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Tire Thumping?

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Old 03-18-2018, 02:55 PM
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djantlive
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This seems to be happening to AWD cars. OP, is yours a 4 or 4S?

adding friction modifier and warming up the car seems to help if so
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Old 03-18-2018, 03:02 PM
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Bradley Scott
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Originally Posted by djantlive
This seems to be happening to AWD cars. OP, is yours a 4 or 4S?

adding friction modifier and warming up the car seems to help if so
4S
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Old 03-18-2018, 03:30 PM
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Originally Posted by Bradley Scott
Perfect explanation. Thank you.

Curious - why can't Porsche solve this?
Well, think about it. Its caused by caster angle. Without caster angle there is no force trying to make the wheel go straight and so you lose all steering feel. Kind of one of the biggies a 911 has historically been known for. Also the car will be darty and unstable, not wanting to go straight and stable at high speed. The more you minimize caster angle the more you minimize steering feel and make the car difficult to drive at speed. Or it could be reduced by going to a tire with a lot more squirm. Smaller tread blocks. Higher profile. Not as wide. Softer compound. Winter tires, basically, or touring or all-season tires. Another thing they could do is use softer suspension bushings to dampen it out. Are you beginning to see a pattern here? Each and every one of these things is the OPPOSITE of what you want in a high performance drivers car like a 911.

So yeah, Porsche could easily solve this "problem". All they have to do is make something other than a 911.
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Old 03-18-2018, 04:24 PM
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Originally Posted by djantlive
This seems to be happening to AWD cars. OP, is yours a 4 or 4S?

adding friction modifier and warming up the car seems to help if so
What? Friction modifier? Warming up car? What are you talking about?

This is NOT an AWD issue. Happens on the rear wheel drive cars too.
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Old 03-18-2018, 05:02 PM
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Right. It happens on all cars. Period.
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Old 03-18-2018, 05:07 PM
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Originally Posted by LexVan
What? Friction modifier? Warming up car? What are you talking about?

This is NOT an AWD issue. Happens on the rear wheel drive cars too.
really, I never heard of it on rwd cars. It happened on my awd only. It was a grinding and groaning sound coming from the front and rear differentials. I put friction modifier in the trans and diff and that minimize the sound a lot. Also, this happened only at cold start and if the car is warmed up more (3-5 min), that helps too.

we maybe talking abt a different sound though. But just sharing my experience
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Old 03-18-2018, 05:13 PM
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Originally Posted by chuck911
Right. It happens on all cars. Period.
I've had 4 S Classes in a row - and rented many cars in the past few years during some travels to Florida.

This thud thud thud doesn't happen on any other car, at least none that I have driven.

But, what do I know.
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Old 03-18-2018, 05:38 PM
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Originally Posted by Bradley Scott
I've had 4 S Classes in a row - and rented many cars in the past few years during some travels to Florida.

This thud thud thud doesn't happen on any other car, at least none that I have driven.

But, what do I know.
Were the tires on all of those super wide, super grippy high performance tires...in cold temps?

I believe their point is that its always occurring, just not enough to notice it unless certain factors occur and the 911 is sporting those factors.
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Old 03-18-2018, 08:29 PM
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I am beyond tired and bored. This topic has a multitude of posts (over many years) explaining it. Why do does anyone give their time and energy to explain a topic over, over and over again after the OP with a legitimate question is guided to the answers that they refuse to research/accept? When behavior like this is accepted and continues, it will do nothing but turn those away with something to contribute. Everyone who wants this board to continue to be a productive source of information puts it in jeopardy with this behavior.
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