So I went ahead and bit the bullet and went with 4.10 gears (had 3.55s) also had the shop throw in a truetrac diff. The truck accelerates great now, I can definitely feel a difference. Mainly did the upgrade to help with towing, 3.7L.. Now after the work, I have a vibration/rumble at 45 mph and 60mph +, below 45 the truck is very quiet and smooth. The shop that did the work told me that the gear pattern was almost perfect so they said they though the vibration would be with the drive shaft. I went ahead and pulled the driveshaft and took it too another shop. As soon as I pulled it out, I noticed the carrier bearing rubber was pretty worn. After balance, u-joint replacement, carrier bearing replacement, the vibration got better but is still there, seems like it might be getting worse the more I drive, granted its only been ~30miles since rebalance. ~50 since gear swap
So the question is, should I have the shop take apart the rear end again? I would think that if the backlash/gears were set incorrectly I would have noise/vibration even at lower speeds. Is there any thing else I can look at. I've read pinion angle also makes a difference but that should not have change with just a gear swap. Any info would be appreciated.

 

Disconnect the rear of the DS, rotate it 180º and re-install it. Sometimes helps, sometimes doesn't, but it's worth a try.

 

Did you do the new gear break-in procedure?

What brand of gears did you get? And if they aren't adjusted quite correctly, you can definitely get vibration at odd speeds, not constant vibrations at all speeds.

 

If your u-joint caps have clips on them where they go into the differential yoke, make sure they're both in place. I've seen where one was missing and the end of the driveshaft was just slightly off center.

With proper gear setup, you should have no vibration. Sometimes, aftermarket gears can be a little bit noisy, but they won't cause vibration unless they're set up wrong.

 

gears are motive, as far as breakin, I have been driving 15-20 miles at a time easy, no towing. I think I will try the rotating drive shaft first but from the looks of it, it seems as thought the gear setup is the problem. The vibration is pretty much back to what it was before the driveshaft work. I'm going to see what the shop has to say. At those said speeds it really sounds as thought the gears are grinding or too deep of a contact.

 

I'm with the others. Sounds like the gears haven't been properly set up.

 

yes your gears aren't set yet, who told you to go easy with breaking them in? once they are in the truck, YOU need to finish the set up, go out and romp the snot out of the truck for the first 500 miles, then you need to go back to who ever did the gears, have the oil changed out and reinspected for any odd wear, hope you got a warrenty fo the install, I never had vibration or whine, just pure power and smoky tires

 

Every gear manufacturer I know of recommends a break-in procedure and none of them involve "romping the snot" out of it. In fact, that would probably void the warranty.