This post has eight parts. Click below to navigate:
Part One
Part Two
Part Three
Part Four
Part Five<- You are here
Part Six
Part Seven
Part Eight
9. Gearing, Diffs, and Lockers
- Stock Setup and Thoughts There Upon
My truck was bought as a fulltime 4wd, with Manual Transmission (MT), and with the ATRAC and rear differential locker options. It was an early version model, and consequently the ATRAC and rear diff locker were setup to be mutually incompatible. Were I to do it again, I would probably buy a base model without the ATRAC and rear diff and would instead do the ATRAC button hack and install a rear ARB air locker. The ARB air locker is reputedly slightly more graceful in failure, while the ATRAC hack works as well as cost but more much less money. That said, for the kind of wheeling I want to do, ATRAC and a rear locking diff are essential. ATRAC is a wonderful system that can get you through very many tricky situations, and the rear diff lock just adds even greater “umph”.
- Manual or Automatic Transmission?
When I came to buy the FJC I had almost no experience offroading. My prejudice was that “surely no serious wheeler would want an automatic, right? That’s just for ease of driving the kids to school and the mall, right?” Well, I’m now not so sure. When the going gets really tough on the trail, the stock MT has a real weakness: it will stall bigtime. There’s a minimal speed that corresponds to the minimum tick-over revs in 1st gear, low box, and if you need to go slower than that, you’re SOL.
Mild rock crawling I would stall all the time. The only way not to stall is through clutch usage or very fancy brake-and-throttle usage. While the latter is possible, there is only a certain number of simultaneous processes that can run on my brain, and I’m usually tied up at these moments watching my spotter and route planning. So it seems to me now that there may be some major advantages to Automatic Transmission (AT). It’s still a lot of fun to use the MT in most circumstances, and I found a great solution to my stalling problem (see the crawler box / 4sp transfer case section, below). I’m not sure I would actually pull the trigger on an AT (I like my current solution), but it’s just something to think about.
- The ATRAC / Rear Diff Hack
I’m not sure why Toyota ever blocked the ATRAC and rear diff from working at the same time (they’d fixed it by the time the first TRD’s came out), but very quickly
people figured out the circumventing electronics hack, and I had it done. No problems.
- Front Diff Locker
I had an ARB front air locker installed to gain extra traction on rocks. It definitely helps even compared to the ATRAC, but I’m not sure it is necessary (in the sense that I can glide up stuff that ATRAC-only vehicles kind of struggle with a bit, but we both end up getting up the same slopes – it kind of almost makes wheeling too easy). The locker is engaged by compressed air that is piped in from my QuickAir3 compressor (
in this video you can hear the locker kicking in between 1 and 3 seconds into the clip - ignore the inane babble). Both the compressor and locker are controlled from the main dash panel inside the cabin. As I said, the grip with the locker on is awesome, but you have to be really careful to release the lock as soon as you don’t need it. The tension in the steering from disabling the front differential is extremely noticeable. I try very hard not to turn at all when using the front locker. My only problem with the front locker is really a problem with the compressor: under the hood it gets so hot that sometimes the thermal switch doesn’t want to allow the compressor to come one. In that case you have no locker.
- Differential Regearing
The front and rear differentials were regearded to 4.56. This was done in anticipation of putting 35” tires on the truck. I’m now pretty convinced that the truck can’t really accommodate such big tires, so maybe the regear was unnecessary. My 33” and 33.5” tires are still 2-3” larger than stock, so it doesn’t hurt any.
- Inchworm Lefty and Crawler Box / 4 Speed Transfer Case
Problems with stalling and with torque when rock crawling led me to want to get better lower range options for the truck. The Inchworm solution for the FJC had recently been pioneered by Jim and Sol, and I was sold on the idea that this would work well for my truck. My stock tcase was replaced by a gear-driven dual transfer case. This case is essentially two reduction boxes placed in serial after the transmission and before the drive chain is split between the front and rear drive shafts (I guess this latter part is actually the “true” transfer case in the sense that what we usually refer to as the tcase is actually the reduction box and center differential (for the MT) or the reduction box and transfer case (for the AT)). The new configuration means that I have two “hi/low” sticks and one “4wd/2wd” stick in addition to my main gear stick.
IMAGE-> The sticks for the Inchworm setup include two reduction box controllers and one 2wd/4wd stick (far right). The custom boot is from Redline Goods.
IMAGE-> The Inchworm lefty and crawler are the blue units at the centre of the photo.
The serial reduction boxes mean that I now have a four speed transfer case. I can have both cases in 1:1 (net = 1:1), I can have one box in 2.28:1 and other other in 1:1 (net = 2.28:1), I can have one box 5.7:1 and the other in 1:1 (net=5.7:1), or I can have one in 2.28:1 and the other in 5.7:1 (net=13:1). This means that all else being equal, my low, low 1st gear yields a forward speed about 5.5 times slower than the stock tcase. In this ratio, the gearing is such that it is effectively impossible to stall the vehicle: you can put your foot on the brake and the truck will literally push through the brake and not stall. Over boulders, the truck now effortlessly and very slowly oozes along. Spotting becomes very easy as one has so much time as the truck very slowly inches along. Kinda like an inchworm. Huh! Good name for a company, eh?
- Crawl Ratio and Components
The crawl ratio is the end-to-end ratio between the rate at which the drive shaft leaving the engine is spinning to the rate at which the wheels are spinning. A higher crawl ratio thus implies a slower forward speed for the same engine revs. By gearing down like this, the vehicle is able to apply much torque at the wheels. The gear components in the system are the transmission gears, the reduction box (tcase) gears, and the differential gears.
Crawl ratio = diff * tcase * gears
For the stock MT truck, the component ratios are:
Axle diffs - 3.909:1
transfer case - 2.566:1
Gears:
1 4.171:1
2 2.19:1
3 1.488:1
4 1.193:1
5 1:1
6 0.799:1 (i.e., it's "overdrive")
So for 1st gear in the low mode, the Crawl Ratio, CR=41.837:1
With the inchworm and the diff regearing (the transmission is the same as stock), my system now has:
Axle diffs – 4.56:1
Tcase (1) – 2.28:1
Tcase (2) – 5.7:1
So for 1st, low, low, my CR=247:1 – so that’s A LOT slower and A LOT more torque than stock.
Check out this video to see how slow.
10. Recovery Gear and Storage Thereof
- HiLift Jack
My jack is a
HiLift 60" red jack. I have a wide base for it, a tool to allow it to lift wheels, a
WabFab rail adaptor, and the HiLift manual winch kit. The jack is mounted on the rear roof rack (see roof rack section, at page top).
IMAGE-> Labeled picture of roof-mounted recovery gear.
- PullPal
For situations where one is stuck somewhere that there is no rock or big tree to winch from, one of the recommended options is burying a big tree branch or tire and winching from that. However, the
PullPal "land anchor" is a much easier option to use. This metal anchor digs into the ground when pulled, being more firmly embedded when applied load is increased. Once secured, the anchor makes a great spot from which to winch.
Air2air had (has?) a cool roof rack mount for this. I just have the canvas bag that it came in and throw it in the back. Although I have
BedNet cargo nets in the back to hold stuff down, there's a lot of mass in the back now - at some point, I need to get a cargo barrier...
IMAGE-> Oh, yeyah, there's junk in ma' trunk...
- Spare Parts and Tools (including X-Jack)
I have spares for the front CV axle and for the steering. These are all just stock replacement parts that I ordered from
"Champion Toyota World". I have a standard toolbox and I have a
ARB X-jack exhaust jack for repair. One issue with the X-jack is that (at least with my custom exhaust tip), it is hard to get sufficient seal on the exhaust to actually lift the vehicle. I'm going to try to play with this to get it to work (only tried it once in the field "in anger"). There isn't a Haynes manual out for the FJC yet (last I checked), but I have the most recent Taco version (which is similar-y).
IMAGE-> Labeled contents of the FJC back end on a recent trip.
IMAGE-> Trying to use the X-jack after a blow-out on the Mojave Road. Getting seal on the exhaust was tricky and we ultimately reverted to the HiLift.
http://i210.photobucket.com/albums/b...h/IMG_1516.jpg
- First Aid Kit
For first aid, I got scared when my friend got a nasty leg gouge while wheeling with me. After that, I ended up ordering this nice
first aid / first responders kit. I also carry a
Scepter 20L water can...
- Jerry Cans
The FJC has no good place to put jerry cans for fuel or water. The stock roof rack is particularly bad. I ended up being inspired by
Air2air's "lay'em flat on the back of the roof rack" approach (see Roof Rack section, above). Leakage is the big issue here. I read a lot about the pro's and con's of metal vs. plastic cans, but ended up going down the route of "if NATO now uses them, it's probably good enough for me." Plus, a lot of reviews from users were very positive on non-leaking. This is a gamble, which I acknowledge and therefore I don't warrantee that "these cans don't leak" only that "they haven't leaked on me yet." I have two
20L Scepter military gasoline fuel cans - but typically I take one fuel can and one water can in the two roof slots that I have. The
jerry can spout works great with the wide-mouth tanks. I got my water and fuel cans from
D and B Safety.
IMAGE-> Fuel and water tanks from Sceptor
- Max Axe and Shovel
Along with a shovel bought from Home Depot, I also carry a
Max Ax multi-tool axe up on the rear of the roof rack. I've not yet used the axe or the shovel, but it's nice to know they're there
- Sand Ladders
While in the "nice to know it's there" category, I have done a moderate amount of driving in sandy conditions. That, combined with reading
4x4 books that were biased towards British readers getting setup for trips to North Africa, I ended up deciding I should have some
sand ladders. These are way too cumbersome to take on mainly rock crawling trips, but for longer trips - and when likely / possibly sandy - they go with me.
IMAGE-> Roof rack clamps to mount the sand ladders "land rover style."
IMAGE-> Sand ladders loaded up, close up.
The sand ladders are supported in three places by bolts. On their lower edge, stick foam tape stops scratching on the roof. This setup held up really well on surface streets and at relatively high speeds on the freeway. No noise (above that emitted by everything else I have on the truck). Still, I wouldn't rock crawl with these suckers on, if I had the option.
IMAGE-> My FJC with both sand ladders on, Land Rover style.
- Warn Winch and Accessories
As a part of the front bumper install, I got a Warn winch installed - as such, this was part of my first mod. I've used the winch several times, so far. In fact, it's the only recovery equipment that I've actually used at all - although on at least one of these occasions, I should probably have used the HiLift instead. I have the basic wired remote and the Warn
medium duty winch accessory kit.
IMAGE-> The afterglow of a bad line choice: using the winch.
IMAGE-> Using the winch for recovery of a second vehicle.
I finally got a hold of a Warn shackle for the tow hitch. This allows direct pulling along the centre-of-mass line of the vehicle. It's like a fifth option for pulling the truck from the rear. Can't have too many options, right?
IMAGE-> Warn tow hitch shackle mount.
- Fire Extinguisher
Finally, in case of the worst, I have a fire extinguisher mounted in the back. The extinguisher is a
HalGuard 2.5Lbs HG250R. This is a "safe" extinguisher in that it uses an agent that won't corrode or short-out electronics. I'm not sure exactly what the agent is, though
In any case, the unit is mounted near the rear door using QuickFist clamps bolted to the interior wall above the left wheel well.
IMAGE-> Fire extinguisher mounted in rear cargo area.
This post has eight parts. Click below to navigate:
Part One
Part Two
Part Three
Part Four
Part Five<- You are here
Part Six
Part Seven
Part Eight
