Ok. Try to sum this up quick. 2010 limited 4runner. (Full time 4wd) or u could say awd. I went crazy and added a ton of parts. Supercharger, 6” fabtech lift, gears, arb lockers, bumpers, yadda yadda. 4wheel parts did the gears and lockers. Got truck home. Following day i went to drive to town to break in the gears. Doing about 30mph on my gravel road the front end locked up. Which in turn locked everything up due to being awd. Towed truck to 4wp. They had to replace full front diff housing. Bad bearing. So lets fast forward a year. I have pit about 10k miles on it. This last week the front output on my tcase started leaking. Pulled front shaft. Replaced seal, both ujoints , greased it all up. Tcase oil was clean. Changed diff oils. Dirtier than i would expect but no metal shavings or anything. Now this sound has been going for awhile now. Ever since the work was done. And i cant figure it out. I dont want to just start throwing parts at it. Wheel bearings are tight, and when jacked up no noise. No popping from cv axles. Im wondering if pinion preload loosened? Or is tcase damaged from the front end locking up? Any one have any input? And dont say never go to 4wp. Already got enough if that. Sound is harsher when applying and letting off accelerator. Faster the faster truck is moving. Not able to attach a video…. 4wd selector works as its supposed to. Drive with front shaft out (in 4wd) still made sound but seems to be more amplified with front shaft in

6” lift? Yeah I bet your U joints are happy with that… do you have any kind of diff drop?


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the full list of mods done resulting in the sound would help. What tires?

Try doing some scenario troubleshooting to narrow down systems.

Regular drive, at speed when noise is present, shift to neutral, is noise still present?

Try the same in 4Hi

Regular drive, at steady speed when noise is present, manually shift to different gear to change engine rpm. Dose the noise change?

Control the variables you can to narrow between engine/trans and wheels/tires/suspension.

Yah. Does it in all speeds. Sound slows with vehicle speed slowing. No change in sound in neutral. No change with manual shifting. No change in 4hi. I would have to say sound started after the destruction of my front diff from 4wheelparts poor install job. The truck has a fabtech 6” lift so yes it has a diff drop. No harsh angles on cv axles or drivelines. With front end jacked up i have no sounds when spinning tires by hand. No play in wheel bearings. I recently changed tcase front output oil seal as it started leaking (sound was already happening). Removed front shaft and drove in 4hi just to see if it was related to front shaft. Sound/vibration was still there, but with front shaft in seems more magnified. Changed ujoints when i pulled front shaft out just because. As posted b4 the gears where changed to 4.56 with arb lockers. The 4runner is a limited, which is awd/full time 4wd or which ever u prefer to say. So always power to front diff. Im wondering when my front diff went out, and locked up if it damaged something else in the drivetrain. Which im assuming it did. Tcase oil was clean when drained for the seal replacement. The diff oils were a bit dark, but no metal chunks or shavings came out in oil.

Also i have seen the posts about the needle bearing for front diff on tacomas. However they dont make it for the limited 4runner when i looked into it. Also reading more into that bearing it sounds like installing arb lockers use a different bearing all together which eliminates the need for the aftermarket bushing. And checking cv shafts i dont the play that they show causing the issue

Sounds like might be tire noise to me. With wheels off the ground, spin one and put your hand on the spring. If you feel vibration in the spring your wheel bearing is shot despite the other checks. Why did your diff bearing go bad? Vibration in front shaft? Maybe out of balance? Good luck!

I'd love to see a Pic of the truck with a 6in lift.

Based on your post, it has to be tires, wheel bearings. My bet is tires/balance.

If the noise does not change in AWD vs 4Hi, then it has nothing to do with your front diff as it is not engaged during normal highway cruising.

Front diff is engaged in hey driving though. Its a limited. So full time 4wd/awd