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Wholly acorns and front end shutter!

Old 01-11-2019, 10:59 AM
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adcampo
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Default Wholly acorns and front end shutter!

I know the acorn effect is a well documented issue. And extremely alarming if you don't know about it.

It's a really cold ( 20's) and sunny day in the DC area today, but I decided to take my 991. in for a hand wash at my local place. I pulled out of the garage and that front end shuttered and crunched like nobody's business. I can't imagine what it looks and sounds like from the outside.

And I realized it takes a good 15-20 minutes of light/moderate driving before the oil/water temps come up. On the other hand, the heated seats take only 2-3 which is nice. I also noticed that the shifting is much slower in all modes when the car is cold. I'm sure that's some cleaver German engineering.

Finally, the P Zero's are worth absolutely ZERO in freezing temperatures. Even after the doing some driving. My aggressive driving confidence on a cold day is pretty pretty low. I can imagine that thing calling some unexpected hot shoe out.
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Old 01-11-2019, 11:07 AM
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LexVan
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What PSI? A few extra PSI (within the proper range) will help a little, but it ain't going away.
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Old 01-11-2019, 11:10 AM
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Steven C.
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The shifting is actually EPA mandated to get the revs up and warm the engine up faster to reduce emissions. Really bad for cold engines but they hate them anyway....... Pull the paddles and keep it below 2K for a while.
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Old 01-11-2019, 11:15 AM
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That's kind of why some of us Northerners tend to put them away for the winter if we don't want to bother with a tire change. Easily, the acorn affect is felt in the low 50s on down. Agree on the P-Zeros...not fun when cold.
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Old 01-11-2019, 12:19 PM
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I'll take a look at the PSI. Do you guys feel the onboard gauge is pretty accurate?

Mine is a second car and will be parked for winter too, but since I just got it, I'm still driving it any chance I can.

After today's wash, I'm planning on some clay bar and Zaino treatment over the next few days. We have snow in the forecast in DC.

Thanks all.
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Old 01-11-2019, 12:24 PM
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Originally Posted by adcampo View Post
I'll take a look at the PSI. Do you guys feel the onboard gauge is pretty accurate?
Yes. Very.

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Old 01-11-2019, 12:26 PM
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arter
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get some winter tires and your confidence will come back......
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Old 01-11-2019, 01:16 PM
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PZeros are garbage in the cold and compound this issue. It's still there with Michelin's but only a fraction.
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Old 01-11-2019, 01:32 PM
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Get some winter tires. I have Sottozeros that I swap on for winter. Here in the DC area, it gets below 40 enough to warrant a different rubber compound. Be safe.
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Old 01-11-2019, 01:35 PM
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I don't drive on summer tires in freezing weather, period. Generally unsafe and if there was ever a bad result (attributable to the tires or not), there could be insurance/liability issues. Low 40s, sure. High 30s, possible. Just my .02. Others may feel differently.
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Old 01-11-2019, 02:37 PM
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In follow up to LexVan. I'm at 32F/39R cold temp in the TPMS gauge.
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Old 01-11-2019, 02:57 PM
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Winter Tires
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Old 01-11-2019, 03:07 PM
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K9PJ/4
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Unhappy Wholly acorns and front end shutter

Is this thread directly related to the shudder I experience? My experience is when backing it sounds/feels like I am driving over a series of 4" diameter logs.
The first time it occurred I stopped, and examined the street for debris and the suspension for damage. Driving forward and avoiding sharp turns it would go
away, time depending on temperature.

The first occurrence was with a 2014 Boxster (Virginia)
The next car a 2016 base 911 was a little worse (Virginia)
Now we have a 2017 911S with RAS is the worst (even here in Florida on 50 degree days)

All with Pirelli rubber.
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Old 01-11-2019, 03:10 PM
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AlBinVA
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Timely thread.

I too was out at 8:00 this AM in RVA. Ambient temp at 28. No way around it, had doctor appt I had to go to. Driving on P0's with 14k miles so tread is not fresh on rears. I was very apprehensive but put myself in a position where I did not make sharp turns, heavy acceleration or quick braking. I have experienced cold weather issues before, but today was just fine. It's not something I do as common practice but beats having to keep another set of rubber on hand for the few times I encounter these temps. It is my DD but being retired means I can pick and choose my outings for the most part.
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Old 01-11-2019, 03:13 PM
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LexVan
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Originally Posted by K9PJ/4
Is this thread directly related to the shudder I experience? My experience is when backing it sounds/feels like I am driving over a series of 4" diameter logs.
Yes.
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