Shaking at 30mph & 40mph

Hi All,
I’m new to the forum, but so far it seems as though yall may know your stuff!
My 2015 SR5 (159k miles) is shuddering or vibrating at precisely 30 & 40 mph then stops. When I switch to “S” mode it stops or if I’m already in “S” mode, doesn’t at all. The dealership wouldn’t look at it. They said new transmission $5k used or $6k new.

Called a mechanic out to diagnose & he was puzzled.

Mods include a leveling kit, 33 tires / 17” rims that are balanced & rotated @ 5k miles routinely.

My baby is sick & she needs help! STAT!!!

 

Welcome to the forum! I would use the search feature to find similar issues because I've seen them before.

My first thought, given the oversized tires, would be a potential balancing issue. I *think* that is usually the culprit. Seems the 4runner is very sensitive to balancing issues.

Second thought would be needle bearing. Really weird that S mode would prevent the shaking but if putting it in 4wd takes it away, that is usually a good diagnosis

 

My car doesn’t have 4wd, but can switch to “sort of” manual which is the S mode. I’ll definitely look into the bearing issue.

You don’t think it’s a transmission issue?

Thanks for your help!!

 

Somebody else mentioned this thread earlier today: https://www.4runners.com/threads/drive-line-shudder.29509/#post-416202

I have no experience with this issue, so I don't know how likely it is. I expect less likely than a tire problem.

 

If you don't have 4wd then you don't have a needle bearing.

I would chase down tire issues before I replace the transmission. 4runners seem overly sensitive to balancing issues, especially if they are heavy. Your 33s are going to be much heavier than stock - especially if they are C or E load.

Again, search the forum because it's been brought up before. I think there is a specific type of road force balancing that helps but can't remember the name

 

maybe this might help: 4 Common Types of Car Vibrations. What They Mean and How to Fix Them (youtube.com)