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2017 Denali Duramax 3500 dually

1K views 1 reply 2 participants last post by  EJCarter 
#1 ·
I just got my brand new Duramax Denali 3500 dually a month ago and when I hit 65-70 mph there is a noticeable vibration that feels like the rear wheels or driveshaft. It only occurs when in 6th gear(Alison) and light throttle. If I shift into 5th at the exact same speed there is no vibration and if I put my foot into it ( gas paddle ) there is no/minimal vibration. I can go 80 or 90 mph and it is silky smooth.
I had the wheels/tires roadforce balanced and it made no difference at all. The picoscope showed lots of T1 after the road force balancing. More than before, but before there was also some E1 readings whereas those dissappeared after the roadforce balance.
At this point the dealer is at a loss and they did contact GM technical who have only let them do the roadforce so far.
Anyone have any ideas. This is the most expensive vehicle I have ever owned and it rides like shit as most of the time is spent around 70mph.
 
#2 ·
Possibly the drive line, carrier bearing, rear end axle(s), u-joint(s), tires, (or a bad tire)? Why is your dealer contacting GM Technical only after RF'ing? Seems like they can do numerous other diagnostic tests under warranty to troubleshoot your issue...I would keep taking it back...be persistent and be polite. It worked for my issue...

I had the 65-75 mph vibration. For the first 5,000 miles, I returned the truck multiple times for re-balancing...the last time it was Road Forced. Each time, it was a little better, but it wasn't gone. Then they tried swapped my stock wheels / tires for a set off another new truck. Still there. Checked the drive line...it was ok. After further research (on this forum and the internet), we realized the stock Goodyear's sometimes had balancing issues. They checked the balance of my stock wheels without the tires and the numbers were much better. Ended up warrantying the stock tires for BFG KO2s (I only had to pay the difference). The vibration was gone and is still gone 10K miles later. I know dealers are different, but all this troubleshooting was done by the dealer. GM Technical Assistance was not contacted. If possible, you might want to check into another dealer...

I'm not familiar with what brand of tire comes on your dually, but just because it was RF'd, it doesn't mean that still might not be your issue...just my $.02 on what happened with me...
 
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