Marlin Dual Ultimate Crawler:

Every rock crawling truck needs two things: Lockers and low gears. Well when it comes to low gear Marlin Crawler is the king. Marlin's single and dual transfer cases are world known for slowing Toyota's down to a crawl on the trail and making difficult rock climbs much easier. The stock crawl ratio is 45 to 1 (3.93 first gear, 2.28 tcase, 4.10 R&P), too high for rock crawling. Having a crawl ratio down around 70 to 100 to 1 makes life much easier on the rocks. One way to do this is to change the transfer case gears. My original case
had a 2.28 low range, Marlin offers the lowest gears for the Toyota case 4.7:1. Just changing to these gears would result in a crawl ratio of 75 to 1. Marlin also offers dual transfer case setup that puts two transfer case units back to back. This dual setup provides a crawl ratio of 84 to 1 (3.93 first gear, 2.28 first case, 2.28 second case, 4.10 R&P) The dual case setup is also a bit more flexible in that it allows for shifting into stock 2WD or 4WD low range as well as double low. Crawl ratio is found by multiplying the first gear, transfer case reduction and ring & pinion numbers together.
A further option is known as the dual ultimate crawler. This combines the two above, 4.7 gears in the rear case and stock 2.28 gears in the forward crawler. I will also be running lower ratio ring and pinion gears to adjust for the larger tires. This combination results on an over all crawl ratio of 223 to 1 (3.39 first gear, 2.28 forward case, 4.7 rear case, 5.29 R&P). WIth two transfer cases I have twenty forward gears and 4 different reverse gears. An All Pro crossmember was installed to mount the dual Marlins and to gain additional clearance under the tcase.

Drive shafts:

The stock 70 to 83 Toyota drive shafts are a little under built with smaller CV U joints and smaller flanges. In 1984 Toyota switched to larger 10 mm bolts on all of their drive shafts, all though there are at least four different hole patterns used on various truck over the years. I chose to switch all the flanges on my truck over to the 84 flange pattern. I did this by redrilling new holes in the flanges. Using a U joint end from an 84 drive shaft and a transfer punch I created a new pattern with larger holes offset from the original pattern. The front tcase output flange could not be redrilled and was replaced.
The finished flanges had two sets of holes. Sixteen new drive shaft nuts, bolts and washers were purchased from Toyota for the installation.
I purchased a set of drive shaft from Jesse at High Angle Driveline for the project. Up front I am have a high clearance third member. This moves the front flange up about 4" as compared to a standard 3rd member. I also have a Marlin dual transfer case, this sets the front shaft mounting point about 6.5" back from the stock location. Over all these two factors greatly reduce the need for a front CV in the drive shaft. I opted for a front drive shaft with U joint at both ends and a 10+ slip yoke travel. With a unique hardening process Jesse totally eliminates the looseness commonly found in other long travel shafts. I found the front slip yoke to be just as tight as a fine spline rear drive shaft. This makes for much smother operation offroad. Heavy duty .90 wall tubing and new U joints were used to complete the shaft.
In the rear the I used a a stock slip yoke shaft as there is only about 1.5" of slip travel through the entire rage of flex. This is due to the the rear axle moving forward as it droops, just the opposite of the front shaft. With aproximently 7" of over all lift I new I would have drive shaft vibration problems. When the rear housing spring perches had all ready been rotated allowing the rear third member to point directly at the tcase output.
The drive shaft was ordered with a CV on the tcase end allowing the CV to eliminate the vibration problems. This particular CV joint is a modified IFS front CV unit. Normally the front IFS CV would not e able to drop this far but High Angle Drive line has a special trick. The IFS CV is opened up and modified so that is has the same flex that the 84 - 85 style drive shaft has. The older shafts are getting hard to find in junk yards and expensive to rebuild. This solution allows the still plentiful IFS shafts to solve the problem. The stock .065 tubing was replaced with heavy wall .090 tubing and the slip yoke was move down to the differential end of theshaft.
http://www.highangledriveline.prodigybiz.com

Engine Progress:

The DOA EFI Motor has been mounted up on stock motor mounts. The stock motor mounts will be replaced at a later time with a non rubber type to reduce drivetrain movement under a load and prevent mount failure. The process of wiring up the EFI motor has begun. I started by removing the entire 83 harness from the truck and replacing it with an 87 harness however when I started to work on interfacing the old new truck to the new harness I found none of the connectors would connect to the truck. After much thinking I chose to do a dual harness. One will run the truck's lights, wipers and such, the other will run the EFI computer and engine. It seem, at this point anyway, that the dual harness will be the easiest way to get the truck running. The 87 harness was removed and the original 83 harness was reinstalled. The 87 harness will be modified to remove many of the unused redundant wires and will then be reinstalled. Both doors have been removed to provide easy access as I run back and fourth between the cab and the engine for the next few weeks hooking up the motor and it's wiring.

Power Crossover Steering:

The factory steering setup used a non power steering push pull type box. When factory steering is combine with long travel suspensions the result is lot's of bump steer on road, and broken steering arms off road. Right from the start I had planned to use crossover steering to resolve these problems. The hardest part of doing crossover steering is the installation of the IFS style steering box. While any 86 - 95 Toyota 4wd IFS steering box can be used it's not a simple bolt on item. First I removed the original axle and steering box.
The bracket for the torque rod and stock steering box were then torched off. With crossover steering there is no need for the torque rod. Next two holes were drilled into the frame and a small bracket was welded to the top of the frame. Positioning these was easy using the supplied template with the mounting kit. Tubes were then installed into the frame and welded into place. The outside of the frame rail need to be completely flat where the box mounts. To get a good weld on the frame sleeves they are made a little wider than the frame, this allows space for a good weld on the inside of the frame. Once the welding was done I bolted the IFS box on and tightened down it's three mounting bolts. The original steering shaft connected to the IFS box without any modification. The original steering box was did not have power steering but this new IFS box is equipped for power steering. I was able to find a donor power steering pump and reservoir from an 84 pickup. To mount the pump I enlarged the pump mounting holes a little bit as the engine block on my 87 DOA motor is slightly different. For the reservoir three holes were drilled into the fender to provide a mounting surface. The pump was connected to the box using the 84 hoses.

Front Axle and Suspension:

The front suspension has been completed and the front axle installed. The front Dana 60/ Toyota hybrid housing was build to prevent birfield failures. It's commonly known that the Birfield joint is the primary weak spot on Toyota axle. This hybrid axle uses a Toyota housing with the knuckles removed and replaced with Ford F450 knuckles, axles, and U joints. The axles were shorted and resplined to fit into the Toyota third member.
Wilwood brakes were installed on special rotors. Warn hubs mounted on modified spindles that allow for the use of stock 6 lug Toyota's wheels. The heavy duty tie rod and drag link with rod ends are used to connect the steering to the IFS steering box. The tie rod has been moved up about 2" from stock to help prevent trial damage.

The front 6 leaf spring packs are 1.5" longer than stock and provide 5" of lift. To mount the longer springs a special front spring hanger was used to replace the stock front hangers. This hanger is mounted 1" forward of the front of the frame and also drops the spring mount down one inch and provides additional support to the front frame. The back of the front springs are attached using 1.5" longer greasable shackles in the stock frame tubes. The front hanger and rear shackle combine to lift the front an additional 1" and the axle will be moved 1.75" forward of stock. A U bolt flip kit was used to mount the spring to the axle. This increases clearance under the axle and prevent damage to the U bolts threads and nuts when on the trail.

The stock upper shock mounts were torched off and replaced with shock hoops that will allow 13.5" travel Doetsch shock to be used. The lower shock mounts had to be cut off when the larger Dana 60 knuckles were installed. I used 1" wide steel tabs to create new lower shock mounts. These tabs were welded to the knuckle.

Rear Shocks and Flat Bed Plans:

Last month the rear suspension was installed but the rear shocks were not installed. Normally the rear shocks are attached to one of the rear frame crossmembers, right where I plan to put the spare tire. Most flat bed designs I have seen place the spare tire on top of the bed (take up most of the open space) or above the bed on a rack. Knowing the truck is going to be driven to it's limits I wanted to keep the spare tire (100 lbs) as low as possible and keep the bed open for camping equipment. In order to mount the tire under the bed the two rear frame crossmembers were removed.
To replace the strength of the lost crossmembers the flat bed has built in crossmembers that support the bed as well as provide a mounting point for the shocks and spare tire. The bed is mounts 3.5" above the Toyota's remaining frame. The long travel 8403 Doetsch shocks are mounted so that they lean slightly forward so as to clear the spare tire. Look for more information on the flat bed in up comming update. Bed plans include an aluminum top, roll bar, integrated tool box, lights and mounting for Power Tank & gas can.

Lot's more coming next month!