Resolution to flutter at 25-30 mph

[TinsleyC]

So driveshaft still turns when engine is off and car is moving.

Maybe the shaft is hitting something under there? Really strange. Torque converter?

 

[Gennadiy]

That’s the million dollar question. Nobody has a definitive solution.

 

[arcman]

(I've most likely posted much of this in previous threads)

I've spoken with a few drive line experts and the most popular opinion is the center support U-joint. As the driveshaft rotates, the joint works ever so slightly back and forth creating wear (flat spots) on the yoke pins from the needle bearings. This pretty much happens with all U-joints.

Why it only makes noise for a few minutes, I can't tell you. Like many others, the noise in my car comes from under the center console. But... the U-joint center support mount point is nearly two feet farther to the rear. My original thoughts were the rubber coupler as it is under the console. But after more conversations with drive line people, they said that noise is consistent with U-joints.

My car has no warranty and I wasn't about to buy a $1,000 driveshaft so I picked up a used one in anticipation of replacing the U-joint. I don't know the miles on this shaft but you can feel the slight flat spot in the joint as you rock it over the center point.

Two things brought this plan to a halt. The joint is non-standard so there's no direct replacement. And, the outer yokes on the rear shaft are staked, meaning no cir-clips to hold it in. (Thanks Hyundai) I could see machining out the yoke bore and adding cir-clip grooves, alternatively tacking it in place or figuring a way to stake it but centering the joint now becomes critical so you don't have vibration. (Miss by a couple thousandths and it's junk) Even if you nailed the centering, the shaft would still need to be balanced, adding to the cost. I decided to live with the noise.

Another thought is the center support rubber bushing that holds the bearing. It's really soft and has sagged down maybe 3/8" to 1/2" over 40k miles. I wonder if flipping the support over 180 degrees (changing the angle and wear points) would make any difference?

It may also be worth a try going back to the coupler approach. It's only $80 and easy to swap (six bolts). Anybody want to give it a try? Part number is: GAH04-004, made by SGF. I spoke with a rep and it's available. (when owners get their shaft replaced, and it fixes the noise, the coupler is part of the new shaft)

 

[Gennadiy]

The problem is that you spend all this time and money on repairing the flutter and the vibration is still there. I had the driveshaft replaced under warranty.

 

[skipgen]

Is it just me or does this just seem to affect mainly V6 cars...?

 

[Kraig Wilkinson]

Is it just me or does this just seem to affect mainly V6 cars...?

I think you may he on to something skipgen... I was seeing if I had the flutter just today.. I seem to be good. 15 5.0. First drive in 2 months but still nice and smooth. I also parked the car on flatstoppers. Makes a huge difference .

 

[Gahaha]

Is it just me or does this just seem to affect mainly V6 cars...?

No, my car is V8 and still has the sound, right now not noticeable at all unless I really strain to listen but its due to warmer weather.

 

[skipgen]

No, my car is V8 and still has the sound, right now not noticeable at all unless I really strain to listen but its due to warmer weather.

Glad I haven't experienced it - my car still seems to be tight as a drum @ 80k. I've heard elsewhere on this forum that subframe collars help get rid of some of the noises these cars have.

 

[Kraig Wilkinson]

Glad I haven't experienced it - my car still seems to be tight as a drum @ 80k. I've heard elsewhere on this forum that subframe collars help get rid of some of the noises these cars have.

I ordered my collars Saturday. I will let you know what kind of difference they make. I am hyper critical about my vehicles..so I will let you know.

 

[Andyj]

These cars are "relatively" well insulated and tomb quiet so you hear stuff that typically goes unnoticed. I could play whining tunes with my 2015 rear differential until it was replaced under warranty. I also have a slight flutter in the drive shaft at low speed but it's not madenning, (yet) so am sitting on the fence to see how a fix plays out. Still love the car and will keep it long term.

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[Kraig Wilkinson]

These cars are "relatively" well insulated and tomb quiet so you hear stuff that typically goes unnoticed. I could play whining tunes with my 2015 rear differential until it was replaced under warranty. I also have a slight flutter in the drive shaft at low speed but it's not madenning, (yet) so am sitting on the fence to see how a fix plays out. Still love the car and will keep it long term.

Yes I agree
.these cars are very quiet. I am hoping to install collars this weekend. Let you how it helps. My 15 is tight no rattles or squeaks. I really believe these cars are solid.. I to am keeping this for the long haul...

 

[Markymark]

Can someone please explain what a subframe collar is? I agree that the car is so quiet that you only notice the flutter because of that. Btw, i haven’t noticed it at all in the warmer weather.

 

[Suburbazine]

Can someone please explain what a subframe collar is?

 

[TinsleyC]

At the 6:55 mark in the video you can really see the space/gap between the frame hole and the bolt - lots of play allowed there. The collar really fills it up.

It would be nice to have anytime access to a lift!

 

[Kraig Wilkinson]

At the 6:55 mark in the video you can really see the space/gap between the frame hole and the bolt - lots of play allowed there. The collar really fills it up.

It would be nice to have anytime access to a lift!

Yes I agree, use of a lift at anytime would be great. I going t oil lubricate the threads of bolts and buts when I install my collars. You can get a lubricated thread tighter with less force..

 

[arcman]

No offense to those who bought these things but those bushings smell of snake oil. Their ad claims the bolts come loose over time and things start to move... What nonsense. If that were the case, there'd be no need to use an impact to get them off.

There is some clearance but this stuff isn't moving, especially with 130 lbs of torque, and they're rubber mounted, reducing the load on the bolt. I didn't see anything shiny on either side of the rear plate, indicative of wear.

In the end.. what are they actually supposed to do? If you're looking to reduce vibration, you're going the wrong direction by 'tightening' things up. If you're looking for some kind of handling improvement, I doubt if even Mario could notice the difference after putting those things in.

 

[Kraig Wilkinson]

No offense to those who bought these things but those bushings smell of snake oil. Their ad claims the bolts come loose over time and things start to move... What nonsense. If that were the case, there'd be no need to use an impact to get them off.

There is some clearance but this stuff isn't moving, especially with 130 lbs of torque, and they're rubber mounted, reducing the load on the bolt. I didn't see anything shiny on either side of the rear plate, indicative of wear.

In the end.. what are they actually supposed to do? If you're looking to reduce vibration, you're going the wrong direction by 'tightening' things up. If you're looking for some kind of handling improvement, I doubt if even Mario could notice the difference after putting those things in.

I guess I will soon find out. I would be ok with having the sub frame bolts sitting square and center in the hole. As far as the subframe moving around IDK. ?

 

[Suburbazine]

No offense to those who bought these things but those bushings smell of snake oil. Their ad claims the bolts come loose over time and things start to move... What nonsense. If that were the case, there'd be no need to use an impact to get them off.

There is some clearance but this stuff isn't moving, especially with 130 lbs of torque, and they're rubber mounted, reducing the load on the bolt. I didn't see anything shiny on either side of the rear plate, indicative of wear.

In the end.. what are they actually supposed to do? If you're looking to reduce vibration, you're going the wrong direction by 'tightening' things up. If you're looking for some kind of handling improvement, I doubt if even Mario could notice the difference after putting those things in.

Hard to tell, but, the subframe didn't move when taking the nut off.


after collar


Also, that's a Genesis Coupe in the video, not a sedan. Much lighter car with less movement readily obvious. Just because there aren't metal shavings falling off the subframe doesn't mean it doesn't move around the bolt.

Genesis Coupe Genesis Coupe nice it's rewriting the shortened term lol

 

[Suburbazine]

Update- the collars didn't completely fix it, but the noise has been changed to a ticking sound at 35-36 only. Took a while to notice it.

 

[Kraig Wilkinson]

Update- the collars didn't completely fix it, but the noise has been changed to a ticking sound at 35-36 only. Took a while to notice it.

Did you have the car alignment after the installation of collars?