GT350R High Speed Vibrations

[DonPatr0L]

Was the vibration present at the start of the track day or did it occur after a session or two?

If it happened after a session or two then it is possible you picked up some rubber or lost a wheel weight or you flat spotted your tries a bit or they started chunking, etc.

Also, you will have a hell of a time getting a dealership to diagnose and repair a vibration that occurs at 115 mph....

The honest answer is I cant remember if it did it in the first session. I believe it did though on the 2nd and definitely the 3rd. I didnt start doing video until the 3rd session so I couldnt go back and check.

And yeah troubleshooting is going to be extra interesting as Im sure the deal will say they wont drive past 60mph

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[WItoTX]

If you are taking it to the dealer, I definitely wouldn't tell them it was on any track. Or that you even know what a track is. Numerous threads about it on here about providing too much info and warranty denial.

Post up a photo of the entire width of the tread. Honestly, I wouldn't even mess with the dealer until you can do basic checks, like wheel bearings/tire inspection/bushings for play. Hell you could have gotten some debris on the drive shaft or axles, and it just needs to get cleaned off.

 

[DonPatr0L]

Second looking for missing wheel weights or excessive rubber pickup on the inside of the wheel. I've had both create vibrations. Also make sure the wheel bearings are good / lugs are torqued. If all those are good (and a wheel isn't bent), then check driveshaft.

Yeah going to do my best to focus my attention on the wheels/tires being the issue. I feel like its too easy, but feels reasonable that weights may have ejected during warm up.

 

[DonPatr0L]

If you are taking it to the dealer, I definitely wouldn't tell them it was on any track. Or that you even know what a track is. Numerous threads about it on here about providing too much info and warranty denial.

Post up a photo of the entire width of the tread. Honestly, I wouldn't even mess with the dealer until you can do basic checks, like wheel bearings/tire inspection/bushings for play. Hell you could have gotten some debris on the drive shaft or axles, and it just needs to get cleaned off.

Yeah fair points. The tires will be obvious case for tracking so will replace the tires before I take it in. Looking to get some 305 v730s since I think these cup 2s are done for.

Also need to clean up the tire marks on the front end/fenders

 

[DonPatr0L]

If you are taking it to the dealer, I definitely wouldn't tell them it was on any track. Or that you even know what a track is. Numerous threads about it on here about providing too much info and warranty denial.

Post up a photo of the entire width of the tread. Honestly, I wouldn't even mess with the dealer until you can do basic checks, like wheel bearings/tire inspection/bushings for play. Hell you could have gotten some debris on the drive shaft or axles, and it just needs to get cleaned off.

Something I didn't consider. This cant be it but figure I'll ask. I was running with both windows down. I can imagine turbulence from that would cause it but maybe? Assuming everyone else is running with windows down. My GT gets noisy but it doesnt shake at that speed

 

[WItoTX]

Mine is kind of loud, but I also added a little gurney flap between the mirror and the door to keep the wind buffeting/thumping down.

 

[mikedahammer]

My GT350 used to do that when I had slag in the wheels. Pittrace is the worst for it if you ever move from the race line. I use high temp foil tape over the wheel weights to keep them on and i always request soft weights to help protect other drivers windshields.

On my ZLE I get a horrible vibration when I run the supercar3rs down to where there is zero tread left and they look like slicks. The wheel and tire almost feels like it is basketball bouncing (which it is). If the tire looks like like that across the entire face then I think that is your issue.

 

[DonPatr0L]

UPDATE: Vibration is gone. Got the car up to 130 twice. Once with windows down and once with windows up, nothing.

Things that have changed since the track.

#1 Most likely issue. New tires were put on and rebalanced. Discount tire rebalanced the cooked Cup 2s I had on the car and said they were ok-ish, but they only spin to 60mph. So could have been the issue. In addition, tire pieces in the barrel could have thrown balance off, or the excessive wear on the shoulders I had.

#2 Aero. The front splitter, the previous owner or installing dealer did a poor job installing it. It didn't have the white half moon clips installed which I think could have contributed to air causing turbulence. In addition, I also found screws missing from the belly pan that allowed it to move up and down. Which could have been causing shaking/vibration.

#3 And I havent confirmed this yet, but I cant rule it out. The stock ford camber plates. Mine are installed backwards and provide camber &caster adjustment in this configuration. I doubt this is the issue, but worth mentioning as I didnt test it again with negative camber/positive caster

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