1st gear hard acceleration vibration

So I thought it was the carrier bearing, so I replaced it. But the noise still there. Only in 1st and only off the line hard, I get a "wop-pop-pop" that feels like its vibrating the floorboard. WTF? U-joints maybe? I get no vibrations any other time. Thanks

 

Check your front axles

 

do you have a lift? 1st gear puts the most torque on the rear third member and cause it to rise up twisting the axle (this is axle wrap) the more the axle twists, the more out of alignment the driveshaft gets and the more vibration you will get. I had this bad when I added a leaf to my rear springs, it got better as they settled, better when I dropped the center bearing a bit, and is 90% gone after I added a 2 degree shim to the rear leaf packs. chasing driveline vibrations is a p.i.t.a. Lubing all the u-joints and slip joint can't hurt either.

Unless you are in 4 wheel drive, I am sot sure how the front axles would impact this, perhaps 99GC8 could explain more.

 

I jacked up the front end and axels seem ok. How do I check em? I've broken one before but it was obvious. They both rotate fine.

 

X2 on this. Mine came with the exact same vibe from the factory due to the limp ass TRD springs.
Fix the spring/pinion angle, support bearing drops are a band aid.

 

I'll have to check for axle wrap. I just put some j59 deaver springs in a few months ago that I bought from another forum member.

 

That's fine but you still need to check and correct (if necessary) the pinion angle. You want it pointing 1-2 degrees below the double cardan joint/support bearing. This way under load the inevitable diff rotation will still be in an acceptable range, allow slight movement of the rear u-joint bearings to (under normal conditions) distribute lube and prevent a continuous "point load" of the rear u-joint needle bearings. Google "double cardan pinion angle" for all you need to know. Correct your angle with tapered shims.

 

Subd, I have the same problem!

 

So it ended up being pinion yoke bearings are loose. You can wiggle the yoke about 1/4". Enough to make it vibrate off hard access in first. So it still drives fine but the shop wanted 850 to rebuild the rear end, more if it needs ring and pinion (probably is ok). You may see my truck in the for sale section soon.

 

So I thought it was the rear end bearing. Then I thought it was the front axle bearing. I had recently lowered my coils springs for a better ride. I just raised the backup and vibration is gone. WTF? Replaced front cv axles and rear carrier bearing to no avail. I have a 1" diff drop up front. When I'd go into 4wd with the coils lower vibration goes away. Screw it I guess. Coils cranked up, vibes gone.