Another Shimmy Question...??

My GF and I have an 09 Taco Access Cab 4WD with only 49k on the clock. It's developed a shimmy, not long after an alignment was done. Tires are using ceramic balancing beads which have worked quite well and for the moment I'll rule tire balancing out. What would be a mechanical cause for the shimmy? The Taco is a daily driver and no wheeling is done with it. Is it possible that the alignment went "out", maybe by hitting a nasty pothole? It tracks straight with no pulling... Any ideas to help a newbie out?

 

Alignment shouldnt cause shimmy. I wouldnt rule out tire balance though. Slight imbalance and you will get shimmy. Do you feel it in the steering wheel, or the truck in general. If the steering wheel, almost definitely the front tires. If its the whole truck it could be driveline.

 

The shimmy is felt in the in the steering wheel. It's also not consistent. Most times it's at 55+ but sometimes it's comes and goes. Very strange indeed. Most times a speed sensitive shimmy is wheel balance. When first I installed the ceramic beads, it rode smoother than it ever had.

 

Rotate your 2 front tires or front to back. The tires are out of round or have some toe in damage. I bet it goes away immediately.

 

is it when you apply the brakes or just normal driving? You might have thrown a weight and your wheels are off balance...especially if its not pulling one way or the other..

 

He's using dynabeads.

 

Nothing is felt while braking so I'll assume it's not warped rotors. One thing that I didn't mention is that when I drive up my driveway (about 600ft) which is rocky and rutted, there seemed to be more back and forth movement of the steering wheel than normal which suggests a steering issue.....

 

I would rotatw the front tires to the back like said above. An rule that out. First and foremost.

 

There is a tsb for that feeling in the steering wheel when going over bumps. There isnt anything 'wrong' or dangerous, youre just feeling the steering shaft u joint rattle. The tsb is simply zip tying something together to keep it from shaking.

 

I re-torqued the lug nuts to 85 foot pounds and adjusted the air pressure from factory specs to 35 front, 34 rear and it made a fairly significant improvement. Still have a shimmy at 55 but only going straight. It disappears on curves (even slight ones). BTW, I'm running General Grabber AT2's....