A quick question for the 4runner hivemind:

My 1999 4runner has 275,000 miles and I’ve just re-done pretty much all of the front assembly. I’m noticing now in certain situations on the highway I get an extreme rocking side to side. It doesn’t happen all the time, just when I’m on a weird bit of paving or I hit a bump just right. But the rocking is dramatic when it happens. My guess is that I need new coils and shocks. Maybe having the front all tight now puts more pressure on the old suspension? Is there anything else I should be considering as the cause? I never noticed it before the front work, but honestly it’s possible that those are still original coils and shocks.

Thanks for your advice and comments.

At that mileage,just about every factory bushing on the rig is likely roached. I had a pretty bad sway/wander as well and found the rear lower arms pretty much had no usable rubber inside them.
This was even present with the new OME springs and Billies, so just those alone may not be the solution...

The shocks and struts can cause this.. I'm with Ghostring on control arm bushings. Also if you're lifted the panhard angle could be the issue. I went with Whitline bushings. They helped a lot (except they squeak). Emkieth kit for the pan hard. Problem solved.

Ok thanks. I’ll check out those bushings. The only ones done so far are the front and back sway bar bushings. I’ve got new shocks waiting to be installed & I’ll order some coils.

Oh it’s not lifted.

Did you happen to get new tires also? Tread design can give a rocking side to side feeling when on some surfaces also. My new Cooper At3 4s tires cause my 4runner to rock side to side when I’m on new concrete sections of I-80, where they trowelled small groves in the concrete. I have Goodrich Rugged Trails on my ‘01 Tacoma and zero rocking on the same section of freeway. I hate the feeling, but getting used to it.

Some of your symptoms suggest other issues, but thought I’d throw it out there anyway.

Not new tires but they did get rotated. They still have decent tread but are worn unevenly because of the other issues. I figured I’d replace them after dealing with the front end and suspension. The tires could definitely be the culprit though, since the problem popped up recently and it really seems connected to the pavement conditions.

i will go for rear control arm bushings and panhard rod bushings.....esp if any kind of lift

You're in CA so likely not a rust problem. My 2001 at 265k had had enough Ohio road salt, and the right rear control arm bracket weld gave out, causing unnerving swaying on its final drive to be traded.