Will I survive this winter?

[Suberman]

Originally Posted by ZDan

The "as I expected" betrays bias. People tend to experience (or *think* they experience) what they *expect*. Blind A/B/A testing would be better, but of course not hugely practical!

"Precisely" implies you made *precise* measurements. Did you?

Weight over the drive wheels will help a bit, but even 100 lb. added only gives you 4% more drive grip, which you may or may not notice.

Weight distribution is nowhere near 50/50. http://media.caranddriver.com/files/...e-napoleon.pdf (55.2/44.8 full tank, no driver). They claimed 53/47 for the car with driver and passenger and a full tank, but as-tested weight distribution with fuel and driver is 54/46. That's not very good in snow... 100 lb. at the front of the trunk even with the rear wheels improves this to 52.2/47.8. Better, but not HUGELY so. 47.8/46 = 1.04x the grip. Might make the difference, might not.
May as well put the weight as far back in the trunk as possible. The car will still be more drive-traction limited than front grip limited. Might put another .5%-1% on the drive wheels.

I don't think so. The torsen is "torque-sensing", in low-torque situations, lockup should be light.

In a straight line, the torsen is ensuring that you don't get a 1-wheel spin and that both wheels are contributing as much as they can before they both start to spin. It is HELPING. Of course when you do break traction, you spin both wheels and lose all lateral stability instead of only spinning one wheel and keeping some lateral stability. But for sure the torsen is close to maximizing the available drive grip.

The PROBLEM is poor static weight distribution. The best solution is good winter tires, which you already have. Putting weight in the trunk in the form of sand or kitty litter or other material that can also be used as traction-compound will also help. I did that with my old 240SX with similar weight distribution and no limited slip.

In my S2000, with Torsen diff, 49F/51R distribution with driver and fuel, on Dunlop WinterSport tires, never a prob

Geez, and I thought you knew a thing or two.

This is all nonsense.

How much weight are we to add to improve traction? 200 lbs?

Anecdotal evidence isn't supposed to be scientific. Also, nobody can actually usefully measure traction in winter conditions because they vary so much. Even travelling twice over the "exact same road" doesn't work.

Torsen never locks up, ever. Low traction on one wheel means low traction times four at the other wheel, then you get wheelspin.

Torque bias remains EXACTLY the same regardless of available grip.

A simple and effective test is to find a steep snowy hill and see if weight makes any difference to whether you can get going from a standing start or not. All of my cars can on this particular hill, with snow tires and no weight. Except the BRZ. All of the cars brake equally well going down the same hill. Two are fwd with significant front weight bias but of course this is countered by the uphill. One is awd. I also drove a rwd version of the same awd car on the same hill in similar conditions. Weight distribution was similar to the BRZ. Performance was superior to the BRZ.

Another simple end effective test is to park and unpark in deep snow by the curb. Same results.

Another simple test is a parking lot skid pad. Same results.

Weight over the axle isn't the issue. I'm not sure exactly what the issue is but I suspect a 4:1 Torsen just isn't very effective in severe winter conditions.

I can't imagine suspension geometry is the issue.

It is a fact, easily demonstrated, that the BRZ is no good as a winter daily driver.

[ZDan]

Originally Posted by Suberman

How much weight are we to add to improve traction? 200 lbs?

As I noted above, 100 lb. ~4% more drive, so naturally 200 lb. should give ~8%.

A simple and effective test is to find a steep snowy hill and see if weight makes any difference to whether you can get going from a standing start or not. All of my cars can on this particular hill, with snow tires and no weight. Except the BRZ. All of the cars brake equally well going down the same hill. Two are fwd with significant front weight bias but of course this is countered by the uphill.

Not so much. A 12% grade would move the c.g. aft about 2.4% for a car with a 20" c.g. height, a 60/40 fwd car becomes 57.6/42.4, still putting a fair amount more on its drive wheels vs. the 54/46 BRZ which improves to ~51.8/47.2 (accounting for its low 18" c.g. height). Even accounting for the hill, still a whopping 22% advantage to the fwd car.

One is awd. I also drove a rwd version of the same awd car on the same hill in similar conditions. Weight distribution was similar to the BRZ. Performance was superior to the BRZ.

What car? Anyway, if its c.g. is higher than the BRZ's (likely the case) it would have a *very* slight advantage from that going up the hill, but shouldn't be enough to notice.

Weight over the axle isn't the issue. I'm not sure exactly what the issue is but I suspect a 4:1 Torsen just isn't very effective in severe winter conditions.

Low percentage weight on the drive wheels is certainly *part* of any drive traction problems you're having.
I don't think the torsen should be a problem in the snow (never has been for me in either of my Torsen-equipped FR cars), particularly in a straight line.

I can't imagine suspension geometry is the issue.

No, me neither.

It is a fact, easily demonstrated, that the BRZ is no good as a winter daily driver.

Hmm, this guy seems to love it...
http://www.ft86club.com/forums/showthread.php?t=54213

Originally Posted by Rosso_Corsa

The FT86 is my perfect winter car. Rear wheel drive, limited slip differential, manual, and a chassis tuned to go sideways. With a set of Michelin X-Ice snow tires, it's an absolute hooligan in the snow. Here's a little winter hoonage filmed in super slow motion @ 240fps!
Hope you're having just as much fun with your 86s this winter!

[Dipstik-sportech]

I loved my brz in the winter!! Handled unbelievably better than my 2wd ranger or my chev c1500, both of which r rwd BTW.

Sent from my Nexus 5 using Tapatalk

[tomato86]

Originally Posted by humfrz

Welcome back ....

Too bad you got stuck so many times.

What tires do you have on your car..??

humfrz

Thanks, and I have the all-season Bridgestones that Toyota equipped, they're not the best so I need to upgrade.

[ZeeK]

Come to northern Alaska.. it's -40 here lol!

[brzr]

my fingers in my gloves were hurting at one point.....i think i have to buy warmer gloves

[Mad1723]

Originally Posted by brzr

my fingers in my gloves were hurting at one point.....i think i have to buy warmer gloves

I feel you, it was -25°C not too long ago here. Madness didn't like the first start in the morning

[Dipstik-sportech]

That's it?! -14??!!! My car said -42 last year lol

Sent from, The Frozen North

[brzr]

Originally Posted by Dipstik-sportech

That's it?! -14??!!! My car said -42 last year lol

Sent from, The Frozen North

lol

the coldest it was here last year was -22 i believe..........i was freeeezing

hate the cold so much....wish i could move somewhere warmer

[Rustyspoon]

I stuck WRg3s on the car, so far drives very well in Albertan weather. I figured deep snow would be the tires downfall, nope. Nokian knows how to make a good tire, makes me wonder how much more traction their dedicated snow tire gives. this car is so much fun to drive in the winter and in -14 celsius i dont even wear a jacket....... but I dont mind the cold

[Mad1723]

Originally Posted by Rustyspoon

I stuck WRg3s on the car, so far drives very well in Albertan weather. I figured deep snow would be the tires downfall, nope. Nokian knows how to make a good tire, makes me wonder how much more traction their dedicated snow tire gives. this car is so much fun to drive in the winter and in -14 celsius i dont even wear a jacket....... but I dont mind the cold

I run one of their dedicated snow tires, Hakka 7s, and they are amazingly good. No fuss off the line and when the tail decides to slide, easy to recover.

[FRiSson]

Simple. The car is designed with as much weight towards the center as possible. That means that the car is designed to essentially pivot around its center. If you place weight towards the ends of the car, you disrupt that carefully engineered principal. You will then create forces that will tend to swing the car away from its center axis, much like placing a weight on the edge of a spinning top will cause it to swing off-axis.

The only time weight might help is if you are stuck or getting little traction up a hill. But once you start taking turns, the weight will be a detriment to the control of your car. So if you must, keep the weight near the center of the car (back seat or passenger foot well) then move it to the trunk if you are stuck.

The idea of putting weight in the trunk comes from your grandfather's day when Detroit cars were too light over the rear axle. Those cars were much larger and differently constructed than the FR-Z.

[jonboy99]

You are Suberman2 and I claim my Soapy tenner.

Originally Posted by FRiSson

Simple. The car is designed with as much weight towards the center as possible. That means that the car is designed to essentially pivot around its center. If you place weight towards the ends of the car, you disrupt that carefully engineered principal. You will then create forces that will tend to swing the car away from its center axis, much like placing a weight on the edge of a spinning top will cause it to swing off-axis.

The only time weight might help is if you are stuck or getting little traction up a hill. But once you start taking turns, the weight will be a detriment to the control of your car. So if you must, keep the weight near the center of the car (back seat or passenger foot well) then move it to the trunk if you are stuck.

The idea of putting weight in the trunk comes from your grandfather's day when Detroit cars were too light over the rear axle. Those cars were much larger and differently constructed than the FR-Z.

[ZDan]

Originally Posted by FRiSson

Simple. The car is designed with as much weight towards the center as possible.

Unfortunately, they missed the center by a bit... 55/45 weight distribution isn't so hot for getting around in the white stuff in a rwd car.

That means that the car is designed to essentially pivot around its center. If you place weight towards the ends of the car, you disrupt that carefully engineered principal. You will then create forces that will tend to swing the car away from its center axis, much like placing a weight on the edge of a spinning top will cause it to swing off-axis.

Nah, it's no big deal. Think of it this way, the car *was* designed/engineered to work just fine with 4 humans in the 2+2 seats and all their stuff loaded up in the trunk, upwards of 1000 lb. on top of vehicle weight. It is no big deal at all to put 50-100 lb. of kitty litter in the trunk to aid a bit in traction and to have an emergency supply of "traction compound" for when/if you do get stuck.

It is not going to ruin the car's handling by any stretch of the imagination. That's exactly how I got around in the snowy months in my 240SX, which weighed the same and had the same weight distribution. No problemo...

The idea of putting weight in the trunk comes from your grandfather's day when Detroit cars were too light over the rear axle. Those cars were much larger and differently constructed than the FR-Z.

But they suffered the same basic problem: only ~45% of vehicle weight over the drive wheels. TBH even 100 lb. in the trunk only increases weight on the drive wheels of even a lightweight(ish) car like the FR-S/BRZ by 4%, but every little bit helps, *and* you have a trunk full of traction compound when needed