In my ever-going quest to squash this front-end vibration, I’m not questioning whether or not the recently-replaced wheel bearings could be bad.

I disconnected the front drive shaft and drove around with the CDL locked, the vibration went away. Reconnected a NEW driveshaft, and the vibration returned. If a wheel bearing was bad, would it vibrate whether the driveshaft was connected or not?

 

Good question, I would think that the vibration would be there if a wheel bearing was bad. What speed does the vibration occur? Have you had the driveshaft checked for balance? Any play in the output flanges on the tcase or diff side?

edit: just saw your other post on this on the diff swap. You have a lot to rule out. If it’s just coming through the steering wheel check your alignment, all steering components ( track rods, etc). How are the ball joints?

 

bearing at the tcase?
it's pretty easy to swap out.

 

I will second checking the tie rod ends and steering damper

 

Both are brand new :/

Same with the driveshaft, track rod, drag link, steering stabilizer, tie rod ends, ball joints, panhard bushings, differential (albeit, used), wheel bearings, springs, shocks, and tires.

I only suspect the *new* wheel bearings because 1 of the 2 I originally installed was bad out of the box and was the source of my three amigos debacle. Maybe a bad batch.

 

Ah yes I remember that thread. My opinion is that it’s either output flange on the tcase or diff. I would bring the driveshaft to a driveline shop and let them know what speed you feel the vibration so they can test it on a balancer. If it was a steering component or suspension issue you would have felt it without the driveshaft attached.

 

You would feel the wheel bearing even without the drive shaft, as the tire still spins. At this point you know the problem is either the drive shaft or transfer case, removing the drive shaft removes the issue.

I have to admit I am I am hazy on this but I would think you would still feel the vibration if it was the diff, samething it still turns drive shaft or no.

But so I am clear you feel the vibration in the steering wheel ?

 

Brandon, can you edit your post and describe in detail the symptoms? I'm sure its clear in your head (or in other threads) but you only call it a front end vibration.
I'm with the others that it's likely not the wheel bearings - to answer your question.

 

For sure, I'll sort of restart with this post instead of editing, which might confuse future readers -

Symptoms:
- Vibration starting at 30mph and tapering out around 45mph.
- It's strongest felt through the steering wheel. If I let go of the steering wheel while it's occurring, it's nearly imperceptible.
- Happens on accelerating, but if I heavily apply the throttle and breeze through that speed range, it doesn't really occur. It happens most noticeably when I'm steadily progressing through the speed range.
- It occurs when I'm decelerating too, and even has a bit more of a "grit" to it if the throttle is completely off, like on a downhill. More grumbly feeling.

Background:
- Truck only has 82,000 miles on it.
- I did a major project this summer (about 500 miles ago) and replaced nearly the entire front end, from the transfer case forward, as a result of the front differential blowing out on the highway and a three amigos light appearing (coincidental).
- Replacement included all the parts listed in the post above, including the front differential, but the front differential was a used unit from eBay, but it looked great and was said to have been tested and working fine. No idea the mileage or service history.
- I didn't replace the axles as a result of the differential grenanding itself. They appeared fine when I removed them to replace the differential.
- Also, FWIW, I drove around with the front driveshaft removed and the CDL engaged for a few hundred miles before replacing the differential, and didn't have this vibration issue.

Troubleshooting:
- Figured it was the front driveshaft. I called Tom Woods, since the driveshaft was new, and they said to send it in. They tested it, didn't notice a problem, but offered to build a custom one for me at no charge. I installed the new one, and the problem reoccured. Vibration was back with a second new driveshaft.
- With the front driveshaft installed, I yanked pretty hard in all directions at the TC flange to see if there was any play. Zero.
- Took the driveshaft off and torqued down the TC and differential flanges just to make sure those weren't a problem. The diff was good. The TC nut took about a quarter turn to reach the 110 ft lb spec. No change at all after.
- Visually inspected motor and transmission mounts, all appear fine.
- Bought new tires yesterday to rule that out. No change. They needed to be replaced anyway due to age.

Suspicions
- Driveshaft: Since the problem went away with the front driveshaft removed, I of course can't rule out the driveshaft itself. It just seems unlikely as this is now the second new driveshaft, AND, the first new driveshaft was installed just before the diff blew, and there wasn't a vibration.
- Transfer case: There wasn't a vibration before the diff blew, so I really don't have a reason to suspect a problem lies with this.
- Wheel bearing: Mentioned earlier, I replaced both, but one was found to be DOA, so I sent it back and got another. Is it possible the second of the original pair is bad too? Wouldn't I have noticed this with the front driveshaft removed if so?
- Differential: Again, the original one died on the freeway, necessitating a replacement. The replacement is used. I can't help but think the problem is with this?