Changing out 3.31 to 3.73

[ander1894]

apologies if this has been asked before. I have a 2022 Max King Ranch with 3.31 gears but everything else for the HD towing package. Can I upgrade the gears to 3.73 and then get a tune to recalibrate the ECM? thank you your eedback

 

[2020FordRaptor]

apologies if this has been asked before. I have a 2022 Max King Ranch with 3.31 gears but everything else for the HD towing package. Can I upgrade the gears to 3.73 and then get a tune to recalibrate the ECM? thank you your eedback

You can Forscan it out. But beware it won’t be cheap to have it replaced. If you are 4wd you have to replace both front and rear axle gears. Pricing would be $3k just for labor if you have 4wd and about half that if your 2nd.

 

[Fastcar]

apologies if this has been asked before. I have a 2022 Max King Ranch with 3.31 gears but everything else for the HD towing package. Can I upgrade the gears to 3.73 and then get a tune to recalibrate the ECM? thank you your eedback

That isn't that big a jump in gearing. Might want to mess around looking for different wheel /tire diameters to get close.

 

[JasonH]

Prior to 2018, the HD Tow package on 4x2 Expeditions came with 3.31. It's not an issue for towing. I have 3.31 and tow 7K. I have enough power to keep up with traffic. Sure, more would be nice. But I've towed thousands of miles without issue on the 3.31 gears.

 

[GlennSullivan]

Prior to 2018, the HD Tow package on 4x2 Expeditions came with 3.31. It's not an issue for towing. I have 3.31 and tow 7K. I have enough power to keep up with traffic. Sure, more would be nice. But I've towed thousands of miles without issue on the 3.31 gears.

Actually not just 4x2 but also 4x4. My 2017, 2014 and 2011 4x4 HD Tow Limited Expeditions, all rated at +/- 9000lb tow are equipped with 3:31 differentials.

 

[chuck s]

Same here. 2017 XLT, HD Tow, 4x4, 3.31 axles, 9200 pound max tow rating. Trailer weighs roughly 6,000 pounds. Don't know why the rating changed.

-- Chuck

 

[iowacarpenter]

apologies if this has been asked before. I have a 2022 Max King Ranch with 3.31 gears but everything else for the HD towing package. Can I upgrade the gears to 3.73 and then get a tune to recalibrate the ECM? thank you your eedback

Tow ratings on these are mostly limited by payload capacity. The 3.5 has tons of power. My ‘16 Expedition has a 3.73 LS axle. My ‘15 F150 with the same engine has a 3.55 axle and I can’t really tell a difference in towing power between the two. However, the F150’s solid rear axle makes for higher payload and a more stable towing experience.

 

[bmpcamry09]

If you have the 3.31 rear, you probably don’t have the 9.75 rear axle like the max tow packages have. To properly do the swap, you’d need a full axle for the rear and gear only swap up front if your 4x4.

Personally I love my 3.31 set up. I’ve towed pretty heavy with no issues. Don’t understand the lower tow rating versus prior gen myself.

 

[JasonH]

If you have the 3.31 rear, you probably don’t have the 9.75 rear axle like the max tow packages have. To properly do the swap, you’d need a full axle for the rear and gear only swap up front if your 4x4.

The 4x2 HD Tow 3.31 axles are 9.75 in the rear.

 

[chuck s]

I see this is still running...

With labor rates being what they are it wouldn't surprise me if it was less expensive (note I didn't write "cheaper" 'cuz it won't be) to swap the entire axle(s) from a donor car.

My '17 has HD tow and 3.31 axles and I've never had any regrets. Same maximum tow as 3.73.

-- Chuck

 

[GlennSullivan]

I just had the rear differential changed on my 2007 Tahoe. Installed a new Power-Trax Limited Slip (like Eaton Tru-Trac). New differential, gears, bearings and seals. Cost was right at $2000.