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#100454 - 18/10/04 08:36 AM
4HI vs 4LO
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Anonymous
Unregistered
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Post up your experiences/reccommendations for when you use which under certain circumstances. I originally thought this would make a good poll but but I don't guess regular board members are aloud to post polls.
Reguarding the topic:
I personally haven't used 4LO yet. I've only used 4HI and the X did just fine. There have been a couple times I think it may have benefited from using 4LO but I never tried.
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#100455 - 18/10/04 08:45 AM
Re: 4HI vs 4LO
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Anonymous
Unregistered
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Use 4 Hi, when on a gravel or dirt road, and need a little extra traction. Or on a snow-covered paved road, if necessary.
Use 4 Low, when offroading, stuck, need a lot more torque at very low speeds. You don't want to offroad in 4 hi, 'cause there's not enough torque, and it causes unnecessary abuse on the transmission.
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#100456 - 18/10/04 08:50 AM
Re: 4HI vs 4LO
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Member
Registered: 17/08/00
Posts: 13694
Loc: Baltimore, MD
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Yup, when 'wheeling I'm almost always in 4Lo, and most of that time I have my automatic in "1" as well unless we're moving along at more than a jogging pace. Better engine braking, less time hopping back and forth between the brake and gas in general.
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#100457 - 18/10/04 08:51 AM
Re: 4HI vs 4LO
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Anonymous
Unregistered
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When in 4LO, is all of the power transfered to all 4 wheels evenly?
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#100458 - 18/10/04 10:58 AM
Re: 4HI vs 4LO
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Anonymous
Unregistered
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As long as all 4 are on the ground. Pick one up (usually the rear end) and the opposite one, as in other side other axle.. will spin also.. example, you put your front right tire on a big rock, and the front left falls in a hole, the trucks weight will be (mostly) on the front right, and rear left. a little on the front left (the front end is slightly heavier then the rear) and the right rear will be in the air. the tire hanging in midair will spin, and the front left (in this example) will also, as it has a few hundred lbs of weight, trying to pull a 5000 lb truck. I got board one day on a jobsite, crossed a ditch lifting my rear left 18" off the bottom of the ditch. after getting out I could almost pull the truck down and rock back & forth, which tells me there was 2 to 3 hundred lbs on the front right. I was able to drive out sence the front was pointed downhill. With my new calmini bumper on the front, it is way heavier, i doubt i could rock it even with 1 other persons help. If I were going up hill, i would have needed to be yanked out by the guy i was doing the survey with. The (almost) open diffs are useless when you unload a tire. A rear locker would have kept the truck moving (or dug a hole) reguardless of how many tires are on the ground. If you are in a position that you need to turn, or hit somthing are lift a tire, either winch out, or you need 2 lockers. just the rear and you (should) move, you may not have much steering with one front unloaded, and the other not pulling.
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#100459 - 18/10/04 11:02 AM
Re: 4HI vs 4LO
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Member
Registered: 23/03/01
Posts: 1906
Loc: San Jose, CA
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Well, to put it simply, yes, that is, that's the easy answer. But more accurately, in 4WD (HI or LO) engine power is equally distributed to the front and rear driveshafts. If all 4 tires have equal traction then engine power is evenly distributed. With open differentials in the front and rear, engine power is sent to the wheel with the least traction. In other words, if you have one front tire in the air and one rear tire in the air, you're not going anywhere. (And now we move on to the "limited slip differential" discusson.)
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#100460 - 18/10/04 11:11 AM
Re: 4HI vs 4LO
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Member
Registered: 17/08/00
Posts: 13694
Loc: Baltimore, MD
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4Lo gives you no traction advantage over 4Hi, just more power to the tires and a slower pace.
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#100461 - 18/10/04 03:45 PM
Re: 4HI vs 4LO
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Anonymous
Unregistered
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Things are starting to make more sense now. Thanks guys for clearing a lot of this up. I've offroaded a few times in and everytime it's just been a sloppy, muddy trail that deep ruts I got stuck once or twice but had a friend pull me out. I was always in 4Hi and I now know to keep it in 4Lo but I guess I'll expect no real traction advantage over 4Hi.
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#100462 - 18/10/04 09:01 PM
Re: 4HI vs 4LO
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Anonymous
Unregistered
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If you are spinning tires in the mud, you want it in 4hi. This will tend to spin them faster, keeping them clean. Just keep in mind the faster they spin, the more stuff that is going to break if they ever get traction.
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#100465 - 20/10/04 05:23 PM
Re: 4HI vs 4LO
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Anonymous
Unregistered
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Originally posted by BlueXBlue: you get a lot more horsepower in 4-hi. No you don't.
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#100466 - 20/10/04 08:27 PM
Re: 4HI vs 4LO
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Anonymous
Unregistered
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Punk.. you went & didn't invite me!!!! Last time I went to Pismo, i think i left it in 2wd most of the time (untill i got stuck).. better rostertails...
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#100467 - 20/10/04 09:46 PM
Re: 4HI vs 4LO
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Anonymous
Unregistered
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I have noticed that people with automatics tend to put it in 4lo a lot sooner/more often than those with manual transmissions.
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#100468 - 21/10/04 11:27 AM
Re: 4HI vs 4LO
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Anonymous
Unregistered
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That's cause we don't want to risk overheating/damaging the torque converter / transmission.
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#100469 - 21/10/04 12:42 PM
Re: 4HI vs 4LO
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Member
Registered: 29/05/01
Posts: 270
Loc: Sunnyvale, CA
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QUOTE]Punk.. you went & didn't invite me!!!! Last time I went to Pismo, i think i left it in 2wd most of the time (untill i got stuck).. better rostertails...[/QB][/QUOTE] Naw, I didn't go and not invite you. I haven't been wheeling all year. I was referring back to 2001 when I went with the dealer plates still on it and mashed my bumper into a dune. (That's why I have an ARB bumper now) I'm tentatively planning an in-Xterra-camping/wheeling trip for Nov. 6-7, probably in the hills above Sacramento with a couple of buddies who live there. Although it's possible we could go to Pismo. If you want - I'll keep you posted.
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-Bob
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#100470 - 23/10/04 11:54 PM
Re: 4HI vs 4LO
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Member
Registered: 09/04/03
Posts: 780
Loc: 100 Mile House, BC
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Originally posted by pnwbeers: Originally posted by BlueXBlue: [b]you get a lot more horsepower in 4-hi. No you don't.[/b]Yes you do. Any time you go through an extra set of gears you get unecessary friction (which I believe is what happens inside the transfer case in 4Lo). And two gears of different ratio will also create more friction than two gears of equal ratio. This is why they geared the MarkVIII to run top speed in 3rd (direct drive) on the salt flats. The 3rd in its transmission goes through no gear, and therefore less hp turned to friction.
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#100472 - 24/10/04 11:07 AM
Re: 4HI vs 4LO
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Member
Registered: 18/03/02
Posts: 622
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The engine has a finite amount of power to produce. You can increase or decrease torque but you cannot increase power from gearing. The delicate balance between torque and RPM dictates dictates exactly how that power is applied. At the wheel you either get high torque and low RPM, low-torque and high RPM, or somewhere in between.
What you are experiencing at the beach is that you need wheelspeed to move around and that 4HI is giving that to you.
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#100473 - 24/10/04 01:21 PM
Re: 4HI vs 4LO
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Member
Registered: 09/04/03
Posts: 780
Loc: 100 Mile House, BC
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In theory, yes, your output hp is constant regardless of your gearing system. HP is a function of torque and rpm. At constant hp, a decrease in rpm is followed by an increase in torque, linearly. This is the way a physicist would analyze it. But because this is real life and not theory, we need to analyze it from an engineer point of view. You'll have parasitic drag in a real system. And the more gears you go through the more drag you have, and therefore more hp converted to hp. Theoretically, you should dyno the same hp numbers in any gear, but you don't. You get the least hp from reverse because it goes through an extra set of gears. You also get more drag with two gears of different ratio (therefore radius and contact points, assuming constant pitch) than you do with two equal radius gears. Assuming that you do not need to go through a set of gears in high range : Then high range would have less parasitic drag loss than low gear. Extreme offroaders who uses a second gear reduction system to further lower the output ratio will experience an even greater power loss. Same goes for geared poral axel systems. In theory hp is constant no matter how you gear a system. But in reality gears cost power.
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#100474 - 24/10/04 02:29 PM
Re: 4HI vs 4LO
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Member
Registered: 18/03/02
Posts: 622
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RJ,
No one is arguing against you. We understand parasitic drag. The fewer moving parts, the better. Same reason why front-wheel-drives typically have lower drivetrain losses than rear-drives.
Due to the radical difference in gearing between high and low and the fact that we are talking about only one extra gear-reduction, a person will not be able to "tell" how much power is going to the wheels and what the exact losses are. It is in the range of just a few percent. The driving characteristics are changed so much in low-range that, especially in sand, it makes the truck feel extremely sluggish. This goes back to the post from above:
quote: -------------------------------------------------------------------------------- Originally posted by BlueXBlue: you get a lot more horsepower in 4-hi. --------------------------------------------------------------------------------
My truck feels like a dog in low range, but maybe that is because when I floor it in 1st running my Calmini gears I can barely reach 1 mph...
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#100475 - 24/10/04 06:45 PM
Re: 4HI vs 4LO
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Member
Registered: 17/08/00
Posts: 13694
Loc: Baltimore, MD
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You don't go through "more" gears in low range, you just go through different pair.
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