High speed vibration?

[Z4Rick]

I recently remounted my dry weather wheels\tires. They were new KUHMOs I got filthy cheap from tire rack. I intend to track the car 3-4 times this summer and hope this set will last. Road Force spun balanced and mounted by a local and very reputable dealer. The car runs straight, smooth and balanced with no issues at all. Until I hit about 85MPH.

At 85 I begin to pick up a high frequency vibration in the steering wheel. It continues up to about 120. Beyond that I don't know - ran out of empty highway.....

It does not result in any bad behavior, just an annoying vibration that unsettles my concentration.....

I have zero clue....
Any ideas?????

Harmonics?

Suspension?

[buzyg]

Definitely sounds like tyre imbalance. I would go back, tell them the issue and get them re balanced, I have done this a couple of times with new tyres. They don't always get it spot on when they are balancing 100s of tyres a day.

[Z4Rick]

Yeah....that was my first thought too.

I think I'll pull the front wheels, rotate the hub/brake disc 180 degrees and remount to see if a harmonic vibration exists first. Then rebalance.

[exdos]

Are your rims OEM or aftermarket and have you used these rims on your car before?? Are your hubs clean so that the wheels fit absolutely face-flush on the hubs? You might need "spigot rings" to ensure a good fit between rim and hub.

Are the bolts torqued properly?

Sometimes the tyre fitters don't balance down to 5gms which can create a vibration only at higher speeds.

[tintoverano]

try increasing front tyre pressure and see what happens

tyre deformity can cause vibration as well

[Busterboo]

Foolishly, I put Nexens on a 4.2 Jaguar. Decent enough, cheap, 'working' tyres. Re-balanced, re-aligned, re-mounted, there was still vibration at 110-120. Put on Pirellis. Perfect to 150.

'Buy cheap, pay twice.'

[BTZ461]

Foolishly, I put Nexens on a 4.2 Jaguar. Decent enough, cheap, 'working' tyres. Re-balanced, re-aligned, re-mounted, there was still vibration at 110-120. Put on Pirellis. Perfect to 150.

'Buy cheap, pay twice.'

Nexen have been some some years a premium brand (Partly owned by Michelin) and they must have a budget tyre for the Jaguar brand. OE fitment to both Porsche and BMW and Audi Vw and Rolls Royce, along with the top end models of Kia and Hyundai.
I'm surprised your Jaguar 4.2 would pull 150, unless its in KPH.

[Busterboo]

Foolishly, I put Nexens on a 4.2 Jaguar. Decent enough, cheap, 'working' tyres. Re-balanced, re-aligned, re-mounted, there was still vibration at 110-120. Put on Pirellis. Perfect to 150.

'Buy cheap, pay twice.'

Nexen have been some some years a premium brand (Partly owned by Michelin) and they must have a budget tyre for the Jaguar brand. OE fitment to both Porsche and BMW and Audi Vw and Rolls Royce, along with the top end models of Kia and Hyundai.
I'm surprised your Jaguar 4.2 would pull 150, unless its in KPH.

Mmm ... everything must be different in New Zealand.

[mcbutler]

Foolishly, I put Nexens on a 4.2 Jaguar. Decent enough, cheap, 'working' tyres. Re-balanced, re-aligned, re-mounted, there was still vibration at 110-120. Put on Pirellis. Perfect to 150.

'Buy cheap, pay twice.'

Nexen have been some some years a premium brand (Partly owned by Michelin) and they must have a budget tyre for the Jaguar brand. OE fitment to both Porsche and BMW and Audi Vw and Rolls Royce, along with the top end models of Kia and Hyundai.
I'm surprised your Jaguar 4.2 would pull 150, unless its in KPH.

Mmm ... everything must be different in New Zealand.

Agreed Buster..... Everythings upside down over there......

[Busterboo]

[Z4Rick]

It WAS a harmonic!

The shop took off the front tires, checked their balance, (they were fine), and remounted them after rotating the disc/hubs 60 degrees.

Worked like a freakin charm! Straight, true, balanced, and smooth all the way to 125 mph!

Fascinating. The physics of rotating masses is a squirrely science.

[Pbondar]

It WAS a harmonic!

The shop took off the front tires, checked their balance, (they were fine), and remounted them after rotating the disc/hubs 60 degrees.

Worked like a freakin charm! Straight, true, balanced, and smooth all the way to 125 mph!

Fascinating. The physics of rotating masses is a squirrely science.

To be pedantic it was a resonance not a harmonic..a body can resonate at a principal frequency and/or at a number of integer multiples of that frequency , those are harmonics..

Indeed resonances can be both irritating as in buzzes in the car interior and destructive if allowed to continue..

Many aircraft have been lost as a result of airframe parts resonating due to repaint, incorrect balance or things like ice building up..

Some times as you discovered it only takes a very small change to make all the difference..

[tintoverano]

The shop took off the front tires, checked their balance, (they were fine), and remounted them after rotating the disc/hubs 60 degrees.

how could they rotate it with 60 degrees?

[Z4Rick]

It WAS a harmonic!

The shop took off the front tires, checked their balance, (they were fine), and remounted them after rotating the disc/hubs 60 degrees.

Worked like a freakin charm! Straight, true, balanced, and smooth all the way to 125 mph!

Fascinating. The physics of rotating masses is a squirrely science.

To be pedantic it was a resonance not a harmonic..a body can resonate at a principal frequency and/or at a number of integer multiples of that frequency , those are harmonics..

Indeed resonances can be both irritating as in buzzes in the car interior and destructive if allowed to continue..

Many aircraft have been lost as a result of airframe parts resonating due to repaint, incorrect balance or things like ice building up..

Some times as you discovered it only takes a very small change to make all the difference..

Yeah...
Squirrely!

[Z4Rick]

The shop took off the front tires, checked their balance, (they were fine), and remounted them after rotating the disc/hubs 60 degrees.

how could they rotate it with 60 degrees?

Good catch!! My math mistake!!....they moved 2 bolt holes. 5 bolt holes divided into 360=72 degrees per hole. 2 holes is 142 degrees. We moved one wheel forward 142, and the other backwards 142 on their hubs.