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Noise while turning in 4 wheel drive?

soslo

Full Member
Joined
Jun 3, 2002
Messages
28
Location
Chico, CA
Hi guys. I am just wondering if it is normal to have a gear whine/rub noise while turning in 4 wheel drive. I don't remember my last 2 truck having this noise...of course, that doesn't mean much - I could have been used to the noises.
 
Noticed that today while driving around gettin to deer stands too. Kinda expected it i guess. I dont think its bad, but maybe someone else can tell me different.
 
soslo said:
Hi guys. I am just wondering if it is normal to have a gear whine/rub noise while turning in 4 wheel drive.
If you are on solid pavement, and the wheels cannot slip easily, and you are in 4HI or 4LO, then yes, it is normal to have some binding and noise while turning in 4WD, but it would be a BAD THING. 4WD should only be used when the wheels can slip, such as snow, ice, mud, and sand. Never use 4HI or 4LO when the wheels cannot slip some. Using those modes on pavement that is not covered with snow/ice can cause damage to your drivetrain!

Auto 4WD mode is safe to use on pavement with variable conditions. In this mode, the front axles are engaged to the front differential, but the transfer case is not engaged until slippage is detected. In this case, there will be a little more gear noise, since the front differential and drive shaft will be turning. You should NOT experience binding in this case.

For more information, check out some of these threads:I think you will find a lot more discussion if you go looking for it.

-- SS
 
SS,
I aggree with you 100%. Never ever on pavement unless snow covered or ice. I didn't think Soslo was discribing binding and in my experience there is always some whine in Four wheel drive. Am I wrong on this? I guess it's possible that all 4 of my 4x4's have had problems. Doesn't yours whine?
 
Guys - thanks for the great info. I turn on 4hi (dry pavement) just because it hadn't been run yet (shame shame, I know), and I thought it should be run periodically for lube reasons...but I could be totally wrong. This is my first new 4x4, so I care a little bit more about the sounds and whatnot.
 
Setemflush said:
SS,
I aggree with you 100%. Never ever on pavement unless snow covered or ice. I didn't think Soslo was discribing binding and in my experience there is always some whine in Four wheel drive. Am I wrong on this? I guess it's possible that all 4 of my 4x4's have had problems. Doesn't yours whine?
True, it is hard to tell what road/driving conditions he is facing based on his limited description. That is why I figured it was safer to cover all of the bases.

As for the whine, yes, I do hear some additional noise, as I stated above:

ShapeShifter said:
In this case, there will be a little more gear noise, since the front differential and drive shaft will be turning.
While my "gear noise" comment was in reference to Auto 4WD, the same applies to all 4WD modes.

I guess the point I was trying to make, and didn't communicate very effectively, is that more things turning means more noise, which is normal. There are also distinct clunk or thunk noises as modes are changed. But there should be no binding, and no grinding, squealing, crunching, or other scary noises. These would either be indicative of a mechanical problem, or incorrect/inappropriate use of the 4x4 system.

-- SS
 
soslo said:
Guys - thanks for the great info. I turn on 4hi (dry pavement) just because it hadn't been run yet (shame shame, I know), and I thought it should be run periodically for lube reasons...but I could be totally wrong. This is my first new 4x4, so I care a little bit more about the sounds and whatnot.
It is a good idea to engage 4x4 occasionaly (every few months?) to distribute the lubrication. If you can't find a grassy/sandy/slippery area to do it, then do it only on a perfectly straight stretch of road, keep your speed down (below 50?) and don't do it for more than a mile or so. Whatever you do, don't take any signficant turns on dry roads with 4HI or 4LO engaged.

-- SS
 
soslo, in your first post, you mention that you did not notice these noises in your previous trucks. Did they have the same type of 4x4 system? Our trucks, as with most (all?) GM trucks, are part-time 4x4 systems. They are not all wheel drive nor full time 4x4 systems. Those full time all wheel drive systems will have a differential or clutch between the front and rear drive shafts that will let them rotate at different speeds during a turn so that things don't bind up. If you had this type of system, then you wouldn't have these problems.

But if you had a system in your previous trucks that is similar to the current part time system, and you took turns on dry pavement while 4x4 was engaged, and didn't get unusual nostes, then you probably just got lucky.

-- SS
 
ShapeShifter,

One question, what is the difference of AWD vs. Full-time 4x4 systems. Aren't these the same thing?

Just curious...

~bekind
 
bekind said:
One question, what is the difference of AWD vs. Full-time 4x4 systems. Aren't these the same thing?
They are very similar. The difference is vague and open for debate. Here is one person's take on the difference: 4x4 ABC. If you click through some links, there is also some explanation of the differences between these systems (like you might find on a Subaru) and our part time system that is typical of full size trucks.

Here is another description: All-Wheel-Drive Versys Four-Wheel Drive. It lists the Avalanche has having Full Time 4WD. I take exception to this and do not agree. Their contention is that the "Auto 4WD" mode is a full time 4WD mode that you can leave engaged all of the time. I don't think so. While it is safe to leave it on where the roads are varaible and switch between dry and slippery, I would not leave it on year round and in all conditions. Leaving it constantly engaged will increase wear on the front end, and decrease mileage somewhat. I think (and the user's manual states) that Auto should only be used where encountering slippery patches in the road is likely.

Here is another take on it: Advance Auto Parts

I did a google search on "full part time 4WD AWD" and came up with a LOT of hits, only the first few are listed here.

As you can see, there is a lot of disagreement on terms and capabilities. My recommendation to anyone with an Av: read and follow the user's manual, and check out this thread: http://www.chevyavalanchefanclub.com/cafcna/index.php?board=18;action=display;threadid=8503 and especially this post within that thread. That will give you information based on our specific trucks, not vague generalities.

-- SS
 
Wow, I was just going to ask the same question about the noise. I took my Av into the mud last night and as I went from the pavement to the mud and out I heard the scrappng noise too. I turn on 4HI just before turning into the mud and turned it off after fully getting on the pavement. I thought my dif. fluid was low. Thanks for the info on this. I'll have to check if ithe noise goes away when I'm in the mud. ;)
 
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