Winter Driving?

[Suberman]

Originally Posted by daiheadjai

Can we actually get Tire Rack stuff here?
Seems like once you factor in shipping and taxes, it might not be the same picture.

I'm on 16s now - for those on 17s/stock size, how are you finding it?
I noticed a little bit of squirm when rolling out, and the sidewall height definitely does not inspire cornering confidence (in the dry)

225/45x17 Pirelli Sottozeros and no tire squirm.

Suspension squirm yes but not tire squirm.

[1Cor10:23]

I have xi3s on and you can definitely get tail happy (quite easily) 2nd gear with a bit of throttle on any turn will make it happen. Especially last night in the fresh snow

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[brzr]

last night


this morning

[Snowball]

Got home at 2am last night...witnessed an accident (spin out) on the highway firsthand (Was slowing tailing a tow truck) right around 410 & Steeles. Hard to tell what happened, but in the end an older Lexus sedan was wrecked and a mustang (seen spinning across about 3 lanes) had a crumpled front passenger corner...lucky tow truck driver I guess to be right in front of the event. Kinda expected it last night tho with the first snow happening, be careful out there...especially of others around you.

FWIW, blizzaks did great on dry snow with snow mode on and careful throttle inputs.


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[Kazuya]

So after drifting in a big lot last night I learned two things.

VSC SPORT mode and just tapping the brakes at 30/km with blizzaks make you go side ways. Winter tires are surprisingly good and snow makes a little rubbing sound >.>

I may take TC fully off, this car is so bomb in the snow.

[navanodd]

Anyone have any experience having gone from studded winter tires to the new studless? My old Accord had a old, cheapo set of studded winter tires on it and I never felt myself wanting more grip. Never stuck once, key was always just to be smooth with inputs.


I went with studless Xice3's for the BRZ essentially because it really seems like studless tech is handily beating studded tires now in wet, dry, snow and ice.


Of course I will need to get experience handling this car in the slick stuff. I've read that the traction/stability control settings for this car also affect the ABS sensitivity. Has anyone experienced this? I've always found ABS to be counterproductive on snow and ice.

[mrceltic]

Originally Posted by daiheadjai

Can we actually get Tire Rack stuff here?
Seems like once you factor in shipping and taxes, it might not be the same picture.

I'm on 16s now - for those on 17s/stock size, how are you finding it?
I noticed a little bit of squirm when rolling out, and the sidewall height definitely does not inspire cornering confidence (in the dry)

Depending how close to the border you are, have it shipped to a shipping depot in the states and have them installed in the US.

I live in Sarnia, ON and cross the border once a week to pick up stuff I ship to the US. Saves big bucks.

[Suberman]

Originally Posted by navanodd

Anyone have any experience having gone from studded winter tires to the new studless? My old Accord had a old, cheapo set of studded winter tires on it and I never felt myself wanting more grip. Never stuck once, key was always just to be smooth with inputs.


I went with studless Xice3's for the BRZ essentially because it really seems like studless tech is handily beating studded tires now in wet, dry, snow and ice.


Of course I will need to get experience handling this car in the slick stuff. I've read that the traction/stability control settings for this car also affect the ABS sensitivity. Has anyone experienced this? I've always found ABS to be counterproductive on snow and ice.

ABS works fine on snow or ice.

Traction control does not affect ABS as that is optimized for grip. Traction control is optimized for stability, slightly different idea.

Studded tires can't be beat except on bare road when they are just awful.

That's why studless rubber was invented.

No Canadian driver actually needs studded or studless tires to drive in winter.

[navanodd]

Originally Posted by Suberman

ABS works fine on snow or ice.

Traction control does not affect ABS as that is optimized for grip. Traction control is optimized for stability, slightly different idea.

Studded tires can't be beat except on bare road when they are just awful.

That's why studless rubber was invented.

No Canadian driver actually needs studded or studless tires to drive in winter.

Glad to hear that the ABS is ok on this car in the snow. My Accord must have had unusually sensitive ABS - if it was especially slick I basically got no braking when at slow speeds, but had enough grip to stop if I used the e-brake.


I must have read some misinformation about traction/stability control affecting ABS thresholds. It seemed a little odd to me that would happen.


Thanks,
Greg

[Suberman]

Originally Posted by navanodd

Glad to hear that the ABS is ok on this car in the snow. My Accord must have had unusually sensitive ABS - if it was especially slick I basically got no braking when at slow speeds, but had enough grip to stop if I used the e-brake.


I must have read some misinformation about traction/stability control affecting ABS thresholds. It seemed a little odd to me that would happen.


Thanks,
Greg

Early ABS suffered from software issues on ice, loose snow, sand covered Tarmac or gravel roads. Early Audi Quattros with ABS had an off switch. Most of those issues have been solved with better wheel speed sensors and better ABS software.

[jonboy99]

Thanks, I didn't type my question properly - I meant when only one wheel is one ice, and therefore has close to zero grip will the torsen be able to transfer any significant drive to the other side? Certianly when one wheel has zero grip, no torque will be transferred, for example when a wheel is up in the car. Rollers can certainly reduce the grip to a level low enough to cause the same effect, I just wondered if sheet ice could too. I imagine not most of the time.

Originally Posted by Suberman

No, they act like a locker when traction is roughly equal. Unlike a friction type LSD or an electronic ABS based LSD the Torsen does not brake the spinning wheel.

The Torsen actually transfers engine torque across the differential gears to the wheel with more traction. The "spinning" wheel reduces its spin because the torque to that wheel is in effect reduced. This torque bias is about 4/1 on the BRZ. On ice four times zero is zero so both rear tires spin up, just like a friction type locker but unlike the ABS electronic type pseudo LSD.

A normal open differential transfers only twice the torque to one side than to the other. When one side spins because of no grip then twice zero is also zero so no torque goes to the wheel with traction.

[Suberman]

Originally Posted by jonboy99

Thanks, I didn't type my question properly - I meant when only one wheel is one ice, and therefore has close to zero grip will the torsen be able to transfer any significant drive to the other side? Certianly when one wheel has zero grip, no torque will be transferred, for example when a wheel is up in the car. Rollers can certainly reduce the grip to a level low enough to cause the same effect, I just wondered if sheet ice could too. I imagine not most of the time.

No, the big drawback of the Torsen is it transfers torque. So, if one wheel has no grip then the other wheel gets the same low, low torque as the spinning wheel multiplied by the bias ratio (which is reputed to be 4:1 in this car). The car is driven forward only by the grip of the spinning wheel x 4. As you know zero x 4 is still zero.

A conventional friction type or ratchet locker type diff will allow the drive wheel with grip to apply the torque to the ground. The diff actually brakes the spinning wheel down to the speed of the gripping wheel. The car is driven forward by the total of the grip available.

The good news on our cars is the TRAC system is an electronic LSD which cuts in and brakes the spinning wheel. This produces in effect a fake torque resistance as if the spinning wheel were actually gripping the road, which the Torsen can multiply by the bias ratio. Brake operated electronic LSD work just like friction disc types which is why they have pretty much replaced friction and ratchet types. The difference is electronic LSD will not allow wheelspin whereas mechanical LSD allow both drive wheels to spin if enough torque is applied. The Torsen has this advantage also but only if the TRAC is switched off. Then in slippery conditions the mechanical LSD has the advantage, but only in the hands of a skilled driver.

Our cars have the advantage of a Torsen which works very well on dry pavement and a friction type electronic LSD for wet or icy roads.

The tricky bit is deciding when to switch off the electronic LSD. In the dry you don't need it. In the wet the car handles much better with the TRAC completely off as long as you're skilled enough to catch the oversteer. With the TRAC active low speed fast corners can open your eyes (and possibly other orifices) in a hurry. Ironically this is because the Torsen transfers and multiplies the fake torque generate by the wheel brake very suddenly. This is deliberate on the part of Subaru and allows for an oversteering chassis that is also relatively safe for beginners.

On ice or snow turning TRAC completely off makes the car a predictable handful to drive. The Torsen gets no help from the traction control so your tight foot must do all the talking. For maximum performance in snow I suspect VSC is likely very effective.

[drewbot]

Reading this, I really want it to snow in the GTA.

However, it is +13 C right now, and raining...

[congee]

How long do you guys usually wait to warm up the car before taking off?