Traction question

Discussion in 'Engine & Drivetrain' started by Splorg, Dec 2, 2019.

  1. Splorg

    Splorg Member

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    As you may remember, I purchased my 2001 Yukon (SLT 4WD 5.3L, 260K) in May of this year, and for the first time in many years I've been itching for it to snow. As an additional layer of challenge a few months ago I was transferred by my company to work in a facility about 22 miles from my home in rural central Pennsylvania. Last night on my way back from work, the roads weren't really too bad, but it did snow and ice somewhat, Auto 4WD all the way home, no trouble at all.

    The problem I had came when I tried to back into the parallel parking space in front of my house. I live on a fair hill (about 28° as I recall), and in auto, giving the thing just enough throttle to move at all caused it to lose traction. I switched to 4HI, thinking that having the front pull from the outset may have been helpful, and no dice. Wheels straight, wheels turned, didn't matter. Still spun. I did manage to get it parked more or less, but it was a loud, spinning affair that was less than graceful to say the least.

    Is this my lack of experience driving such a vehicle? Or has anyone else had this sort of issue? Oh, and this one is equipped with the Eaton locking rear end, code G80, 3.83 rear gears (if memory serves) and has a nice set of Hankook DynaPro AT M tires at about 70% tread.

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  2. Scottydoggs

    Scottydoggs Full Access Member

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    was either front wheel spinning? almost seems like it was back wheels only.

    typically you dont want to spin em much, or slowly at most, then you get better traction. spinning at high speed is a 100% no traction.

    then theres crappy tires or the road was iced up under the snow. and ice is gonna make that happen no matter tires or skills.
     
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  3. swathdiver

    swathdiver Full Access Member

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    Check your manual and see if she'll start out in 2nd somehow. In the generation after yours, we can start out in 2nd for more traction. Oh, it's 3.73 gears.
     
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  4. PNW VietVet

    PNW VietVet Full Access Member

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    If you just had snow you could have gotten more traction. You said ice as well. 4 wheel drive or not, it just means 4 wheels spinning on ice on that degree of hill. Plus, if you were nosed down the hill and backing up that hill you had little weight at the rear.
     
    Last edited: Dec 2, 2019
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  5. Fless

    Fless Supporting Member

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    I can't tell if you are saying that the front tires spun when in 4HI. Did they? Or were only the rear tires slipping on the incline?

    Are you certain that the 4x4 is working in Auto mode? When in Auto, can you feel the front diff engage when you accelerate (spin or break the rear tires loose) on slick pavement? It'll take a second or so for the front diff actuator to engage when the speed sensors sense the rear wheels slipping, so there should be a slight delay in getting all four tires to be driven. That should be an apparent increase in traction and reduced slipping on the road.
     
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  6. Fless

    Fless Supporting Member

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    He was in reverse....
     
  7. Splorg

    Splorg Member

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    Just the rear in auto - in 4HI all 4 were spinning. I may not have given it enough of a chance to engage the transfer case in Auto, given it was a short distance and not wanting to increase my own or my neighbor's car insurance policy ;)

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  8. Fless

    Fless Supporting Member

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    Probably just the slick pavement, then. But watch the Auto next time you get into something slick and see if you can feel it kick in when the rears spin a little. The front diff actuator can get lazy or the ground may be dirty (underbody underneath the driver's foot area, behind the LF wheel, two grounds there, one is for part of the 4x4 system). There should be a short delay, 1-2 seconds at most, then power to the front wheels.

    I had a somewhat different problem with mine -- I would select 4hi and the mode light on the switch would show that, but it would actually be in Auto. It never went into full time 4x4, and the only way I found it was with the Tech 2. Ended up being the encoder motor on the transfer case, but your symptoms aren't the same. Your front wheels were powered in 4hi.
     
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  9. Floep

    Floep Member

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    In Canada we carry a container of sand(Ashes if available) Not high tech, but can't argue with success. An ice cream tub full parked in the driveway and another in the vehicle.
     
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  10. SnowDrifter

    SnowDrifter Full Access Member

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    Little tough to tell if it was road, rig, tires, or a mix from the post.

    TBH these rigs to quite well in the snow between the locker in the back, 4wd, and tall first gear. If you're on ice, however, all bets are off. Tough to do anything in there without studded tires no matter what you have. I've driven mine on black ice and hills, and gotten it out of unplowed places that have snow up to the front license plate. But I also have a fair bit of experience driving in the stuff. So YMMV I guess?

    As far as diagnostics to rule out the vehicle side, toss 'er in 4hi, goose the throttle, and either check for front tire spin or have a friend look.
     
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