Project traction

[TundraBay]

Originally Posted by Jowett Engineering

This swap is now 99% (I say 99% because I'm still curious what will happen when significant wheel spin happens up front) To reiterate, the truck is AWD when the dial switch is set to the 2WD position, 4WD on the dial locks the center diff, and 4 Lo is still 4 Lo.

The physical changes made to incorporate this case into the Tundra include swapping the rear output flange, swapping some parts from the Tundra transfer case 2WD - 4WD actuator into the Land Cruiser AWD - CDL actuator.... and last are some simple mods to the front differential disconnect actuator that allows it to function while keeping the fork that locks the coupling sleeve to remain in the locked position. No wires or ecu's need to be bothered with.

Exactly one custom part is required, that is a small spacer that holds the front diff actuator shift fork in the locked position on the shaft which it normally slides on. Over the weekend I will snap some pictures and write up some basic instructions on the mods required.

The truck is an absolute blast now... the street manners are much improved in normal driving with the front end pulling a bit. Recomended....

Is it safe to assume by AWD that in a slip situation, you maintain an electronic limited slip (via braking) in the rear, and there's an open diff in the front?

I've been stuck in soft sand before: in 4LO each wheel spins approximately 1/2 turn, then the brake stops that wheel from spinning and so the next wheel takes over. Surprisingly, this was a very effective mechanism and I slowly walked the truck forward despite the very low grip situation.

[Jowett Engineering]

A very good question! I'll go cross the vehicle up on an obstacle and see what happens.

[Jowett Engineering]

Here's the first part, beta version, don't take this as gosepl yet, rather as a general swap guide...I'll refine it as needed. I'll note right away here that these pictures show the Tundra 2wd/4wd t-case with and the Land Cruiser 200 series upper actuator piece (neither are used for the swap) The actuator has minor differences internally that look a little different from the Tundra upper actuator piece, they do not effect the swapping and clocking of the unit.

The following can be done out of the truck, on the bench.

Here's the actuator, remove the 5 screws on the top section and remove the cover... do the same with the actuator on the Land Cruiser case. You will placing the top cover/gear/section of the Tundra actuator into the Land Cruiser actuator case.


Cover removed, the gear will probably stay behind. Pull it out


Inside of top cover


Remove the gear and reinstall it in the cover, note the position of the mircro switch to the gear (red pointer).


To make sure the actuator gear is parked in the proper position, you can check the resistance through the terminals with a meter.

3 (4WD) - 7 (GND) 100 kΩ or higher

4 (TL1) - 7 (GND) Below 1 Ω

5 (TL3) - 7 (GND) 100 kΩ or higher

Terminals in below picture run 1 - 7 left to right. Below checking terminal 4 (red) and terminal 7 (yellow). The cover dosn't need to be installed to perform this...


Additionally, you can take the upper section of the cover with gear and plug it into the wire harness on the truck. Have a buddy turn the key on and the ECU will move it to the proper park position.

Before the cover goes on the shift rod needs to be clocked, too. 22mm (just under 7/8") from the inner edge of the case to the rod will park it in the unlock position.


Now carefully reistall the Tundra cover into the Land Cruiser case, being careful to keep the gear in the upper section so it seats properly w/o jumping position.

The front diff ADD mod is next, I'll add that asap.

Please feel free to use your criticisms constructively to make these instructions better!

[Jowett Engineering]

I'll have the second part of the write up within the next week.

New England has been receiving some significant rains in recent days, so one of the major benefits of the system has really shown itself, wet weather traction. The truck stays planted when you want... come through a wet corner and put the hammer down, the torque split comes in fast and precise and then this big boy thinks it is in the WRC (World Rally Championship). It hangs the tail out smooth, extremely well controlled.. I was surprised it had the power to do it being stock. The supercharger is going to be interesting.

[tinik]

Now I am wondering if I could do something similar to my 03 Tundra? (May be get parts of GX470?) what do you think?

[ChitownTundra]

I would think that a v8 4 runner transfer case would work for you on that one!

[Jowett Engineering]

There is very likely a compatable transfer case for the gen 1.... the GX470/4-Runners (same chassis) would be a good place to look. Don't tell my brother in law... he'll want me to swap one into his!

Start comparing parts diagrams at ToyoDIY.com

[thumbster]

Originally Posted by Jowett Engineering

Start comparing parts diagrams at ToyoDIY.com

Cool link!

[Jowett Engineering]

Yes, great link... maybe sticky it? Very useful...

[Bradscc]

It's probably premature to ask this but I'm gonna anyway...I'm sure this mod affects MPG's downward...it would be nice to eventually know how much worse it gets...

I'll look back in the thread to see if this is a Torsen-type of AWD, I think thats what you described, but maybe I'm wrong here...this looks like a great mod, depending on the $$...thanks for the write-up & pics! Brad

[tinik]

I just looked at my sequoia, and looks like almost identical transfer case (and I can use 4wd option full time if needed, even on pavement)

So I think I going to do this mod, now I have to gather more parts.

[CACressida]

I thought the Sequoias drive train was similar to my 2002 4Runner's drivetrain. I can shift into AWD or lock the center diff.

[TundraBay]

Brian, I have a question about the way this works. If you're in AWD (switch in 2WD) and one of your front tires slips, does the power get reduced, does the brake on that wheel get applied, or does it just slip because it's an open differential on the front? Then when you switch to 4X4, (which I understand from your description locks the transfer case, and makes it operate just like 4HI already does with the stock) you get some degree of limited slip via the electronic application of brakes front and rear?
If that's the case, you get the following benefits when in AWD, namely, some application of torque to the front wheels but no binding because the front-to-rear is not locked, nor is the left-to-right on the front. If this question makes sense to you, do you know or have the answer?
Another thing I wonder is the VSC: it is disabled when in 4HI at least in my 2007 truck, I understand the newer models retain VSC when you switch to 4X4 -- have you heard or do you know of any way of reformatting the older truck's computer to gain that benefit, or are there mechanical differences to contend with as well. . . can anyone answer that question?

[cliff clavin]

Originally Posted by TundraBay

Another thing I wonder is the VSC: it is disabled when in 4HI at least in my 2007 truck, I understand the newer models retain VSC when you switch to 4X4 -- have you heard or do you know of any way of reformatting the older truck's computer to gain that benefit, or are there mechanical differences to contend with as well. . . can anyone answer that question?

x2, anyone have this answer?

[Jowett Engineering]

As far as I can tell the front axle receives no traction control. I ran one of the front wheels up against a large stump and tried to drive up and over it. That wheel just sat there, no power flowing to it. The other front wheel spun some, but didn't have nearly as much torque being applied as the two rear tires, both started to dig holes as the brakes moved the power back and forth between the rear wheels, then the power reduction. The neat thing about the AWD t-case is the T3 Torsen Center Differential with rear axle bias (up to 30/70)... if the front end is overpowered (wheel spin) it will send more of the power to the back wheels, which can cope with it better as they do have traction control.

No idea on changing the 07 to the 08 VSC... bound to be someone on here that does.