Why haven't you answered my or Mr. W's questions?

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1983 M-B 240D-Gone too.
1976 M-B 300D-Departed.

"Good" is the worst enemy of "Great".

now you have made a statement about a single tire. There are four tires in a car or truck. What you have described can be applied in what instance, please? Entering a turn, exiting a turn, solid state turning, or some other instance?

As for qualifications do you have advanced education in vehicle dynamics?

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

Alright I will examine your second paragraph. You say that the cornering ability of the tire has nothing to do with the torque applied to it but then say that if too much torque is applied it will lose traction. I agree with the second portion not the first. Having accelerative forces in addition to cornering forces will diminish the cornering ability of the one tire (but not necessarily of the entire vehicle when what is happening to the other three wheels) because some accelerative force is being applied to either:
1. maintain the speed already traveled or
2. accelerate out of the corner.
If neither is true then the vehicle is by definition, losing speed, so if it is on the limit of adhesion it will soon be well under it. Unless it is being coasted down a large hill.

I will not deal with the no power applied because we seldom coast through corners and if we do it will not matter if the car is 2wd, 4wd or unpowered.

If the car applying accelerative force is 2wd then when the powered wheels are applying the accelerative force the other two are going to be well below their cornering limit and in essence, coasting.

If all four wheels are receiving power then all will be equally (theoretically) loaded and each can approach the limit of adhesion at the same time, resulting in faster corner speeds.

In a snowy situation, if a 2wd car can take a corner at 20 mph does this mean a 4wd can take it at 40? Of course not, no matter how many doofuses think so. Can a 4wd car take it at 21, 22 or 23, perhaps.

The reason doofus gets in trouble with the 4wd vehicle on snow is not because it has less cornering power than the 2wd vehicle it is because it can accelerate much better in a straight line than the 2wd vehicle thus instilling in his tiny brain the idea that it will have superior traction in all conditions and it will not be true (for the most part) when it comes to cornering or braking.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

I agree with most of the above.

My statement that "the cornering ability of the tire has nothing to do with the torque applied to it" is technically incorrect. If a tire tire has no applied torque, it can achieve a specific lateral g force before it slips. Once you add torque, the tire needs to perform two functions at once (accept the lateral force and transmit the traction force). Asking it to do both, simultaneously, will diminish it's capability of accepting the lateral force.


However, if the vehicle is not quite at the cornering limit, the traction forces can serve to change the direction of travel and may be more effective than the loss of lateral force capability. This is the likely reason that a 4wd vehicle can turn faster in marginal conditions than a 2wd vehicle. The addition of the traction force is much more effective than the loss of the lateral force.


This might allow you to understand why a 4wd vehicle will outperform a 2wd vehicle when neither of them are at the cornering limit.

This needs a bit of correction.

If a 2wd vehicle is in a turn, the other two might be close to or at the cornering limit........depending on the radius of the turn and the speed of the vehicle.

Your statement would be absolutely true if the vehicle is traveling in a straight line, but, seriously, that's not what the discussion is about.


This also needs a bit of correction. Say four tires are equally loaded to the limits of traction while traveling in a straight line. If power is maintained and the front wheels are turned, you will absolutely lose control of the 4wd vehicle because the front tires instantly exceed the cornering limit. The "faster speed" that you anticipated has now taken you right off the road.

The only benefit of the 4wd vehicle can offer is faster speeds in a turn when operated below the cornering limit of the front tires. Naturally, very few owners of such vehicle know where the limit lies.

Sounds like we are mostly in agreement.

I will mention that a vehicle does not need to be traveling in a straight line to be coasting. so two wheels can be coasting in a turn and well below their limit of adhesion whilst the driven wheels are applying acceleration.

all other things being equal, a rear wheel drive vehicle will out corner a front drive vehicle because the front driver needs to turn and apply power to maintain speed simultaneously.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

All of this began with post #56 where you associated "cornering" with the capability of a 4wd vehicle to outperform a 2wd vehicle, and, therefore, by definition, it was better at "cornering".

I simply take issue with the word "cornering". I would prefer if you reserved "cornering" for the lateral g force that a given vehicle can withstand under a set of conditions. If this is the accepted definition, the 4wd vehicle does not have an advantage. However, it is agreed that the 4wd vehicle has improved "handling" in the turn when below the "cornering limit" and will certainly outperform the 2wd vehicle because of it.

And, no, I do not have, nor do I need an advanced degree to analyze this relatively simple subject.

It is actually a lot more complex than we got into.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

How about we use the term cornering to denote the activity of going through corners? If we use that, then a 4wd vehicle will very often have an advantage over a 2wd vehicle for reasons already discussed.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 401,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 26,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.
99 Mazda Miata 183,xxx miles.

All things being equal, I agree with the author of the article linked by the OP.
I haven't heard any arguments here which dissuade me from that agreement.

It's disingenuous to say or infer that AWD enhances cornering prowess, or that it'll help a driver avoid a fallen tree or dodge Bambi. When it comes to handling, all-wheel drive is overrated (not to mention heavy and gas-sucking), especially in foul weather.

AWD is great at aiding accelerating on slick surfaces and keeping a vehicle moving on snowy roads. Rally racers like AWD because it helps their over-powered cars accelerate on gravel and dirt paths

However, my experience—hard-earned from wrecking more than one AWD vehicle during snow-handling tests for a tire company—is that AWD is counter-productive when the roads are slick. At the same time AWD doesn't improve your handling, it does offer an overly optimistic sense of available traction, and it provides the potential to be going so much faster when you need to stop. (Note to those from warm climes: Snowbanks are not puffy and cushiony.) The laws of physics mean a vehicle's cornering power is the job of the tires and suspension.

Some disagree, saying AWD helps bad-weather handling because it quells power on oversteer, the fishtailing rear-drive cars experience when a ham-footed driver is too rough on the accelerator. It is true that AWD is excellent at preventing the tail from stepping out under power. But this is not "improving handling." It's really aiding acceleration.

If you're looking for the peace of mind in knowing that you'll be able to get home if an unexpected snowstorm hits, AWD may be a good choice for you. However, if you think that AWD will help your car better grip slippery corners or dodge an indecisive squirrel, you're sadly mistaken.

The myth of the all-powerful all-wheel drive - Yahoo! Autos

YMMV

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On some nights I still believe that a car with the fuel gauge on empty can run about fifty more miles if you have the right music very loud on the radio. - HST

1983 300SD - 305000
1984 Toyota Landcruiser - 190000
1994 GMC Jimmy - 203000

https://media.giphy.com/media/X3nnss8PAj5aU/giphy.gif

4WD makes a huge difference in driving simply in a straight line on icy roads. ... here is why....if it is very slick, if only two wheels are driving it is able to lose traction with the driven wheels and the vehicle will slew to one side or the other. If FWD that will mean it will simply begin to plow off the road and a total loss of steering capability as soon as the front wheels lose traction. If RWD the car will fishtail.

I have driven my Montero on slippery highways in windy conditions I stopped and engaged 4wd high range and straight line stability improved markedly. My car was fishtailing just traveling on a straight road because it was icy and windy.

I think the author overstates the reality in the article above.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.

"Handling" is the term you want.

"Cornering" is the term used at the limit of the tires.

The author explicitly stated and explained the exact situation that you experienced:




The author is correct regarding the physics of the situation. However, I would also agree that the vehicle has "improved handling" in such a situation. The fact that the tail does not slide out or get forced out by the wind is not necessarily "aiding acceleration", because the vehicle can be traveling at a constant speed.

The point that I disagree with, and the only point in this lengthy discussion, is the statement that the 4wd vehicle has "improved cornering".

Brian Carlton, if someone told you the sun just came up, you would argue the alternative, however lame, and even if God struck you with a bolt of lightning.

(Happey Easter for all those celebrating)

So, I ask you this, did you or have you ever owned an early eighties 123 that was BRAND NEW (as off the showroom floor, and not a 123 that you bought used that was 5 years old or more)?

I bought a new 280 that was junk in 1977. In 1980, I bought a new 300D, and every three years after that, I leased new Mercedes diesels for my work.

So, Brian, you have no idea of what you are talking about or profess to know. You are a k-i-a, and you know litttle. For whatever reason, you try to define everything that goes on in this forum, whether it makes sense or not. Does your dad or uncle own Peachparts? Had you driven the car NEW, you would have known about how it reacts, not what your naive gel set tells you. Yet, you want to tell the whole wide world about something you know nothing about. I absolutely love telling guys like you in front of the whole world, that you zipper is down, and in your case, down every day you visit the forum.

For everyone else out there, the rear suspension on these cars is unique. Between the rear subframe and control arms, I cannot think of any car out there like this. I profess not to be an expert, but I have a feeling the car dips because it is a long way between the front of the subframe mount to the trailing arms to the hub. If I were to guess, the the rear caliper action creates a upward force on the back end of the trailing arm, compressing the springs, and causing the rear end to dip. Now, I am not an engineer, but this "dip" (however it is caused) effectively lines up the rear axle to the front, so they continue to be the same distance above the ground. This keeps the rear end low in more extreme braking, not allowing the rear end to pivot upwards off the front end. I imagine that most of us buy ceramic pads for these cars for longer wear and no dust. I do know that the organic pads (or whatever they are called) bite into the calipers which also made pad replacement more frequent. They also tear up the rotors more quickly, and they too need replacing more frequently than using a ceramic pad. On the plus side, Mercedes used them over metallic pads for a reason, and the reason being it was (is?) the pad with the most stoppiing power. The faster and more power pressure is applied, the more the car dips. The more the rear dips and the earlier it dips, the more the center of gravity stays balanced at the rear end.


Now, I know that I may not be 100% right in the above description, but I do know that the rear end is designed to dip when braking. I know this because I have driven these cars when new (about one millions miles total), and not driven around in a 20 year old bag of hot air.

I've never been able to buy a Mercedes new, but I have owned quite a few of them, including some that had less than 100K miles on them. I have never had a 123, a 124, a 115, a 126 or a fintail that the rear did not rise as the nose dipped when braking.

I know there are cars out there which have geometry in their suspension which is designed to mitigate the effects of it but the only way to make it not dip would be very complex active suspension, which our Mercedes certainly do not have.

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.