Final Drive

[crosswhite]

Ok, so this may be a new one for y'all. I know some may wanna criticize, but my runner is a "pretty" daily driver, not an off roader. I have the 4.7 and drive about 40 miles to work one way. I was looking to stretch my final gear so that I can lower my rpms as opposed to increasing for more torque. Anyone know how to go about doing this? What is my final gear and does TRD offer anything like this?

Thanks in advance.

Michael

 

[WXman]

Well, the overdrive gear I think is 0.72 which is a fairly "tall" overdrive to begin with. And I'm pretty sure we've got 3.73 ratio in the axles. So IF such thing exists you could go down to a 3.55 for the axles or something along those lines and lower your cruising RPM another 150 RPM or so.

BUT... I have lot of experience with this from my Jeep days and the same thing will apply to Toyota. You will spend a small fortune to get the axles regeared properly even if you find the parts you want. And the fuel you'll save will be minimal at best. It'll take 10 years to pay for the modification. The 4.7 operates in it's sweet spot already and if you drop the RPMs down you'll create a situation where the transmission shifts from 4 to OD and back to 4 more often, therefore offsetting a lot of the fuel savings.

A cheaper way to go about the same thing would be to install a taller HT tire that is lightweight. Something like a General Grabber HTS or Cooper Discoverer HTP in a 265/70 or 255/75 on your factory 17" wheels. Get the P-metric version of the tire. That'll effectively lower your RPMs on the highway without screwing around with your drivetrain and will save you fuel.

 

[zopperman]

Well, the overdrive gear I think is 0.72 which is a fairly "tall" overdrive to begin with. And I'm pretty sure we've got 3.73 ratio in the axles. So IF such thing exists you could go down to a 3.55 for the axles or something along those lines and lower your cruising RPM another 150 RPM or so.

BUT... I have lot of experience with this from my Jeep days and the same thing will apply to Toyota. You will spend a small fortune to get the axles regeared properly even if you find the parts you want. And the fuel you'll save will be minimal at best. It'll take 10 years to pay for the modification. The 4.7 operates in it's sweet spot already and if you drop the RPMs down you'll create a situation where the transmission shifts from 4 to OD and back to 4 more often, therefore offsetting a lot of the fuel savings.

A cheaper way to go about the same thing would be to install a taller HT tire that is lightweight. Something like a General Grabber HTS or Cooper Discoverer HTP in a 265/70 or 255/75 on your factory 17" wheels. Get the P-metric version of the tire. That'll effectively lower your RPMs on the highway without screwing around with your drivetrain and will save you fuel.

The v8's do have a 3.73 ratio in the axle. I think some of the earlier models may have had a 3.91. I know that the earlier V6's were 3.91 but eventually became 3.73

Either way, doesn't matter, regearing would cost way too much. I like your above idea of running a taller, lighter tire.

 

[Martinjmpr]

Ok, so this may be a new one for y'all. I know some may wanna criticize, but my runner is a "pretty" daily driver, not an off roader. I have the 4.7 and drive about 40 miles to work one way. I was looking to stretch my final gear so that I can lower my rpms as opposed to increasing for more torque. Anyone know how to go about doing this? What is my final gear and does TRD offer anything like this?

Thanks in advance.

Michael

Am I right in presuming this would be done to help your fuel economy?

If so, you need to crunch the numbers and make sure you aren't spending a dollar to save a dime. :

Assuming a gear swap would cost ~$1500 (which I think is probably accurate, unless you have the ability to do the work yourself), you could buy a LOT of gas with that money, even at $4.00/gallon.

I know the standard/smartass answer to "how do I get better MPG out of my 4runner?" is "trade it in on a Civic" but when it comes to MPG, I think it's important to have realistic expectations.