KNOCK IN REAREND 5.0 Ultra

[Mac West]

HEY Kids , I have been having a problem with my Bitching 5.0 on Launch under full acceleration. I first thought it was the sunroof and was posting in that thread ( sunroof rattle). But after I got my wife to sit in back seat for once not naked. Its coming from the rear.The car must be hot to replicate the issue this meaning driven on highway or local for about 20 minutes. When I just cruise around no issue but wide open I get a knocking noise that can be felt in rear through the ski pass through in the trunk you have to put you hand down right at that point of the trunk floor to feel it . If you are driving you just hear it and don't feel shit. It has been driving me crazy. So doing research on rear end noise the fluid in the rear gets hot and the knock starts. I will be draining mine next week end and first checking the level maybe not filled correctly. Please let me know if anyone else is experiencing this knock. Wont go to dealer just a waist of time until there is a service bulletin. Thanks Mac

 

[Alwaysforward]

When you drain it drop in a magnet to see if you find any chips. At what speed are you going when you here it?

 

[Mac West]

DEAD stop launching WOT. Mac

 

[Alwaysforward]

Are you using the Auto-Hold function?

 

[Mac West]

No auto hold being used

 

[Aquineas]

(subscribed)

 

[jimb100]

HEY Kids , I have been having a problem with my Bitching 5.0 on Launch under full acceleration. I first thought it was the sunroof and was posting in that thread ( sunroof rattle). But after I got my wife to sit in back seat for once not naked. Its coming from the rear.The car must be hot to replicate the issue this meaning driven on highway or local for about 20 minutes. When I just cruise around no issue but wide open I get a knocking noise that can be felt in rear through the ski pass through in the trunk you have to put you hand down right at that point of the trunk floor to feel it . If you are driving you just hear it and don't feel shit. It has been driving me crazy. So doing research on rear end noise the fluid in the rear gets hot and the knock starts. I will be draining mine next week end and first checking the level maybe not filled correctly. Please let me know if anyone else is experiencing this knock. Wont go to dealer just a waist of time until there is a service bulletin. Thanks Mac

This has been mentioned in a few other threads and I've experienced it just as you described.

At this point, I don't think anyone knows what causes it but its real.

 

[Mac West]

I am going to change out the fluid this weekend i will let you know the outcome

 

[Mac West]

No freaking luck changed the fluid and noise still there. Take a look at pics and look at the amount of metal shavings look at my hand thats all off the magnetic drain plug. My miles are 1380. I always change my fluids after break in. Wish i could find the knock noise.

 

[Alwaysforward]

Thanks for the update. Would you say that the small amount of metal shavings is normal during break-in period?

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[Mac West]

Yes its normal . I was making the point why if you want to keep your car for a long time its is always good to drain your fluids after initial break in . The magnet on the drain plug is an indicator that the manufacturer knows there will be metal in the fluid. As long as there was no metal pieces which there weren't its all good. Just one thing from this fluid change. Anyone having that winey noise when decelerating, you can hear it with radio off this fluid eliminated it. I just ordered taller race ramps so I could go further up the driveline to see if I can find this noise. While you are all eating your Thanksgiving Turkeys , I will be on my back in the driveway looking for it . Happy Thanksgiving all. Mac

 

[Mac West]

Well another update. I was under the car with my new taller race ramps and still cant figure out where this noise is coming from . I cant see any visual clues where contact is being made. One thing i learned is you can make the noise appear by brake tourqing motor bouncing rearend I heard it. Im still looking . Mac

 

[Gunkk]

There are a couple threads on this. My original 2-cent diagnosis-from-afar was a design or assembly defect in the early-build 5.0's that was later corrected. My guess: Suspension bind, body-frame mismatch, or bad weld that's causing the noise due to induced strain. Hyundai knows what it is, but getting them to admit it might be difficult.

 

[Mac West]

Are you saying on the 2nd generation or 1st generation 5.0? And can anyone point me to the threads discussing this because I cant find anything on it Thanks . Mac

 

[Mac West]

YEAH I THINK I FIXED IT!!!!!!!!!!!!!!!!!!!!!
Like I said before I was underneath tightening every bolt well today I was under again only this time with a pipe on the end of the wrench, then you really feel what's loose , I drove it all day and noise is gone I hope its gone for good. I don't know what it was since I wrenched on so many bolts

 

[Mac West]

Noise is back Ahhhhhhhhhhhhhhhhhhhhh. Same symptom car has to get hot knock is back THe only other thing I can think of is its something in the gas tank or the exhaust. F$Ck ME. Mac

 

[ckon]

Noise is back Ahhhhhhhhhhhhhhhhhhhhh. Same symptom car has to get hot knock is back THe only other thing I can think of is its something in the gas tank or the exhaust. F$Ck ME. Mac

MAN! So frustrating thinking you finally found it only to have it return after a couple of days.

 

[2ez24get]

Noise is back Ahhhhhhhhhhhhhhhhhhhhh. Same symptom car has to get hot knock is back THe only other thing I can think of is its something in the gas tank or the exhaust. F$Ck ME. Mac

If I were to guess I would say it was caused by high pinion angle on launch. Driveshaft drives up pinion of the differential causing the noise. Check for any signs of scratches around the driveshaft tunnel and differential. OE Soft rubber bushings lower vibration but will allow more movement in the suspension. The 2015 Genesis has two driveshaft joints. Check both one of them is probably hitting the body or frame.

 

[homeofstone]

Noise is back Ahhhhhhhhhhhhhhhhhhhhh. Same symptom car has to get hot knock is back THe only other thing I can think of is its something in the gas tank or the exhaust. F$Ck ME. Mac

Leave at dealer and demand a loaner until your car is fixed correctly. If they take a month you have a loaner that you could drive 5000 miles if you want.

 

[2ez24get]

Two suggestions.

One is to pursue the Lemon Law in your state. This would get Hyundai's attention. Follow up with your local better business bureau.

Two is to test drive another Ultimate with the service tech and compare the two. Still my guess is a bad bushing in drivetrain and when heated by the exhaust causes excessive travel. Every bushing is measured by (durometer) bushing stiffness.

If you need extra weight then get a couple adults in the back. Extra weight adds load which causes more drivetrain loading.