First-gen Tacoma 5th gear swap?

[monkeyodeath]

Hi all, thought I'd ask for a bit of advice before I tear into my transmission...

My rig is a 2004 Tacoma, manual, V6, riding on 33s and 4.88 gears.

At freeway-type speeds, my revs are fairly high -- I'm doing 3000RPM at 72MPH. My gas mileage is generally in the mid-teens.

I've seen on other forums that it's possible to swap a taller 5th gear into the R150f, which would have the engine turning about 2500 at 72MPH. Parts aren't exorbitantly expensive and the job fairly non-invasive.

I like the idea of lower revs at freeway speeds and maybe improving my gas mileage a bit. My rig is mostly used as a road-trip machine and wheeling rig, so the idea of dropping the revs a bit on some daylong freeway slog appeals to me.

I'm a little worried, though, that the result might be an OD that's too high. The 3.4 isn't exactly a powerhouse, and while I hate screaming it above 3k just to keep up with traffic on Utah interstates, I figure having it lug at freeway speeds is probably worse. I don't have as much weight as a lot of people here do, but I do have a hardshell RTT and solar panel that acts as a bit of a sail, not to mention that the truck is fairly lifted.

Anyone have any thoughts on this? Very intrigued by the idea, but my experience in playing with gearing is minimal, and I'd rather not spend a day writhing around in gear lube if the results aren't going to be worth it.

 

[bkg]

Hi all, thought I'd ask for a bit of advice before I tear into my transmission...

My rig is a 2004 Tacoma, manual, V6, riding on 33s and 4.88 gears.

At freeway-type speeds, my revs are fairly high -- I'm doing 3000RPM at 72MPH. My gas mileage is generally in the mid-teens.

I've seen on other forums that it's possible to swap a taller 5th gear into the R150f, which would have the engine turning about 2500 at 72MPH. Parts aren't exorbitantly expensive and the job fairly non-invasive.

I like the idea of lower revs at freeway speeds and maybe improving my gas mileage a bit. My rig is mostly used as a road-trip machine and wheeling rig, so the idea of dropping the revs a bit on some daylong freeway slog appeals to me.

I'm a little worried, though, that the result might be an OD that's too high. The 3.4 isn't exactly a powerhouse, and while I hate screaming it above 3k just to keep up with traffic on Utah interstates, I figure having it lug at freeway speeds is probably worse. I don't have as much weight as a lot of people here do, but I do have a hardshell RTT and solar panel that acts as a bit of a sail, not to mention that the truck is fairly lifted.

Anyone have any thoughts on this? Very intrigued by the idea, but my experience in playing with gearing is minimal, and I'd rather not spend a day writhing around in gear lube if the results aren't going to be worth it.

Interesting idea, but nothing that I'd ever bother to explore. Your RPM's are right in the range of stock @70mph, maybe just a tad low. I think the ROI for the effort is all in the creativity and the learning, not in the end result.

 

[nickw]

Hi all, thought I'd ask for a bit of advice before I tear into my transmission...

My rig is a 2004 Tacoma, manual, V6, riding on 33s and 4.88 gears.

At freeway-type speeds, my revs are fairly high -- I'm doing 3000RPM at 72MPH. My gas mileage is generally in the mid-teens.

I've seen on other forums that it's possible to swap a taller 5th gear into the R150f, which would have the engine turning about 2500 at 72MPH. Parts aren't exorbitantly expensive and the job fairly non-invasive.

I like the idea of lower revs at freeway speeds and maybe improving my gas mileage a bit. My rig is mostly used as a road-trip machine and wheeling rig, so the idea of dropping the revs a bit on some daylong freeway slog appeals to me.

I'm a little worried, though, that the result might be an OD that's too high. The 3.4 isn't exactly a powerhouse, and while I hate screaming it above 3k just to keep up with traffic on Utah interstates, I figure having it lug at freeway speeds is probably worse. I don't have as much weight as a lot of people here do, but I do have a hardshell RTT and solar panel that acts as a bit of a sail, not to mention that the truck is fairly lifted.

Anyone have any thoughts on this? Very intrigued by the idea, but my experience in playing with gearing is minimal, and I'd rather not spend a day writhing around in gear lube if the results aren't going to be worth it.

I just did a quick calc and you are +/- 300 RPM difference from a stock rig with 30's and 4.10's. I wouldn't sweat it. I'd argue the Tacoma with that drivetrain was very much a 90's inspired vehicle which means it was probably designed to cruise in the 55-65 range comfortably. You'll also be using 4th a lot more with a big jump to 5th....I don't think it's ideal.

 

[roving1]

Can almost guarantee you would have to shift out of 5th everytime a bug hit the windshield with only 2500 in 5th.

Crunch the numbers and see if you can borrow some bigger tires for just the rear and go for a highway cruise to see if you like the cruising RPM. I'm betting you won't like it running 35 or 37 inch tires. There is also no guarantee you will get increased MPG either as their are a lot of factors.

Not exactly apples to apples but my 2.7 manual on stock 30.5" tires and 4:11 was terrible on the freeway and I always needed to downshift for every hill or headwind into 4th with a cruising speed of 72 at about 2600RPM. With 32" tires and 4:56 I most of the time keep it in 5th and I am cruising along at about 3000 at 72MPH. I get about 1-2 MPG more with the higher cruising RPM. Flat level windless ground one might get a better cruising MPG with lower RPM but loaded with bigger tires that can go right out the window with a truck or SUV and you are better off not having to constantly downshift and operate outside of peak torque RPM all the time.

 

[monkeyodeath]

Great, sounds like a bad idea and now I won't have to spend hours taking the backend of the transmission apart. Took a gander at some torque band charts for the 5VZFE which reinforced this.

I think it was one of those things that seemed like a great idea at first, but I'm realizing that lugging the engine in 5th just trying to keep up is probably a whole lot worse than just having some higher revs on the freeway.

Thanks for the help!