4.46 vs 4.7 Gear Ratio Discussion

[JBowles]

FWIW Forscan has fields for both the axle gear ratio and tire circumference. IME though the tire circumference math is a little wonky, the numbers ford uses seem quite low, but the speedo jives well with the gps

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[Jimmyleetennessee]

There is NO vehicle speed sensor on a 6G Bronco. ABS doesn't measure the voltage of the WSS, it measures frequency. Most vehicles built in the last 10 years are this way. A taller tire at a given road speed will generate a lower speed signal than a smaller diameter tire. You are correct, as long as all 4 are the same, the computer doesn't care, however, the speedo, and the data sent to the PCM will be lower than true road speed when a taller tire is installed. Steeper gears will not affect this. There are easy ways to reprogram it also, but trust me this is how it works

If there is no speed sensor, how does the vehicle know how fast you are going? It's not done by GPS or ABS sensors, so there IS a speed sensor somewhere.

 

[Sixtysixpride]

During development, 4.46’s were originally the highest gear ratio planned to be available. 4.7 was going to be a catalog item but it was later determined that 4.7 would be a more optimal gear for the multi-role build characteristics.

4.46’s were more than healthy during the early stages (talking T6 skeletons with Ranger top hats). The 4.7 gear ratio actually helped increase the power capacity of the 10R60. Paper specification is now 550 foot pounds in U725

 

[Bmadda]

If there is no speed sensor, how does the vehicle know how fast you are going? It's not done by GPS or ABS sensors, so there IS a speed sensor somewhere.

It IS done via ABS, over CAN. Unplug your abs module and go for a drive if you don't believe me

 

[JBowles]

There are wheel speed sensors, but I suspect the output is just a digital blip mulitple times a revolution, and one of the computers along the way does the math on how many blips per second and what the tire circumference is to sort out the speed of the vehicle

 

[F OR D]

My Toyota and Chevy didn't have an issue when regeared, and I doubt the Bronco will either. Like I said, it's easy enough to reprogram if needed. It won't be an issue for me. If there is a permanent light on the dash, that's easy enough to deal with as well.

black electrical tape usually fixes it.

 

[JT58Bronc]

I have had so many trucks all the way back to the 70's where I installed larger tires and did not change the gearing to compensate. Each and every time the gas mileage and performance suffered. Maybe not a lot but it definitely did to some degree. I think Ford got it right with the gearing- based on the tire sizes. So when I saw that the Sasquatch was available with 35" tires and the proper 4.70 gearing it was so worth it to get it- based on my past experience. And I am so happy with my 2 door- the thing is fast to me and delivers darn good MPG for what it is riding 35" tires- 22 MPG average. Very happy with that. Most of my trucks and SUV's in the past with larger than stock tires got mid teens at best.

 

[Boreal]

If there is no speed sensor, how does the vehicle know how fast you are going? It's not done by GPS or ABS sensors, so there IS a speed sensor somewhere.

Your WSS IS YOUR ABS SENSOR.

 

[Jimmyleetennessee]

It IS done via ABS, over CAN. Unplug your abs module and go for a drive if you don't believe me

It is not done via abs. ABS tells the vehicle which wheels are rotating, and which ones aren't. Not how fast the vehicle is going. That value is measured from the driveshaft or rear differential. The inputs are then put together and translated to determine the vehicles speed.

 

[Jimmyleetennessee]

Your WSS IS YOUR ABS SENSOR.

Yes you are correct but the "VSS" is an entirely different component.

 

[Bmadda]

It is not done via abs. ABS tells the vehicle which wheels are rotating, and which ones aren't. Not how fast the vehicle is going. That value is measured from the driveshaft or rear differential. The inputs are then put together and translated to determine the vehicles speed.

Years ago that's how it was...not anymore. I'm not a fan either...just the way things are now

 

[Jimmyleetennessee]

Years ago that's how it was...not anymore. I'm not a fan either...just the way things are now

Here is the part number in question. It is the vehicle speed sensor or "output shaft sensor."

 

[broncobase1]

Your Badlands *came* with a 4.7 ratio as standard, Sasquatch or not. It was the optioning of the automatic transmission - either intentionally with the standard 2.3L motor or by choosing the 2.7L motor with required auto - that changed the ratio to 4.46. To say that one can not have the 4.7 without optioning Sasquatch is not correct (and this bronco has been beaten to death, repeatedly, on numerous other threads here).

The point the OP was trying to make is the relationship between drive ratios and tire size, which is valid and correct, not get into a pissing match on what is available on a particular Bronco model. Not only that, the vast majority opt for automatic.

 

[Jimmyleetennessee]

The point the OP was trying to make is the relationship between drive ratios and tire size, which is valid and correct, not get into a pissing match on what is available on a particular Bronco model. Not only that, the vast majority opt for automatic.

You said it all... thank you for the comment.

 

[Bmadda]

Here is the part number in question. It is the vehicle speed sensor or "output shaft sensor."

MT doesn't have that. OSS is for auto trans to calculate slippage. VSS is still a signal from ABS. Seriously try disconnecting your ABS and drive it

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