Warning: Significant math and science content ahead.
Much has been said about the Ford Bronco since its debut, but little coverage has been given to the crawler gear for the seven-speed manual. It’s an ultra-low ratio designed to literally let the Bronco crawl along with prolific on-demand torque for climbing mountains. But a deep dive on the mechanicals from Engineering Explained details why it’s really about speed. And Tesla fans might not be happy with the news. More on that in a bit.
We will leave all the complex calculations to the video, but here’s what you need to know in a nutshell. The crawler gear in the Bronco’s manual transmission has a ratio of 6.588 to 1. That’s an extremely tall gear – first gear is 4.283 to 1 by comparison so as you can imagine, the crawler gear’s speed is very limited. The flip side of that is torque, and in this case, the video focuses on wheel torque as opposed to engine torque. With the transfer case in low range, the crawler gear paired with the Bronco's most aggressive final drive ratio yields a whopping 29,372 pound-feet of wheel torque. In a word, that’s insane.
Or is it? As the video astutely points out, there’s only so much torque that can be effectively used before tires begin to slip. With some additional calculations based on the Bronco’s weight and 33-inch tires, only 5,000 pounds of force can be utilized effectively. With different tires and more mass, more of that torque can be put to the ground but there isn’t a scenario in which all that available force can be wielded, impressive though it might be.
Interesting Ford Bronco Information:
Here’s where the hard truth comes in for Tesla fans, and indeed many EV backers who prefer to preach the benefits of electric wheel torque. Because it can be such a fantastically high number, some brands promote these figures over engine torque in a manner that suggests superior performance. The reality is that such numbers are mostly for show, as wheel torque typically can’t be fully utilized. As a measure of performance, the forthcoming Tesla Roadster boasts 7,400 pound-feet of wheel torque and that's not remotely close to what the Bronco offers in its crawler gear. Does this mean the Bronco will be faster than the Roadster?
Of course not, because wheel torque doesn’t accurately convey overall vehicle performance. In the Bronco’s case, its calculated speed range using the crawler gear with the transfer case in low is just 1 to 7 mph. That’s the real benefit of a crawler gear such as this – exceptional low-speed control. Furthermore, the driver won’t have to slip the clutch to maintain this control, as the Bronco should move along at 1 mph with the clutch engaged and the engine turning a lazy 1,000 revs.
It’s all there in the numbers, and for readers who love the science behind such things, this video offers an exceptional take on the Bronco’s low-speed, off-road prowess.