Doc's 05 Tacoma Build Thread

Dave Bennett

Dave Bennett

Adventurist
Aluminess Pioneer Tool Mount

Next up for the rear bumper:

IMG_0522.jpg


IMG_0525.jpg


Won this at the T4T raffle, I'm pretty stoked.
 
mvbeggs

mvbeggs

Adventurer
Gearing, Why lower than 4.10?

TACODOC said:
Here's how I did with the first tank of gas and the 4.88's:

With the 3.73's I was averaging a dismal 12-13 MPG with the 255's and armor etc.

With the new 4.88's I got 15 MPG on my first tank ;) ....

Before the regear I was averaging about 2,200 RPM's at 70 MPH in 5th gear (AT OD).
With the 4.88's, on the highway at 70 MPH I am averaging about 2,600 RPM's which is not bad and does not sound/feel "buzzy" at all....

I have much more power with these gears and I am VERY happy that I went with the deeper 4.88's vice the 4.56's....
Click to expand...


I'm exploring purchasing a Tacoma to use for my trips where heavy off road use isn't the main focus. Although I love my JKU, and her capabilities in almost every category, I'm just not satisfied with her fuel economy and range. (5.13 gears, 37" tires, 5.7l Hemi, etc, yields an approximate 200 mile range per tank) The main goal of a Tacoma build would be to create a vehicle with a minimum 300 mile range while still maintaing substantial offroad and towing abilities (can't leave the Chaser at home).

While researching the Tacoma, I've been looking at the gearing options available for the Tacoma. I've read where many people go with lower differential gears than I would have thought necessary. I've ran some engine RPM vs speed calculations for the stock configuration and several differential gear ratios with the 255/85R16 tires.

Tacoma Engine RPM vs Gearing Chart.jpg


It appears the 4.10 gearing gets you pretty close to the stock RPM/speed configuration. (I assume this is where we want to be, assuming Toyota is designing the tranny to best utilize the power band of the engine.)

Please share why you choose the 4.88 gearing over the 4.10 or 4.56? (I've read that 4.10's are hard to come by for the Tacoma)

In your opinion, does the Tacoma lack the power in the 2,000- 2,400 RPM range for the added weight and towing requirements?

If you're running 2500 RPM at 70mph, how is your gas mileage on the highway? With the 4.88 gearing, do you highway drive according to the speedometer or drive to keep engine speed at a particular level? For fuel economy, I typically highway drive to keep my engine speed below 2600 RPM. From the table above, the max speed at 2600rpm and 4.88 gearing is 73mph. If you go 4.56 the max speed at 2600 rpm is 78mph, and increases to 87mph with the 4.10's. With some highway speeds set at 80mph, it would seem 80mph is the very minimum you would want to consider.

Sorry about all the questions, just trying to do my homework. I don't want to go down the Tacoma path if I can't significantly improve on the JKU's range.

Thanks.
 
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Dave Bennett

Dave Bennett

Adventurist
mvbeggs said:
Please share why you choose the 4.88 gearing over the 4.10 or 4.56? (I've read that 4.10's are hard to come by for the Tacoma)

In your opinion, does the Tacoma lack the power in the 2,000- 2,400 RPM range for the added weight and towing requirements?

If you're running 2500 RPM at 70mph, how is your gas mileage on the highway? With the 4.88 gearing, do you highway drive according to the speedometer or drive to keep engine speed at a particular level? For fuel economy, I typically highway drive to keep my engine speed below 2600 RPM. From the table above, the max speed at 2600rpm and 4.88 gearing is 73mph. If you go 4.56 the max speed at 2600 rpm is 78mph, and increases to 87mph with the 4.10's. With some highway speeds set at 80mph, it would seem 80mph is the very minimum you would want to consider.
Click to expand...


When I regeared, 4.10's were unobtainium unless you paid $$$ and bought them from Toyota or a junkyard wrecked 2.7 liter Taco. Honestly, I probably could have been fine without regearing but with the added weight and taller tires it was lacking power.

My options at the time were 4.56 or 4.88 - I chose 4.88's because I wanted POWER because I'm heavy, and I wanted that little bit lower crawl ratio in 4LO 1st gear on the trail (it really is noticeable). Had I been choosing solely on fuel economy I would have went with 4.56.

When I'm driving I am fairly heavy footed i.e. I dont really try to drive for RPM or MPG. I drive for fun. Anything over 70 MPH and the 4.0 will drink gas no matter what your gearing IMO (I experienced this with 3.73's). When you add armor and gear MPG will go down and nothing short of weight loss will bring MPG back up to anywhere near stock. I can get 270 out of a tank with the hammer down and with a Scepter can my range is well over 300 miles. I'm happy with that.

The bottom line is 4.88 gearing is a personal preference for me. YMMV.
 
maxama10

maxama10

Welcome to Nevadafornia
mvbeggs said:
While researching the Tacoma, I've been looking at the gearing options available for the Tacoma. I've read where many people go with lower differential gears than I would have thought necessary. I've ran some engine RPM vs speed calculations for the stock configuration and several differential gear ratios with the 255/85R16 tires.
-snip-
Click to expand...

You may want 4.56s with the 33s to get a little lower grunt on the trail, but 4.10s would probably work well. This is probably better achieved with a crawl box if you have the money. In fact I'd say with 33s you really don't NEED to re-gear. I ran with 285s and stock gears for a long time, on the trail lower gears would be awesome and had I kept 33s and not blown money on fitting 35s I might have considered keeping the stock gears and running a crawl box. Then again add a lot of weight and do a lot of driving in the hills and gears would probably be a nice addition.

Here is a bit I posted in this thread some time ago.

The 6 speed has a ratio of .85 in 6th gear.

Using an online calculator I came up with...

@ 75 mph

3.73s:
265/70/16 = 2611 RPM (stock baseline)
285s = 2434 RPM
315s = 2309

4.56s:
265/70/16s = 3192 RPM
285s = 2975 RPM
315s = 2823 RPM

Ideally to get it back to stock RPMs with 35s you'd want about a 4.22 gear ratio, obviously you can really only get 4.10s, 4.56s, and 4.88s and the 4.10s are hard to make work so 4.56s make the most sense. 4.10s would also make a good choice as this would lower your RPMs to about 2538 and probably help improve mileage as the 6th gear could be a bit taller.

The auto's 5th gear at .72 is putting you at 2391 @ 75 mpg with 4.56s or 2520 with 285s.

http://www.ringpinion.com/Calc_RPM.aspx
http://www.snoman.com/HTML/axlecalc_5a.html
http://www.tacomaworld.com/forum/tirecalc.php

5 spd Auto
1st= 3.52
2nd= 2.04
3rd= 1.4
4th= 1.00
5th= 0.72
R= 3.22

6 spd
1st = 4.17
2nd = 2.19
3rd - 1.49
4th = 1.19
5th = 1
6th = .85
r = 3.73

Random tid bit:
T-case 2.57:1
6 spd overall crawl ratio with stock gears = 39.97:1
6 spd with 4.56s = 48.87
auto with stock gears = 33.74
auto with 4.56s = 41.25



75MPH, 6th gear, 4.56s
285s = 2975 RPM
255s = 2954 RPM

vs stock at 75
2611 RPM


4.10s are about the best option for 33s IMO but, they're hard to do.

You'll basically have to translate how this will affect gas mileage but... RPMS correlate with MPG pretty solidly I believe.
Click to expand...
Originally Posted by RelentlessTaco
yes its possible, I'm going to be doing it.... but for the front you need a new carrier for the 4.10's. Either one of the 3.90 FJ cruiser front carriers, or an ARB locker setup for 3.90up gears.
The Toyota 4.10's also wont fit the E-locker 8" rear diff in the TRD Offroad trucks, only the 8.4" rear.
Click to expand...

FWIW I ended up running 35s (3" lift only) and 4.56s from ECGS, I find this to be a pretty decent combination.

Here are a couple links to some installs.

http://www.tacomaworld.com/forum/technical-chat/179500-re-gear-writeup.html
http://www.tacomaworld.com/forum/2n...removal-installation-e-locker-3rd-member.html
 
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