zinvant

I just got my first yota, its a 93 ex cab 4x4 with a 22re, 150,000 miles, It has a 4 in body lift and what appears to be 2in blocks in the rear and the tortion bars turned up to raise the front. So about 6in total lift, When I test drove the truck It had this shimmy of the bed, it would bounce back and forth about 3/4in from 50 to 60 mph. I got under the truck and found one of the rear shocks had ALOT of oil comeing out of it so i wrote the shimmy off as a bad shock and baught the truck. Ok so I went down and baught 2 new rear shocks , trailmaster ssv for the rear and put them on, same thing except the passenger seat rattles with the bed shimmy now, so I took it to les schwab tires and had the front end alighned and the tires balanced and rotated. And i know they balanced them because I removed the old tire weights right before I went there!!!! So the front end was in great shape, a little adjustment on the toe but thats it. I drive my new truck home and same darn thing, some days are worse than others but olny from 50 to 60. checked u joints , they are in great shape. And I am willing to bet my paycheck that this shimmy is coming from the rear of my truck I am just out of ideas, Could it be that the shocks in the rear are not strong enough to control the heavy tire and wheel? the tires are 33x12.50 wild country (les schwab brand, they are big here in the north west) . And the wheel is 15x10 aluminum modern wheel. I have even went as far as removing the rear driveline and driving in 4hi to get to 55mph and shimmy is still there. I tightented the bed mounting bolts down tight and same thing. This truck runs great other than this problem. I have done searches on this forum and found 1 other simular problem but his was in the front, mine is in the rear, My stearing wheel doesnt even move when this happens, I can let go of it when this is happening and truck goes straint and stearing never vibrates. Any advice would be helpful. Stronger shocks?? what brand?? Am I forgetting something?
Thanks for your time!!!

BAZ

4 inch body lift is a little excessive, are you sure the bed/cab mounts aren't loose or worse yet broken? The "puck" could have busted through the bed from un-needed stress. I'm sure someone else will chime in on the subject...

abecedarian

bent rim or out of round tire?

edit- are the wheels weights on the inside lip of the rim, the outside lip, or both or on the inside of the rim?
was it a static balance or dynamic?

zinvant

do most tire shops have a way to true a tire if its out of round?

abecedarian

most of the shops I've been to don't
some off road shops may have the equipment, possibly industrial tire dealer / truck stop

zinvant

the weghts for balancing the tire are the strip type that have adhesive and they are not attached where the beeds ride they are near the center of the wheel.

abecedarian

That may be part of the problem.
Placing the weights in the center of the rim is not as accurate as weights placed at the outer edge of the wheel.
Since it is possible for a heavier / denser part of the tire to not be in the center of the tread, placing the weights in the center of the wheel won't be able to compensate for the wobble as well as weights out at the bead. Therefore the wheel may be balanced in the vertical plane, meaning they won't 'lop' around up and down, but not balanced in the horizontal so they may wobble side-to-side slightly.
Also, worn bushings in the springs could amplify the bed vibration problem and the body lift isn't helping.
Finally, larger tires are harder to balance well. You may look into a hub mounted wheel balancing device similar to what a lot of truckers use.
4crawler has a write-up here: http://www.4crawler.com/4x4/CheapTri...ce/index.shtml

SwampThing

I'd check the weights on your driveshaft. Out of balance driveshaft can cause odd vibrations at certain speeds/rpms.

HAVOC

And get rid of that body lift!

nk

Curious if this was ever resolved (2 year old post). I have had a similar issue with my 94 xtra cab (4" block lift in back), not bad just enough to make the rear-view mirror see triple as my truck does its little dance down the highway. Shimmy seems to match tire rotation cycle so Im hoping tires are the culprit. I actually have the same tires as zin too.

Anyway I just did a 5" tg rear lift, new 5.29 gears with full install kit, and am going to a one-piece driveline. When I finish the front and can drive it I am going to test if the shimmy is gone. If not I am replacing the tires next...fingers are crossed.

offset442

I'm thinking tires and rims, there is not much inside of an axle that can cause out of balance conditions, except maybe a wheel baring gone bad. I doubt bearing because it would have to fail with a forced wobble. I think that would be a type of condition that would like cause it to catch fire sooner than later, and don't laugh i have actual had a wheel bearing catch fire b4 on my 87 22re pu almost lost the tire to it and it turned the output shaft to blue oxide, almost replaced it because i was worried about the heat treating being compromised.

Propeller shaft issues are usually felt as annoying vibrations because of there small diameter they cant generate much in the way of low frequency shimmy's very well

so thats my 2 cents, spend it