1998 Chevy Suburban shimmy (bad)
 

Here's the deal, I have a 98 K2500 4x4 suburban with 222,000 miles on it. I recently noticed the front end was quite worn so I replaced the inner/outer tie rods, upper and lower control arm bushings, pitman/idler arm, steering gear, sway bar links, bushings, pads and shocks. Had truck aligned and all is well..that is until I towed.

I had a brand new empty trailer, weight maybe 2000lbs that after about 40 minutes of driving time started a shimmy as if the lugs were loose. Hit the brakes to pull over and it nearly tripled the shimmy. After checking everything I went on my way, after a few minutes it came back. anything over 50 mph and it gets noticeable, even by simply letting off the gas it gets more noticeable, but hitting the brakes makes the dash move!!

Today I went to tow again, truck was perfect (towing 9500+) no shakes or anything until I hit that 40+ minute mark again. After slowly getting boat to the ramp I left the boat there and truck was perfect the whole way home. It seems as if adding weight in the back, thus raising front, is causing this... No extreme tounge weights either. Please help. Thanks

I had a milder but similar shimmy in my F250....turned out to be a stuck caliper, overheating the rotor. Does it pull to one side? You can check brake temps with an infrared gun or by touch (be careful!).