StealthP3D
Well-Known Member
Oh, I don't know. Maybe the part where you wife has only driven the car 800 miles since taking delivery of her new baby!
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"Full-Time" AWD Winter Mode
- Thread starter sir_log_alot
- Start date
Oh, I don't know. Maybe the part where you wife has only driven the car 800 miles since taking delivery of her new baby!
Well she was deployed overseas for 6 weeks, two weeks after it arrived. And whenever we go places together I drive. And it’s lack of surefooted ness in the slippery stuff makes her feel uneasy. I also drive it back and forth to the ski resort every weekend when I can since it is EV and my truck gets 12 mpg.
StealthP3D
Well-Known Member
Math Test:
Say you make a 100 mile round trip and 20 miles are on snow/ice and 80 miles are on pavement, what percent of that trip is on snow/ice?
A. 100%
B. 90%
C. 80%
D. 20%
Well, enjoy the fresh snow with your wife, no friends except spouses on a powder day. We all know the car needs help in this regard, regardless of Stealth’s protestations. I’ve got 3100 mi since Dec 31. I live 800 vert above a ski area on a gravel road. I know how it drives, and it isn’t close to my Audi(s). I trust it will get fixed, or Etrons will win out.
StealthP3D
Well-Known Member
I know how it is. My wife is a timid snow driver also. Whenever we go somewhere together we take her Model 3 and I drive. Same thing when we had the Volvo. Some people just aren't comfortable driving when there's going to be slipping or sliding. Other people love it. Go figure! She still hasn't driven my P3D and I have 3800 miles on the clock.
Do you ski at Alyeska? It looks like they only have a 19" snowpack at the base. Mount Baker only has 153" at the base area so we are below normal a bit too. I assume Alyeska normally has more than 19" at the base area by mid February?
Not sure where you got “19 for the base measurement? Possibly the magic carpet below the day lodge. I was at Alyeska today for the U16 state championships SG. But we mostly ski Hatchers, Turnagain, and Thompson in the spring. Alyeska and Baker are in the top 5 for snowfall almost every year. I think if you look at the 10 year average Baker is 1 and Alyeska is 2. Per the Alyeska snow report today 90” packed base where it matters. The thing that is differant about way up north is on low snow years the roads are way worse because it dosnt melt and there is not much fresh snow to add grip. so what is left is old cold compressed snow and ice. I’m sure there are Canadians that can relate. We don’t use salt on the roads as well. Also in S central AK it’s much like Norway fjord’s where every morning we get a nice fresh layer of frozen frost to make sure the roads are extra slick.
StealthP3D
Well-Known Member
I got the base measurement from the official report of Alyeska Ski Area. The 90" is the summit measurement not the base by the road. That's a 19" base. You can't drive to the summit! Mt. Baker's published stats are all taken from the base area, 30 feet from the road. That's where the world record snowfall was documented, not at the top of the highest lift!
Thinking of this thread, last night I tried to fishtail the M3 in some open parking lots, and although it's easy to make the back wheels come lose, the traction control brings it right back in line pretty dang quick. It is one of those quirks that literally every car has, where someone who drives it daily for a year or two doesn't even notice after awhile.
diamond.g
Active Member
As long as everyone emphatically states that they do not want dry performance changed. Last thing we need is Tesla pulling a Walk Up Unlock and just nerfing the car all together.
ConcordeSST
Member
For me though the problem isn't in those scenarios. If you punch it or try to drive aggressively, the car is amazing. It's in slow speed situations going uphill (even when driving in a straight line) where it develops this very unsettling wiggle. I know how to to correct for it, it's just alarming when it happens because I'm usually surrounded by traffic where I have little room to correct.
StealthP3D
Well-Known Member
Since you know how to correct for it I suspect you have "expensive car syndrome". I know it costs a lot and is all new and shiny but this worry will go away after the car is not so new anymore.
But I'm surprised you can't prevent it from happening with more delicate throtttle control. My P3D does not behave as you're describing.
Do you keep your tire pressure within 1 PSI of each other? I have found modern cars in general to perform a lot better on very slippery surfaces when the wheel speed sensors are getting data from tires that are as close in diameter to each other as possible. This doesn't matter on older vehicles that have less resolution in the wheel sensors.
There is something different about your car compared to mine. I keep my tires to within 0.5 PSI of one another. I do this out of an abundance of caution because I drive on a lot of dangerous, slippery, potentially deadly roads and the safety of my family is important to me. I would rather do something that is unnecessary than find out the hard way it mattered. Sometimes people do (or neglect to do) things that they assume simply don't matter. But sometimes they are wrong. This is far more common than many realize.
I'm curious what tires, wheels and cold pressures you are running. Something definitely seems different and I doubt it's the software (but it could be).
ConcordeSST
Member
I am already pressing the throttle so lightly when this happens that I feel like I would have to have surgeon-like control of my foot to be any lighter. It happens to me when it is icy out, generally about 30 mph (in 45-50 mph zones), and almost always when I'm on some kind of an incline where I have to apply slightly more pressure to maintain speed and keep up with surrounding traffic. It is during this application of additional pressure when it starts to happen. Any less though and I feel like I'd be dropping speed quickly enough where I would become a hazard to traffic around me.
I'm genuinely happy for you that you like it the way it is, and can manage it with such finesse. While I can only speak for myself, I am willing to bet there are others out there that don't want to have to do such a delicate dance with the car in such plain vanilla situations as driving in a straight line at the speed of traffic. All I'm asking for is choice to make it handle more solidly (and perhaps less fun) when I want to, and looser when I want to, in the same way that we can change steering modes at the press of an on-screen button. Clearly this can be done with S owners reporting completely different behavior than 3s.
When I checked last week, 3 of my tires were at 42, and the front-right was at 41. I normally run at 45, but it's been a while since I adjusted for the colder temps. I'll try it again with more uniform pressure the next time we get snow. This is with the 18" aero wheels and Pirelli Sottozero II winter tires.
StealthP3D
Well-Known Member
One thing that may be significant to your issue here is that the accelerator is different from an ICE throttle. I know you know this and I'm not trying to talk down to you but hear me out. With ICE you can run at low rpm's in a high gear and go from gentle accel to gentle coast by pushing a bit or not pushing the pedal. With regen, the area of neutral throttle is more nebulous and it may not be as obvious when you are giving it more or less throttle. I might have a really sensitive "butt dyno" because that is how I tell whether I'm on throttle, on regen (or coasting). On a very low traction surface it's possible that you are simply giving it more than it seems like and that it should be able to do it but the ice is just that slippery. The Model 3 is pretty heavy and it will take it a little time to increase speed in such conditions even when all drive tires are perfectly at their maximum limits (of their coefficients of friction). You might just be expecting too much and are therefore pressing the acceelerator into the region where the TC system says "aha, you want a little extra" even though you don't.
I really don't feel like I'm using any more finesse than I've used with my previous AWD ICE vehicles (even though the Sottozero 2's have slightly less ice traction than my the winter tires on my previous ICE). It may be that my feel for neutral throttle is a little better than yours but that is why I wrote the first paragraph. Because I thought it might help you to focus your attention on this and maybe reset your butt dyno to the way your tires behave on various icy surfaces considering the mass of the AWD Model 3.
That's fine, I'm not opposed to Tesla coming out with software enhancements (including tunable throttle mappings, selectable TC modes, etc.). With how full Tesla's plate is at the moment, I'm not sure how realistic it is to think they are coming this winter. I'm pretty sure they are not. But I do think that regardless of the large amount of human variability in how we percieve the world and naturally react to different stimuli, we all share an amazing ability to learn and adapt. And until Tesla releases selectable upgrades I think you should realize it is probably within your ability to modify your behavior so this is no longer a problem for you. I'm assuming since you have the same model tires* I have, and basically the same car, it probably behaves much like mine does. By this I mean that the tires don't go into "slip mode" until your throttle request is a good amount past what the tires can handle.
I've been running 46-49 PSI all winter (currently at 47 PSI stone cold in the morning, sitting on snow/ice outside at 20F). I've paid very close attention to how tire pressures affect my traction my entire adult life. With the advent of electronic TC, the difference has actually become bigger, not smaller as one might expect.
*However, I do believe we have different versions of the same model tire. If you bought your tires from Tesla they are the XL version. Tesla was out of stock and I bought the lighter duty version. These suit me as my load is generally very light, typically no more than 2 people and often solo with only two pair skis, two pair boots and a small pack weighing only 15 lbs. The lighter construction could very well have better grip. In fact, I would expect this but to what degree I don't know. I've experienced this with motorcycle tires on my Ducati. Avon had a wonderful Sport-Touring tire that was simply amazing. Until the tire started self-destructing on larger heavier, more powerful Sport-Touring motorcycles in the summer heat with too low of air pressure. Instead of Avon instructing buyers the tires were not suitable for the heavier, more powerful bikes, or insisting that tire pressures be higher, they beefed up the construction of the tire. But it still had the same name because the tire had a great reputation (other than the failures due to under-inflation). After they beefed up the construction the tire lost it's wonderful qualities. I went through 4 sets of the original constructiion and two sets of the new construction considering that tires in the ST class only last 5-6000 miles/set. But the new, beefed up tire no longer self-destructed when under-inflated on larger, heavier bikes. I imagine car tires might have similar relationships between weight/power handling and grip. But probably not as pronounced as the rounded profile of a motorcycle tire.
Regardless that I don't have first hand experience with the XL version of the Sottozero 2's, I do think you might be under-inflated. But I have a cautionary note about chaging air pressure and concluding the new pressure is no good on ice. A tire's tread wears into the shape of whatever pressure it's being run at. When you change pressure by more than around two PSI, especially when increasing the pressure, it will take quite a few miles of bare pavement driving for the tread to wear flat again. Until this happens your ice traction will likely decrease, even if the new higher pressure ends up providing more ice grip once the tread wear has flattened. This effect is very real and has the unfortunate result of causing even experienced drivers to misjudge the best tire pressure for ice traction. In otherwords, most people who pay attention to tire pressure and how it impacts ice traction pick a pressure that is as much as 3-6 PSI too low for optimum traction due to this effect. For these reasons I maintain my tire pressures in a fairly narrow range and when I do make a change I give it some time to judge the effects. On a summer racetrack this is not necessary because the rubber becomes softer and the tire wears in so quickly. That is not the case in snow/ice.
Another factor to consider is that how the car is driven on bare or bare/wet pavement affects snow and ice traction due to the tread wear pattern differences that various driving causes. A tire that is driven relatively normal and conservatively on bare pavement wears into the best shape for overall ice and snow traction. A tire that is accelerated hard, near or exceeding the traction limit but never braked hard has poor ice/snow acceleration but better ice/snow braking. A tire that has been braked hard repeatedly but always accelerated gently will have good ice acceleration but poor ice braking. Tires that have been pushed hard on pavement corners will have reduced cornering ability on snow and ice because of it. Some kinds of winter conditions cause treadwear that naturally reduce traction even when driven with the flow of normal traffic. Pavement that has consistent but reduced traction due to water and coldness can cause micro-slipping even when not being driven particularly agressively that can cause treadwear that is not favorable to ice snow traction.
None of these tire factors are unique or particular to the Model 3 except perhaps for the tendency of Model 3 owners to make use of the impressive motor torque when they have the bare pavement with which to do so and to limit hard braking due to the ease of regen braking. So Model 3 owners could be inadvertantly wearing their winter tires into unfavorable tread wear patterns for ice/snow hill climbing/acceleration.
Sorry this post is so long but I thought someone might find my observations over the years useful. This is a thread about winter driving after all.
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ConcordeSST
Member
Thank you for the thoughtful reply. I genuinely appreciate the time it took to write all of that. You clearly have a lot of experience in this area. While I'd still prefer a mode to save me from my own weaknesses and moments of inattentiveness, I'll definitely try to keep all this in mind the next time nature gives me the opportunity to experiment with it!
Got this quote from an online pub:
"The Tesla Model 3 Performance comes with two motors, one up front and one in the rear. These two motors are locked to the tires on each axle, so the Model 3 uses the brakes to adjust the speed of one side or the other to maximize traction and minimize slippage."
I was under the impression that there was a kind of torque sensing (vectoring) that modulated power to the wheel. This statement just seems to suggest the brake pads are being smoked to slow tire movement.
Am I mistaken?
"The Tesla Model 3 Performance comes with two motors, one up front and one in the rear. These two motors are locked to the tires on each axle, so the Model 3 uses the brakes to adjust the speed of one side or the other to maximize traction and minimize slippage."
I was under the impression that there was a kind of torque sensing (vectoring) that modulated power to the wheel. This statement just seems to suggest the brake pads are being smoked to slow tire movement.
Am I mistaken?
StealthP3D
Well-Known Member
Only if the electronic driver aids need to kick in due to slippage. This is how all modern open differentials are modulated for better performance. It's not a new thing, ICE cars have been doing it for years.
And it's a very good thing, at least until we get dedicated electric motors for every drive wheel and the mechanical differentials can be sent to the ICE graveyard where they belong.
So every time I straight line launch on a wet roadway my brake pads are being used to slow the most slipping tire? Seems primitive and hard on the pads but maybe that what is happening. Thanks for the comments.
DR61
Member
Yes; brake pads are relatively inexpensive. Most modern cars do not have mechanical limited slip differentials; instead they use inexpensive brake pads controlled by the ABS computer and various other sensors.
Knightshade
Well-Known Member
to be fair- most modern cars are FWD non-performance vehicles so an LSD would be pretty wasteful on them anyway.
Most RWD/AWD performance cars still offer an LSD at least as an option
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