When traveling above 35mph, GM's full size trucks and SUVs are experiencing cabin vibrations along with terribly loud noises from buffeting wind that is making owners sick. GM says these vibrations are within their acceptable vibration range, but I think they need to adjust their scale.
The problem affects GM’s 2014-2016 lineup of full size vehicles using the K2XX platform1. This includes the Chevy Silverado, Suburban, and Tahoe, as well as the GMC Sierra, Yukon, and Cadillac Escalade.
GM Vibrations and Wind Batter Issues
The Chevy Shake, as it is not-so-affectionately known, is most notable at speeds above 35mph or so. It’s a combo punch of awfulness:
- The vehicles vibrate so strongly that mirrors shake and cups rattle in their holders.
- Owners are audibly slapped by strong wind buffeting noise
It’s believed that the issue is most pronounced when the engine switches to V4 mode, where cylinders have been deactivated as part of the engine’s active fuel management (AFM).
The problem gets worse the faster you drive.
What is wind buffeting or body pressure booming?
Wind buffeting is that terrible noise and pressure you feel when someone cracks open a single window while driving down the highway. Except in this case, all the windows are closed and there’s nothing you can do about it.
GM also refers to this issue as body pressure booming.
Beyond the annoyance, there is legitimate concern about the dangers of being exposed to wind buffeting for prolonged periods of time. Many owners say it makes them feel nauseous or dizzy, neither of which are good when you’re trying to safely pilot a 5,500lbs2 hunk of steel and glass down the road.
GM’s Preliminary Information Bulletins and Repairs
GM certainly can’t deny they know about the problem. The automaker has released a series of vibration and noise related preliminary information bulletins to help give dealership technicians something to look for when owners come in with complaints.
Is the roof not properly bonded to the frame?
In PIT5318C GM says the vibration and buffeting issue may be due to bonding issues between the sheet metal roof and the roof bows.
GM recommends technicians remove the headliner and repair any disconnected bonds between the roof bows (crossbars) and sheet metal roof. In some cases Dynamat, a special sound damping foam, is installed.
However, the bulletin acknowledges this doesn’t always work.
In some cases, correcting the roof bows may not eliminate the body pressure booming issue due to the fact that the roof is being excited by some other input(s). These other areas will need to be addressed if the body pressure booming is still present at the completion of this PI3.
Is active fuel management creating vibrations at certain RPMs?
In PIP5228B GM talks about the possibility that active fuel management is to blame for vibrations when the engine is between 1200-1400 RPMs.
A resonance, or buffeting, can also accompany the vibration.
Technicians are advised to use a vibration analysis tool to measure the frequency of the vibration to narrow down where it may be coming from.
Potential solutions include lifting or shifting the cab body, checking alignment, look at body mount positions, etc.
What about the tires? The exhaust? The axles?
From there, GM continues to go down the rabbit hole of try anything just to make the owners leave us alone, including:
- Inspect, balance, and potentially replace the wheels to reduce road vibrations in line with PIT1354H.
- Check for exhaust back pressure valve issues which have been known to cause buffeting issues outlined in PIT5405D.
- Look for pitch line runout issues with the rear axle and potentially replace the entire assembly
Did GM find a fix for newer model years?
According to AutoGuide.com, GM believes it addressed the issue at the end of the 2015 model year.
Try telling that to 2016 owners.
Investigations Underway for Potential Legal Action
The law firm of Migliaccio & Rathod LLP is investigating claims of the vibrating cabins. Since the platform of the vehicles itself may be at fault, solutions to this problem may run deeper than a few service appointments.
As part of their on-going investigation, Migliaccio & Rathod LLP is looking for qualifying vehicle owners who have experienced this defect. To get in touch with them, please visit this page & fill out the contact form for more information.