jd23dr6

My LS460L 2014 has 150k miles, and very rarely (like once a month), when im cruising on the highway, I get this very sudden very random shudder/ vibration. It’s not too pronounced and it just feels like the car suddenly became rougher, like it stopped being a luxury car and became a truck.

Goes away when I slow down and doesn’t come back for a while, probably 2 weeks or a month. Very random.

What could it be?

dan25man

Is this shuddering from the engine or suspension? If engine, do you have any store codes? Suspension wise the upper control arms are known to go bad at some point. I'm currently dealing with a similar suspension issue. I have some crunchy sounds coming from the drivers front. I think it's the lower ball joint, or the lower, forward control arm bushing. I've got to get it up on a lift this weekend and check it out. At 73-78 mph I get a slight shimmy/vibration from that tire. Like a dynamic unbalance, but the tire's have been balanced multiple times so I think a bushing or ball joint is worn. Once I get to 80mph the vibration goes away. And anything under 70 mph I don't feel or notice it. The front suspension of the LS460's have 4 ball joints so if one of them is worn it's allowing your wheel to move in not-nice ways.

Gerf

Next time it happens take your foot off the gas pedal, if it's still there shift into neutral and see what happens.

jd23dr6

Thanks I’ll try, so assuming it goes away if I take it off the gas, means it’s what?

and if it goes away under neutral it’s transmission mount?

jd23dr6

I feel like it’s felt throughout the vehicle, in a homogeneous fashion. I didn’t perceive it as coming from engine or transmission as it didn’t get any worse under acceleration or downshift

Gerf

When you're at a constant speed and shifting to neutral immediately stops the vibration then everything from the wheel bearings out is eliminated and then you can have a look at the driveline, diff/trans mounts etc.
If it only happens once a month it could even be the section of road you happen to be on and the condition of your tires...you said it stops when you slow down. You need to drive it and have a plan to try a few different things when it's happens, make a few notes if you have to.

Striker223

Do as Gerf says, it will help let us know what is causing it.

Dean2

In addition to the above good advice, is your car AWD. If it is, have you had the Transfer case oil changed? These cars use a specific oil that has no other source than Toyota. You cannot use an alternate and if you don't use the $200 a quart Toyota stuff you will get a shudder. Good part is it only takes .75 of a quart to change it.