Got a 2020 t680 with x15 and endurant 12 sp auto. Recently i have developed a low speed vibration. When i say low speed i mean its not fast like a u joint would be at this speed. It doesnt start until i get above 70 mph. It doesnt do it all the time. It will start and go a mile or so and go away. Of course it comes back. I cant make it do it but if i let off accelerator if does get better but will come back. Put new michelin tires on and Have balanced all tires.i have put the old tires back on and reinstalled the new ones. No difference. centramatics on all axels. I took them off and now have back on, no difference. I have put new rotors on front and drums on back along with brake pads. New carrier bearing. Had king pins and bearings verified on all 3 axels. New bushing in rears and 3 axel alignment. Nothing i have tried has made even the slightest difference. Has anyone else had a similar situation? Do you mind sharing your solution? Thanks
Somebody might be able to make a little money putting together a bunch of information regarding trouble shooting vibrations, say like in a "flow chart" format. Eg, if you feel the vibration in the steering wheel, then it's coming from the front end; if you feel it in the floor, it's in the rear. I believe trying to figure out a vibration is the most asked question. I had a front end vibration like this once, but it would start in the 45-50 mph range, and then quit after 60-65 mph. At first I believed it was a tow out condition. A steer axle alignment helped, but didn't completely get rid of it. This is what prompted me to try aligning my own truck for the first time with 48" aluminum channel, string, and a tape measure, thinking it wasn't quite towed in enough. I didn't want to go thru taking it back to that alignment shop only to find out it was aligned precise, and be compelled to pay them $. Well the alignment was dead on: 1/16" tow in. I had been told my king pins were fine, and they shouldn't cause a vibration anyhow. I checked them myself and saw they had some measurable movement. So I had them replaced, since the truck had 1.5 million miles, and I didn't know if they had ever been replaced. My truck has had a slightly twisted frame since I bought it. And I was guessing that maybe that with wearing king pins could cause a vibration. I am figuring so, because the vibration was gone after new king pins.
Does it do it bobtail? With trailer on? Spring ride front end or air ride? How about when you are pulling hard even at lower speed. Does it have a rear trans support to the frame? If so the wear pads ok? Drive line out of phase?
No they wouldn’t. After all of the complex vibration analysis I have done over the years nobody wants to pay for the time. Most would rather just spend thousands on parts, tires and ujoints and then complain when it doesn’t fix it.
