Project FJ40

Oct. 01, 2005 By Eric Stegall

Project FJ40

Since I bought my 78 FJ40, I have been trying to improve its off-road performance and its on-road comforts.  The more I wheel it, the more I want to improve it.  Not only is this Land Cruiser my trail rig, but sometimes it is my daily driver.  I do not have a tow vehicle for it (yet), so this rig has to be driven to the trail, through the trail, and back from the trail without any problems.  Therefore, the main goal of Project FJ40 ? ROK CRZR is to make it into a bulletproof rock crawler without sacrificing reliability and on-road handling.

The Cruiser I started with:  a nearly stock December 1978 FJ40

Motor Stock 2F, I6, 4.2L
Drivetrain 4 speed transmission (3.55:1 first)
Stock transfer case (1.99:1 low)
Axles Front:   Stock disk brake axle, open 
Rear:    Stock drum brake axle, open 
Gears:  4.11:1
Suspension Front shackle reversal kit (~1.5" lift)
Rear extended shackles
Rims / tires 15x8 White spoke wheels
33x12.50 mud tires
Protection / accessories None

Future Upgrades / Modifications

Below is a list of future upgrades and modifications that I have planned for Project FJ40 - ROK CRZR and the reasoning for them.

Motor Header, exhaust, tune up
2F fuel injection kit or 350 TBI swap
High torque gear reduction starter
Drivetrain SM420 transmission swap (7.05:1 first)
Transfer case swap - Dana 300 or Atlas II
Axles Front:
Custom width Reverse Cut Dana 44
ARB / Detroit Locker, 5.13s
8 lug, alloy axle shafts
Dana 60DH Full Floater, disk brakes
Detroit Locker / Spool, 5.13s
35 spline alloy axle shafts
Suspension Spring over axle conversion
Longer springs / lift springs
Streach the wheelbase a few inches
Rims / tires 38.5x14.5x15 Super Swamper TSL SX
8 lug 15x10 Beadlock rims with 3" back spacing
Protection Full roll cage
Skid plates / Quarter panel protection
Rocker panel protection
Body Soft top, bikini top, half doors
Poly body mounts
Tub liner / carpet kit
Rear fender flares / mud flaps (for street)
Accessories Saginaw power steering conversion
Beefed up tie rod / high clearance steering
Rear bumper with tire carrier and gas can rack
Front winch bumper and Warn 8274 winch
Welder, dual batteries, On-board air system
Auxiliary gas tank, hot water shower
New bucket seats, center console, CB, stereo
Auxiliary lighting, roof rack or roll bar rack

Suspension Upgrades:
After 20 years of use, the stock leaf springs have sagged to the point of being almost flat.  While a flat spring provides excellent articulation, they do not provide much in the way of tire clearance.  My Cruiser currently has an aftermarket shackle reversal kit that has really improved the freeway handling, but is not so good in the rocks.  It hangs down a few inches from the frame and I am constantly banging it into rocks.   More lift will help out some, but not enough.  Another problem with my suspension is the leaf springs mount below the axles which greatly reduces ground clearance.   I plan on doing a spring over conversion which will mount the leaf springs on top of the axles and provides close to 6 inches of lift.  No more springs and u-bolts to get caught on the rocks.   I will also redesign the shackle reversal so it still hangs down from the frame some.  I am also planning on moving the rear axle back a few inches and install some longer leaf springs to add some more flex.  I am not too sure on the exact suspension set up yet, but either way, I will still have to have enough lift to clear much bigger tires.

Wheel and Tire Upgrades:
The easiest way to gain ground clearance is to install larger diameter tires.  When you install bigger lift kits to make room for these bigger tires, you must also think about installing wider tires to make the vehicle more stable.  I plan on replacing my worn out 33x12.50 mud tires with some 38.5x14.5x15 Super Swamper TSL SX tires.  In order to get more sidewall flex out of the stiff SXs and help protect from punctures, I will have to air them down very low.  To help prevent blowing the bead on when aired down I plan on installing some custom 8 lug, 15x10 inch beadlock rims.  These may have to be custom made with the correct backspacing (about 3") so the tires to not rub on the body, suspension, or steering components while 'wheeling. 

Axle Upgrades:
Wider is better!  Since I am planning on running much larger tires and lift, I feel that I need stronger axles and a wider stance.  Probably the weakest link on Toyota Land Cruisers is the Birfield joint in the front axle.  I really don't think it can handle the 38" tall tires.  There are a few stronger aftermarket axle shafts, but you still end up with a CV style joint in the front axle.  Since I want to avoid the Birfield joint all together and swap in wider axles I must look for a non-Toyota axle.  I have decided to swap in a Reverse Cut Dana 44 which will be a custom width.  This axle will have a more ground clearance, the pinion will exit above the centerline of the axle shafts, more drive shaft clearance, and no Birfields!  Reverse cut gears are stonger in the front end than standard cut gears when going forward since they are driving on the drive side of the ring gear and not the coast side.  If I have a problem with breaking front axles or u-joints, I will swap in some alloy axle shafts. 

The rear axle will be a full floating Dana 60 heavy duty model.  Since the Dana 60 rear axle has a centered differential, I will have to change my transfer case to a Dana 300 or an Atlas II which both have a centered output yoke.  The stock Cruiser transfer case has an offset output yoke to line up with the off set rear axle.  The benefits of a full floater axle is the load is carried only by the wheel bearings and not the axle shaft like a semi-floating axle.  If I happen to snap a rear FF axle shaft, I can keep driving without having to worry about the rear wheel fall off!  For the utlimate beef, I want to install some 35 spline, 1.5" alloy axle shafts.  I should never have to worry about breaking one of these.

Getting traction to all 4 wheels is a must when wheeling.  Crossing ruts and climbing rocks with open differentials can be a bit scary at times.  I plan on installing an ARB Locker or Detroit Locker in the front, and a Detroit Locker or a spool in the rear.  I feel the benefits of a manual locker such as the ARB will be a huge advantage with the D44 front axle.  Being able to turn it off will help minimize the breakage of the front axle shafts and u-joints.  It will also help save the steering system by allowing the wheels to turn easier when turned off (ever try to steer a rig with a front locker?).  The Detroit Locker is known for being practically bulletproof.  This is a great choice for rear axle applications.  However, a spool may be a better solution since it has less parts and is always LOCKED.  Some people say that you get more predictable handeling since you know it won't unlock and lock causing the vehicle to sway in certain situations.  I am not too sure on what gear ratios I will run.  This will depend on wich motor, tranny, and t-case I run.  I will most likely run 5.13 gears.

Drive train Upgrades:
In order for a rig to be a good rock crawler, it needs to have super low gears.  The lower the overall gearing (crawl ratio), the more control the driver has while negotiating tough obstacles.   The crawl ratio is calculated by multiplying the tranny's first gear by the transfer case's low range by the axle gears.  The overall crawl ratio in my Land Cruiser is 3.55 x 1.95 x 4.11 = 29:1.  This is way too fast for hard core trails that I want to run.  Installing a granny geared transmission like the SM420 with its 7.05:1 first gear will drastically improve my crawl ratio from 29:1 to 57:1.   To further lower my crawl ratio, I can install one of the earlier Land Cruiser (pre '74) transfer cases with its 2.3:1 low to get a crawl ratio of 67:1.  While 67:1 is a very respectiable crawl ratio, it really doens't cut it when you factor in larger tires and larger bolders.  A better setup would be to to swap in a centered output Dana 300 (2.6:1 low) or Atlas II (4.3:1 low) and that would get me about 75:1 or even 125:1 overall crawl ratio with 4.11s.

Motor Upgrades:
The stock 2F motor already has plenty of torque for rock crawling, but it lacks horsepower for normal street driving.  With the addition of bigger tires, the street performance has lots to be desired.  A smog legal header and better flowing exhaust system will help out somewhat.  However, a 350 TBI swap would be the best solution to improve street performance and it will continue to run in those really off camber situations where carburetors tend to flood.  An added benefit to a V8 swap is that I will gain some rear drive shaft length since I will be able to move the tranny and t-case forward a few inches.  Another cheaper alternative is to add an aftermarket fuel injection kit to the 2F motor.  There are a few kits out there now, but none of them are smog legal in California.  I guess I will just wait and see.  Also, a high torque gear reduction starter will help out when the motor and gears just can't cut it.

Protection Upgrades:
Protecting the Cruiser's vitals is a must no matter how easy the trails are.  You never know when you might slip off a rock and hit your transfer case, transmission, or even land upside down.  A full roll cage is a must if you plan on taking your hard top off.  A transmission and transfer case skid plate is necessary as well as a flat belly pan to help skid over the rocks.  To help protect the body, I plan on installing some sort of rocker panel protection and quarter panel protection.

Body Upgrades:
Since I am going to be running bigger and wider tires, I will have to add rear fender flares to keep those big meats covered.  I really doubt I will find fender flares to cover the wider axles and tires so I will probably have to make some kind of quick disconnect mud flaps to keep it somewhat legal on the street.  I really want to take the hard top off of my Cruiser so I do not damage it too much.  And it is always cool to drive without the top on anyway.  I will have to get a bikini top for the summer months and a soft top for the winter months.  Half doors will also be a great addition for the trail allowing the driver and passenger to get a better look at the terrain. 

My stock rubber body mounts are nearly flat and showing their age with cracks.  It is time to convert over to polyurethane body mounts.  The body mounts help isolate the body from the noises transmitted through the frame.   I also want to add some type of spray or paint on tub liner or maybe a carpet kit to help out with road noise.

A Saginaw power steering conversion is going to be one of the major improvements to my Cruiser.  There are many unnecessary links and tie rod ends in stock steering system that can be eliminated with the Saginaw conversion.   A rear bumper with a beefy swing out tire carrier and gas can holder will be a must since the stock tire carrier was not designed to carry a full size spare (36-38 inches).  It will also have to have some kind of recovery gear mounted to it since the stock bumper does not.  I plan on adding a Warn 8274 winch that will also require a heavy duty front bumper.  Dual batteries will have to be added just in case the alternator can not keep up with the current demands from the winch.

An on-board welder will be a great asset on the trail in the event when something breaks and there are no spares to be found.  I have witnessed quite a few situations where a welder had saved the day.  An on-board air system will also be a great asset on the trail so you can run air tools, re-seat tire beads, dry off wet components, actuate ARB lockers and fill up tires at the end of a trail run.  One not so important trail accessory is the hot water shower.  This will not get you unstuck, but it will sure get you clean after a hard day on the trail.

My gas tank will hold about 16 gallons and at 12 MPG, my freeway range is not so great.  Last year on the Rubicon trail, I had to borrow about 5 gallons of gas just to get out.  An auxiliary fuel tank will greatly improve my freeway range and let me go farther into the outback.  With the addition of two more family members (two yellow Labradors ? Toby and Roxy), more storage area is needed so the four of us can fit.  A roof rack, roll bar rack, center console, and other clever space saving storage goodies will have to be added to make the already limited cargo area a wee bit bigger.  I will probably look into getting one of those M416 ? ton military trailers or just figure out how to carry less gear (yeah right).

And to make getting to the trails a little more comfortable, new bucket seats and stereo system of some kind would be nice.  I will also have to add a means of communication both on and off the trail ? a CB radio.

I am sure I will add many other little things along the way that I have not thought about yet, but I will add them as I think of them.  I hope this project will enlighten others to the way I have modified my Cruiser and the results I achieved every step of the way.

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