Front driveline noise

I'm going to be rear gearing my front end, but before I do there seems to be a problem I need to correct. When I'm in 4wd (hi or low), going up hill and really putting out a lot of torque, I get a whap, whap, whap sound from the front end (like its bucking.) It sound almost suspension like, but I tend to think its in the drive line. So far I haven't been able to locate it, but I don't know much about the driveline components (yet.)

I've got a 3in lift but no axle, u-joint changes. Its a 96 with 100k

Any help would be appreciated.

Matt

Check the front driveshaft.
The ujoints in the double cardan joint will go bad and cause that sound from slop in the driveline. Also, there is a small ball joint with a pin and spring that keeps the DC from flopping around within its play range.
I had to replace the ujoints and the ball on my 1999 with 80k on it.
I have a 3.5 inch lift and the higher angles accelerate wear on the joints, even with the HP housing.
A driveshaft shop will rebuild it totally for about $180, with 3 new ujoints, new ball and socket, and balancing.
Try to use Spicer of Napco ujoints. The off brands with the zerk between the crosses makes me nervous, and I have seen more than one of them where the yoke is slightly 'eating' the zerk. Get sealed Spicer units and replace them yearly if you like to run in the slop.
Good luck.

I was thinking about that also. In 4-wheel drive when I turned the shaft by hand, I couldn't feel any backlash or slop. I guess I should take it out and change the joints anyway. Is there any problem driving with the front driveshaft removed?

That should be the first thing you do to diagnose front end noise.
Driving without the front shaft is fine, and wont hurt anything. In fact, it helps because there are less parts moving than under normal driving conditions .
I could not really 'feel' slop either, but rebuilding the driveshaft made a world of difference.
The difference between 2 and 4wd is that the angles are made different in the double cardan joint when there is power applied.
When in two wheel drive, the front shaft spins due to the front axle spinning. When in 4 wheel drive, the spinning comes from the transfer case, stressing the driveshaft in a different way.
Take it out and give it a try.
I would be willing to bet you a crisp $5 that removing the front shaft fixes your problem.
For the longest time, I had vibes at over 80 mph and thought it was due to the rear hack and tap, but removing the front driveshaft fixed everything.
I spent some time and love rebuilding it and painting it and all is well.
HTH.

It just so happens that I spent 2hrs this weekend trying to pull a guys 4-runner back onto the trail. It turns out he owns a driveline shop, I guess I'll call and tell him I've got the perfect way for him to repay me .

Thanks,

Matt