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6 24th May 03:25
steve barker
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Default Axle ratios: what does it mean?


That reminds me, we have about 24,000 behind our PSD at work very regularly.
I'll have to check and see what ratio it has in it.

--
Steve Barker

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7 24th May 03:25
joe
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Posts: 1
Default Axle ratios: what does it mean?


One thing to watch out for with the 3.55, is that with the automatic
overdrive, around .65:1 ratio, the engine doesn't really get into its power
band, at least in my opinion. My truck turns ridiculously low rpms on the
interstate, and with the small engine you're planning to get, it may not get
up a hill without shifting gears or slowing down. If I lived somewhere
really flat I think I'd like it, but as it is I really don't. I'm always in
3rd when I tow, so in that case it's fine.

So be sure and test drive one with the V-6/3.55 extensively before you buy.
Drive it though your commute. I think you'll like it, as Steve and others
have suggested, but you're not buying a powerstroke, and it may seem a
little wimpy on the highway.
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8 24th May 03:25
sandyon66xyz
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Posts: 1
Default Axle ratios: what does it mean?


[snip]

I have no practical experience with this, but have looked into it as I will
be buying my first pickup and will be towing a boat and trailer weighing
just under 5,000 pounds on long highway trips, as well as short trips.
Regarding axle ratios, as a general rule, a Lower Axle Ratio gives you
better fuel economy, is quieter, is faster and has a longer engine life,
whereas a Higher Axle Ratio gives you increased pulling power, better
acceleration and poorer fuel economy. Good ratios for towing are between
3.50:1 and 4.10:1.
See the Towing Guide published by "TrailerBoats" magazine
http://www.iboats.com/sites/trailerboats/site_page_1483/article_page_162.html
Chapter 2.

TrailerBoats also has a Tow Ratings Database which may be helpful
http://towrating.trailerboats.com/

According to the 2004 F-150 45-page brochure published Sept. 2003 (Ford may
have made some changes since then), for the FX4 4x4, you can only get it
with the Limited-Slip Rear Axle. With the P255/70R17 A/T OWL tires the
3.55:1 axle ratio is Standard and the 3.73:1 is Optional, but with bigger
tires (18" wheels and also wider) you can only get the 3.73:1 axle ratio.

Whether you are going to be doing mostly highway driving or mostly
off-roading (which is what the FX4 is designed for) may make a difference in
your choice. Others can tell you that better than I can, but I think that
the bigger tires and higher axle ratio are for better off-roading than the
standard tires and 3.55:1 axle ratio.

Sandy
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9 24th May 03:25
steve barker
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Posts: 1
Default Axle ratios: what does it mean?


Well the #1 rule for towing is to turn the OD off anyway. So that should
take care of that potential problem.

--
Steve Barker

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10 24th May 03:25
steve barker
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Default Axle ratios: what does it mean?


You have your "higher" and "lower" backwards.

--
Steve
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