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4 x 4 Q u e s t i o n s

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Old Jan 29, 2008 | 05:58 AM
  #1  
idanity's Avatar
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From: seattle WA
Question 4 x 4 Q u e s t i o n s

when i drive in 4x mode, i hear a heavy gear noise when turning at full chalk.

plus, the truck seems to have a lot of resistance (especially at turning), and when i come to a stop, i do not even need to keep the brake pedal depressed b/c the truck will not roll (like it does in 2x).

is this normal ?



i know what a bad cv joint sounds like, and its not clunking.

sounds like the front wheels are not spinning at different speeds (and i dont think its a locked front end).

also, in 2wd, i have to go up a steep hill at my house(with a curve), and i hear one tire spinning sometimes.
but when in 4x, i hear rubber tearing.

when coming home, and down the steep curving hill, my truck will actually stop (1. i go real slow, and 2. the wheels just feel like they're locked).



whats going on?


how can i tell if this is bad, or normal ?
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Old Jan 29, 2008 | 06:10 AM
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If this is on dry pavement, the sound you are hearing is your transfer case going to hell. In a turn, the front and rear tires will travel different distances, so the truck will start to bind on dry pavement.
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Old Jan 29, 2008 | 06:15 AM
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That is not normal. Sounds your diffs are not geared the same. Do you know this truck's history?

Frank
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Old Jan 29, 2008 | 06:15 AM
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From: seattle WA
is that normal ?

it does turn, and run ok, but on full chalk turns, the truck will roll to a stop. (yes, on dry pavement)
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Old Jan 29, 2008 | 06:18 AM
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The noise you hear at full turn may be the steering stops. Put a dab of grease on them. DO NOT drive in 4wd on dry pavement. The transfer case is not designed for that kind of abuse. What you are hearing is normal binding that happens in the front end on dry pavement. You are transmitting all that energy back to your transfer case.
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Old Jan 29, 2008 | 06:20 AM
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Originally Posted by Victor
The noise you hear at full turn may be the steering stops. Put a dab of grease on them. DO NOT drive in 4wd on dry pavement. The transfer case is not designed for that kind of abuse. What you are hearing is normal binding that happens in the front end on dry pavement. You are transmitting all that energy back to your transfer case.
The binding is not in the front end, but between the front and back.
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Old Jan 29, 2008 | 06:33 AM
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If you were geared in different ratio's front and rear you t-case would have exploded by now. Not to sound like an ass, but have you checked the ATF in the P/S pump? A few of your complaints sound from the way you wrote them to be PS related.
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Old Jan 29, 2008 | 06:37 AM
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Whoa, I saw the Seattle Wa and figured you were on wet pavement or snow. You don't need 4wd for wet pavement.

The thing is that while the outer wheels spin faster than the inner when turning, the average speed of the front wheels is higher than the average speed of the rear wheels. So in 4wd, where the two shafts are forced to spin the same speed, there is binding as mentioned in the transfer case.

You should not drive in 4wd on dry pavement. Sure our trucks can take a load of stress on the trail, but that's usually in shorter intermittent durations. On dry pavement for any length of time that continuous load on the t-case will heat it up and that heat will break down the fluid and soften the gears. The result is ends up destroying the t-case.

Frank
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Old Jan 29, 2008 | 07:49 AM
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Originally Posted by elripster
Whoa, I saw the Seattle Wa and figured you were on wet pavement or snow. You don't need 4wd for wet pavement.

The thing is that while the outer wheels spin faster than the inner when turning, the average speed of the front wheels is higher than the average speed of the rear wheels. So in 4wd, where the two shafts are forced to spin the same speed, there is binding as mentioned in the transfer case.

You should not drive in 4wd on dry pavement. Sure our trucks can take a load of stress on the trail, but that's usually in shorter intermittent durations. On dry pavement for any length of time that continuous load on the t-case will heat it up and that heat will break down the fluid and soften the gears. The result is ends up destroying the t-case.

Frank

Dude dont speak. seriously
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Old Jan 29, 2008 | 08:04 AM
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Originally Posted by BAMF_CT2004
Dude dont speak. seriously
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Old Jan 29, 2008 | 08:13 AM
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I think he is trying to imply that "elripster" is a dumbass. I would tend to agree. Heat up the oil and soften the gears.
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Old Jan 29, 2008 | 08:15 AM
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Originally Posted by neoworm0
Heat up the oil and soften the gears.
Yeah, don't know about those statements, but the rest is true.
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Old Jan 29, 2008 | 08:37 AM
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On reading it again, I think he means the oil will break down and reduce it's ability to dissipate heat and reduce friction, thereby possibly allowing heat to build up in the gears and softening them. I think that would take a while though.

Last edited by neoworm0; Jan 29, 2008 at 08:39 AM.
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Old Jan 29, 2008 | 08:39 AM
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Im sure the t-case would explode before the heat got a chance to soften the gears that much.
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Old Jan 29, 2008 | 08:41 AM
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Neo, Rune, things happen when you start to shear the fluid. First it gets thin and stops lubricating. This causes two types of failure. One is adhesive failure which is what one observes when, for example, a cam shaft is pitted. The other is an annealing effect on the case hardening when this metal on metal contact is heating up the material. That softens the material and makes it more prone to the adhesive failure mode as well as more catastrophic failure such as a broken tooth.

Peeps, before you talk smack you might want to at least ask why the person said what they said. I have a masters degree in mechanical engineering and my experience is in the area of automotive machine design and control systems. I'm not trying to steer anyone wrong, I know what I'm talking about. Had I known I was going to be insulted as a result of my post I would have included this explanation with it.

Anyway, all that one really needs to know is that driving for extended periods of time on dry pavement will ruin among other things, the transfer case.

I have spoken... dudes.

Frank
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Old Jan 29, 2008 | 08:43 AM
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The "exploding" is a result of what I just described. Trust, I have seen heat and lack of lubrication up close as far as it's effects on gears and their strength.

Again, it's not important. I was just trying to explain why a truck can wheel hard trails for years in 4lo which puts the drive train under severe stress and then fail in 4hi on the flat street. That is all.

Frank
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Old Jan 29, 2008 | 08:48 AM
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Sorry, didn't mean to talk smack. Should have structured my statement better. You are correct however, i think the pressure build up would be a more immediate issue. In a gear drive case isn't there a lot of binding as a result of the different wheel speeds?

Last edited by neoworm0; Jan 29, 2008 at 08:50 AM.
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Old Jan 29, 2008 | 08:49 AM
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Originally Posted by runethechamp
Yeah, don't know about those statements, but the rest is true.
ARE YOU KIDDING ME?
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Old Jan 29, 2008 | 08:53 AM
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BAMF, why would any of us be kidding you. If you like I can recommend a book, chapter, and page where you can read about this stuff in detail.

Neo, I think I understand what you are saying. The force on the teeth over the area of the teeth does produce a pressure. So in effect I think we are talking about the same thing?

The pressure build up is what is causing the fluid to shear and heat.. and the process goes forth towards eventual failure.

Frank
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Old Jan 29, 2008 | 08:54 AM
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How is the average speed of the front wheels higher than the avg. speed of the rear wheels, though?
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