I was driving along the other day and suddenly felt like I was driving over rumble strips, but wasn't, then the feeling just went away. The vibration is coming back more often now and more prominent. I tried switching the truck to 4wd the last time this happend and the sound changed then went away. The sound/vibration is coming from the front end and is intermittent. I am hoping it isn't the front diff, but what else could this be?
2004 Sport V6.....

P.S. it is quite violent, it feels gear/cv ish to me.

Did you ever resolve this? I just started getting the same issue.

Very intermittent. Can be very shaky for a couple minutes and the rest of the drive it is perfectly smooth.

Wheel bearing maybe? Have you both tried seeing how turning or braking or both affect this vibration? Have either of you had brake work done recently?

No recent brake work. I've tried braking, coasting, switching gears, putting into neutral, throttle/no throttle. It doesn't seem like any sort of input changes the vibration when it is happening.

It's tough to pinpoint due to the intermittent nature. I cannot reproduce this except when taking it out for the first highway drive of the day.

Weird. Have you tried to see if speed bumps or hill climbing have any affect? I would say try and record the sound if you can.

Pretty sure I have a seized passenger front caliper. Guessing the wheel is vibrating at a certain rotor temp due to unevenness and when it gets beyond that point it smooths out. Not 100% sure it is the cause, but this is my only sign at the moment

The part numbers I'm getting back are saying "For casting #13Wx" where x = G, H, or L. Is this stamped on the back of the caliper? (Trying to minimize work by not removing the wheel). The prices I'm seeing range from $100-450. With my luck, I bet I'm going to be requiring the $450 one

Check this thread to compare your symptoms. It sounds similar. They recommend doing a drain and fill little by little.

"Rumble Strip" Transmission issue

Has anyone figured this one out? I have an intermittent vibration. It showed up last winter during a bad cold snap. I would get a vibration on the freeway, then it would suddenly disappear. There is no sure way to re-create the vibration. During the summer it would show up every once in a while but not as intense. We are having another bad cold snap this winter and the problem has surfaced again. I took my 4Runner to a mechanic last year and this year and they have no clue what's going on.

994runner SR5 V6

Hey dgmorr, did you fix your issue with the new brake caliper? I have exactly the same issue and found a passenger side wheel bearing might be the cause of it (Did 180 degree test and the wheel moves at the top and bottom). Ordered the new wheel bearing hub assembly from eBay but still haven't receive it yet.

When does this happen? When braking, accelerating, idling? Could possibly be a torque converter issue as well. Good luck

The vibration happens early in the morning or later in the evening when it is parked outside for the day. Also it happens more often, louder and longer when it's getting colder outside.

Usually it happens between 40km/h and 80km/h when I accelerate and cruise. It does not happen when I brake or idle. It feels as something is stuck inside the transmission (as gears would hit each other or when shifting a manual transmission and a gear does not engage completely). It could sound like driving on a rubble strip but not exactly maybe sounds more like a hand wash board.

I thought about the torque converter as well. I did a drain/refill of ATF WS and added two tubes of Shudder Fix but it did not help eliminate the issue.

I'm having a similar problem, if not the same. I have a 2007 SR5 V8. Here's what I've noticed:

• When it happens, it happens for awhile. Most noticeably in the 50-65 mph range.
• The vibration is quite violent. The steering wheel shakes like crazy.
• I notice a burning smell, smells like the catalytic converter.
• Acceleration is sluggish. I check several times to make sure the emergency brake is not set.
• The braking is weird, it "crabs" when touching the brake pedal.
• The car pulls to one side.

Then, without any reason, it stops. Everything is great, the car is completely smooth and doesn't pull or brake weird.

The burning smell, the crabbing braking, the pulling to one side, and then it stops doing all this suddenly without any reason, makes me think it has to do with a braking problem.

Anyone figure out exactly what this is?

This exact thing is happening to me. It's my front/driver's side differential needle bearing. The tell-tale is how it disappears when in 4wd.

See Toyota TSB: T-SB-0026-15

It might be your solution

I'll look at the bulletin, but the V8 is in full-time 4WD.