dicktahoe

An interesting article as we approach winter. AWD/4WD gives traction for starting up, but all cars have 4-Wheel Brakes which makes them equal for slowing or stopping. Tires make the difference.

https://www.yahoo.com/autos/do-you-r...215517939.html

snagitseven

Unless you are downshifting to maintain control which makes AWD like
Quattro, superior to 2-wheel drive for slowing..

Sportstick

Yes, correct, tires are the critical factor, not how many wheels are powered. There is no part of an all-wheel-drive system which makes contact with the road. Therefore, it is correct to say that all-wheel-drive does not (contrary to some conventional wisdom) "add traction". It powers the wheels and, therefore, the tires to turn, and if the tires are capable of generating traction on a low mu surface, they provide the traction. Four low traction tires (all seasons in sub-freezing winter on snow/ice) can spin just as easily as two. And, of course, getting going is a convenience...stopping and turning is the stuff which saves lives and prevents injuries and those generally don't involve adding throttle in an emergency. We typically see at least some mystified SUV drivers with all season tires who climb out of a ditch and tell the "LOCAL whatever" reporter, "But I have four wheel drive!?!?"

irenesbob

That depends on where you are. I had a weekend chalet in NYS’s Catskill Mountains; my house was at just about the 3,000 ft. elevation – fairly high for NYS. It was on a ¾ mile long unpaved dirt private road that was maintained by the joint efforts of the 8 houses on the road. The Town refused to take over the road because it was way too steep and would cost too much to meet their standards. No delivery service (UPS, FedEx, etc.) would deliver after the snow reached a certain level. Likewise, fuel deliveries. I heated with kerosene and a Monitor heating system. The dealers would not accept orders after mid-November and that road was off limits until April 1st.
In that situation I had two cars: a Nissan Altima and an Isuzu Trooper. For winters I had Bridgestone Blizzaks on the Altima and cheap house brand generic truck tires on the Trooper. After about the third snowfall the road was a bobsled run for the winter. The Trooper never once got stuck, but the Altima got stuck every time I tried to go up. I even tried backing up so the weight would shift to the drive wheels, but no go. I wound up making a deal with a homeowner at the bottom of our road to park in their driveway for the winter and then walk up the private road.
I will say that although the Trooper was able to get up and down that road (as opposed to the Altima with dedicated winter tires), it was much more squirrely on “normal” winter roads. I always tried to switch to the Altima once I got down my road because it had better traction and braking except on that extreme kind of road.

Barrels41

Last winter I gad a ride with a friend of a friend in a Porsche Cayenne. The SUV skidded slightly going up a slick VT road. I wanted to suggest winter tires but kept my mouth shut. Very few vehicles in the NE use winter tires. It is an undersold product. The owners of luxury AWDs don't realize the benefits.

2008A6

Tires are critical, but I think what snagitseven was alluding to below is that AWD comes into play when you're using engine braking via transmission to slow the wheels down and you're applying that speed reduction at all four wheels. The assumption is that will yield better results in terms of reduced slippage vs. slowing only two of the wheels on a rolling 4-ton beast.
I haven't studied this phenomenon in detail but certainly seems like a valid point.

Sportstick

Yes, it would seem logical that he has a point. However, this is a very rare technique among most folks here. Unless I am in my manual trans car and dealing with shifting and braking when entering corners, I have always worked under the assumption that it is more economical to replace brake pads than transmissions, but I also don't deal with prolonged downgrades where brake capability can be compromised over time and rate of descent. If you live in a significantly hilly/mountainous area, that technique to maintain descent control is indeed helpful.

snagitseven

The "I'd rather wear out my brakes than my transmision" argument keeps popping up and frankly, I've not seen any data to support it. In fact, one could make the opposite argument that using the transmission to slow the car saves wear on the brakes.

I've been using my Audi tiptronics equipped cars manually for years and have never had any issues with the transmissions. These ZF trannys are designed and built for manual down and up shifting and Audi and other brands have used them for many years with that capability. The Audi marketing name itself comes from the ability to manually "tip" the gearshift. As I wrote, I've been happily "tipping" up and down with four Audis without any worries.

Also, I dont think it takes a great amount of skill to take advantage of Quattro for slowing in snowy conditions. I've been doing it for years. Dropping a gear or two while using the brakes as necessary slippery conditions can add additional traction and control in most situations - hills or on the flat. Not hard to do at all and I'd bet many tip drivers here employ it.

Sportstick

You are right that no data has been presented...it is speculation, and has been around a long time, probably long in advance of these transmissions. It may well be that these can easily handle the load over time. I just see no advantage if the brakes are not being overly stressed into fade, such as on a long descent and the real or speculative risk to the trans is reduced. Given the low cost of pads, I also never have had concerns about replacing them when needed, which is also infrequent. It may just come down to different driving style preferences with no strong advantage either way, based on data.

snagitseven

Well, my data shows manually downshifting helps me control the car in any situation and no tranny issues in 13 years of Audi tips confirms it for me.