I am the original owner of a 1999 4Runner 2WD Limited. The vehicle has over 277K miles. I began noticing some bad vibrations at speeds over 60 mph about 4 months ago. There is a slight vibration in the steering but not as much as I feel it in the body of the vehicle.
I have had the following replaced. The front suspension shock and strut and the rear strut a month ago. I did not replace the rear coil springs. The vehicle has had an alignment 2 weeks ago. The rear tires were replaced a little over a year ago and the front tires were replaced this week. The brake rotors and pads were replaced a month ago.
I was told when the brakes were replaced that the suspension was worn and the front tires were badly cupped. I was hoping that after replacing the suspension and tires would have fixed the vibration. No such luck.
I am looking for suggestions as to what could be causing the vibrations. A weird thing that I noticed a week ago was that when the temperature was cooler in the morning, the vibration was less. Don't know if this relevant, but it did seem odd.

 

Let's start with have you ever replaced upper and lower ball joints or tie-rods? Any of the bushings in the front and rear control arms?

 

No, I have not. How can I check to see if the parts you suggest are bad? Is it better to replace the control arm or just the bushings? Can these items be replaced by myself or does the vehicle need to go to a shop? Can you recommend a good brand but not too expensive? Thanks for your response.

 

I wouldn't throw any more parts at it until you eliminate some possibilities or actually locate the vibration. You say you feel the vibration more through the seat than the steering wheel, that usually points to something on the rear end of the vehicle. Try putting your truck up on jacks and run it at low speed while watching the rear wheels/tires for any wobble. Could be bent wheels/axles, flat spots on tires, out of balance wheels and tires, brake dragging slightly, something like that. you say you replaced the rear tires a year ago and started feeling the vibration 4 months ago, maybe one of the weights fell off, rebalance the rear wheels or rotate them to the front and see if your vibration is then in the steering wheel. If you go to rebalance the wheels keep in mind that Toyota trucks have fairly large tires for the weight of the vehicle, so they are run with a fairly low pressure and are susceptible to "cold flat spots" when parked. Be sure that if you take it to a tire shop for balancing that it is driven for 10 minutes or so to build some heat in the tires and then put on their lift soon after. You will get a much better outcome than having it balanced with a flat spot, then the tires warm up and presto, they are out of balance. This may not be much of an issue in Arizona, but it definitely makes a difference in Alaska.

 

You would hope The tech that did your alignment would have pointed out any front end parts needing attention but now days who knows .

Look to the rear of the vehicle

 

Jomoka, you mentioned a possible transmission shift malfunction from the tps switch.
I do notice that with the AC on in 110degree heat, the runner is very sluggish. Almost as if its in high gear too soon. I know these 3rd gens are powerless and my timing belt has 300,000 miles on it , so power is an issue. I'm going to check the tps after work to see if i can get it to stumble while under the hood. I have little faith in aftermarket parts these days. Tps / autozone is 3 months old.
Thx!

 

I had a seat-of-the-pants rumble appear a few months ago and have tried to isolate it (it appears at about 65mph and fades after about 75mph). Although my Nitto Terra Grapplers have around 88,000 miles on them, they are not the source - I borrowed a set of Lexus GX wheels & tires recently and the rumble persisted. All of my u-joints are good and get a shot of grease every oil change or so. My rear wheel bearings are less than a year old - I replaced them when I installed my Zuk-refreshed third member.

So at this point I’ve decided that the rumble is coming from the transfer case. Or more specifically the output bearing. Other than fresh oil every 50,000 miles or so, it has 441,000 miles on it. I’m searching for a low-mileage case to swap in.

Lastly, I recently replaced the transmission mount and found that the rumble is noticeably reduced. Which gives some credibility to my thought that the transfer case is the culprit. The original mount was almost completely collapsed.



Andreas

 

Looks like you covered everything i was thinking.
Any chance the rear dogbone bushings might leave the rear end moving a bit?

 

I installed new Toyota lower arms a couple of years ago, and new upper arms earlier this year. I also replaced the Panhard bushings this year.



Andreas

 

Any resolution on this BigKnuckles?