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Please please please help me understand this

I’m driving myself insane. I have taken my car to 3 different shops with all 3 having different answers to my problem.

I own a 2010 Hyundai Genesis 4.6L my car has 115,000 miles on it. Every time the car goes from a complete stop or slows down when making sharp turns the driver seat and the middle console vibrates or shakes or rattles, it ONLY does it then. The car feels very smooth always after gets into 2nd or 3rd gear. You can feel it ONLY at 2000 rpm+. The higher the rpm the more you feel the vibration. And again it goes right away always after car gets to 20 mph and always starts at 15 mph, at 2000 rpm and above.

One mechanic told me it could be your driveshaft or u joints or engine mounts. I paid them to lift up the car because they said tires looked good nothing looked bent everything was all aligned as well. They told me after lifting it they inspected it all and everything from what the eye could see looked good in shape and not wore out. They also checked fluids and bacsically did a whole check on the car but from what the eye could see nothing. I was told just keep driving and if it gets worse bring it back.

It bothered me so much I took it to another shop and they drove the car and said they believe it could possibly be my transmission only because it seems to only happen from 1st to 2nd gear. They also lifted it and did a full Check around inside and out and said from what the eye can see she seems to be in good condition.

I was driving home and a check engine light came on. I was right next to my dads old buddy’s shop so I asked him to read the code and I wish I knew what the exact code was but I forgot, it definitely was a code about my throttle body. He called my dad and said I cleared the code just see if it comes up again.

Could this be the reson the car is vibrating?because everyone has lifted the car and looked at it all around and said it was good until this code came on at the last stop which was my dads mechanic. All mechanics said the drive shaft and u joints looked good but it could maybe be transmission they just don’t know until they dig deeper which would cost way to much for me right now. I have been told throttle body check engine light would not make the car vibrate the way I’m describing it.

Any tips or advice will help so much thank you again means the world to me I can’t stop stressing.

What about taking it to a Hyundai dealer for an opinion?

Hey thank you so much for replying. I called one with really good reviews online but they seemed to have blowed me off on the phone. I was going to take one there but I hate that I keep spending 100 bucks for somone to do the same Checks around the car they have been doing.

Have you ever had the transmission fluid changed?

“Every time the car goes from a complete stop or slows down when making sharp turns the driver seat rattles”?
goes from a stop means accelerates. comes to a stop is clear.
so it rattles when you start moving and rattles when you stop?

Hi there yes fluids are al up to date

Hi there. It happens when I accelerate from a stop. It feels a like vibrates right under driver seat And center arm/console rest but again ONLY when taking off in that rpm and mph range I posted above. It does not happen when slowing down but when I pick up speed after slowing down it does it. But again ONLY at 2000+ rpm at 15-20 mph. I feel like it’s my transmission only because the car vibrates a lot like my clutch is wearing out. But I could be wrong I don’t know too much about cars

My very first thought is that it is your driveshaft which is to say your U-joints. Depending on the frequency of the vibration this should easily be diagnosed. Is the vibration fairly fast or quick in cadence? If so the only item able to do this is the driveshaft…and you have one in your vehicle.

My money is on the u-joints in the driveshaft…

If I replace u joints should I might as well pay to replace the driveshaft? I know it will be very expensive but if is the u joints are doing it would you say the driveshaft also needs to be replaced with them? And by the way yes the vibration feels fast and quick.

Thank you so much for helping with al this to everyone I wish I could take y’all out of some drinks.

No… when you need to replace U-joints in a driveshaft… You simply replace the inexpensive joints… they come out and are replaceable. Usually around $20-25 each… You will have at least 2 on every shaft.

Awsome. But let me ask you this, If 3 different mechanics lifted the car and looked at the u joints and the driveshaft and all 3 said it looks good from what they can see then do you think it’s probably not the u joints and driveshaft? They checked without ripping things apart. are you not able to see the problem until you take things apart?

U joints in my experience can be inspected for play without disassembly. A misfire can certainly feel like another problem. When your code come back start there!

Honestly I cannot speak to the mechanics skill level that looked at this issue. Sometimes u joint failure is very easy to spot and in those circumstances you would already be on the side of the road or wanting to be on the side of the road stopped.

Other times they fail in a more subtle fashion and it only takes one side of one u joint to seriously throw the shaft out of balance. If you have a high frequency vibration at such a low speed then the driveshaft is the first place to look as it is really the only thing spinning that fast in that general location.

I have diagnosed and repaired countless u joint failures over time and each time I thought it was the u joints…it was. Maybe I am lucky, I dont know. It should be apparent once the shaft is removed and in hand so to speak. I would not feel comfortable discounting the u joints based on 3 guys who just “looked” at the shaft and did no deeper investigation. You can use a pry bar or similar device to test or stress each joint…any movement in that joint is immediate cause for replacement… So no…you cannot diagnose this issue by sight alone. Hell with a lift you can actually run the vehicle and watch the shaft… Its been done many a time I can promise you.

Ok guys I will take all this advice and if I find out I will let you guys knows. My final question is this, could it possibly have to do anything with that throttle body Check engin light that came on or does your throttle body have nothing to do with casing vibrates the way I described

Possibility.

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Your vibration is probably caused by worn and hard engine mounts, there is more torque placed on the mounts in low gears than high gears, that is why you feel the vibration when accelerating at lower speeds.

BTW, there is only one universal joint, it is located in the middle of the drive shaft. There are flexible couplings on each end of the drive shaft. Most luxury cars use flexible couplings in place of universal joints.

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