Ultimate Adventure Tacoma - 4-Wheel and Off-Road

Ah, it's that time again. It seems like just yesterday we were building a giant red, heavy, Chevy Avalanche for last year's Ultimate Adventure trip, and now this year's trip is coming around the bend, and we're hoping to head out with a little less bulk.

We know many of you are wondering what ever became of the Ultimate Avalanche after the story "Avalanche Goes Home" (Dec. 2003). We promise that within the next few months we'll give you a complete rundown of its current state, but for now let us introduce this year's project, Ultimate Taco.

We decided that we wanted to try something smaller this year. Though the 9,000-pound Avalanche made a big impression (pun intended), we decided that a mini-truck would be an interesting direction for 2004, and when it comes to mini-trucks, Toyotas make some of the best (our 1986 Toy Clampy just can't be killed), so we decided on a Toyota Tacoma. Plus, we thought we'd try to keep this year's rig a little more within reach of the average Joe or Jane. We'll still be pushing the envelope, but others have tried almost everything we will do to the rig, and hopefully this will keep us in the truck and not under it with wrenches in hand.

Finally, our biggest goal is to keep the weight down, so much so that Pw and I have been restricted to just a few Coronas and tacos a week and a healthy regimen of sit-ups (I think we can both do about 15 now before we need to rest with a cold one and some chips). With some simple, strong, and lightweight upgrades we should be able to head down the trail for UA and have a really good time wheeling.

This month we address some lower gearing for our 2001 Tacoma, but tune in next month when we tear into the suspension and start building some protection.

We are starting this year with an '01 Tacoma that we got from Toyota after it had served as some sort of press fleet/test vehicle, and we will eventually return the truck to Toyota (if there's anything left after two years of serious modification and wheeling). Test fleet trucks, like rental cars, often seem to get serious abuse by media folks who think they are pro off-road racers, and from the looks of this truck, it's seen more than a few inches of air time by some Ivan Stewart wannabes. After someone's "test," the frame must have flexed so much that the bed hit the cab and left this dent. Lucky for us Toyota puts a pretty serious semi-boxed frame under its rigs, and this abuse didn't leave any damage to the parts we are concerned with.
We are starting this year with an '01 Tacoma that we got from Toyota after it had served a
Amongst Toyota trail-truck owners there is one upgrade that is a near-must for all rockcrawlers, and that is a dual transfer-case setup. What this entails is taking the reduction box part of an early Toyota transfer case and installing it in between the transmission and the current transfer case. This allows for a doubling effect of the low range, and the guy who started this craze in the U.S. is Marlin Czajkowski of Marlin Crawler. We felt it only appropriate to go see him with our new Toyota, so we headed to his Fresno, California, shop to get our slow on.
Amongst Toyota trail-truck owners there is one upgrade that is a near-must for all rockcra
We'll tell you right now that this truck is going to eventually get a solid front axle, and because we planned on that we also had to figure out which transfer case we would use behind the doubler. Czajkowski has kits to run either the older mini-truck passenger-side front-output geardriven case or the stock driver-side front-output chaindriven Tacoma case, and though some of us think geardriven cases are stronger, we decided to stay with the Taco case to facilitate an easier install of the solid axle (no need to mess with the exhaust, plus we can keep the IFS working till we get ready to tear it out). So Czajkowski's tech Rockey Gleson pulled the driveshafts and transfer case to start the rebuild.
We'll tell you right now that this truck is going to eventually get a solid front axle, an

The Marlin Crawler can be installed with a 2.28:1 low range in the reduction box, or upgraded with the 4.70:1 low-range gears that we chose. These gears would then allow for three low-range options from the transfer case alone: 2.57:1 with the rear case in low, 4.70:1 with the front case in low and the rear in high, or 12.079:1 with both the reduction box and the transfer case in low. Here are the gears attached to the MC09 adapter plate that allows the stock transfer case to be attached to the reduction crawler box.
The Marlin Crawler can be installed with a 2.28:1 low range in the reduction box, or upgra
In order for the larger 4.70:1 gears to fit in the reduction box, some clearancing must be done to it first. The crew at Marlin Crawler can do this step for you, or it can be done at home with a die grinder.
In order for the larger 4.70:1 gears to fit in the reduction box, some clearancing must be
Once the gears are set up and the reduction box clearanced, the unit can be reassembled. Eventually this box will have a shifter that will allow for 4.70:1 low range, even in two-wheel drive.
Once the gears are set up and the reduction box clearanced, the unit can be reassembled. E

Here is the final unit ready for install with a T6061-billet, five-speed manual transmission adapter on the front, a reduction box with 4.70 gears next, and an MC09 adapter plate in front of the stock transfer case.
Here is the final unit ready for install with a T6061-billet, five-speed manual transmissi
With the new doubler kit in the truck we now had to make room for a second transfer-case shifter. It turns out that the crawler-box stick came through right where the transfer case used to be, and the transfer case happened to fall right in one of the cup holders. Other than the fact that we can now only have one drink at a time, everything worked out great. We also installed a short shift kit on the Toyota five-speed transmission. This helped give us quicker shifts through the pattern, but requires just slightly more effort.
With the new doubler kit in the truck we now had to make room for a second transfer-case s
Since the doubler moved the transfer case backwards, we also needed to modify the crossmember that supports it. Czajkowski's fabricator Andy Widner built a new crossmember that not only supports the dual-case setup, but will also allow the driveshaft to droop when the solid front axle is installed, in addition to acting as a skidplate.
Since the doubler moved the transfer case backwards, we also needed to modify the crossmem

Finally we headed over to Driveline Specialist to bring back our driveshafts. We had sent them there to get the rear shaft shortened and the front lengthened. Then it was time to simply bolt them back in and we were ready to go really slow.
Finally we headed over to Driveline Specialist to bring back our driveshafts. We had sent
After we had the dual cases installed, we headed to 4Wheeler's Supply in Phoenix to begin measuring for our suspension and axle install. 4Wheeler's has a long history in Phoenix, and was one of the first shops that our own editor Pw worked in when he was growing up. We wanted to come up with a flexible, but controlled, link and coilover-shock suspension for the Tacoma, and the fab shop at 4Wheeler's wasn't worried in the least that they could figure it out.
After we had the dual cases installed, we headed to 4Wheeler's Supply in Phoenix to begin
We had originally planned on a high-pinion front axle, but measuring what was under the engine revealed that a low-pinion might give us more clearance. We wanted to keep the truck as low as possible so the low-pinion would also work better in that respect by allowing the front suspension to compress more before driveshafts started hitting engine parts. We decided on a low-pinion Dana 44 measuring roughly 64 inches from wheel-mounting surface to wheel-mounting surface with the pinion offset about 9 inches from center.
We had originally planned on a high-pinion front axle, but measuring what was under the en

Once again Dynatrac signed up as the official axle of Ultimate Adventure, so we headed down there to see how they would build our pigs this year. Another benefit of using a low-pinion Dana 44 is that the centersections are still available brand new, where there are no new castings of the high-pinion variant, and Dynatrac strives to put brand-new parts in every axle it builds. When we arrived they had machined the 3-inch tubes to step down and fit into the housing. Dynatrac presses the tubes into the centersection and plug-welds them. No butt welding here!
Once again Dynatrac signed up as the official axle of Ultimate Adventure, so we headed dow
The first step was to press the end forgings/ tube forks/C's onto the tubes. Owner Jim McGean was out in the shop helping us, and explained how the camber is set by first pressing on the C's and then tacking them in place at the desired camber of 0 to 1/2 degree positive.
The first step was to press the end forgings/ tube forks/C's onto the tubes. Owner Jim McG
After pressing the tubes into our 44 housing, Rob Brewer checked to make sure everything was straight and true with a long bar that runs through two pucks that sit under the bearing caps. Then the many rosette plug welds were burned in to keep the tubes from ever coming out. We had the knuckle set to 4 degrees of positive caster.
After pressing the tubes into our 44 housing, Rob Brewer checked to make sure everything w

We did it last year, and we liked it, so once again we are running Detroit Lockers front and rear in the Ultimate Adventure truck. We won't have the weight or rear-steer ability that we had last year, so it will be interesting to see if the performance is noticeably different. Also we repeated the gearing choice of 5.13:1, though this year we are going with a Precision Gear set as well as an installation kit from Drivetrain Direct. Detroit Locker and Drivetrain Direct are both sponsors of UA this year as well.
We did it last year, and we liked it, so once again we are running Detroit Lockers front a
The ring gear is first installed on the Detroit Locker and torqued to 85 lb-ft, and then begins the process of setting up the gears until a perfect pattern is achieved. Remember that with any new gearset, careful break-in procedures help assure a long-lasting ring-and-pinion, so be sure to take it easy for the first few hundred miles and stop often to let the differential and gears cool down, and then change the gear oil after about 300 miles.
The ring gear is first installed on the Detroit Locker and torqued to 85 lb-ft, and then b
Our rear axle is the well-known Dynatrac Pro-rock 60. With tires over 36 inches, we would be pushing the limits of the stock rear axle, and the high-pinion Pro-rock should have no problems whatsoever with our lightweight Tacoma. Of course, the Pro-rock will add some weight, but hopefully in the right areas. We had the housing machined and added a differential bridge to give another option for mounting the rear suspension links. Next month we'll show you how these axles will fit under our Ultimate Taco.
Our rear axle is the well-known Dynatrac Pro-rock 60. With tires over 36 inches, we would