12.7 Series 60- Issues after rebuild

Can't blame you at all. I'd be completely postal by now if I were in your shoes. Places like that really get under my skin. Never mess with a man's livelihood.

 

Throw out bearing?

 

Did they do a engine swap?
If they used the bolts to pull the transmission up, then that may be the problem.

 

The drive shaft may be out of phase. Even if it’s in phase, sometimes taking it out, and turning it 180 degrees and re installing it will fix a vibration, if it was originally installed that way. Look for marks on the drive shaft and u joints, if there’s no marks, they probably didn’t mark it, and may have it off 180 degrees from original. Only other thing that come to mind is ride height. The spec is 2.5-2.75” Ideally 2, 5/8” measured from the top of the spring bumper (located on top of spring, under u bolts). to the bottom of the frame bumper, on right front axle. Some claim to measure at left front axle. Either way. I’ve even checked both and split any small amount of difference. Easy way is to cut a piece of cardboard 2 5/8” use it as a gauge. Check the torque bars, or spring bushings. Check Cab air ride height, if equipped. Spec is about 1” space at the Cab number, located at the center on the rear of the cab, between the air bags. Engine vibration damper, if it’s original. Worth the $600, for a new aftermarket Vibra-Tech brand, if needed. Bad damper can cause premature wear on the crank bearings.Bad cab bushings, or bad cab torque rod, can amplify of mimic driveline issue. The Transmission linkage is reliant on good cab bushings. Bad bushings can cause vibrations in the cab, through the clutch linkage. Don’t start changing parts, just inspect them for slop. My first suspect would be a bad tire. Truck sat fit a long time. Might have one out of whack. Maybe now with the new motor mounts, you’re feeling drive line vibrations that weren’t as obvious with bad motor mounts. No telling. Flat spots on tires from sitting, might go away, after running a while. Bad drive tire will be more noticeable bobtail, not as much loaded heavy. Might want to rule out a loose wheel end, or a bad wheel bearing. I’m doing my brakes and bearings/seals now. Found one bad bearing, caught it just in time. I could feel it, when spinning the hub.

 

I don’t remember if it was mentioned before. But the exhaust cross pipes are in a tight spot on the FLDs. It’s easy to get a terrible vibration, from pipe hitting the bottom of the cab. Make sure it’s clearing the frame, and cab, and it has proper rubber hanger, intact.

 

In my experience every engine is different. I’ve had 3 overhauls on a 3126 in one medium duty truck over a 22 year period and each time it rattled something different in the cab a different way. We just recently rebuilt an old NH 220 that had a bad liner. No steering wheel shake at factory spec 500 rpm idle before. Now it vibes it so much the horn button keeps popping loose. We had to raise the idle up a couple notches to smooth it out. Same engine different day. So to speak.

All my cars have been the same way. I’ve found a fresher tighter engine puts more resonance through a car then a worn one.