4L Question

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McGilli

McGilli

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I'm hopefully just giving the newbie the background physics of some of the things involved
Just wanted to let you know I actually read your post -thanks for taking the time!





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Aframedweller

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Oh and Based on the great and lively comments here in this thread - I was also able to test - repeatedly LOL - this hill I could not get up today - and trying it with pedal down, spinning away and climbing... But then also - just start from zero with barely any gas, letting traction do its thing...

It was enlightening. In the end... I think I need snow tires with big knobs on them :CWL: for just a little extra traction maybe... I don't know.. I'm sure that's another topic haha!
I was with a group a couple summers back in the Sierra and there was a large snow drift in the middle of the trail. The leader with an old Dodge 4x4 truck made it over the drift just fine. There were about 3 Wranglers after, a couple very heavily modified with lockers, that could not make it over after several attempts. They got strapped by the guy in front and pulled over. Next was me in just a slightly lifted ZJ and made it over no problem. Next a guy in a newer gen 4 Runner made it over no problem. After that, we had a bunch of stuck Wranglers again. I suspect it may be a wheelbase issue. I credit my success to visualizing driving over a large Tahoe driveway berm after the plow dumps a huge load right in front. I've had to do that several times before late at night and you only get one chance to pull it off, or else you're shoveling bulletproof cement snow for an hour. That and very steady momentum with just a pop of acceleration at the right time.
 
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jeepoch

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Just wanted to let you know I actually read your post -thanks for taking the time!
You are most welcome. My pleasure. Sorry I can get carried away sometimes. Enjoy learning this stuff in whatever way you feel best.

Have fun no matter where your travels take you.

Jay
 

RubiSc0tt

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As others have mentioned already: my own rule of thumb is 4Low, (3rd gear in manual trans), and gradual application of the throttle. Keep in mind excess speed and momentum doesn't just equal broken parts, it can also equal a split second loss of control with disastrous results. Key is to keep the wheels moving forward, not digging. The second you lose forward momentum and start to dig, you should ease off the throttle and reassess.
 

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Of course one cannot argue with the science, the laws of physics, and safe driving.

However, one guy has seemed to overcome many of those hurdles.
In the words of Jeremy Clarkson. "More Powerrrrr and Speeeeeed." :D

Speed and Power.jpg


Those words work for Jeremy, but he has a whole support crew behind him.
 

DavidArmen

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I disagree with the theory of more raw power. The art of off-roading independent of any obstacle is traction. With even a small amount, momentum can be maintained. Without it, your momentum will decrease independent of the drag resistance encountered, including hills.

Certainly with an increasing slope, this increases resistance in the form of gravitational drag. Without either sufficient inertia or motive force in the form of traction, your momentum will decay to zero, or worse, loss of control.

The art of managing momentum is to keep motive traction (period). Spinning wheels, while sounding either cool or scary is your worst enemy!

I have only open diffs (owning a Sport S), thus only having the maximum of only two working wheels, one on each axle. Still I've made many difficult obstacles, including some hills by focusing primarily on not spinning anything. Modulating power with an emphasis of using the grip of the tires, rather than shear acceleration, sometimes even using my parking break to slow the angular momentum of just one axle actually improves tractive grip.

This phenomena is actually the exact nature of limited slip differentials. The internal axle clutching creates differing amount of breaking force between the two wheels with an emphasis on decreasing slip between the two. Hence it's name.

The secret is to never spin the wheels under any circumstance. Of course this is easier said than done. Especially when gravity is working harder due to an increased slope.

Next time combine your inertia with careful application of your throttle, with a lighter foot perhaps, and look for the sweet spot and just focus on maintaining momentum, rather than just increasing power in getting to the top. I think you'll be rather surprised at your success rate.

Outside of drag racing, pure acceleration and unbridled torque is not the off-roader's friend. In fact, it's his worst enemy. Remember, it's never about raw power, but rather just enough torque to maintain motive traction. This always means a lighter rather than heavier touch on the accelerator pedal.

Jay
This scientific take on off-reading physics and technique was entirely very enjoyable to read.
 

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