How which gears affected your 1st gen Tundra MPG?

We all know bigger tires burn more gas. It would make sense to think shorter gears would do the same as they require higher RPM for any given speed. I recently changed my gears from the stock 3.91's. I had available- a set of 4.10's, and a set of 4.88's. Due to the fear of horrible gas mileage, I opted to install the 4.10's. I've since noticed that I'm actually getting better MPG on the freeway, and about the same in the city stop-and-go stuff. I'm curious what #'s other 1st gen owners are getting who have changed gears on their 1st gen Tundras, and on what tire size, as I plan to make the jump to either 4.56's or 4.88's.
I'm asking for true MPG #s, so don’t forget to input tire size into whatever app or scangauge you’re getting the data from, unless you’re on stock size tires.
I am on 35" tires and use scangauge

 

https://www.tundras.com/threads/re-geared-to-4-10s-on-oe-tires.80540/#post-2182011

City mileage went from 12-13mpg to 16mpg going from 3.91 to 4.10's on stock tires.

17-18mpg to 18-20mpg freeway around 65-68mph (best I saw was 20.5mpg, but that was at 60mph for testing).


With 35's you should have gone to the 4.88's. Mechanical advantage > higher rpms for fuel mileage. Engine may spin faster but there is less load (ie: less throttle) when cruising.

 

stock gears. before the headers i could eek 19mpg on the highway with 33s.

post headers im lucky to get 15 highway... really need to fix the running rich issue..

i plan on 4.10s honestly. just a slight bump. and next set of tires i'll probably just go 32s. the 33s are no longer needed since i uh.. bought too many tacomas to not just use them offroad. LOL

 

Hindsight I should've also asked speeds, and I thank you for mentioning yours. I've noticed that whether I'm traveling at 60, or 80mph, the difference in MPG isn't significant, as long as the speed is consistent. Fluctuating speed within any range costs more fuel than a constant 90 mph on a straight. And where the hell were you when I was trying to decide on gears? From a table graph I saw somewhere, 4.56's on 35's is a near perfectly matched ratio to stock gears on stock tires. You still think the 4.88's are a better choice? I should mention the majority of my miles are freeway averaging 85'ish mph.

 

I’m on “33s” but I definitely want to go 488, all the weight, and being a ridgeline, I think it will be a good combo

I think darkness runs 456 on the same size tire, and love them, but not as much weight, so I bet that’s perfect for him

 

3.90's are taller than 4.10s.

bigger tires are like having taller gears, but also heavier and usually wider adding to extra rolling resistance.

imagine riding a bicycle up hill, taller gears are more difficult, and require more effort, but spinning the pedals with shorter gears is easier.

and the 4.7 is a spinner, not a weightlifter. Non-VVTI has peak torque at ?3400?rpm. Thats where the engine uses its fuel the most efficiently. I mean, i havent seen any cylinder pressure mapsfor the 2uz, but its usually pretty close to peak tq rpm.

 

Maybe that’s why better mileage is seen at highway speeds vs normal in town.
Which doesn’t help me

 

https://x-engineer.org/brake-specific-fuel-consumption-bsfc/

theres a limit. Like aero forces are usually strong enough to be more efficient at 50 rather than 80. But under 55 i turn off OD (sometimes up to 60 if im climbing a hill) the instant mpg calculator in the sequoia taught me that.

 

92.7% of my driving is under 45-50mph

 

Turning off OD is like having 5.33's

 

30% underdriven?

 

What would cause it to run rich?

 

Knew I might have fukt that up, edited to correct. Thx. Still don’t understand what’s taller about a lower ratio with less teeth on the ring gear.

 

Longer legs.

I'm 5'10", and take appropriate sized steps, theres some 6' something behemoths walking like they're hurdling, and some 4' something chicks shuffling their little legs as fast as they can manage.

 

That's because you're not in an efficient range of the engine/fuel map the way your engine is loaded with current gearing and tires.

Fluctuation eats gas because extra fuel is put in every time you tip the throttle in. This is to prevent engine damage from leaning out if you stab the throttle.

No idea, did you post anything? Lol.

Numerically 4.56's match. But it doesn't take into account the significantly heavier tires and increased wind resistance from being taller. Go 4.88's.

Think of the max speed each gear set will reach.

Shorter gears mean a lower top speed and reaching that top speed in a shorter amount of time. Taller means higher top speed and taking longer to get there.

I think the terms were originally coined by those drag racing.

 

Maybe a 2 speed rear end would be the best of both worlds?

Now if they only made them to fit a pickup truck and could make it shift either manually or automatically based on need.

 

Thank you. All very helpful stuff. And I think you just talked me into the 4.88’s. Bonus is I already have them and would need to buy 4.56’s if I went that route.
Here’s a fun fact that you @assassin10000 should get a kick out of; the 4.88’s that I have, are the Motives that you sold to @chrisb a while back. Without knowing it you just talked me into installing your old gears into my truck.

 

Nice!

Solid pinion spacer the diff while you're in there.

 

X pipe.

seems to be a common occurrence

 

I've actually got an extra 3rd member to use, and will be building it when i get my hands on a locker of some kind. you wouldn't happen to have one layin around huh? but yes, solid spacer. When I recently went from the 391's to 4.10's, I had also picked up an LSD to install. That's why i hunted down an extra 3rd, so I could build it, then swap it in with no real down time. Now I've got my original 3rd on the bench, which is where I'll install the 4.88's and locker (and solid spacer). When I was just building the LSD diff, I was having a difficult time sourcing the solid spacer, and running out of time, I just had to use the crush sleeve. It was a bit confusing because the 8.4 was also in the T100's and certain years of the taco's, and that's how the parts are listed on the sites. In other words, I was having to search for T100 or whatever years of tacoma parts to find parts for the 8.4. Then, sometimes (not always) 1st gen tundras would be listed as compatible, even tho that search came up empty. Anyways, all that being said, Got a link for the solid spacer for an 8.4 diff?
Another question I have is; what, if anything, is compatible between the 8" and the 8.4"? I read that toyota labeled them as such only for identification, and the ring gears are actually the same diameter, but the 8 is 10 bolts and the 8.4 is 12 bolts. And there's also a 8.2". Anyone know and care to elaborate?

 

Gears are the same, housings are different iirc. Maybe some of the bearings/internals too.

I got my solid pinion spacer from here or 4wp (had to call and order, wasn't on the website a couple years ago:
https://trail-gear.com/toyota-solid-pinion-spacer-kit.html

 

Yeah, people always think higher RPM means lower mpg. If the load on the engine is high at low rpm, you’re going to burn more fuel.

As always, there is a point of diminished returns.

 

Not to hijack a thread but what is a Ridgeline Tundra?

 

The best of the best, the double cab

 

I'm on 285/75/17 (33.8") with 4.88's and I'm getting about 15-17 MPG on average, according to the Fuelly app and my Scangauge. You can use a simple math formula to help you choose gears to get you close to stock. For me, 4.56 would probably have been best but I do plan on towing and for that reason, I went with 4.88's.

Also, I installed the YellowBox tire calibration module and my odometer is dead on, so my scangauge should be giving me an accurate readings of my MPG.

This picture below was from a 2 hour drive/145 miles. Mixed with Traffic and open road.

 

I have never heard of it being called that. Thanks for the info.

 

I thought it meant a Tundra that's never driven off-road, kinda like a Ridgeline.

 

The body positive movement was built on the doublecab truck. Look at how big a half ton is. My single cab ranger does half ton things, but its not bloated with gizmo's (distractions) and like all 1gt's didnt need to be approved by a dude with a beard.

 

There is an option in the scangauge settings to input % of change to ratio due to non-stock tire size. Unnecessary for you, but helpful for anyone without the yellowbox. Once set up, the scangauge will show actual mph and mpg, despite the speedo being incorrect. Yellowbox is the way to go for sure, I just haven't gone there yet

Never heard a double cab called what? a ridgeline? or the best of the best? Neither are truly accurate..