2018 4Runner - Severe Vibration in Steering Wheel When Letting Off Gas at Highway Speed

[dan50]

2018 4Runner - Severe Vibration in Steering Wheel When Letting Off Gas at Highway Speed​

2018 Toyota 4Runner Limited, 113k miles, 1GR-FE 4.0 liter V6 engine, A750F 5 speed automatic, VF4BM electric full time transfer case with torsion center diff, second owner (since ~90k miles), original bushings, control arms, shocks/struts, U joints, etc. POS tires that came on it when I bought it; balanced 8k miles ago, new rotors/pads/stainless steel lines/brake fluid 5k miles ago. I aligned the vehicle 5k miles ago (1 deg thrust angle to the left, front wheels aligned with the thrust angle, 2/32” toe-in total, 1/32” per wheel, which is what I’ve always run my 5.0 liter Mustang at. I hope that’s enough detail.

Last night when returning from dinner, a severe steering wheel shimmy appeared when I let off the gas after merging onto the highway. Speed was ~60 mph and the shimmy was present at any speed between 50 and 70 mph when letting off the gas. Getting back on the gas eliminated the shimmy. Severe enough that I was wondering if my lug nuts had backed off. Does not appear, or I couldn’t detect it, at speeds under ~40 mph. Was NOT present on the drive TO dinner 90 minutes earlier. Never been an issue before last night, either.

What should I look at? It’s not the lug nuts.

 

[gomiami]

2018 4Runner - Severe Vibration in Steering Wheel When Letting Off Gas at Highway Speed​

2018 Toyota 4Runner Limited, 113k miles, 1GR-FE 4.0 liter V6 engine, A750F 5 speed automatic, VF4BM electric full time transfer case with torsion center diff, second owner (since ~90k miles), original bushings, control arms, shocks/struts, U joints, etc. POS tires that came on it when I bought it; balanced 8k miles ago, new rotors/pads/stainless steel lines/brake fluid 5k miles ago. I aligned the vehicle 5k miles ago (1 deg thrust angle to the left, front wheels aligned with the thrust angle, 2/32” toe-in total, 1/32” per wheel, which is what I’ve always run my 5.0 liter Mustang at. I hope that’s enough detail.

Last night when returning from dinner, a severe steering wheel shimmy appeared when I let off the gas after merging onto the highway. Speed was ~60 mph and the shimmy was present at any speed between 50 and 70 mph when letting off the gas. Getting back on the gas eliminated the shimmy. Severe enough that I was wondering if my lug nuts had backed off. Does not appear, or I couldn’t detect it, at speeds under ~40 mph. Was NOT present on the drive TO dinner 90 minutes earlier. Never been an issue before last night, either.

What should I look at? It’s not the lug nuts.

Hard to say over the Internet but, if there is no noise (just steering wheel vibration,) it is a wheel or tire problem. You can probably eliminate a bent wheel fairly easily with a visual inspection. Same with tire damage, looking for bulges or uneven wear. A tire or wheel imbalance can't be seen, only felt and the recent balancing doesn't mean anything.

If the tires are junk, a new set with proper balancing...