Hunting a Vibration
Hi,
Long story coming...
I've got 107k miles on the '09 in my signature, lots of it towing a big fiver. But it's been maintained well, all service at the proper intervals, etc. Overall a good performer.
Two months ago, I had the tires rotated. Not long after, I noticed a vibration in what felt like the rear at most speeds above 35 mph. Putting the truck in neutral at highway speeds and revving it did not change the vibration, which is more "seat of the pants" than "shake your sunglasses off the dashboard" in nature. It was sort of subtle and our roads are miserable and that might have just been confounding what I was feeling, so I took the truck on a 1,000 mile interstate trip at 70-75 mph, during which the vibration didn't change much.
Got back home, and had the tires rebalanced at Firestone. No real improvement.
Went to my Chevy dealer -- Bob Jass in Elburn, IL, which has given me decades of good service. They checked the motor and transmission mounts, exhaust hangers, looked for leaks at the seals in the transfer case and differential, and balanced the tires again. No real improvement. After several test drives with the service manager, we decided that it could be a driveshaft out of balance; it was very rusty and had done a lot of heavy towing. Off it went to a driveline specialty shop, and they recommended replacement, which we did, along with new U-joints of course. No real change.
The dealer then did a road load balance test on the tires, and concluded at least two of them might have a slipped or damaged belt. He then pulled the new tires off another truck on the lot, put them on mine, and we drove it again. Some of the vibration went away, but not all of it.
Back to Firestone. They listened to my account of everything I had done, and offered to fully warranty the tires, no further questions asked. (Two were 18 months old and the other two were 40 months old. As with my Chevy dealer, it pays to have a longstanding relationship with your tire guy also.) So for their mounting and balancing cost, I got four new tires. But I didn't get improvement in the vibration.
Back to the dealer for more road time. This included getting it up to 60 mph and shutting off the engine in neutral to see if the vibration went away. It didn't -- suggesting it's something in the driveline that moves even when the engine is out of the equation.
The vibration did change somewhat after the new tires were put on. It is accompanied by a very low noise, and is only barely felt in the steering wheel. It now is almost like I had put snow tires on the truck, even though these are a street pattern. The seat of my pants tells me it's coming from the rear, and if the driveshaft and U-joints were not brand new, I'd say it was a U-joint going out.
I want to cure this before I start towing my fiver to Arizona in January. But there seems to be nowhere to go now but to start tearing down things that show no outward sign of being the cause -- looking for a bad bearing that is early in the failure stage, for instance. So we are stumped now.
Which brings me to you guys. Any fresh ideas would be greatly appreciated.
Thanks in advance.
Rich Phillips
Member #27
2019 K-2500 Crew Cab Z71
Cedar Creek Silverback 33RL Fifth Wheel
In The Past: '82 6.2 Jimmy Blazer, '93 6.5 GMC K-2500, '01 DMAX K-2500, '09 DMAX K-2500
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Originally Posted by richp
