regearing a 4x2 for MPG

I just purchased a 99 taco, reg cab, 2wd, with 2.4L and auto trans. It doesn't have a tachometer so I don't know what RPMs it's pulling at 65-70 MPH but it sure seems like it could pull at that speed at a lower RPM resulting in better fuel economy. Has anyone out there ever done a rear dif gear change on a 2wd with improved fuel economy the primary objective? Would love to hear that someone else has done it successfully before I try it!

 

Come on people Someone out there has to have thoughts on this!

 

It would be a lot cheaper and a lot less permanent to put taller tires on the back.... You'd need an awful lot of economy to offset the cost of regearing.

Good luck, let us know what you decide to do and what the results are.

 

taller tires weigh more so it would kinda cancel out the effect... try to find a whole used third member from a 95-99 2wd manual tranny tacoma 5 lug like yours. you have 3.58s because your auto but a manual truck in those years has 3.42s like mine. that would be the cheapest and easiest way


heres my source by the way.

http://www.customtacos.com/forum/showthread.php?t=84297

 

Larger tires isn't an option because the previous owner of this tacoma dropped it 3" in the front and 4" in the rear then put 14" rims on it. It looked absolutely stupid and scraped the frame anytime I pulled in and out of parking lot or hit pot holes, not to mention the speedo was way off. I bought a set of 16" alloy Camry wheels (which I wouldn't have thought of if it wasn't for TacomaWorld.com) and put on some 206/55s. That made the speedo accurate again and it also increased the ride height so at least I can drive it daily. With the amount of highway miles I drive, I am not concerned about the expense of regearing the rear end because at $4 a gallon, it won't take that long to recoup. (Also I have a friend who owns a junk yard so I don't pay much for parts).

Thanks for your help so far.

 

What kind of mpg's are you getting now ?

 

27 at 65mph. I'm not complaining, I just have a theory that this taco should be able to do better. Toyota has to engineer these trucks with fuel economy and towing in mind. I don't care about towing so I figure I should be able to change the gearing and get better fuel economy. The 2.4 motor has a decent amount of torque in the middle range so I just think that regearing makes sense. Of course, I could be wrong and I sure don't want to go through the time and expense to do this experiment if someone else has already tried it and failed. Also, if I'm completely wrong, let me know. I'm humble.

 

id go with the 3.42 3rd for what your sayin man, unless you can find a smaller gear than that.... theres not very many gear options for the 7.5" rear.

 

Yeh, I haven't been able to find any ring/pinion sets smaller than 3.42 so I think you may be right. First I am going to invest in a tach so I can get a better feel for how it drives and responds at different RPMs.

 

I have a 98 extended cab 4x2 2.4 auto. and it came factory with 14'' rims. I also have it lowered. Im not sure what gears i have but i get around 27 to 28 mpg at 60mph Im not complaining at all. Im intrested in maybe doing the swap if it will help out enough to reep the benifits. POST some results.