911.2 C2s back end kicked out
#17
+1.
I have had the rear twitch out on a hairpin turn on the Milwaukee Mile in-field track, no noise. Summer, dry track.
You can't repeal the Laws of Physics.
Low friction (Summer Tires in cold temps) and sideways acceleration that overcomes the friction force and you will lose traction in many conditions.
BTW driving carefully will not insure you will not have an accident, Abrupt maneuvers due to accident avoidance can cause a loss of traction.
I have winter Wheel/tire set on on my 991.2 C4S.-Richard
I have had the rear twitch out on a hairpin turn on the Milwaukee Mile in-field track, no noise. Summer, dry track.
You can't repeal the Laws of Physics.
Low friction (Summer Tires in cold temps) and sideways acceleration that overcomes the friction force and you will lose traction in many conditions.
BTW driving carefully will not insure you will not have an accident, Abrupt maneuvers due to accident avoidance can cause a loss of traction.
I have winter Wheel/tire set on on my 991.2 C4S.-Richard
#19
Initially I thought that noise was a rumble strip on the side of the road but after another look, that is not the case.
First time I have heard antilock brakes kicking in without applying the brake pedal.
Agree with Lexvan on the tires.
First time I have heard antilock brakes kicking in without applying the brake pedal.
Agree with Lexvan on the tires.
#22
I understand that summer tires in cold temps are a bad thing and it would be very easy to rear end someone in that situation. Needing to stop fast and you can't. So car will stay garaged. I have another car for cold weather duty. One thing that has surprised me a lot is the sensitivity of these tire compounds to temperature. I had assumed that car tire tech was way ahead of motorcycle tire tech so tires would be pretty sticky over a wider temp range. In the sport bike world there are harder compound race tires that need tire warmers to be safe on early laps but most DOT sport bike tires still work OK in cooler temps. Also it seems like the traction control on my KTM 1290 Superduke R must work pretty well as it makes 160hp at the rear wheel and weighs 435 lbs. Even with me on it the power to weight ratio is pretty crazy. I did a track day with temps in the 50s in the rain on Pirelli Super Corsa tires with no problems except for the brief hydroplane on puddles. But the bike's traction control enabled me to get on the gas aggressively out of corners with the tc modulating the power output well enough to keep control. Sport bike tires do have softer compounds on the edges and harder in the middle. Maybe that is part of it. So I was exiting that turn in the video and in the back of my thinking how that would go on my KTM and no problem. Then the back end is coming around! Call it a learning experience. I ride dirt bikes too so am comfortable with very little traction and the bike sliding around a lot. Thanks to everyone commenting on this forum. I am learning a lot.
#23
I understand that summer tires in cold temps are a bad thing and it would be very easy to rear end someone in that situation. Needing to stop fast and you can't. So car will stay garaged. I have another car for cold weather duty. One thing that has surprised me a lot is the sensitivity of these tire compounds to temperature. I had assumed that car tire tech was way ahead of motorcycle tire tech so tires would be pretty sticky over a wider temp range. In the sport bike world there are harder compound race tires that need tire warmers to be safe on early laps but most DOT sport bike tires still work OK in cooler temps. Also it seems like the traction control on my KTM 1290 Superduke R must work pretty well as it makes 160hp at the rear wheel and weighs 435 lbs. Even with me on it the power to weight ratio is pretty crazy. I did a track day with temps in the 50s in the rain on Pirelli Super Corsa tires with no problems except for the brief hydroplane on puddles. But the bike's traction control enabled me to get on the gas aggressively out of corners with the tc modulating the power output well enough to keep control. Sport bike tires do have softer compounds on the edges and harder in the middle. Maybe that is part of it. So I was exiting that turn in the video and in the back of my thinking how that would go on my KTM and no problem. Then the back end is coming around! Call it a learning experience. I ride dirt bikes too so am comfortable with very little traction and the bike sliding around a lot. Thanks to everyone commenting on this forum. I am learning a lot.
#24
Right: 1st day I picked mine up from Zuffenhausen went around a sharp on-ramp to the A-bahn and I hit a wet patch, out goes the rear. I had not yet had any track time or learned the handling at the limits ... needless to say I was more circumspect the rest of the trip.
Last edited by 917k; 12-04-2016 at 08:17 PM.
#25
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Originally Posted by dflowerz
I understand that summer tires in cold temps are a bad thing and it would be very easy to rear end someone in that situation. Needing to stop fast and you can't. So car will stay garaged. I have another car for cold weather duty. One thing that has surprised me a lot is the sensitivity of these tire compounds to temperature. I had assumed that car tire tech was way ahead of motorcycle tire tech so tires would be pretty sticky over a wider temp range. In the sport bike world there are harder compound race tires that need tire warmers to be safe on early laps but most DOT sport bike tires still work OK in cooler temps. Also it seems like the traction control on my KTM 1290 Superduke R must work pretty well as it makes 160hp at the rear wheel and weighs 435 lbs. Even with me on it the power to weight ratio is pretty crazy. I did a track day with temps in the 50s in the rain on Pirelli Super Corsa tires with no problems except for the brief hydroplane on puddles. But the bike's traction control enabled me to get on the gas aggressively out of corners with the tc modulating the power output well enough to keep control. Sport bike tires do have softer compounds on the edges and harder in the middle. Maybe that is part of it. So I was exiting that turn in the video and in the back of my thinking how that would go on my KTM and no problem. Then the back end is coming around! Call it a learning experience. I ride dirt bikes too so am comfortable with very little traction and the bike sliding around a lot. Thanks to everyone commenting on this forum. I am learning a lot.
Bottom line, summer tires lose a ton of traction at the 40 degree range. And some compounds like the wet a lot more, regardless of their groove pattern and ability to displace water.
On a bike, you have much more control over the physics of the vehicle, since you can shift your weight and literally change the weight distribution by 25%, 50%, maybe? And you have a much better feedback loop as to what's going on. Your whole body is engaged in supporting and controlling the bike, so you feel changes in your arms, legs, core, etc. Much more information coming to you.
because you're dealing with a much, much bigger contact patch, your absolute amount of grip is much higher. Which means when it lets go, you have a lot more momentum to catch, and a lot more grip to restore. Finally, the breakaway in such a large contact patch is naturally going to be less progressive and more instant.
Having said that, your bike skills dealing with slides and how to restore grip will help you learn the car control much more quickly than your average driver, who panics when the rear lets go!
#26
When the back let loose I just steered into it as a reflex and that comes from riding dirt bikes. But even doing that I think the back end would have come around without the PDCC doing its thing. A trip down to the Porsche experience center in LA is in my future. Just like with sport bikes I need some instruction and track time to understand my 911 better. I am also a new member of PCA so that is a good resource.
#27
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From: The Woodlands, TX.
When the back let loose I just steered into it as a reflex and that comes from riding dirt bikes. But even doing that I think the back end would have come around without the PDCC doing its thing. A trip down to the Porsche experience center in LA is in my future. Just like with sport bikes I need some instruction and track time to understand my 911 better. I am also a new member of PCA so that is a good resource.
#29
Welcome to the world of rear engined cars. I'll give you scary. If anybony knows the rt202 bear mountain drive in NY. Picture a 997 going sideways with the edge of a cliff in view. Now that's scary! What you had is a wake up moment. As good as these cars are. It's down right dangerous to loose control no matter what scenario you wind up in. Always good to know the limit. Best place is the track.