Thoughts on 4.56 Gears with 33's

I checked that sight out after you or someone else mentioned it earlier and that's pretty much exactly what I have posted here.

No worries about listing your setup its right there to the left in your description, but not everyone has that. After the thread got started I kind of would like it to list the Regears that people have done and their opinions on how it feels for various combinations.
Regearing is a pricey and tough, IMHO decision to make. Thanks for all of your input

 

4.0, 4wd, auto

 

I'm back home now and have been driving around in my Tacoma. Getting some real world numbers. As someone had stated the numbers in the first post looked off, they were achieved using a formula then a site such as www.grimmjeeper.com

But here are my actual numbers, for those that are just curious.

Here is the setup, 2007 Tacoma 4dr, 5spd Automatic (A750F) 4x4 with the AC off.

Tires are 285/75/17, the ratio is stock 3.73
with these tires the 3.73 should act like 3.36 unless I am doing something wrong here

25mph = 1048 RPM
30mph = 1250 RPM
35mph = 1085 RPM
40mph = 1138 RPM
55mph = 1572 RPM
70mph = 1998 RPM
75mph = 2125 RPM
80mph = 2280 RPM

Now that I have done this I have simply made things more confusing because none of the numbers are even remotely close no matter what ratio calculator I use.

 

Oh and the speeds that I'm posting are corrected for tire size.

Well here is what I am finding strange, as per my way of thinking.

Simply entering in 3.73 and my current tire size of 285/70/17, should turn up the wrong info because 33's are not the stock tire size. However that is very close to what I am actually seeing. How is that so? I know that the difference is small but it's equaling roughly 6mph and 200rpm differences. Obviously will vary at different speeds. Is my way of thinking here flawed?

 

They won't be close in many cases because you are in different gears at those speeds, so a standard straight line calculator won't work. you need to also plug in the transmission gear ratio for the gear it is in at the specified speed. I can help out if you like. Let me know what your factory tire size is, what tire size you are running now, and what your factory diff ratio is.

 

I'll take any help. lol Oh and I wasn't expecting them to be similar at lower speeds because, like you said the trans will be in various gears. I'm mainly looking at 55-70mph.

I've been both converting/correcting the Ratios to be correct for how the truck will feel with each gear and tire combo. When I was doing the math. But I started to second guess myself whenever the wrong (in my opinion) ratio and tire combo are getting closer to the right speeds and RPMs. My first post was simply using formulas to get the speed/RPM, but today I actually went out and marked what the truck is actually doing.


The Trans is the A750F
1st-3.52
2nd-2.04
3rd-1.4
4th1.00
5th-.71
Reverse-3.24

And feel free to correct me if I'm wrong here but with the 33's ratios would feel or react as follows.
3.73 = 3.36
410 = 3.72
4.56 = 4.12

The stock tire that I pulled off of truck was a 265/65/16 (29.56")
and now I'm running a 285/70/17 (32.71")
My stock ratio is 3.73 but planning for 4.56, hence the reason for the number running.

 

I do understand what you are saying to and extent but I can't seem to grasp the concept, of should I say I don't understand how the calculator could be correct even though it is.........

Simply put: The 4.56 gears won't actually be 4.56 when installed on my truck with the 33's. So why wouldn't I have to correct it. They have to offset one another.

 

Yeah the tire size was taken into account. Using a scanguage to get actual numbers.
I understand what your saying. I'm just over thinking it. I wasn't realizing just how much the calculator was doing. Which makes the fact that with 33's and the stock 3.73 that the calculator is getting that right. I'm a little slow sometimes and I tend to over think things. Thanks for the patients.

 

I always want the best of both worlds and I tend to try to plan for all situations.
I've had this truck since new and it only has 65k miles, it was my daily driver for 5yrs. Now I have a company truck, and the Tacoma gets driven less but I always plan for that what if, and that's the reason that I have been looking so hard at these numbers. For that what if I don't have that company truck one day.
Hell I was even tossing around the options for incase I don't like the 4.56's, moving up to 35's but that really wouldn't help with anything, considering weight and all.
Either way thanks for the time and input. Now to try and find a local shop that I can trust to install the gears and lockers.

 

Not sure where you got these numbers from.
But....... 4.10 for 33
4.56 for 35s
4.88 for 37s.

 

Stock tire 265/65/16
Stock gear 3.73
New tire size 285/75/17
New gear size xxx

When you go from the old tire to new tire size, you changed by 3.15 inches (Negating tread wear, which of course will change as you drive, but negligible for this purpose) this equates to a change of 10.66% increase. To match the power band you will need to go taller on the gear by as close to 10.66% as you can. (Taking into account that a taller tire has a larger rotating mass, and a higher truck has more wind resistance, however most rotating mass deductions are eliminated once you have actually gotten to speed, and can be dismissed for the most part unless tire mass changes more than 30%) If your stock gears are 3.73, then the new taller gear should be around 3.73 X 1.1066 = 4.1276. So a 4.10 gear ratio would bring you back to as close to stock RPM and power band. Going to a 4.56 WILL increase your power to the wheel, but will also give you an average of a 9% fuel economy hit at highway speeds.

This is confirmed because I had the exact same gear ratio as you (3.73) and although the calculator showed 4.10 gears as the best (4.12 actual) I opted for the 4.56 gears because I off-road a lot, and want the power. I do however suffer on highways. In the city I can get 20.6 MPG average, but on the interstate I drop quickly to 19 if I am gentle with the throttle.

The stock tire size IS actually important. When the engineers designed the engine, transmission, and final drive ratio combinations, they were designed to get the best overall average of fuel economy, and power. Not a perfect match always, but that is the intended design. So when you start playing with gears and tires, you want to try and get back as close to factory as you can, with the RPMs to get the best AVERAGE of fuel economy and power. Too tall of a gear and you get better highway economy, but you lose power. Shorter gears and you get good power, but weak economy. So knowing what his factory tire size is important in matching gears and the new tires, to get him into the best power band for economy AND performance.

 

lol. Oh I know how important it is. Learned from experience with some SS Chevelle's. They're still rolling today without any whining so I seem to have managed. If I'm not mistaken I think East Coast Gear offers a full third member pretty much setup, basically a plug and play so I'll likely go that route.

 

Worded way better than I was capable of getting out there, this is/was my train of thought. But for some strange reason the Calculator is in fact very close to my current setup. But from this way of thinking it should be wrong because the gears with current tires should act like a 3.36 instead of the 3.73. and like you say the 4.56 would actually be 4.12 with the current tires and 4.56 gears.

When playing with the calculator I was correcting the numbers to represent the real world figures when plugging them in. So I was using actual tire size an 3.36 as opposed to 3.73.

My concern is minimal but still there that I have the 4.0 Auto, and most that have done such a swap (atleast that have commented) are running the 2.7 and sticks. But based on what I have looked at I think you are dead on with the numbers and expectations for fuel economy.

 

Those numbers were run through a calculator of sorts while I was offshore away from my truck, sort of like research. However when I got home I drove the truck and posted the actual numbers which is what spawned this new conversation. And you are correct....kind of.
4.10 with 33's will get you back to a stock feeling gear 3.72
and the 4.56 with 33's would do something very similar almost a 3.73, and like wise with the 4.88's. But who said I wanted to be stock? I was actually wanting to be closer to a 4.10 and that would be achieved with the 4.56, giving me a ration of 4.12.

 

Yep. You are right OP. However remember that if you do a lot of highway driving, you WILL see an MPG hit of about 9%, which can add up if you do a lot.

 

I haven't come across that ratio, but it wouldn't be a bad choice.

There is a local Toyota guy opening a shop in the near future so I'll try to throw some money his way to help. He build rock crawlers, well his own but he helps out a lot with other peoples builds.