Drive Train Gearing Bible for the Toyota Hilux

Many thanks to Max for digging up all of this technical info for the 2005-2015 Toyota Hilux, we have collated all of the information we can about the Hilux drive train.

First, let's look at the gearing specs from the brochure

Hilux Drive Train Specs Diesel

Petrol

The standard tyre sizes on the Hilux vary about 0.2" between the SR and the SR5 but for all intents and purposes, let's call them 29 inches in diameter.

As you are aware increasing tyre sizes affect gearing and because the Hilux has a 1:1 straight through configuration in the transfer case, this cannot be changed so let's look at the theoretical Diff ratio required so that the drive chain is returned the stock specification. This varies based on the stock diff ratios from the table above.

Diesel Auto (3.727:1 Diff)

Petrol Auto, Petrol Manual, Diesel Manual (3.583:1 Diff)

Now the reason we are quoting a 33.5" size is that this is what you get from the 255/85 R16 that are probably the best tyre size when going larger tyres as it fits in the guard nicely with the right offset. So to return to stock gearing, what can be done to the Diffs? Max has kindly sourced this info which I have collated:

Rear Differential

Front Differential

Where JD's is listed as the vendor, this refers to Just Differentials in the US See http://www.justdifferentials.com

A Note on Diff Carriers

A lot of these diffs are sourced from the Toyota Prado and they have a different diff Carrier for the front diff. So if you go to a ratio lower than 3.727:1 (ie. The number is bigger than this), you will have to purchase new a front diff carriers.

Whats a Diff Carrier?

Bull wrote:

Sometimes called the diff centre. It's the thing that the crown wheel bolts to and the other gears sit inside of. When you choose a full strength traction aid like the ARB Air Locker or a Detroit locker, you replace the factory carrier. If you choose the factory style plate type LSD or a "budget" auto locker you keep the factory carrier.
This is a list of the Prado Diff Carriers available from Toyota:

Prado Diff Carriers

*as at 05/2009

You can avoid this additional expense by installing an ARB front locker at the time you regear and you have saved $360 odd to put towards the front locker.

Just Differentials in the US (see http://www.justdifferentials.com) list some thick cut gear sets that fit into the Hilux standard Diff carrier and would be useful if you already have a Hilux Locker in the front you want to retain

How to Use This Data
well it is pretty simple really. If you want to restore stock gearing to your truck, you check out the tyre size you want to fit and look at the theoretical diff ratio required to restore stock gearing.

Then you select the closest available gear set from those listed and either scour the wreckers to find the parts or buy the parts from Toyota or JD's and quote the part numbers provided. Note that Max has received a quote from Just Differentials at the time of writing and their parts are quite expensive, so by the time you land a set over here, it might be just as cheap to buy the carrier from Toyota unless you already have a Hilux locker which you wish to retain.

So let's say you have a Diesel Auto truck and want to run a 33-inch tyre. from the table, you can see this requires a 4.24:1 diff to be exactly the same as stock gearing. The closest sizes are either 4.1:1 or 4:556 so you have a decision to make which way you go. remember that JD's thick-cut gear that fits the only comes in the 4.556 so in some instances, your decision may be made for you (eg if you already have a front locker installed). You got to decide which is the best way for your intended use.

Here is what Max had to say to me about this choice for his Auto Diesel with a front locker already installed:
Maxx wrote: yes for the Auto Diesel, it is either 4.1 or 4.5 that we should be aiming for...... I'll be fitting Just Diffs 4.5 when I'm ready......
you'll get a better low range on 33's than stock Hilux does, and around town, it'll shift into higher gears a tad earlier and still not rev out too much on the freeway.

This is about 7% over the original factory setup. This difference is pretty much exactly what it would be like driving on 31's with the stock diff a dropping back to the stock 29" rubber. You probably would not notice the difference. I think Max is pretty close to the mark here.
If you have a manual transmission, a 4.1:1 Diff is a perfect match for 33.5" tyres

ARB Air Lockers

Here are the ARB Air Locker Part Numbers see http://www.arb.com.au/resources/pdf/airLockers/application_chart.pdf

Rear

Front

The next part of the drive chain equation is crawler gears and dual transfer case setups and maybe even gearbox substitutions.

Crawler Gears and Dual Transfer Cases(Added 7/08/09)

There is no point rehashing this topic here as it has been very well covered in two other threads. However, briefly, the problem with regearing our transfer case is that Toyota has used a planetary gear set, which is very strong but does not lend itself to being regeared in the way a conventional cogged transfer case can be.

Furthermore, the front driveshaft exits on the left side of the transfer case and the earlier Hilux's had a "Right Hand Drop" transfer case where the output shaft is on the right-hand side. Because of this, we can't simply resort to using an older transfer case.

Inchworm Gear in the US has devised a solution for this called the Lefty which converts the old right-hand dropbox to a left-hand drop and it is more or less a drop-in replacement for our trucks. Once you have a Lefty, you can add a set of Crawler gears made for the old model Hilux.

So here is the good oil I posted rodw wrote: Guys, I finally got my head around the gears etc I talked about on previous threads. Anyway, back to crawlers.

There are two suppliers of Toyota Specific gear:
Marlin Crawlers http://www.marlincrawler.com/
and Inchworm Gear http://www.inchwormgear.com/store/
Of these two suppliers, Inchworm has a superior product from all reports.
The other ones of note are:
Klunehttp://www.klunev.com/ who make a crawl box 
and Atlas which are distributed by Marks Adaptershttp://www.marks4wd.com/products/advance_adapters/atlas_transfer_case.htm These two products are sometimes combined together.

Ignore the Atlas and Klune stuff for now and let's go back to Inchworm (because I read enough bad reports about Marlin not to bother with them in any way, shape or form.

Inchworm has developed the Lefty which is a conversion of the old t/case which can accept crawler gears adapted to have an output shaft location to suit our truck. It should fit without any major modification of cross members etc. Seehttp://www.inchwormgear.com/store/product_info.php?products_id=985

They also have a set of crawler gears fitted to the Lefty so that would change the case low range gearing from our stock 2.556:1 to 4.17.
So what if you don't want to go down that low? Why not? Well, you might live out west where there are no mountains to rock crawl over and want a higher low gear for mud etc.

Well, you can fit another crawl box to the driveline in front of your transfer case. This is essentially the gearing section of the Lefty (or the older Hilux Box) See http://www.inchwormgear.com/store/product_info.php?cPath=21_89_93_110&products_id=71 

This comes with 2.28 gears as standard but can be fitted with the 4.17 crawler gears. You could put this in front of your stock transfer case but you would need drive shaft and mounting mods to make it all work.
Now, this is where I got confused. At the bottom of this page is the link to the thread which I incorrectly previously referred to the shootout. http://www.pirate4x4.com/forum/showthread.php?t=592937

I was initially wrong on this. Inchworm was not bagging Marlin but simply quoting some maths and explaining why a lot of Tacomas blew output shafts when crawl boxes with lower ratios were fitted in front of the stock transfer case (which is the same as the Hilux)
Here is the diagram Jim from Inchworm put up.

Now you got to do the maths with me. Take 100 foot-pounds of torque at the front, multiply it by the gear ratios and you get the numbers on the top line. What he is demonstrating is that the right place to put your crawler gears is in the transfer case itself, not in the crawl box in front of the t/case.

By putting reduction gears at the front, the torque is multiplied enough to shear the output shaft of the stock Tacoma Gearbox regardless of whether you use his crawl box or the inferior Marlin one.

So the idea of putting a crawl box like the Inchworm one or the Klune underdrive will probably result in a busted case output shaft. So no, I won't be fitting a Klune in front of my stock t/case. So what are the options?

You got to do the maths for your truck based on the driveline ratios I have published in the new bible thread I refer to right at the top of this long post. Interesting with the Auto Diesel, the torque ratings are lower because of the different first gear ratio. I think the options become:

1. An Atlas Tcase with 3.8:1 gearing from Marks Adapters
2. An Atlas/Kluane Combo
3. A Lefty with 4.7:1 crawler gears
4. A Lefty with a 2.28:1 Crawl box in front of it
5. A Crawl box with 2.28:1 gear in front of the stock Hilux T/Case
6. A Crawl Box with 4.7 Crawler gears in front of the stock T/case and run the risk of blown output shafts
Now if you have the Auto Diesel like me, you might take the risk on option 6 as I calculated the torque to be about 30% lower than the Tacoma's 1880 because of the different gearbox ratios between the Hilux and the Tacoma. Just go easy on the right foot under pressure.
Personally, I think a good solution would be Option 5 as you could choose to engage one set of low gears or both. Engaging both low gears gives a low-low ratio of 5.83:1.

However, an extreme solution would have to be option 4 which would give you a choice of 1:1, 2.28:1. 4.7:1 and a low-low of 10.72:1 
So anyway guys, I think if you take on board this info and the driveline stuff about diff ratios if your pockets are deep enough, you will be able to build an awesome truck Are you listening to Bull?

I also obtained some quotes from Inchworm which I posted in the same thread and worked out-landed costs (including freight, tariffs and GST)at the going exchange rate.

rodw wrote:Anyway, Back to Crawler Gears. I emailed Inchworm Gear a couple of times and they came back with some prices.

Crawl box 
As far as I understand your talking about a 2007 Hilux with an automatic, 4-speed tranny and looking to add a crawler box in front of the transfer case you've got. In situation, you'll want our Tacoma Double Case Setup (see link below). The good news is that we just lowered the price! http://www.inchwormgear.com/store/product_info.php?cPath=21_89_93_110&products_id=71 .
Crawler box and adapters $1,450 with 23 Spline, Stock Gear Ratio of 2.28:1.
Shipping around $650.

Build Your Own Crawl Box
Crawl Box Parts- (will need a gear-driven transfer case)
Tacoma Transmission Adapter: $399
Tacoma Double Case Adapter: $625 (comes with our double case adapter)
23 Spline Input Shaft: $165
Shipping Estimate via UPS: $520
Shipping Estimate via USPS: $290

Built Lefty
Tacoma Transmission Adapter: $399
Built Lefty: $1,995
Speed Sensor Adapter: $100
Shipping Estimate via UPS: $790
Shipping Estimate via USPS: not an option or... 
build the Lefty yourself- (will need a gear-driven transfer case)
Tacoma Transmission Adapter: $399
Lefty Adapter: $799
4.7 Gearset: $399
Chromoly Output Shaft: $280
Speed Sensor Adapter: $100
Quad Flanges (2): $39each
Shipping Estimate via UPS: $645
Shipping Estimate via USPS: $405

We can get the shipping estimates more accurate if you give me a full address.
Here is a link to our warranty and shipping instructions: http://www.inchwormgear.com/store/shipping.php; please note we only accept international payment via wire transfer.

I have not had time to think about this or add up the prices but thought you'd like to see the costs guys.
And the landed costs:
rodw wrote: So at an exchange rate of 0.7696, and allowing for Customs duties and GST with UPS freight, these prices work out to:

If you go either of the DIY options you will need to also source a gear-driven transfer case from an older model Hilux.
These are based on the Auto transmission, not sure how the manual affects these prices as it needs a different tranny adapter.

In addition to these costs, you would probably end up with a bill from a right forwarding agent who looks after the customs clearance. There is probably not much benefit to be gained from going the DIY option by the time you buy an old t/case and get it built up if you can't do it all yourself.
In this, Max got some pricing on some options as well.

Here is a gearing chart that Rod put together to help all of you understand which diff gear you should be going for in relation to the tyre size. It shows the standard wheel diameter on the top left-hand side of the chart and going down the left-hand side is a list of various larger wheel diameters.

In conjunction with that, across the top going across is a list of available diff ratios for the Hilux. So in the top left hand yellow box, is the standard wheel diameter and diff ratio showing the rev's the engine is doing at 100kph......then you just go down, choose the tyre diameter you are after and find the diff ratio that gives you the required revs that is as close to standard as possible.