Vibration at highway speeds

[CanadaCalvin88]

Hey everybody, as the title states, I am getting a vibration in the body of the car at highway speeds. My car is a 2015 Gt with about 41,000 on it and original struts, but about 4 months ago I installed eibach pro line springs which gave it a 1"drop. I don't do much highway driving and everything had been fine until I got on the interstate and hit about 80 mph when I noticed the vibes. Immediately I thought a tire was out of balance even though they are all brand new recently balanced tires. My next thought was maybe stock struts are going bad due to the 1" drop. I have done a few highway runs since installing the springs but just started noticing the vibration last weekend. So my question is, should I have the tires re-balanced or could it be the struts that are causing my problems on the interstate. Side note, I did notice some bouncing and the ride was a little more squirrely than I remember which is why I'm leaning towards the struts now.
Thanks for any input, Cal.

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[Roger Blose]

Start with the basics...have the tires rebalanced using a Road Force balancing machine. Next, try and figure out if the vibration is in the chassis, front end, rear end, steering wheel shimmy, driveline vibration, tire pressure too high, and at what speed does it come in and disappear such as either side of 80 for example. You can also put the car on a lift and run it up to speed and see if anything is shaking / vibrating to isolate the front to back issue.
I fought a vibration on my old 2006 GT after replacing the original Pirelli P Zeros with a fresh set of the same brand. The car would shake at 70 +mph. I tried multiple tire balances, rotations, and no help from the manufacture. After two months of misery, more than a $1000 , the Pirellis went into the garbage can and my problem was solved with 4 Michelin Pilot Sport AS 3s. Of course my new 2018 GT has factory Pirellis again but I know what to buy when the time comes for new tires.

 

[CanadaCalvin88]

I appreciate the insight. As far as I can tell it's not coming from the front wheels, because I cannot feel any vibration through the steering wheel. It was more noticeable through the body. I could feel it through the floorboard. I also noticed it was fairly smooth at 70 but around 80 is when it became bad. I popped the car in neutral and let it coast and the vibration was there until it fell back to 70. But I will follow your advice and have the tires re-balanced using the road force machine. One other thing I thought I should mention is that I installed a blowfish shifter bracket about a month ago to aid in the high rpm lockout. I do get minor vibration in the shifter but I don't think that is the cause of my issues.

 

[Bluelightning]

Sounds like the rear tires are out of balance.

 

[Genxer]

I appreciate the insight. As far as I can tell it's not coming from the front wheels, because I cannot feel any vibration through the steering wheel. It was more noticeable through the body. I could feel it through the floorboard. I also noticed it was fairly smooth at 70 but around 80 is when it became bad. I popped the car in neutral and let it coast and the vibration was there until it fell back to 70. But I will follow your advice and have the tires re-balanced using the road force machine. One other thing I thought I should mention is that I installed a blowfish shifter bracket about a month ago to aid in the high rpm lockout. I do get minor vibration in the shifter but I don't think that is the cause of my issues.

Make sure your Blowfish bracket isn't contacting anywhere it shouldn't on the body.
If the problem didn't start until you changed the springs, I would check the install to make sure everything is tight and properly positioned. Could have left nuts loose on the struts or any number of things.

 

[ChiTownStang26]

Did you have your bushings clocked after you installed the springs or at least an alignment to remove some of the preload?

Also did you check the obvious like a nail in the tire, make sure the lug nuts are torqued to 144, or even a bad wheel bearing (jack the car up, pull on the wheel and see if it wiggles)

 

[CanadaCalvin88]

I double checked the blowfish bracket and even lowered the shifter box a little so that it left a little gap between the gasket and the body. Also, yes I had an alignment after I installed the springs. I installed them myself and am pretty confident that I got everything tightened back up properly. But I will definitely Jack the car back up and take a look, and check wheel bearings while I'm at it. Rechecking the wheel balance is also on my list.

 

[CanadaCalvin88]

Good news! Just had the wheels re-balanced and the vibration is gone. Not sure how they got so out of balance though. I checked out the inside of the wheel and some of the weights were moved to opposite sides of the rim.

 

[pyrophilus]

Good news! Just had the wheels re-balanced and the vibration is gone. Not sure how they got so out of balance though. I checked out the inside of the wheel and some of the weights were moved to opposite sides of the rim.

I would inspect the tire carefully. In 1996, I had a 1 month old, new '97 pathfinder, that had vibrations from rear right after delivery. Dealer said rear wheel was off balance, moved weights from original location to other side of wheel, and then ADDED more weights. I got home, was suspicious, so I took the wheel off, and carefully inspected. There was a big bolt with black head embedded in the inner tread of the tire. I took vehicle back to dealer and lost my shit. Said if there is THAT huge of change on a wheel, shouldn't they have looked for a cause first, before slapping crazy amount of weights on it? They were apologetic, and they took off the tire and patched it from the inside.

Similar thing happened to a coworkers friend.

 

[CanadaCalvin88]

I would inspect the tire carefully. In 1996, I had a 1 month old, new '97 pathfinder, that had vibrations from rear right after delivery. Dealer said rear wheel was off balance, moved weights from original location to other side of wheel, and then ADDED more weights. I got home, was suspicious, so I took the wheel off, and carefully inspected. There was a big bolt with black head embedded in the inner tread of the tire. I took vehicle back to dealer and lost my shit. Said if there is THAT huge of change on a wheel, shouldn't they have looked for a cause first, before slapping crazy amount of weights on it? They were apologetic, and they took off the tire and patched it from the inside.

Similar thing happened to a coworkers friend.

Good point! I will take a look and see if there is anything in the tire that they missed.

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