Regearing and doing 37s right

[userdude]

I'm recovering from ACL surgery at the moment, so it will be a bit before I can get under there and remove the bash plates to get a picture, BUT that's something I want to do anyway. I'm pretty sure I have a front diff fluid leak, so getting under there and taking a good look around is in my future plans.

That's awesome man! One day soon I want to make my way up there and Bunker Bomb again. I went to both and was literally the only one there on a Thursday/Friday, so I didn't get too jiggy. I don't have a winch to get myself outta jams... lol

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[Chritaka]

As you can see, gearing opinions on here are widely varied, but you definitely don't "need" 5:13's to turn 37's. Plenty of real world uses of members running 37's on the 4.7's (myself included on a 4-door) and it truly is a good combo. And I as said, especially so on the lighter 2-door. I wheel fairly regular and prefer rocks over the mud. I also am still on the stock steering rack and unreinforced stock tie rods (gasp!) so don't get sucked into having to spend mucho bucks upgrading those components or your Bronco will explode while off-roading bit.

I’ll echo the same as I have a ‘23 WT , 2.7 with 4.7’s and heavy 37” Mickey T Baja Boss AT’s (but 8lbs lighter wheels) and sitting at 108lbs per corner. One thing to think about is MPGs vs you real world usage on and off road as gears will further impact. Once I made my Forscan adjustments, and after driving a while to let the comp readjust, my MPGs regulated at 15.1-15.5 avg. I always planned on 37’s and that I needed the 4.7s from the start.

It still performs amazing offroad , as well as on road, with plenty of power and pep. I haven’t had any issues going over or through obstacles where lower gearing was needed. It has plenty of passing power and no prob hitting 100+ mph. That’s not even getting into Sport mode.

It is a slightly different comparison though since you have an MT… I’d just wheel it, do your lift/wheels/tires, wheel some more and then upgrade where you feel lacking. Also you may not need the JKS depending on your lift/wheel/tire combo. I don’t have it, running 2.5” lift with +0mm offset 17x9 wheels and only get a light rub with steering fully locked and suspension stuffed. At some point I’m just going to do a slight notching of the crash bar mounts to clear, but it’s not bad enough to cause concern.

 

[Tricky Mike]

Don't fear the gear. Almost nobody says they wished they had geared less after the fact. If I had the option I'd prefer something even steeper than 5.38, look at @Aonarch's chart, 2209 RPM is borderline lugging it, the 2.3 cruises best around 2300-2500 IMO.

 

[Aonarch]

Don't fear the gear. Almost nobody says they wished they had geared less after the fact. If I had the option I'd prefer something even steeper than 5.38, look at @Aonarch's chart, 2209 RPM is borderline lugging it, the 2.3 cruises best around 2300-2500 IMO.

Agreed!!!

I'd do 5.38s with 37s on the manual.

 

[Oldhippie]

You guys beat me…I was just gonna say if I was spending the time and money to regear, I would go to 5.38s…my 2dr 2.7 lost a lot going to 37s your 2.3 will lose more and the gearing will bring some of it back…factory gearing is is a “mileage” compromiSe…adding bigger & heavier wheels and tires means ya need more than factory rpms to make up…

 

[mpeugeot]

The benefit of having such an overly overdriven 10 speed (or 7 speed) transmission is that you can run an absolutely ridiculous amount of gear without destroying the on-road nature of the Bronco.

The only exception is if you are running portals, in which case you don't need to regear the Bronco because of the of the 1.22 ratio (making a 4.46 ratio essentially the equivalent of the 5.38 ratio).

 

[Aonarch]

The benefit of having such an overly overdriven 10 speed (or 7 speed) transmission is that you can run an absolutely ridiculous amount of gear without destroying the on-road nature of the Bronco.

The only exception is if you are running portals, in which case you don't need to regear the Bronco because of the of the 1.22 ratio (making a 4.46 ratio essentially the equivalent of the 5.38 ratio).

100%

Hell I could see Sasquatch owners going with taller gears with portals.

 

[SierraBronco]

100%

Hell I could see Sasquatch owners going with taller gears with portals.

I’ve been considering it to get the strength gains, but we’ll see what the 5.734 gearing is like with 40’s

 

[Aonarch]

I’ve been considering it to get the strength gains, but we’ll see what the 5.734 gearing is like with 40’s

That will be sweet.

The 2 door fuel tank is TOO DAMN SMALL though.

I don't think I am going to turn my Bronco into a crawler. Right now it is on overland duty.

 

[5GENIDN]

I’ve been considering it to get the strength gains, but we’ll see what the 5.734 gearing is like with 40’s

For me... It feels like it did stock, gearing wise.... I do feel the additional rolling resistance and the added unsprung weight... I feel it very clearly. But it is not a negative for me. The rolling resistance yes, But the unsprung weight no. Acceleration with the Procal installed seems ever so slightly improved. Rolling resistance really comes into play at maintenance of highway speeds. I am hitting the snails a lot more often on hills when at speed. Plenty (very significant) accelerator left though.

I am running the 4.7s with the 1.22 for an end result of 5.73.... Seems perfect to me on the 40s.... I am running 4.11 with my 35s on my Canyon.... It could use a little more gear mostly because it has a 4 speed and relies on a very long torque curve with the V8 in the little Canyon.

 

[5GENIDN]

That will be sweet.

The 2 door fuel tank is TOO DAMN SMALL though.

I don't think I am going to turn my Bronco into a crawler. Right now it is on overland duty.

You are right about the Gas tank being way too small... That is why I had to modify a spare delete to carry two 3 gallon rotopax. I am getting right around 13... (I still drive with a heavy foot, and probably will till the day I die considering how my great Uncle drove well into his 90s/with a very heavy foot. Opposite of most old people) which really sucks with a 16 gal tank. Off road I do like just slowly tooling along though.

 

[Aonarch]

You are right about the Gas tank being way too small... That is why I had to modify a spare delete to carry two 3 gallon rotopax. I am getting right around 13... (I still drive with a heavy foot, and probably will till the day I die considering how my great Uncle drove well into his 90s/with a very heavy foot. Opposite of most old people) which really sucks with a 16 gal tank. Off road I do like just slowly tooling along though.

I carry 4 gallons, but have capacity for three more two gallon rotopaxs. I normally have 4 gallons of fuel and six gallons of water while overlanding.

 

[kodiakisland]

Always go low, especially with a MT. People with an AT can just give it more gas and wait on it, but no so with a MT. I know a lot of people who have regeared, myself included, and I've never heard anyone say they wish they went with a higher gear.

For the time and expense, I'd go 5.38 over 5.13. No, it's not a huge difference, but always go as low as you can within reason. I just see no upside to picking the 5.13s over the 5.38s.

 

[5GENIDN]

Always go low, especially with a MT. People with an AT can just give it more gas and wait on it, but no so with a MT. I know a lot of people who have regeared, myself included, and I've never heard anyone say they wish they went with a higher gear.

For the time and expense, I'd go 5.38 over 5.13. No, it's not a huge difference, but always go as low as you can within reason. I just see no upside to picking the 5.13s over the 5.38s.

The up side of a 5.13 over a 5.38 is tooth thickness.... The 5.13 has a stronger tooth profile... And when you are getting over 5.0... Personally I think that really should be considered... I think there are times to go to the 5.38... Just be aware of the compromise. Your ring and pinion WILL be weaker.

Unless of course you are changing the diameter of both the ring and pinion... But then you are changing the entire housing.

 

[kodiakisland]

If you want to drive in 4WD they have to match. In this case, @MrCooper already said he was going to replace the M190 front drive units with M210 front drive units. So whatever FDUs gearing @MrCooper decides to buy... the rear gears will have to match.

If you only drive in 2WD... then doesn't matter. Just don't accidentally put it into 4WD.

Old school vehicles this is true. Front and rear can be mismatched as long as it's not in 4WD. I do wonder if all the sensors and traction control devices on the Bronco would allow it to operate mismatched.

Back when I was much younger and poorer, I did a regear over several months. I could only afford to do the rear, so I just put a sticky note on the transfer case selector that said NO. Probably should have just pulled the front driveshaft to be safe, but everything was good 3 months later when i got around to doing the front. Had another old 4wd that only had the front driveshaft installed, so it didn't matter what the rear ratio was.

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