Going the other way with gears

[JoshT]

I know that the common move on this forum is to go from 3.XX to 4.10 or 4.10 to 4.56+, in general moving to lower ratios for more tire turning, stump pulling power. That's kind of the opposite of what I'm looking to do.

So I've got a 99 Ranger 4x4 4.0L Auto. This truck came from the factory with the towing package, meaning heavy springs and 4.10:1 gear ratio. If I'm being honest, in the 17 years I've owned it, I've never really pulled with it. At best a utility trailer with a few hundred lbs on it and any Ranger could handle that no problem. Actually I can't think of a single time I've pulled a meaningful load with it, because when I bought my ATV my engine was screwed, so I borrowed dad's truck and the ATV has lived at the hunting club since. I won't need it to ever pull a load again,Between the F-100 and F-250 I have much more capable options.

I also did the mild lift and oversized tire thing in the past. Not a lot, 32" tires, torsion bar twist, explorer springs, and lift shackles. Didn't really do anything for me. The F-250 has the same tire size stock, and the F-100 looks better in that configuration (and arguably more capable offroad). Infact I've already dropped the Ranger back down to near stock 30" tires. I'm thinking about going smaller still when these wear out dependingon how much I can do with suspension. I really don;t need the truck for offroad adventures, I might drive it to the hunting club, but from there I'm taking the ATV into the woods. The 4x4 is mostly to keep from getting stuck on wet grass or boat ramp (it's never pulled a boat either that I recall). If I really needed it both the F-250 and F-100 are 4x4 as well, and once again are (IMO) more capable.

So instead of swapping to a lower ratio for more tire turning and stump pulling prowess, I'm planning to go with a higher ratio for better cruising, interstate running and highway driving. I plan to start with a 3.73 gear ratio because I've got a spare axle around that would be easy to bolt in test out, especially since I plan to grab the springs and shackles from that truck anyway.

I guess I'm curious as to what y'all think about this gear change? What do you think the outcome will be? Do you think the 3.73 is high enough to make a difference or should I go higher? Don't want to go too high though.

FWIW: I am planning to give it a try regardless of what the responses are. I am aware that I will have different ratios in front and rear, I will not be using the 4x4 for the duration of the different axle ratios. In the extremely unlikely event that it were accidentally engaged I have manual hubs that stay unlocked. If I like the new ratio converting the front to live axle will be part of swapping to the matching ratio in front.

 

[ericbphoto]

Sounds like a good idea for your purposes. 3.73’s should be plentiful. I’m not sure what other ratios you’ll find in used Ranger axles. But you should be able to order some others if you need to.

 

[2011Supercab]

My only experience with gear change was on a 1982 Dodge 4x4 with automatic transmission

Went from 3:21 to 4:10 and had speedometer recalibrated

Of course performance went up, but what really surprised was gas mileage increased, went from 10.5 mpg to 13 mpg

 

[Uncle Gump]

My old camper special 4x4 had 3.73 gear with a manual and a 4.0L. I toted my skamper all over with it. All of my automatic 4.0L trucks have had 4.10 gear and I probably wouldn't change a thing. With the manual truck I could be more selective with the transmission gear and it never bothered me... this was with 31x10.50 tires.

 

[Josh B]

I did something similar with my tires. It had 265's and I dropped it to 235's.
Basically a 7% difference according to an online tire guide.

I keep meticulous mileage records, and also check my speedo whenever on the turnpike.

So my ground power should have increased and my mileage decreased, but I got a surprise.
I don't run checks when only on the highway etc, but between each fill up.

With the 265's ( although it has been a while since I changed tire size ) I believe was around 16/18 MPG, and after the tire change it went to 21/23 mpg.

It is a 4.0 w/3.73, MD50, 4X4, and a fairly heavy tool box

 

[racsan]

my 93 4.0 had stock 29” tires (235/75/15) and 3.73’s it got at best 19 and most of the time my commute got me around 17. I feel 3.73 is the best all around ratio with a good balance of performance & economy. My 94 2.3 I have now came with 3.45’s and I swapped that axle out for a 4.10 Well worth it, sure it only gets 21 but Im running either 235/75/15’s summer or my winter tires which are at the moment 215/60/16’s (26”) 3.55’s would be better with the 26’s but they are just there for winter and take offs from another car thats no longer in use.

 

[RonD]

If your stock tires were 29" and are now 32" then your 4.10 Ratio now "acts like" a 3.73 ratio

If you changed to 3.73 ratios in BOTH front and rear axles then 32" tires would "act like" 3.38 ratio

29" tires would be 3.73

If you ran 34" tires now, the 4.10 would "act like" 3.50 ratio

People with larger tires go with 4.56 to get BACK to 4.10 ratio, lol
if you go from 29" to 32" tires a 4.10 "acts like" 3.73, a 4.56 "acts like" 4.10

 

[19Walt93]

If you own a 3.73 rear end I'd stick it in there and try it- just don't use 4x4 until the front is swapped, too. If you live in a hilly area like me, the 3.73's are likely to cause more downshifting and could hurt gas mileage along with the additional transmission wear. If you have to buy gears, bearings, etc, it'll take quite a while to offset the cost with gas savings. Tall all season tires will reduce the rotations per mile just like a higher(lower numerical) gear would. If you run aggressive off road tires mileage will suffer but you won't get stuck as much. Everything is a compromise.

 

[don4331]

Just as reference point: 1999 2wd Rangers came with 3.55s & 225/70r15s; and the "mileage ratio" for 4wds was 3.27 with 215/75R15s.

The cool part - the tone ring is same, assuming both axels have same size ring gear i.e. both are 8.8s. so your speedometer doesn't change.

 

[RonD]

Speedometer changes with tires size, only the 1998-2000 Ranger used that ABS sensor for speed

 

[superj]

I would bolt the 3.73 in and try it out.

 

[Roert42]

My ‘11 has 3.73 from the factory with 4.0 auto + towing package. It’s a 2wd so it came with shorter 235/70R15 (approx 25/26”). Never been left wanting for a lack of power.

I would think If you live in a fairly flat area you would want to go higher. Especially if you are going with shorter tires.

 

[19Walt93]

Just as reference point: 1999 2wd Rangers came with 3.55s & 225/70r15s; and the "mileage ratio" for 4wds was 3.27 with 215/75R15s.

The cool part - the tone ring is same, assuming both axels have same size ring gear i.e. both are 8.8s. so your speedometer doesn't change.

Could be, we never stocked many 2wd Rangers and no 2wd F series, Explorers, or Expeditions. Some companies used 2wd Rangers for delivery around here.

 

[don4331]

Speedometer changes with tires size, only the 1998-2000 Ranger used that ABS sensor for speed

@JoshT has a '99, so in that magic range. Anything else, changing ratio and/or tire size impacts speedometer.

Note: 7.5" VVS has 102 teeth; 8.8 has 108 teeth and if you want to install a 9.75", its VVS would have 120 teeth. Important when swapping axles in '98-'00 Rangers as that messes with speedometer too.​

My ‘11 has 3.73 from the factory with 4.0 auto + towing package. It’s a 2wd so it came with shorter 235/70R15 (approx 25/26”). Never been left wanting for a lack of power.

I would think If you live in a fairly flat area you would want to go higher. Especially if you are going with shorter tires.

Interesting - Ford doesn't list 3.73 as an option in 2wd Rangers with 4.0 (Any ratio so long as it is 3.55s in 4.0/2wd). But this is Ford, so unicorns exist. I've been thinking of 3.73s in my '99 2wd, I have spare Explorer axle in that ratio, and most of my driving is in city, so additional acceleration would be appreciated.

p.s. 3.55 front axles are common under Explorers especially those with V-8s.

 

[00t444e]

I highly doubt going with 3.73 gears would get you much better fuel milage at all and it might actually go down in some situations. It certainly wouldn't be enough to be worth the swap.