Thump-bump

[Palazzoblues]

Okay, so here's the deal... I just purchased a brand new 2016 Chevy Silverado 1500 High Country crew cab short bed 4X4 5.3 8speed (Not Z-71). I have already noticed a weird issue and want to know if this is normal or something I should take it back in for. What it's doing is a pretty strong thump-bump somewhere in the rear end when I make a slow left hand turn with little or no gas. Basically if I am in a slow rolling turn to the left the rear end makes this somewhat violent THUMP! I don't think it is transmission related. I think this is more transfer case or even rear end differential related. This pickup does have the auto-locking rear end diff. I wonder if it has anything to do with that? Also, this seems to be an intermittent issue. Thoughts?

[Thomcat]

Okay, so here's the deal... I just purchased a brand new 2016 Chevy Silverado 1500 High Country crew cab short bed 4X4 5.3 8speed (Not Z-71). I have already noticed a weird issue and want to know if this is normal or something I should take it back in for. What it's doing is a pretty strong thump-bump somewhere in the rear end when I make a slow left hand turn with little or no gas. Basically if I am in a slow rolling turn to the left the rear end makes this somewhat violent THUMP! I don't think it is transmission related. I think this is more transfer case or even rear end differential related. This pickup does have the auto-locking rear end diff. I wonder if it has anything to do with that? Also, this seems to be an intermittent issue. Thoughts?

Six speeds annoy the crap out of me making a slow turn, I'll bet 8s are even worse, making turns slowly and letting off the gas just before the shift point. The greater the number of gears, the closer the ratio between gears and the damn things are always downshifting half way through the turn. To rule out a tranny downshift, go to manual and lock it in 2nd before the turn and see if the thump disappears during the turn......if so then try it in automatic keeping slight throttle during the turn and see if it still disappears......if so then the thump could simply be the downshift related causing slack taken up in the in the driveshafts U joints and rear end gears which may be normal.

[Palazzoblues]

Thomcat,

 

Yeah, I bet its a 2nd to 1st thing when it does this. It really slaps the rear end pretty hard. I might even stick my go pro under the truck somewhere to see if I can catch the drive shaft doing it. That's the problem. It is very intermittent and the conditions have to be just right. have one small turn here in the yard where I can almost reproduce it. It just annoys the heck out of me.

[Thomcat]

Thomcat,

 

Yeah, I bet its a 2nd to 1st thing when it does this. It really slaps the rear end pretty hard. I might even stick my go pro under the truck somewhere to see if I can catch the drive shaft doing it. That's the problem. It is very intermittent and the conditions have to be just right. have one small turn here in the yard where I can almost reproduce it. It just annoys the heck out of me.

Sounds similar to the condition in my Avalanche which had the typical problem with the 2-3 upshift and 2-1 downshift clunk caused by a momentary release of the throttle just at the point where the tranny was ready to shift gears......Chevy dealers were aware of this and some vehicles were worse than others.....some posters in the forum claimed temporary correction by removing and greasing the splines in the end of the driveshaft but no corrective actions formally taken by Chevy because the condition was not dangerous or damaging, just annoying..... .mine calmed a bit after the tranny warmed up....attributed to a combo of normal slack in the drive train combined with a condition known as driveshaft reversal before the shift point......condition was aggravated in 4WD vehicles which had more moving parts associated with the transfer case. Yes, it was annoying....sometimes the clunk and thud was so loud you'd swear that damage was being done.

[mookdoc6]

_{I don't have 4x4 but have 5.3 with 8speed....Not apples to apples but I will try to recreate your driving style and post as to what happens to mine. Maybe it will help you............}