Mickey_D

I had a 2014 GMC LB CC Z71 that I had to trade in last year because we bought too big of a RV to safely tow with it. Truck drove great and did not have the high speed vibration issue but it did vibrate very badly on certain roads (freshly paved with slight oscillations). Despite this issue I really loved that truck. One road near my house made it feel like it was coming apart at about 45-50 mph - a little slower or faster and it was fine. I suspect the stutter bumps were matching a frame frequency and having a party. In the replacement 2014 Cummins Ram the road just feels a little bumpy, same in our Tahoe and the half ton loaner Ram that I had last week. This is a frame problem. Thinking that this is going to be fixed forever with a new rear end or super road force tire balance or better rims is insane. What happens when your front tires wear a little funny and get out of balance just from driving them? Or you go to Discount Tire or WalMart to get new ones in two years and all they can do is spin balance them? I guess they will be popular at the Sherwin Williams stores for shaking paint cans. GM needs to fix this problem by adding vibration dampening cartridges like Chrysler had to do (and from what I have read Ford will have to do on their new ones as well). This is really sad because GM makes the best looking trucks by far and when they are not shaking they drive great.

The Ram half tons ride great but don't have near the capacity as the GM half tons (I have customers with half ton Rams and when you put a 2000 pound pallet in the back of them it is a little scary, GM half tons are nowhere close to bottoming out). I went with the Ram 2500 CC 4x4 with the Cummins and it makes my previous 2014 GMC CC 4x4 with the Z71 package feel like a Cadillac around town. Even with the rear coil suspension it is VERY firm, and having to run at least 60PSI in the tires to keep the computer from griping does not help. I could not tell much difference between the Ram 2500 and 3500 in ride. On the highway though it really smooths out, or put a couple of thousand pounds in the bed and the ride is great. So far the most I have carried in the bed is 3800 pounds and it still had spring travel and it drove fine. The downside of the Ram is it is not as good looking as the GMC, but like a good dog that is kind of ugly, it grows on you after a while.

I traded my 2014 Sierra in on a 14 Ram 2500 Cummins and have been very happy. I really liked the GMC, looked great (and not a vibrator), nice to drive, but it fell down in the towing department compared to the old 2005 Sierra. The Chevy dealers (I actually like to see in the dark) were not dealing on the HD trucks, and Ram made a screaming deal. The Ram (19K trouble free miles so far) surprised the hell out of me. Much nicer interior, infotainment system is way better, the headlights actually work, and visibility is much better. I have had a lot of trucks over the years, but the Ram is by far the most impressive. I hope GM gets its act together and gets the vibration and other problems fixed because the competition is really getting serious.

My theory is that the natural frequency (or frequencies) of the new stiffer frame is well matched for an out of balance tire, driveline, or even rough engine in V-4 mode. Until frame vibration dampers (like Dodge uses) are added, these trucks are going to always have this problem. Slightly worn and out of balance tire - vibration, engine running a little rough from bad gas - vibration, tight u-joints - lots of vibration, etc... Dampers are an inexpensive and tried solution and will fix the problem, GM just needs to admit that there is one. I wonder how much money they have spent on this compared to actually fixing the problem?

With the roads in Louisiana how are you going to tell...

The vibration on my SLE 4x4 was slowly getting worse (especially in the 40 to 50 mph range during acceleration or climbing a hill). I had an appt. at the dealer and the service writer seemed knowledgeable about the problem and said that it would be in for a week or more. The truck drove great otherwise but was not quite up to the task of pulling our travel trailer, so I started looking at 3/4 tons. Drove a Chevy 2500 LTZ with both the 6.0 and the Dmax, the 6.0 showed 11 mpg on the DIC while cruising at 65 on flat highway and shook like crazy and the front and back end did not feel like they were connected. The Duramax was a lot smoother, but again, the rear end of the truck danced on any kind of bump. The dealer was not discounting the Duramaxs very much, and I was not impressed with the 6.0, so I walked. Went to the Ram dealer and drove a couple of 3/4 tons, the 6.4 hemi felt too high strung and barely bumping the throttle led to a lot of tire noise - felt like the first 10% of travel was 90% of power, and the rest did not do much, so it did not feel like a great daily driver. But the chassis and frame were smooth and vibration free, almost like a big go cart. Drove another (Laramie 4x4 CC SB) one with the Cummins and it was wonderful like a truck should be. You know the Cummins is there because you hear and feel it, but it is not obnoxious. The ride is very firm but not harsh, interior is nice (but not as "clean" feeling as the GMC), visibility is better, the headlights are wonderful (I can see in the dark again!!!), and the fit and finish are about the same. Downside is it is tall (parked next to the GMC and I was looking over the roof) and not as easy to get in and out of, running boards are ugly, and you almost need a ladder to climb in the bed. I am going to leave a rake in the back for stuff that rolls to the front. The Ram dealer was offering 10K off and gave 2.5K less in trade than I bought the GMC for in July (7500 miles so not too big of a bath), so I bought it. It is not as good looking of a truck and won't be as easy to live with expensive diesel and higher maintenance costs, but I think it will work out better with what I will do with it. But I still miss that good looking black GMC....

I have a 14' Sierra regular bed crew cab 4x4 that seems to have two sources of vibration, the lovely Good Year tires, and the engine when it is running at light throttle at around 1250 rpm. The tires do best around 40-42 psi, but sometimes the tire vibrations line up just right and the whole truck gets a little buzzy. The engine one generally comes on with slight uphill steady cruising but can be knocked out by engaging tow haul mode and kicking the rpm up a little. I am going to see if the dealer can rebalance the tires at the next oil change and start that ordeal. I have a machine shop and we design, tweak, and build everything from heavy oil field parts to tiny valve assemblies and shooting sports accessories. We build a lot of different things and deal with a lot of different materials. Harmonic resonance is the enemy of getting a good finish and long tool life. A good rule of thumb is that the stronger and harder a material is, the more efficient it is at maintaining and transmitting vibration, just like a tuning fork. The new high strength frames that all of the automakers are using give us bigger payloads, better handling and mileage, and a lot more safety, but they have a downside by being more susceptible to vibration resonance. The old mild steel frames had a much lower natural frequency (plus the softer steel absorbed more vibration converting it to heat) and the new high strength ones seem to have a frequency around 8 to 10 Hz, one that is pretty annoying to people. As long as high strength steel frames are used on body on frame trucks this will be a problem. From looking at the Ram and Ford forums, this does not seem to be just a GM problem. The real solution is adding either a passive or, even better, an active damping system to the truck frames. Could be something as simple as bolting a 20 pound box of lead shot to each side of the frame.