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Loud Bang In 4lo
darren509
post Nov 19 2017, 03:43 PM
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While in my drive way with the trans in neutral i pressed the 4 lo button and it goes in to low but with a loud bang. Shifts into 4hi nice and quietly but bangs hard everytime in 4lo. Could this be just a bad u joint or something in my transfer case.
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Gary P
post Nov 20 2017, 05:34 AM
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I think it's pretty normal, depending on how LOUD the bang is. I mean, I can hear it on mine, and feel the bump too. I wish it were 'silent', but every 4WD truck I've had has done this, so I think you're OK. thumbsup.png


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hdwrench99
post Nov 21 2017, 07:30 AM
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I agree with Gary. Mine has very noticeable clunk when going into 4LO. It's hard to determine sounds over the internet, but more than likely, you're fine.


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darren509
post Nov 24 2017, 03:12 PM
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Thanks guys. Ill replace the u joints and see if it wuiets doen or not
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Andrew
post Nov 25 2017, 12:03 AM
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It is not very likely that a u-joint is going to cause a banging sound, especially not simply shifting the transfer case. About the only thing that will "bang" while shifting is the high/low range sleeve. It has a brass synchronizer ring built into the sleeve. If that ring is excessively worn, then the sleeve will not smoothly slide over the splines like it is suppose to. The splines will misalign and hang up for a brief moment, then the splines will align and slam into place. That could be the source of your "bang". Even in normal operation it will make a noise, so you kind of have to have an experienced ear to tell whether or not something is wrong. As long as it shifts and functions through the ranges, I wouldn't lose too much sleep over it. Chewed up brass isn't going to damage hardened bearings, chains, or gears. It COULD clog the oil pickup screen, so I would go ahead and change the fluid out. If the old fluid looks like Goldschlager, you've found your problem. If you see brass particulate, I'd run it a few thousand miles, then change it again and check for more debris. When you see clean fluid, you can stop worrying about it. Without the synchronizer, you may eventually see wear on the sleeve and shaft splines. You'll recognize this by having issues shifting through the ranges.

If you see silver metal in the fluid, you have a bigger problem and need to address it before you tear up expensive parts. There is a magnet in the bottom of the case next to the oil drain hole. You can stick your finger or a borescope in there and see if there is any steel stuck to it.

These transfer cases are tough as nails though. As long as they have fluid, they rarely have problems. The only exception to that is cases that have clutch packs in them (auto-trac). Those clutches eventually wear out and cause slipping and binding issues.


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darren509
post Nov 25 2017, 08:49 AM
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Thank you Andrew. Ill check the fluid and see how it looks. Appreciate your help
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darren509
post Nov 25 2017, 04:14 PM
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I know this might not be the loud bang but after replacing my encoder sensor just now and looking under the truck i saw this on the passenger side. Looks like the axle is throwing grease? I cant drain the fluid in transfer case yet as my pan is full of oil from my other car. Is my axle shaft done for ?

Here is another picture
Attached File(s)
Attached File  F96CC56F_9B3E_4824_9D99_74407787A489.jpeg ( 72.35K ) Number of downloads: 3
Attached File  3D1C1B63_4E7C_49DC_BCA9_9D3E6941CA08.jpeg ( 66.34K ) Number of downloads: 3
 
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Andrew
post Nov 30 2017, 11:45 AM
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Might just need a new boot depending on how long it ran without grease. Axle shafts are fairly inexpensive though, so I'd go ahead and replace it.


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jipioneer07
post Dec 1 2017, 08:28 AM
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I snapped one of those shafts shifting into 4lo once. I doubt that has anything to do with your problem though.


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