Maybe do some driving at the problem speeds in manual mode and just pick a gear or two lower and see if it all goes away? Then you know if its tires, or drivetrain engine rpm or converter shudder?Not likely that it is tires/wheels. Because vibration is more harmonics than shaking, he was in a car and I felt it (with my ears) he on the other hand did not, neither does my wifeI know, I know, perhaps I need to go to the doctor instead but I do know my car well. Harmonics is there, but finding it is next to impossible, until it rattles your teeth out.
Vibration (like buffeting) 68-73MPH new tires, 3 different shops checked
- Thread starter smokey_2020
- Start date
Did the diag include using a Pico NVH analyzer?Not likely that it is tires/wheels. Because vibration is more harmonics than shaking, he was in a car and I felt it (with my ears) he on the other hand did not, neither does my wife
Yes, I asked for the Pico (know that tool from my previous 2020 Tahoe days) and he said, he can only instrument Pico test if he senses any level of vibration
if 2nd fluid change does not address it, then I will take it in one more time to do Pico on my own dime. I am already $580 into all re-balances and various tests, I need to decide if I should invest another $240 for the Pico ride.Just throwing out a personal issue that I caused. Any brake work around this time? I did a brake service in a hurry before I drove my son 12 hrs back to the navy base. I swapped my slide pins backwards on one side which caused a bit of drag when the rotor got a little warm. Half way into my trip, I fixed my screw up in an advance auto parking lot. All has been well since. Just enough heat to distort the rotor above 65 mph, and didn’t start till things heated up. Generally 20 miles down the road.
How hard did it hit the car wash railings / guides? Have you had a chassis ear on any parts to pick up on vibrations? I’ve read through this thread off and on in full but I don’t remember all the suggestions and what’s been acted on. I wonder if a wheel bearing was damaged in the incident but isn’t loose and isn’t rumbling yet.
Very light touch, was not even a bump. Tech did not find bearings problems but there was no mentioning of chassis ear, GM uses Pico from what I gathered. Never heard of Chassis Ear until today, may need to find a shop with it.
If you are thinking TC shudder, altering the fluid characteristics should also modulate shudder affects. Have you tried adding something like a very small dose of lubegaurd red as a TEST? I had a lot of issues with my ford 10 speed and a 1/4 dose of lubeguard red was the difference between missed shifts, flashing error lamp … and Lexus-smooth driving. Throw a splash in and see what it changes. And stay at a small partial dose to avoid any regrets from putting a full dose in and not liking it.
thanks for the tip, which Lubeguard shall I use in the thread folks are telling LG Platinum for 10-speed ULV transmissions. Will red work for 10-speed ULV?
I tend to be a “less is more” kinda guy when it comes to additives. I personally used lubegaurd Red, about a quarter dose in my ford’s version. It was a big help.
You could use either. I personally haven't noticed much difference between the two in real world driving. @meep suggestion is a good one to
CleanSump
Site Donor 2026
Shudderfix really helped a 97 Blazer I had. I've used the Lubegard in several GMs, and it's in our two BMWs (one GM trans, one a ZF trans) and our Mercedes ZF now. It can't hurt and may help.
Folks, I have driven 200 miles today and I have tried the test of putting into Neutral when I felt harmonics, Neutral did not change the harmonics vibration. I guess we can rule out transmission, but it leaves all other rotation parts in scope. Anyone knows a reputable driveline shop around Asheville, NC?
You have a drive axle or drive shaft out of whack. All universal joints and CV joints should be checked.
Do you know what tests I should be asking for? Dealer told me that they checked them but as we know, dealers are not always keen as they only do what GM tells them to do. Any thoughts what shop can help? I hate to give up on this truck, it was fantastic ride until this issue emerge.
It's going to need to be put in the air and front and rear axles will need to be moving. Everything that makes the wheels go around will need to be looked at while in motion.
Thanks @MParr I will drive to Knoxville in March sometime they have a shop called Knoxville Driveline that seems to be all about drivelines. Drain/fill the transmission again today but no change as expected as Neutral confirmed that issue is in the driveline somewhere however an interesting observation vibration is strong when tires/car is cold. I am merging onto a highway within 3-5 mins after leaving my garage, once car/tires warm up after 5-10 mins on the highway vibrations are less obvious but far from being gone.
Tires? How can it be, they have been re-balanced 4 times but chance is that none of the Hunter Elite operators really knew how to use it. Tires are these so-so tires from Tirerack - https://www.tirerack.com/tires/tires.jsp?tireMake=Michelin&tireModel=Primacy+LTX&partnum=665TR8PLTXV2&autoMake=Chevrolet&autoModel=Tahoe+4WD&autoYear=2023&autoModClar=265/65-18
My model is Primacy LTX DT TPC Spec. Reviews are quite poor, while my OEM tires that came on the truck were Primacy LTX too and they were perfect, chances are that these LTX DR TPC are the problem.
The Primacy line isn't Michelin's best. The Defender would have been a better tire.
yes, this is what I am learning, I am contemplating buying new tires, before trading my truck, seems like a lower loss vs. trade-in losses.
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I ran primacy’s for 50k. If they aren’t one of Michelins best, you could have fooled me. Although the tread depth starts out a little less 8/32 versus 10/32. They rode much softer and were quieter than the defenders I had on another vehicle. In fact, I wouldn’t use defenders after that experience. There’s always a chance that you have a tire that’s out of whack, but the rotation should have discovered that.
Tire jockeys are imo one rung above quick lube techs. Going to 10 shops is about the same as going to 2.