HELP // 2005 2500HD Loud Buzzing / Grinding / Bang

[LineC]

Scratching my head a little.

 

2005 2500HD 8.1 4x4 / Allison / Manual Transfer Case

Under 30 mph I sometimes get a loud sharp buzzing / chatter / grinding noise under acceleration.  Feels like is coming from front drivers side in engine compartment and is fairly loud and sounds not healthy.  It will hit hard then go away.  Lasts about a second, and I can feel it thought the gas pedal until I let off.  Sounds like a loud buzz, and almost like when you try to shift an ATV into gear and the dog clutch chatters a hair. 

 

I cleaned wheel speed sensors / pulled ABS fuse and disconnected the front wheel speed sensors and it still happens.  Front hubs seem tight and doesn't seem to do it over 30 mph, or if in 4wd.  Also doesn't do it all the time, and I don't have any lights on.  Any ideas? I'm thinking its an ABS modulator.  It just showed up randomly. 

 

 

Edited December 20, 2020 by LineC
More info

[riverbanks]

Can you post a video?

[LineC]

LineC

 

Here is a link to the sound when I'm driving.  More I think about it I am thinking torque convertor shudder, or something up with transfer case.

 

https://streamable.com/bdgrsq

Edited December 22, 2020 by LineC
more info

[flyingfool]

did you find out the source? i have a 2500 hd that will squeel at wot ,  its not the serp belt or tensioner changed those out.  i hope its not the TC

[LineC]

Sorry, don't check this forum much but I did find the cause.  The snap ring in the transfer case broke.  Let the gear move back and forth.  Snap ring was $6 but quite a bit of time to remove and reseal.   I guess this is a common problem 2nd to the pump rub, and I heard some later years they hardened the snap ring.  Here are some pictures.