i just put in a 4 inch rear lift and am awaiting my bj spacers, but get a little vibration on the drive shaft right now, i expected this and got the adjustable upper control arms to help it, but I get this weird grinding around 50km/h which is about 30 mph. kinda sounds right under my seat and I'm freaked out my driveshaft wobble is wrecking something expensive... any ideas?

 

Perhaps the slip joint is stuck. That would cause vibration.
do you regularing lube all the joints?

 

Put the rear on jackstands, truck in neutral, chock the front wheels, get under there and turn the driveline, see if you can feel the ujoints binding, or maybe you have a long bed with the carrier bearing... Which hates lifts anyways

start the rig up and put it in gear and got through the gears and speedometer and listen and look for binding and noises.. you might get more noises than normal with no load on the rear but you should atleast be able to get under the truck and hear your specific noise or grinding and pinpoint it.

be careful tho

 

4wd or 2wd?

 

its a 4wd 4runner.... 94 22re. I cant quite get the sound pinned down. its only really when I go from coasting in 2nd or 3rd to speeding up for about 5 seconds. i just lubed all the joints except the double cardans cause I gotta get a tube of moly. although i may try adjustng the upper arms so they are shorter see if that helps... i dont wanna rip off the upper arm mounts like so many guys have... lol


keep the ideas coming... i"ll let ya know if i find it i mean it could be a loose piece of metal that now dances at certain vibrations when I drive who knows

 

what kind of rear lift did you put in?

 

well its kinda a mesh of parts.... procomp springs (4") rancho 9000 adjustables, used and I hate them. some adjustable upper control arms, made my own panhard drop got a buddy to weld it up for me, and a nice brake braided brake line.


i may have found the sound... i just noticed the hanger to the cat was broken and hanging loose... so maybe it was banging around down there... will find out when I go to the store...