TL;DR - I'm going to try replacing my 5th gear with a taller gear that should lower my RPMs at highway speeds and will hopefully improve my fuel economy (MPGs).
On the freeway, it's high revs all the time.
The Tacoma has never gotten great gas mileage. Even when I bought it, I was taking a step backward in the MPG department, since my previous vehicle - a 1982 Honda Accord - was putzing along at 35+ miles-per-gallon, and achieving speeds significantly higher than the Tacoma.
Still, the 18-19mpg that I averaged for the first 16 years of ownership wasn't aweful (for a Tacoma), though I was using the Tacoma entirely on pavement and hadn't weighed it down with a million mods.
Part of this "weighing down," was installing 4.88 gears, a mod I've thoroughly enjoyed except for one thing: it increased RPMs dramatically over the stock 4.10 gears, so that when I'm cruising along the highway at 65mph, the engine is screaming away at nearly 3000 RPM.
That's a little more than 500 extra revolutions every single minute, and those revolutions consume fuel, especially on long trips from northern Washington to Southern California. And back.
Recently, I've gotten wind of a possible solution: replacing the 5th gear in my R150F manual transmission with the 5th gear out of a R452 transmission. This seems to be - if you can find all the right parts and happen to have exactly the right R150F transmission - a reasonably straight forward process.
Magic in the making.
If it works, it should give me a little more than 500 RPM drop in engine speed at 65mph, and hopefully that will result in a wee bit better fuel economy.
For now, I'm gathering parts and planning a shop day at Zane's. There's no way I'm tackling something like this on my own!
In this Series
