A lot of 4x4s and even trail rides have been ruined by improper use of gearing. And I’m not just talking about the smoking-clutch, under-geared ’80s CJs that featured pathetic five-speed, car-like transmissions and ridiculous 2.72:1 axle ratios; over the past decade or so, many people have improperly used aftermarket gears to build 4x4s that are just as (if not more) ridiculous and annoying off-road.?>
It really started sometime in the mid-to-late ’90s. I remember Toyota guys loading up their solid axle trucks with dual (and even triple) transfer cases. It was a nightmare to come up behind a group of Toyota trucks because each driver insisted on idling up the trail in the lowest gear possible without ever touching the throttle pedal. I’d lose my mind when they often didn’t have the courtesy to pull over and let people by.
Now, don’t bother getting up on your soap box claiming I’m some sort of Toyota-hating brand loyalist. I’m not. I’ve owned three Toyota trucks in the past. I’m also the hack that puts a GM Ram Jet 350 V-8 under the hood of a presumably rare 1-of-445 Jeep Panel Wagon. I’m the anti-purist that strips a flatfender clean of pretty much every bolt and only reuses the vintage GPW body, modified frame, and transfer case for a trail rig. And I’m the sadist that puts a Chevy V-8 and a TH400 under the hood of a late-’70s Ford F-150. So don’t even try to claim I’m a Jeep-, GM-, Ford-, or whatever-guy. I simply use what I know works for me on the trail.
Anyway, much like the goofy-suspension RTI ramp-champ trend in the mid-’90s, low gearing became a hot competitive topic of conversation by the end of that same decade. There was (and still is) always some guy trying to prove his 4x4 would idle slower than anyone else’s. And of course at some point he would feel obligated to get out of his rig and walk next to it while it chugged along across a parking lot in stupid-low gear with no driver, not exactly the greatest measuring stick of off-road prowess.
Today I receive letters from readers who get upset when I put the Jeep Rubicon in its place. Sure, it’s the most capable production 4x4 ever offered, but it still has its limitations. In my mind, its biggest downfall is the 4:1 transfer case. Don’t get me wrong, that extra-low gearing is awesome in the rocks or if you need to maneuver through a really technical section of trail. But the truth is that the increased low range is totally overkill and actually a hindrance in most off-road scenarios. And in those same scenarios, the high-range can be too high. We need something in the middle.
In low range a Wrangler Rubicon’s top speed is about 25 mph. This is way too slow to build up proper wheelspeed in the mud and sand. It’s really a bummer if you’ve gotten into a situation where you need to rock the vehicle back and forth from Drive to Reverse and back. In high range you’re kind of stuck toggling from First to Second gear while bouncing off the rev-limiter or lugging the engine, especially in sand dunes and mud. I’ve begged the Jeep guys for a factory three-speed transfer case for a long time. They’ve existed in the aftermarket for many years so it’s possible, it’s just not a cost-effective factory option, so we’ll probably never see it on the Jeep dealer floor.
If I plan to actually drive my trail-friendly 4x4 long distances on-road or commute to and from work in it, I’ll stick with taller gears and make up the difference with a transmission that has a really low First gear. For example, my current V-8-powered fullsize pickup sports 37-inch tires and only 4.10 axle gears. It doesn’t have an Overdrive gear, but the T-18 manual transmission in the truck has a 6.32:1 First gear. I rarely use First on the street, but it’s really handy off-road. The overall crawl ratio of the truck is only about 52:1 but I don’t expect it to be a rock monster. It’s more of a trail truck that hits every possible terrain I can find including deep snow, slick mud, tall sand dunes, mild rocks, or whatever. And it seems to do well in all of it. I’ve never wanted for more or less gear.
I’ve built 4x4s with too much gearing as well. They typically become too specialized and are really only any good in rocky technical terrain. One of my lighter 4x4s had 40-inch tires, a 400hp V-8, a TH400 auto transmission, an Advance Adapters Atlas 3.8:1 T-case, and 5.13:1 axle gears. Like the Wrangler Rubicon it worked great for crawling around, but in the dunes it was a total pig. It didn’t have enough power to hold Second gear in high range and it revved out too quickly in low range. It really would have been a much better all-around 4x4 with a 3:1 or even a 2:1 Atlas, or better yet a three- or four-speed transfer case.
I had a really heavy, underpowered, V-8 truck on 49-inch tires with a T-18 transmission (6.32:1 First gear), a 3.8:1 Atlas, and 6.72 axle gears. The crawl ratio of 161:1 was a bit overkill. I rarely needed First gear. Before I swapped in the Atlas the truck had a transfer case with a 2:1 low range. This gave me a crawl ratio of 85:1, which wasn’t quite enough for some of the situations I put that truck in. On that particular 4x4 I would have been better off with a 3.0:1 Atlas.
I could go on about the different 4x4s I’ve assembled and how my selected gearing did or didn’t work. Ultimately the gearing you choose for your 4x4 should be dictated by the kind of terrain you frequent and not to win some sort of bragging rights competition. The more versatile your gearing package is, the more versatile your 4x4 will be.