4 Low & Rear Diff Questions (Full Version)

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4 Low & Rear Diff Questions

  

dmb7280 -> 4 Low & Rear Diff Questions (6/18/2007 9:27:11 PM)

sorry to start yet another thread, but i'm a little concerned.  i used my 4 low for the first time during an outing this past weekend.  when i had it in 2nd or 3rd gear (auto tranny), i notice there's a really hard shift between 1st and 2nd (a lot of rpms in 1st, then a hard kick into 2nd).  after washing the mud off tonight, i gave it another go for a few feet on the payment and the same thing happen.  is this normal?  dont get me wrong 1st gear worked like a charm crawling up and down hills on sunday, but when i'd accelerate the kick into 2nd would shake me.  any help is appreciated as usual.

also, i've got this dang adventure pkg.  can someone tell when i should be using the locking diff?  is it mainly for climbing, mudding, or sand?  the owner's manual says not to engage it when you get stuck or when the wheels are spinning, so is it best to just leave it on when im in 4 low?

thanks in advance!

Lil D

ps - sorry for the rudimentary questions, but i feel more comfortable asking you all than the dealer.

  
alrock -> RE: 4 Low & Rear Diff Questions (6/18/2007 10:07:33 PM)

Red Raider,

I cheated a bit and grabbed info from about.com for you (below). I'm not an expert at off-roading but I can give you a bit of my experience first, before the about.com stuff.

1) 4L is only for low speed, grinding over the hard stuff or going up/down steep hills. I've never used it above 2nd gear. If I can go faster than I need to go in 2nd gear then I'm sure I can switch out of 4L.
2) For my area, desert, I rarely use 4H locked. I'm either on trails in regular 4H or in 4L. I switch out of 4L as soon as I can.
3) As long as I don't think I'm going to get stuck, hurt myself or the H3, I like to leave it in regular 4H as long as I can. My Jeep buddy leaves it in 2WD as long as he can just to see how far he can go before putting it into 4WD.
4) I like turning off the traction control in the sand so the wheels can spin and I can fly around. It turns off automatically for 4L but turns back on again as soon as you go back to 4H (if it was on before).
5) Can't help you with the locking diff-I don't have Adv. package. (Told you my info was limited!)


Tips & Advice For Using High-Range vs Low-Range The gearing options found in 4WD vehicles help a vehicle tackle many of the unique situations encountered while driving off-road. Following are a variety of conditions in which you would want to use 4WD to avoid sliding or spinning:

Hi Range 4WD
4H allows you to drive full speed, if necessary. The high range ratios in 4WD mode are the same as the gear ratios in 2WD.

When to use 4H: (my note: this would refer more to 4H locked for us. If regular 4H is working, why switch out of it?)
  • for traction when the area isn't steep
  • when stuck in sand
  • extremely slippery conditions
  • snow
  • ice
  • rocky, gravel roads
  • gullies
  • extremely muddy areas
  • ridges
Low Range 4WD
4L is for creeping along at slow speeds. It reduces the strain on your vehicle, just remember to stay below 25mph in low range. While it does not provide more traction, it does provide 2-3 times more torque at about 1/2 or 1/3 of the speeds in high range.

Low range gear ratios are approximately half that of high range.

When to use 4L:
  • on wet, slippery surfaces
  • passing through sandy areas
  • on rough trails
  • through shallow water
  • rock-climbing
  • climbing steep hills
  • through mud
  • descending steep hills
Additional Tips:
-Don't change gears in the middle of a water crossing, going up or down hills, or in sand dunes.

-Be prepared: Engage low-range 4WD before you need it.

-Don't operate 4WD on hard dry surfaces.

-When in doubt, use a lower gear!

http://4wheeldrive.about.com/cs/offroadingtips/a/aa021203a_3.htm


dmb7280 -> RE: 4 Low & Rear Diff Questions (6/19/2007 7:52:37 AM)

thanks al!  that's some good info...including your tips.  i guess its just going to boil down to me getting more experience under my belt.  im sure that'll make all the difference.  btw, any clue on my hard shifting b/w 1st and 2nd gear question while in 4 low?  i just want to make sure that i dont have any problems w/ my tranny or transfer case.

thanks again!

Lil D

Dennis -> RE: 4 Low & Rear Diff Questions (6/19/2007 8:29:38 AM)

Great Info Al..I'm gonna put this in the FAQ section above...

Desert Dan -> RE: 4 Low & Rear Diff Questions (6/19/2007 10:05:59 AM)

Pull the shifter in to 1st gear and it won't shift up.  In low range 4:1 and with the automatic, the shifts are hard becasue of the torque in low. Go easy on the gas when in low
 
The rear locker locks the rear diff together some both rear tires turn together.
 
I usually put the locker on before I need it.
 
Don't engage the locker while spinning the wheels or turning a corner.
 
Drive it w/o using the locker and when you get hung up or stop moving get out and look to see what is going on.  Look to see if a wheel is off the ground or if you are on a rock etc.
 
Also learn where the low hanging parts (diff, shock mount etc) are.  This is good to do at home in the driveway rather than on your back in the snow or mud.

dmb7280 -> RE: 4 Low & Rear Diff Questions (6/20/2007 12:40:12 PM)

thanks dan!  that totally makes sense.  i figure for any higher speed off-roading keep in 4-hi or 4-hi lock.  i know i just need more experience.  i just wanted to make sure 1) nothing was wrong and 2) that im using the functions when appropriate so i dont f*ck anything up [;)]

i appreciate the help!

dave

dmb7280 -> RE: 4 Low & Rear Diff Questions (6/28/2007 5:29:20 PM)

dd, spent the past couple of days (a few more than i intented...long story) in el paso, tx.  all desert, but various types of terrain (i.e. dunes, montains, hills, etc).  followed your advice and used my rear locker very strategically.  i think you would've been proud.  definitely got a better feel for that and the 4lo.  climbed a few hills, one in particular where the rear locker made it laughible.  also found out that 4 hi lock with a running start is better when taking on dunes than 4lo (at least for me).  i've got some pics that i'll share in the H3 forum.  anyways, thanks again for the advice!

lil d

pgreene -> 4 HIGH (7/11/2007 8:18:00 AM)

Hello to anyone reading, I am an American in France with my 2006 H3 LUX, I bought it at the Local Hummer Garage, They know nothing about service. My H3 decided to go into 4wheel  High (locked mode) yesterday evening all by itself and no matter what I do it won't release. I've tried releasing when the car is both parked and in neutral, but nothing. I hear a click from what I believe is the actuator trying to disengage/engage the system but it still remains locked in 4 high. Before the Garage comes to pick it up for repair, can anyone give me an idea as to what the problem(s) might be. Any help would be greatly appreciated.

Dennis -> RE: 4 HIGH (7/12/2007 4:45:12 PM)

Sounds like the "Transfer Case Control Motor"..A Simple fix and a common probelm with the 06 MY.

  

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