Bang when turning too sharply in 4WD

[Erik Jenkinson]

I believe I inadvertently did something stupid. Once in a while, I will put my m1009 in 4WD, and take it around the block just to keep the juices flowing. I intended to three point turn at the end of my street. I then turned very sharply to the left, and entered a really sharp turning radius. Shortly thereafter I heard quite a bang. Im guessing the turning radius on the drivers side wheels was so much smaller than the passenger side, that something had to give. My question is, what? I couldn't see or feel any obvious damage afterword, but I do think it would be smart to take a closer look. What might that bang have been? Transfer case? Where should I inspect for damage?

 

[ralph3162]

Check axle and axle u-joint

 

[shotty]

You should never use 4WD on pavement unless theres dirt/snow/or something else slick on top. When you turn the wheel on the inside of the turn rotates less than the wheel on the outside, and the wheels on the front will rotate differently than the wheels on the back. Eventually something will give. There's a chance you didn't break anything, it was just that binding unloading. I've heard that the rear locker can do this on pavement in 2wd and is normal.

I would put it up on jackstands, put the transmission in neutral, the transfercase in 4wd, and start spinning tires to see if anything is broken.

 

[True Knight]

Another vote for u-joints here. That's probably the best place to look first. Just jack up the front end and make sure the hubs are unlocked and you can easily check their condition. As long as someone didn't install a locker in the front axle it shouldn't break anything driving on pavement, however it does put more unneeded stress on all the front drive components. Most front diffs are open type, with a few in the M1028s being limited slip. Bad u-joints seem to enjoy making loud scary parts breaking type sounds. Ha ha. Hopefully that's where the problem is and not inside the diff housing.

I had what I originally thought was a steering issue- the steering would not return to center after a turn. Upon checking the front end I found the front u-joints were pretty much seized up solid. There were no grease fittings on the original u-joints and they were bone dry with rusty dust inside. Quick and easy fix with new grease able u-joints and problem solved.

 

[Skinny]

If you bound it up hard and your truck has some mileage on it, you may have experienced the NP208 chain skipping.

 

[armytruck63]

You should never use 4WD on pavement unless theres dirt/snow/or something else slick on top. When you turn the wheel on the inside of the turn rotates less than the wheel on the outside, and the wheels on the front will rotate differently than the wheels on the back. Eventually something will give. There's a chance you didn't break anything, it was just that binding unloading. I've heard that the rear locker can do this on pavement in 2wd and is normal.

I would put it up on jackstands, put the transmission in neutral, the transfercase in 4wd, and start spinning tires to see if anything is broken.

Excellent explanation of what happens during a turn. This is why full-time 4WD systems have either a differential or viscous coupling in the transfer case.

 

[True Knight]

Quoted from West Coast Differentials:

"Open Differentials

An open differential allows both tires to spin at different speeds. This is perfect on dry pavement when the vehicle corners and the axles turn at different speeds, but it doesn’t work very well when one or both tires lose traction. In this situation, the tire with no traction spins, and the tire with traction does nothing."

The M1009 came with an open differential. If a locker was installed some time later the differential would need to unlock before the turn, or else the tires would have to slip or some mechanical part would break.

Now there's still a chance that something broke. Parts wear out and weaken so check the easiest parts first, such as hubs and u-joints.

Here's a good video of how the open style of diff that's installed in the M1009 works.

http://youtu.be/gIGvhvOhLHU

Let us know what you find Erik!

 

[phil2968]

The M1009 does indeed have a locker. A Eaton Governed locker. A loud bang could be from a axle gear missing teeth. Ask me how I know!
https://youtu.be/tTGZOJQQBeE

 

[True Knight]

The M1009 does indeed have a locker. A Eaton Governed locker. A loud bang could be from a axle gear missing teeth. Ask me how I know!

True, but that's only in the rear. To me the post sounded like he was referring to the front axle, although he didn't specify.