@ok4450 stole the thought from my mind… Torque convertor lockup malfunction can cause the same sensation. This can be tested by running the vehicle up on stands…with and then without wheels… Also with the lockup solenoid either disabled or disconnected…and then connected again.
Even if it isnt that…it can simply be the Torque convertor internals that messed up…Not a too common occurence but I have diagnosed and repaired this condition prior…and it took me a long while to finally reach this conclusion. I was trying to rule out everything before “Going There” to the Convertor…bec honestly I didn’t want it to be the convertor for obvious reasons. In the end…that was it.
Another test you can do is to “power Brake” the vehicle… Foot on brake…foot on gas simultaneously…do you feel a vibe at that time? If there is a torque convertor fin problem it will be felt at that time…if nothing is felt…move on to the lockup solenoid. Your solenoid may be weakened and barely able to fully engage lockup…and its sort of vibrating like a tattoo needle…engaging and disengaging lockup rapidly… Id be looking into it…but thats me…
Transmission? Is there any rhyme or reason why this symptom would occur immediately after tire replacement then? Or, if it turns out to be a transmission problem, were the tires just a coincidence?
To answer GeorgeSanJose’s question: "Transmission? Is there any rhyme or reason why this symptom would occur immediately after tire replacement then? Or, if it turns out to be a transmission problem, were the tires just a coincidence? "
I was in the tire business long enough to suspect that many folks turn up their sensitivity when they buy a new set of tires, and they discover problems that they immediately associate with the new tires - only to find out later, the problem had nothing to do with the tires.
For example, I had someone claim their new set of tires were leaving marks on their painted garage floor. They even sent photos to prove it - EXCEPT the photos showed 2 different tread patterns!
CapricRacer is exactly right. Maybe this truck has 2 problems with one being covered up by the other.
The bit about someone claiming their new tires were leaving marks on the floor is downright weird. I’d say the life expectancy of tires that dissolve would be measured in minutes.
Just curious, but when the tread pattern discrepancy was pointed out what was their reaction to that?
Folks get hyper-sensitive to prior existing problems after installing new tires? hmmm … I guess I can see that. I’d never noticed a high pitch fuel-injector whine on my old VW Rabbit until after I did a fuel injection test where that whine was readily apparent and somewhat annoying when standing in front of the engine compartment during the testing. Afterward, when driving the car I immediately noticed this weird, very low volume, high pitched whine noise. Then I realized it must have been there all along but I just hadn’t noticed it.
Staying along the line of Trans/Torque Convertor logic…
The new tires you installed are almost certainly a larger diameter than the old ones…even if you bought the stock and or same size tire… the new ones will have a larger circumference. Perhaps this addition of outer circumference uncovered a Torque convertor issue that was hidden or dormant at the old tires circumference… Perhaps you found the convertors “tipping Point” with this newer and larger value of circumference and load it places on the convertor?
Was the truck driven in ice/snow sometime prior to the problem arising. Heavy wheel spin and shifting to rock out of a rut seems to be a possible cause for lock up converter clutch problems. And I recall that the shudder from my failing Ford lock up clutch might have been associated with rear end problems. How did I let that go over my head on this post?
Can anyone provide feedback on possible ‘missfire’ issues with plugs and coils? Can missfires create a vibration ? Would a missfire automatically bring up a check-engine light? Curious because I ran a scanner but it brought up no codes. If this is the case, then I would assume no issue there-
Other possible thoughts in mind:
a)Changing out Tranny fluid again and adding friction modifier/shudder fix.
No…Misfires are easily detected and reported. In fact they are extremely sensitive to this…if you have a true misfire condition…it will be reported.
Did you ever try to “Power Brake” this truck? Foot on brake…apply accelerator…does it shudder while under this load?
Ive seen a lot of guys misinterpret vibrations… You need to keep in mind how fast the engine is turning…how fast the tires would be spinning, how fast the driveshaft spins…etc. When someone assumes its a tire, the frequency of the vibes would tell you otherwise…Its one way to rule things out anyway.
It putting strain on the torque convertor… You can do it on the ground or up in the air really… Its just something quick to check and eliminates the shaft, wheels and rear diff simultaneously…
Yes misfires can cause a vibration and odd as it sounds the symptoms can vary greatly I can provide an odd example of one I ran into many years ago on a Ford 4 cylinder.
The car would start instantly hot or cold, idle as smooth as a Swiss watch, and would run equally smooth even if driving it hard and up to 90 MPH.
The symptom of this one was a shudder around 40 MPH and it would only happen if the accelerator was eased up on slightly. In other words, trying to kiss a steady speed along.
No diagnostic codes, no Check Engine Light, and well maintained.
The cause? Corrosion on a coil wire terminal. Nothing more. Cleaned the coil terminal and problem solved.
I just thought about the “Power Brake” test…its quick…and it will help to try and narrow things down… But it occured to me…you wouldn’t be testing the “Lockup” of the convertor…just the convertor basics as lockup isnt seen till the last gear. So it is a semi test of the convertor… Just an FYi
Yeah I know…but it can still weed out if its the convertor pre lockup…and if the issue is pre lockup its a big one. But the goal was to check the lockup ability too… That can be done by not using the brake in the test till the end…after it reaches the top gear and goes into lockup. Do the test without the wheels and or with them.
Was just an idea…its taking longer to discuss than perform