MPG Difference Between 4.56 vs 4.88

I know the regearing debate has been had multiple times. But my question is for those who have switched from 4.56 to 4.88, was there a difference in MPG?

I have a 2000 automatic 2.7L with 285/75R16. It has a 3in OME lift, hidden winch, Yakima bed rack with molle panels to hold some RotoPax, recovery boards, etc. That's the only weight on it, so very minimal. I don't use a roof top tent nor do I have aftermarket bumpers.

It's my daily driver. I only go "off roading" 1-2 per month. And its only to get somewhere secluded that I can shoot in piece or to get to certain trails for hiking/camping. Nothing major. But to get to these places I'm looking at a one way 1-2 hour drive and my normal freeway speed is 80MPH.

I'm debating between regearing to 4.56 or 4.88. Stellar Built in NorCal has a great reputation and they are asking for $2800 plus tax. They're recommending 4.88 but I'm leaning more to 4.56 if there will be a difference in MPG.

So, for those who have experience with both, is there a difference in MPG? How bad would I be revving at 80MPH? And would my MPG tank at that speed?

 

Use the Tire Calculator.

Enter factory size from your door sticker and the size you are using as your 'new tire'.

Scroll down a bit and you'll see gear ratios to 'pick', and it will show RPM with your new tire size @ 65mph.

While not MPG, it will give you a comparison that's valuable. You can extrapolate to get close to your MPG killing 80.

 

How can I find it without the door sticker?

 

Owners manual. Tire Rack, or multiple websites

 

I just called the dealership. Based on the VIN, they said there's two options. It can either be 4.10 or 4.55.

They also said that Toyota hasn't been allowing them to order stickers for about a year because of some issue. But they recommended

https://ecsvin.com/ (Needs a federal business ID)
or
https://automotiveid.com/ (Needs a photo of the original sticker.)

 

There will definitely be a difference in MPG. This is vastly over simplifying, but think of it like this:

(4.88-4.56) / 4.56 = .07

So, essentially, your RPMs with 4.88s will be 7% higher than 4.56s, which (again, vastly over simplifying) will mean 7% worse fuel economy. Really, it'll probably be a bit less than 7% worse - maybe in the 3-5% range. Personally, I'd look for whatever gearing kept me around 2,500 RPM when I was cruising at whatever speed I wanted to cruise at. That's the place where the engine likes to cruise and is the most efficient.

Of course, on dirt, the 4.88s will be much nicer, esp. with an AT, since they'll give you more control/slow. So that's the tradeoff you're looking at. Personally, I have 4.88s on my MT (which is already geared lower than an AT, and so already has ~500rpm higher revs at fwy speeds), but I've also installed a higher 5th gear, to bring my revs back down when cruising the highway.

Here was my 4.88 gear install (No More Lugging – Re-Gear to 4.88’s and Front ARB Locker) and impressions (Breaking in the New Gears)

Here's what I found after installing the higher 5th: First Impressions of Dyna R452 5th Gear – AdventureTaco

AFAIK, there were no 4.55 gear sets from the factory so they probably meant 4.10 or 4.30. And you can definitely install whatever you want. 4.56, 4.88, 5.29 - lots of folks on here have all of those on 2.7 ATs.

 

I have a 2.7 however with a 5 speed manual. I ran 33x10.50 and now a 34x10.50. Weighted a little more than your truck, with the 4.88 gears that I have, it brought back a lot of power, which is why I went 4.88 of 4.56, if you drive highways with hills I would suggest the additional power of the 4.88. I average around 18-19 on a usual tank. a hair down from the 23 I had stock but I expected that going with a heavier and taller tire. But in every vehicle I have regeared I also aim for a little more power, so that on the highway, when you hit a small grade you might not downshift thus keeping rpms lower under load.
The RPM difference is only 7% between the 2 gear sets. So lets say at 65 you are at 2750 with 4.56 gears you will be at 2943 with 4.88. Which is a very minor difference and likely non noticeable when it comes to fuel economy.

 

I do see 4.55

 

Alright everyone, I called five dealerships in total. None of them are able to get me a replacement sticker because my VIN doesn't have one assigned in their system. Two separate locations told me that at those times, not all vehicles came with a door jam sticker since it was mostly just tire information.

One of the guys said that he's been there for over 20 years and that if I don't have a door jam sticker, that I most likely don't have a firewall sticker either, which is true. I don't have neither. He said that that's how he remembers it being when he used to work on nothing but older first gens.

But three of those locations gave me a code of B04A which is a 4.556 gear ratio. That's the only information I've been able to find anywhere. So unless anybody else knows where I can find the axle code, please let me know. For now I'm going with the belief that I have a 4.56, essentially.

So what signs should I be looking for to see if I need to upgrade to 4.88? If I feel like I need more power? Specifically at hills?

 

You're only running 32.8s.. not a huge difference from stock, and you're already on a higher FDR than most. You have a 150HP motor...
If you feel like you need 7% more torque, do it. But for that cost, you could almost go forced induction

 

You should only upgrade to 4.88s if you are finding that you don't have low enough gearing to slowly navigate obstacles in 4Lo when offroad. You're more likely to notice the offroad issues with much larger (34-35") tires. Otherwise, 4.56 is great gearing/compromise for light offroad+daily duty and will definitely result in better MPGs for daily duty than 4.88s will.

 

You can easily determine your current gear

https://www.moderndriveline.com/how-to-determine-your-rear-axle-ratio/

 

4.56 gears came in 2.7L AT Tacomas and 4Runners. I've found multiple sets in junkyard trucks.

I think you're right about having 4.56. You can confirm by getting the truck up on jacks and counting turns of the wheel, but I'd put money on 4.56 given everything you've said.

Since you already have 4.56, I don't think 4.88 will be almost $3000 worth of improvement. It will probably drive better off-road and in hills, and probably feel better at low speeds on road, and probably be slightly more annoying (because of higher RPMs) at 80mph.

Fuel economy could go down or up depending on driving habits and tires--with oversized tires, sometimes regearing helps the engine stay in the more efficient parts of its RPM range, again depending on driving habits. Best to assume it'll go down by 1-2mpg though.

So, for something that's maybe a little bit better in some ways and maybe a little worse in other ways but almost certainly not life-changing in any way, is that the best use of your $3000?

 

Thank you, I'll do the driveshaft turn test next time I have it jacked up.

 

I was under the assumption I had 4.10 but after talking to three different Toyota techs, I might be wrong. I'll confirm with the driveshaft turn test this weekend.

If it's 4.10, then I'll most likely upgrade it. But if the Toyota techs are correct at 4.56, then I'll keep it as is unless I end up getting more serious about this new hobby.

As I'm sure many of you started the same way, I told the wife I just wanted a small reliable truck to get me from A to B. Not even a year later, I've done quite a lot to it so we'll see where life takes me. Especially since I've already told her we're setting 3K aside for the "needed repair."

 

I finally got around to doing the driveshaft turn test.
It did 4 full revolutions and then about 2 inches past the mark.
That means I have 4.10 gears, right?
Since it didn't go halfway past the 4th turn.