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JK and wet roads

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Old 01-16-2007 | 03:15 PM
  #11  
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Originally Posted by Dean
mwilkie is right, avoid using 4WD on wet or dry pavement.

When you turn the wheels, the inner and outer wheels spin at the same rate. Since the outer wheels should spin faster to compensate for covering more ground (but they don't in the TJ and JK), you end up with this grinding of the inner rubber on the asphalt. I don't know what the exact risk is of this, but I've been told my a few mechanics that it's ill-advised.
This only happens if you're using the lockers. You still have differentials as long as you're not locked.

-E
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Old 01-16-2007 | 03:29 PM
  #12  
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I lifted this from a website on the ABCs of 4 wheel drive..... it's not about the tires rotaing it's about the front and rear axles turning at the same speed.
So, with part time 4WD engaged your front wheels are forced by good traction on the ground to rotate faster than the rear - but since the front drive shaft delivers only the same rpm as to the rear there is a fight between front wheels and rational force coming from the front drive shaft. The front drive shaft in effect tries to slow down the front wheels. This results in very wide turns (understeer) and dangerous handling on pavement.
When traveling with part time 4WD on high traction surfaces like asphalt, concrete, etc. handling of the vehicle will become unsafe (understeer) and the "driveline binding" will eventually cause component failures. Part time 4WD should not be used on high traction surfaces! Even when going straight most of the time, slight differences in tire pressure front to rear or vehicle load resulting in different axle speeds will cause "wind up" and eventually damage.

Hope that helps!

Marc
2dr Black Sahara
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doc5339 (12-18-2020)
Old 01-16-2007 | 04:52 PM
  #13  
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Originally Posted by mwilkie
I lifted this from a website on the ABCs of 4 wheel drive..... it's not about the tires rotaing it's about the front and rear axles turning at the same speed.
So, with part time 4WD engaged your front wheels are forced by good traction on the ground to rotate faster than the rear - but since the front drive shaft delivers only the same rpm as to the rear there is a fight between front wheels and rational force coming from the front drive shaft. The front drive shaft in effect tries to slow down the front wheels. This results in very wide turns (understeer) and dangerous handling on pavement.
When traveling with part time 4WD on high traction surfaces like asphalt, concrete, etc. handling of the vehicle will become unsafe (understeer) and the "driveline binding" will eventually cause component failures. Part time 4WD should not be used on high traction surfaces! Even when going straight most of the time, slight differences in tire pressure front to rear or vehicle load resulting in different axle speeds will cause "wind up" and eventually damage.

Hope that helps!

Marc
2dr Black Sahara
, now let me give you a scenario and based on what you just quoted, what should I do:
I work 20 miles away all back roads and last year we had these storms that made some of the roads become covered with snow enough to slide around if you had rear wheel drive. Now, let's say this year it happens again ( which BTW it hasn't snowed a single time), what do I do?...drive in rear wheel until the snow looks deep enough to switch to 4 wheel?....and lets say I see that the roads are plowed , I go back to 2W and back and forth thru out my commute?...trust me, one of the reasons I got the Rubi is for those occcasions now lets talk caked up snow packed by cars driven over it so that now I have these icy bumps all the way to work, my TL has great traction and the 6 spd made all the difference as i down shifted instead of using the brake, now it seems I have one more thing to do if I decide to drive the JK to work that day, kind of doesn't make much sense to me but....maybe I bought a vehicle on my wife's impulse instead of something like the FJ, which I believe has a different set up, correct me if I'm wrong but when I asked the sales guy at the Toyota dealer he said the one wheel in the front and one in the back had the power and when you engaged it to 4 wheel drive a third wheel was powered up ...maybe I'm wrong but anyway that's my dillema now, I'm glad I asked ......
Old 01-16-2007 | 05:00 PM
  #14  
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Hek, if your driving on dry or just wet paved roads you should not need 4wd. If the roads are slick from ice, slush, snow, or some other slick hazard I don't believe it will hurt to leave it in 4wd hi all the way to work. If the roads go from slick and frozen to dirt dry, probably not likely, then you may consider switching back to 2wd.
Old 01-16-2007 | 05:42 PM
  #15  
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When I am up at Lake Tahoe I leave it in 4wd when the road has snow on it or slushy icy. However, as soon as I see black top, I take it out. Even when it is out of 4wd the Jeep has no problems getting through it all. This is a part time 4wd system.... it was one reason I loved the GC and had 3 of them, but I could not resist the new wrangler and put up with the hasle of taking it in and out of 4wd.

Marc
2dr Black Sahara
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SprkEng56 (12-23-2020)
Old 01-16-2007 | 05:59 PM
  #16  
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Originally Posted by mwilkie
I would also not use the 4 wheel drive on roads, even in the rain. The system on the Wranglers is not like the "all wheels drive" systems in other autos. It relies on the wheels slipping in order to not have diffs binding. Read the manual, it states when the 4 wheel drive system should and should not be used......

Just my 2 cents..

Marc
2dr Black Sahara
This is why I am hoping to see SelecTac on a JK someday.
Old 01-17-2007 | 02:01 AM
  #17  
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Today we are having a boring meeting at work, therefore I'll take the owner's manual and study this subject, thanks for sharing your knowledge with this 1st time Jeep owner, and most likely the questions will continue as the years go by....thanks HEK
Old 01-17-2007 | 03:05 AM
  #18  
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I usually drop it into 4hi if the road surface is covered with snow or ice. Just because I like to see how the rig performs in the conditions. I never put it in on wet roads. We've had snow here in Seattle for the last week and when I run around on town (lots of hills) I drop it in but take it out if the roads turn wet. I drive a lot in eastern Washinfton where we have lots of snow and regularly see speeds of 50-60 mph on hard pack in 4hi driving our old cj. It's easier on the transfer case if there's a very small amount of slippage(snow, ice, gravel, dirt) while engaged in 4wd. I've never had a failure or binding of the drive train while sticking to those rules in 30 years of 4 wheeling-which doesn't make me an expert. Best advice: Slow down and get to how know your vehicle reacts to differing driving conditions.
Old 01-17-2007 | 03:25 AM
  #19  
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Originally Posted by HEK
"boring meeting at work"

Do they make interesting ones? :confused:
Old 01-17-2007 | 03:36 AM
  #20  
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When it's raining pretty hard out, I do reach down & throw in to 4H, It's not FullTime 4 Wheel Drive so I'm still going to use this on slick Wet Road's as well as severe Mud, Snow, & Ice Condition's. If I see the roads are getting much better I'll reach down & pop it back to 2 Wheel. No Problem, at all. If it breaks it's going back to the Dealer.
Introduced along with the Jeep Cherokee (XJ) in 1984, Command-Trac was standard on XJ models built with 4WD. This system offers a basic "shift-on-the-fly" transfer case, for manual ease and assist while engaging. Although Command-Trac does include 4x4 capabilities, it can only be driven under temporary usage; due to the axels locking and all four wheels rotating in unison giving out extra traction, therefore it cannot be driven on dry pavement under most circumstances. 4-wheel modes are most commonly used for wet/slick surfaces or extreme weather conditions (rain, snow, etc.) (4H), towing (N), and off-road activities (4L). Even though Command-Trac was created over 20 years ago, it is still readily available in Jeep vehicles (except Grand Cherokee and Jeep Commander) even now.


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