First drive in snow probs: Tires, I hope...ABS brakes frightening

First of all, ABS is better and faster than you'll ever be able to dose yourself. ABS also keeps the car in curves while breaking. Secondly, Audi awd doesn't overrule the natural forces. If you want to really play with it I suggest you attend one of these Audi workshops in snow conditions, they're really good! Last but not least, real winter tires are much better than all others in the cold, not a bit, a lot!

Ronald

Get snow tires, really.

One thing: Despite the ABS, if you want to brake well, slam the brakes as hard as you can even with the ABS on. The force on the brake is still determined by the pressure of your foot and not by a brake-by-wire-automatic-full-braking-servo.

The ABS only makes your car steerable while on the brakes and it remains under control. It is not a solution for poor driving skills (not implying YOU have poor driving skills here).

Regards

Wolfgang

Hi,

I've got a 98 A6Q, 130K miles. Also got a UK racing licence, although not sure that qualifies me to offer advice :-)

Firstly, tyres ARE the most important item on your car. We have very little snow in the UK. I use Goodyear F1's for the dry, wet and ice, they are without doubt the best tyres I have ever tested. They are, however, USELESS in the snow, so I have a friendly tyre dealer who will put different tyres on when it snows.... And they really help.

Quattro can be both good and bad in snow and ice. The problem is, the Audi system puts 25% of the power to each wheel unless one or more are losing traction, meaning that if you are not accelerating, all four wheels are locking up together when there is no traction. Also, all modern cars are designd to understeer, and this can make the quattro a real pig to drive in snow/ice/wet unless you know what to do.

ABS is the absolute worst ever invention for snow driving. The problem is that snow has no grip, so the ABS doesn't actually do ANYTHING. In the old days, when you locked your wheels in the snow, a pile of snow built up in front of the wheels, and you were able to also push the snow out of the way and maybe get down to the road, but no longer. In the snow, best not to get into trouble in the first place, but if you do, try to drive out of trouble, using the handbrake (as long as you know what you are doing) can be your best ally.

Finally, if anyone has worked out how to disable the Audi ABS, please let me know. I know someone said you'd never stop as quick without them, but quite frankly, they are wrong. For someone that has just the slightest driving talent, you can pull-up quicker without them. The key issue is never panic-brake.

Ashley

ACK.

That's a little harsh. In fact, the most common error is that drivers are now not pressing the brake pedal as hard as they would without ABS. You gotta practice that.

The pile of snow itself would also slow you down.

Err.. I would agree if you do have a racing licence ;-) However, for most folks on the road (using ABS) I would just say, carefully keep on steering.

Yes, they are wrong. ABS is not there for quicker braking (although on dry roads it takes an experienced, well aware driver to outperform it). The major advantage is that the average Joe (or Jane for that matter ;-)) can just slam down on the brakes without caring about braking at the borderline of friction _and_ the car remains under control, i.e. you can steer around obstacles.

I agree, but IMO 8 out of 10 drivers _will_ panic brake and have never trained braking, releasing the brake to steer clear and reapply the brakes properly. ABS helps a lot there.

Oh, and I think just pulling the ABS fuse should do the trick. :-)

Regards

Wolfgang

There is no such thing as an all season tire unless you live in Florida, Southern Cal, etc. Buy a good set of snows for your A4 and you will have no problems. You may have the "I-have-all-wheel-drive" syndrome which makes you over confident. Check out the cars that are in the ditch or median on an interstate during a snow storm. Many (most?) are 4x4 or all wheel drive vehicles. Quattro doesn't compensate for poor driving habits. However, it is very "forgiving" and in the hands of a good driver will out-perform just about any other passenger car in adverse conditions.

ABS? Best thing since sex! ABS does not mean you can stop quicker. In fact, in deep snow or gravel roads, you get your best braking without abs. I had an opportunity to test a car with/without ABS. With ABS, it stopped at 100 feet from 50 mph. Without abs, I (and several other drivers) stopped the car in less than 100 feet using threshold braking. We then took the car to a dirt road and performed the same test. With the abs OFF, we stopped in 120 feet. With abs ON, it took an amazing 180 feet to stop. It was a very eye-opening experiment.

Audi used to have an on/off switch with their abs, but I can see where such an arrangement would bring forth a plethora of law suits. ABS allows you to

*maintain* maximum braking while still being able to steer. In the "old days" folks would jump on their brakes, lock up the fronts, and become an unsteerable object. ABS does away with lock-up. However, poor driving habits still abound with drivers jumping on their brakes, NOT steering, and still hitting the car in front or whatever.

So, bottom line? Buy four steel wheels ($50/wheel), and mount some good snows (Blizzacks?). I have been to Audi, Corvette, and BMW factory driving schools (i.e. Audi Hands On) and cannot recomment too highly the knowledge/skill attained from these courses. Next best thing would be a Sandy Stevens school (northeast)

or a Bud Stanley school (Florida) These schools are inexpensive and concentrate on ABS braking and vehicle handling. And if you mention my name, you may get a discount - I used to teach in both schools, but health (and old age) has caused me to retire.

Dave '03 RS-6 Avus and Ebony

I am, but in a nice way.

AWD is good for applying power to all four wheels. It does not, now follow me here, improve coefficients of friction - in other words, traction.

Anti lock brakes categorically improve both braking performance and steering while braking. There is absolutely no doubt about that. Multi million dollar airliners - with which I am very familiar - take a huge penalty in stopping distance on snow covered runways if their antilock systems are not working properly. This fact is undeniable by anyone who has any information on the subject. ABS works better than we do. It just feels funny.

Your experience goes to your learning. Congratulations. You are now a better driver than a few weeks ago.

Snow tires create traction in snow. Some better than others.

Good luck, and slow down.

Grover

Ahhh, but there is ":doubt about that." A trained driver can outperform ABS

*in a straight line* most of the time, using threshold braking. I've done it. What abs allows is better steering performance (as you have stated). Problem is, most folks will panic in an emergency and jump on their abs equipped brakes and not steer, still hitting the vehicle in front of them (or whatever). On a dirt/gravel road or in deep snow, the vehicle *without* abs will stop in a shorter distance.

A problem first arose with abs when drivers would engage the abs and hear/feel it working. They would do the worst thing possible - take their foot off of the brake. Systems have improved since those first used in the 80s on automobiles, but when abs first came out, there were a lot of problems with drivers not used to the noise/feed back from the system.

Dave '03 RS-6 Avus and Ebony

X-no-archive: yes

Clearly you dont live in Scotland!! :-)

They get their fair share of snow up there, more the further north you go. Its unusual for a year to go by without a reasonable amount of snow to fall. Not enough to block you in but enough to make driving a real nuisance.

Type?

Doesn't the ABS system have its own fuse? Guess you could always remove that one.

Right, that's sorted out airliners. Now back to cars..

A quick recap on Newtonian friction (it would be helpful to have a graph at this point - if anyone can supply a link, then please do so!)

You apply a retarding force to something moving (e.g. applying the brakes) and you get a roughly proportional force applied by the tyres themselves to the road. Up to the static limit, that is (if memory serves - this may be the wrong term in this context).

At this point, the tyre slips, the brakes grab, and you've locked your wheel(s).

You can sort of duplicate this by tilting a flat surface with something resting on it (e.g. your wallet on a book); when you tilt the book far enough, the static limit is exceeded by gravity, and the wallet slides.

Back to cars, this has two effects. Firstly, you have reached the total traction limit of the tyre, so applying a sideways motion ("arrrggh! Tree! Tree! Steer left!") does absolutely nothing. .

Secondly, in real life, the coefficient of friction on a tyre will often /drop/ when it locks, meaning that you're not decelerating as hard as you might.

The technique of threshold (or cadence) braking is to try and get right up to that breakaway point - where the tyre is working at its hardest - and stay there.

A bump in the road, or a bit too much pressure, steering motion, or a gas pocket in the pads can all cause you to exceed that limit and lock the brakes. So you release the brakes (just enough to unlock the wheels) and try again. "Cadence" - geddit?

ABS simply attempts to mimic that mechanically. But it doesn't have braking "feel" - it simply pummels the brakes on each side of the static limit.

Theoretically, then, a human is capable of stopping in a shorter distance than the type of ABS systems fitted to current cars. He can also steer, assuming that he's not panic-braking. A Google should probally throw-up a few tests - I've read a few in magazines where this has been demonstrated.

You don't need to have a racing license to do this - just practise (and preferably off the public highways!).

An airliner, though? I dunno. And would this still hold true if the pilot had sufficient brake feel and skill? Well, since someone like Boeing is unlikely ever to expend the energy finding out, I'd say the point is a little moot... personally, I'd hope that he'd concentrate on improving his flying skills ;o)

Good advice!

Particularly since ABS disperses that wedge of snow that would otherwise slow you down. Mk.I ABS was even worse - it used to release the brakes entirely if all four wheels locked, hence the off-switch on older Audis.

The tires are your problem. You could have 10 wheel drive and it won't make any difference if your tires don't have any traction. The most sensible thing to do is to buy an extra set of cheap rims and get 4 decent snow tires. I've been using Dunlop M2 Winter Sport tires and I had absolutely no trouble at all in 8-12" of snow the other day. I passed a number of SUVs in ditches on my way to work and on the way home. I also passed a number of rear wheel drive BMW and Benz vehicles just left on the side of the road with angry occupants likely waiting for a tow...two wheel drive with wide rear tires ought to just be left inside in rain/snow. Lastly, all season tires are just that. They have decent performance in many different conditions (some better than others), but aren't top performers in any of them. If you insist on using them, get used to driving much slower in the snow.

Cheers,

C

Just for completeness: Tires don't comply with pure Newtonian friction. In fact the rubber interlocks with the surface it's rolling on.

I.e. the achievable negative acceleration is actually higher in this case than compared to pure friction.

Which of course does not invalidate your points.

Yes, but only down to a certain speed. I have in mind that for this reason ABS switched off a something like 12 km/h. I think it still does, though. (Hopefully)

Regards

Wolfgang

Huh? You *do* know that Newman's *79* and still racing (a little), don't you? =;^)

-- C.R. Krieger (Been there; still doing that)

Yeah! Ain't old Blue Eyes sumptin else? d;o) Last race I saw him was at Lime Rock this past summer and he came in 5th overall. Terrific guy. Terrific driver. I first met him at the piss trough at Lime Rock about 20 years ago. Was right there when he went into the kitty litter at Turn 1 at Road Atlanta during the Nationals about 10 years ago. Got out of the car, faced the fans, smiled and went on his way to lots of cheers.

Wish I could still do it, but the lungs are shot with emphysema and interstisial lung disease. One day at the track would mean three days recovering! d;o( Dave

This is all good news. Thanks.

in article snipped-for-privacy@mb-m21.aol.com, Dave LaCourse at snipped-for-privacy@aol.comPirate wrote on 12/9/03 7:37 AM:

Point taken. I believe you. I should not have used the statement "categorically improves." I can see that highly trained, and practiced, drivers can do better - especially in gravel or some surface that has lots of mini-skids. I'm willing to bet that that is a fraction of a percent of drivers.

Le Mans cars don't have ABS, right?

My tone of frustration is due to being stopped for hours on mountain roads while they haul away multiple spin outs from people thinking their 4x4 was a license to groove.

I've nearly been hit (like the trees - but I bleed more) by guys in a side slip or spin, hitting their brakes all the while and cursing their AWDs.

I start to loose sympathy for the Sport Ute folks who will be spending several grand in the body shop.

Ok. Back to something positive...

Quattro is amazing. My hat is off to the guys who design this stuff.

Heading into the snow as soon as I hit "Send",

Grover

Of course. I guess I was hoping that I could get away with not having to deal with 2 sets of tires.

Pig is the word. The primary goal of the Quattro designers obviously was not snow and ice performance.

I was surprised to discover during the first weeks driving this car the effect Quattro has on driving on bone-dry roads. It makes a difference and I'm not sure I understand why. In the rain, of course, it grips like crazy, but again in the forward direction--lateral traction (terminology?) being heavily dependent on the tires. The RE950s are pretty good in this respect.

One would think the primary design goal of an AWD vehicle would be snow and ice performance. A stupid assumption, and explains a lot about Quattro behavior.

Some weeks ago, I made a tremendous blunder--mistaking red lights for green and was forced to do some severe braking. I was going about 60 mph and stopped in short order. That bloody ABS system was going crazy. This was in the dry but I'm not sure what effect ABS had on overall stopping distance.

Regarding over-confidence. Actually I purposely started out with great care, but I think my brain is still programmed to drive old Saabs in the snow. I didn't crash, but it was eye-opening.

It is incomprehensible that ABS actually reduces accidents. Why does it survive?

Fabulous.

You've got to be kidding! ABS allows all of us to brake at maximum efficiency and steer out of possible trouble, *without a whole bunch of track-side training*. It took me many times and quite a few flat spots on tires to learn threshold braking (applying the brakes with maximum efficiency without steering lock-up. Hell, now my 16 year old grand daughter can do it right out of the blocks! ABS "threshold brakes" for you. It is a no-brainer. Jump on the brakes and steer. You no longer have to worry about becoming a sled (front wheels locked). Dave

No drive or braking system is better than the tires that put it on the road! I believe the tires on the A4s of that vintage are Eagle RS-A's. I would like to get a set of those for my next set of summer tires on my '95 90Q but I wouldn't want them for the winter. The tread pattern on them is way too tight to get a bite on the snow, they will simply spin on top like a slick. Also, the tire compound is much harder in the cold, adding to the previously mentioned "slick" effect.

When I got my 90Q used, it had balding Eagle GT's on it. I was forced to drive it in the snow with them before I got snows. They were positively frightening on the snow, although it was a lot of fun playing with oversteer and such at low speeds and torques!...until there was any reason to stop or slow down.

Bottom line- if you want nearly unfettered mobility in the snow with the Audi, get a set of soft snow tires with a nice, open tread pattern on a set of steel wheels just for the winter. Quite litterally, the only thing that stops the quattro so equipped is smooth ice or a deep snow drift. :-) It tends to stop when the wheels aren't on the ground anymore.

The "Tire Rack" sells wheel and snow tire sets already mounted and balanced and sized for the car for $400-$600. This also gets your nice alloy wheels out of the salt and sand that can eventually start to eat at the relatively chemicaly active magnesium alloys.