Rennlist - Porsche Discussion Forums

Rennlist - Porsche Discussion Forums (https://rennlist.com/forums/)
-   991 (https://rennlist.com/forums/991-221/)
-   -   Wholly acorns and front end shutter! (https://rennlist.com/forums/991/1123493-wholly-acorns-and-front-end-shutter.html)

adcampo 01-11-2019 09:59 AM

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.

LexVan 01-11-2019 10:07 AM

What PSI? A few extra PSI (within the proper range) will help a little, but it ain't going away.

Steven C. 01-11-2019 10:10 AM

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.

PJ Cayenne 01-11-2019 10:15 AM

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.

adcampo 01-11-2019 11:19 AM

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.

LexVan 01-11-2019 11:24 AM


Originally Posted by adcampo (Post 15558211)
I'll take a look at the PSI. Do you guys feel the onboard gauge is pretty accurate?

Yes. Very.


arter 01-11-2019 11:26 AM

get some winter tires and your confidence will come back......

garfunkle 01-11-2019 12:16 PM

PZeros are garbage in the cold and compound this issue. It's still there with Michelin's but only a fraction.

stealthboy 01-11-2019 12:32 PM

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.

Avalon911 01-11-2019 12:35 PM

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.

adcampo 01-11-2019 01:37 PM

In follow up to LexVan. I'm at 32F/39R cold temp in the TPMS gauge.

ENCT 01-11-2019 01:57 PM

Winter Tires

K9PJ/4 01-11-2019 02:07 PM

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.

AlBinVA 01-11-2019 02:10 PM

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.

LexVan 01-11-2019 02:13 PM


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.


All times are GMT -3. The time now is 06:19 AM.


© 2019 MH Sub I, LLC dba Internet Brands