Hey everyone, first post here. Sorry if this is in the wrong place, still figuring the site out. Seems like a great site!

Anyways, I picked up my third ranger last week, a 2001 4.0 4x4 5 speed. It’s in decent shape and I’m loving her so far. It has brand new 30” tires on it and it looks great. However it seems my revs are extremely high on the highway, even higher than my 4 banger fusion. Running around 2900 at 70 mph. I’m thinking the previous owner swapped out the axle ratios for .456’s which is way too high for my needs. Any input is appreciated, thanks

 

Welcome to the forum

Go here:https://www.crawlpedia.com/rpm_gear_calculator.htm

Plug in your numbers, leave axle ratio as 3.73, most common Ranger axle ratio
Tires 30
speed 70
Transmission ratio .79 <<< this is Overdrive, 5th gear, 4th gear is 1, you have an M5OD-R1 transmission, AKA, M5R1

Calculate

Should get 2,310

Now change axle to 4.56
Calculate
Should get 2,824

So yes previous owner did change BOTH axles to 4.56
On 4x4's both axles must have same ratio

Now change tire size, try 32" and 35" and watch the RPMs drop, my guess would be previous owner was running larger tires, and kept them, put on the "new" 30" to sell it


There are off-roaders that would love to have 4.56 axles so a trade might be in order, 2001-2009 Rangers or Mazda B-series 4x4s are direct swaps
You may find someone will to do all or most of the work just to get the 4.56 axles

Jack up the rear axle and spin either wheel, if the other wheel spins in the same direction then its a Limited Slip, worth more, if it turns opposite direction then OPEN axle, regular axle
Front axle is always OPEN type

 

Wow! Thanks so such an awesome response! So I definitely have 4.56’s. Interesting. I really don’t need that high of a ratio, I don’t plan to do hardly any off roading except for the occasional deer blind trail. I only do light towing, I really wouldn’t mind 4.10’s. Maybe I’ll sell the brand new Michelin tires and throw some 35’s on haha.