Next car?

[Irvrobinson]

I could tell you how to dial-out the understeer on your S3, but you're smart enough to figure that out on your own now, aren't you?

Just don't buy the M2 and complain about its ride!

No, I'm not smart enough to know how to "dial out" understeer on a car with a 58/42 weight distribution and symmetric wheels and tires, so please enlighten me.

The original M2's ride was okay for me on a test drive. I haven't driven the M2 Competition yet, but given my history I doubt it would be a problem.

 

[GrimSurfer]

No, I'm not smart enough to know how to "dial out" understeer on a car with a 58/42 weight distribution and symmetric wheels and tires, so please enlighten me.

The original M2's ride was okay for me on a test drive. I haven't driven the M2 Competition yet, but given my history I doubt it would be a problem.

Elementary problem, with an easy solution.

I won't tell you directly, since you haven't accepted what I've written to this point.

I will give you a phrase that, with some reading and research, will tell you precisely what you need to address your problem.

Lateral weight transfer.

Feed a man a fish, and you satisfy him for a day. Teach him how to fish, and he'll be satisfied for a lifetime.

 

[Mikado463]

Elementary problem, with an easy solution.

I won't tell you directly, since you haven't accepted what I've written to this point.

I will give you a phrase that, with some reading and research, will tell you precisely what you need to address your problem.

Lateral weight transfer.

Feed a man a fish, and you satisfy him for a day. Teach him how to fish, and he'll be satisfied for a lifetime.

LOL, all of it meaningless if you drive on these God forsaken roads of Pennsyltucky !

 

[GrimSurfer]

LOL, all of it meaningless if you drive on these God forsaken roads of Pennsyltucky !

... and it won't affect the ride comfort of the car. LOL.

But let's not give Irv any more clues. The one I've provided is obvious to a car guy (not somebody who likes cars, but somebody who also knows how they work). I've also given him three book titles, each of which that contain enough info on their own to the answer the riddle.

Trust me. He's better off working this out on his own.

 

[Irvrobinson]

... and it won't affect the ride comfort of the car. LOL.

But let's not give Irv any more clues. The one I've provided is obvious to a car guy (not somebody who likes cars, but somebody who also knows how they work). I've also given him three book titles, each of which that contain enough info on their own to the answer the riddle.

Trust me. He's better off working this out on his own.

So, just for my edification, Yoda, when you say "dial in", do you mean an adjustment of existing parts, or do you mean replacing parts with other parts?

 

[Irvrobinson]

Re: PSM vs PASM. Ok wrong acronym. I guess I'm just an air cooled guy in a water cooled world!

Re: Traction. None of this changes how a friction circle works. When you're steering and putting power into the same contact patch, lateral load limits will be less. Why? The Tire only has so much traction to give.

Example: Easy to rotate a RWD car while spinning the tires. The traction used for acceleration leaves nothing for rear lateral grip. Basic car control stuff.

Re: Polar moment of inertia, moment of inertia. Splitting hairs.

Re: Lying about BMW's emphasis on 50/50 weight distribution. If you're going to call somebody a liar, aircon, at least do a google search first (BMW + ad + 50/50). Otherwise, you come off looking like an idiot.

BMW is still using this line as the focal point of their advertising, which started in the 80s. How do I know this? Cause I was there, son. I could find a link for that too, but you'd only ignore it.

Re: Old 911s and narrow tires. They didn't weigh 3400-3500 lbs either, Irv.

A 70s 911S was about 2400 lbs. Those tires had about the same size contact patches as a new, heavier watercooled Porsche on wider tires. So this begs the question why newer Porsches have higher lateral grip than older ones. Lots of reasons, but tire compounding is a big part of it.

As you probably know, tire size doesn't equate to contact patch area... unless it's flat. The real issues are vehicle weight and inflation. Club racers and autocrossers fine tune their car's handling through inflation adjustments. Basic stuff, with one or two psi capable of making a bigger change in handling than 5-10 mm of cross ectional width.

Don't take my word for it. Read Carrol Smith's "Prepare to Win", Fred Puhn's "How to Make your Car Handle", Jay Lamm's "All Wheel Drive Handbook" or Skip Barber's "Going Faster!". I could name others on my bookshelf, but start with those. They're really good.

Re: FWD cars with yaw control. Yes, they will spin and in very dramatic fashion. Yaw control systems only work to a point. They do not and cannot overcome the laws of physics. Once the car starts to rota fast enough, yaw control can't stop it. If things worked as you suggested, we'd never see rice rockets slide sideways into telephone poles. Yet, it happens all the time.

It sounds like you've never been on a track, much less competed on one. Maybe you read other books. That's OK too. This stuff is not everyone's thing.

Wow, that's quite a patch you made to that post. Ya know, one difference there seems to be between you and I is precision in use of language. You claimed the ultimate driving machine marketing was "based on" that 50/50 weight distribution factor. "Based on" tells me that it is the primary factor, and you couldn't know that (because it wasn't the only factor in their marketing story) unless you were part of the BMW marketing organization. Were you?

Also, are we discussing street driving or track driving? I thought we were discussing street driving. Which is it?

 

[GrimSurfer]

So, just for my edification, Yoda, when you say "dial in", do you mean an adjustment of existing parts, or do you mean replacing parts with other parts?

No clues more, me give you. Figure it out for yourself young Skywalker. Use the force, you must. Or some research you must do.

 

[GrimSurfer]

Wow, that's quite a patch you made to that post. Ya know, one difference there seems to be between you and I is precision in use of language. You claimed the ultimate driving machine marketing was "based on" that 50/50 weight distribution factor. "Based on" tells me that it is the primary factor, and you couldn't know that (because it wasn't the only factor in their marketing story) unless you were part of the BMW marketing organization. Were you?

Also, are we discussing street driving or track driving? I thought we were discussing street driving. Which is it?

I just added a vid. You know, in response to your post saying I make things up which I initially let slide... until I concluded you were actually serious. (It's hard to tell, sometimes you say the silliest things).

Street driving, track driving? Is there a difference driving the Dragon's Tail, swerving to avoid an accident, or auto crossing? Sure, the location and duration of the "events" are different, but the dynamic handling challenges are similar.

The track is a great place to hone skills and learn set-up without endangering lives or breaking laws. So it's a much better place to dial in a suspension than trying to do it on the street (where a poor choice of mods or adjustments can send your car off into the rhubarb or worse).

P.S. The difference between us is that I actually know what I'm talking about. Otherwise, you would known exactly what solution I was referring to when I used the term lateral weight transfer. It's so obvious.

P.P.S. Still not going to tell ya! Not while you're being an ass.

 

[Irvrobinson]

The difference between us is that I actually know what I'm talking about.

The evidence demonstrates otherwise.

 

[BoredSysAdmin]

I enjoy this bickering so much

 

[GrimSurfer]

The evidence demonstrates otherwise.

If you knew what you were talking about, you wouldn't have complained about your vehicles handling. You would have avoided disappointment through a rigorous test drive or resolved your handling issue by now. It's been three years after all.

It's really not that hard to change handling in a car like an S3. The basic elements are there and the foundation is a solid one. The trick is knowing how manufacturers build understeer into their suspensions and what to do to change this without the car turning into an oversteering and directionally unstable (read: dangerous driving) go-cart.

So good luck with that. You know what you're doing and I don't. No need to ask me how to solve your problems. You've got this.

 

[Irvrobinson]

If you knew what you were talking about, you wouldn't have complained about your vehicles handling. You would have avoided disappointment through a rigorous test drive or resolved your handling issue by now. It's been three years after all.

Actually, you're correct about the test drive miss. I didn't intend for it to be a tight-curves car, and it drove so nicely on the roads I did test it on, that after about 45min or so I just said I'll buy one. I didn't realize how compromised it was until last summer, and then on a challenging road in our new location I was appalled. As I suspected by my look underneath with the car lifted, Audi experts I consulted said essentially nothing was adjustable. I made the decision not to do any parts swapping or mods, since the architecture of the car is so compromised. Another test drive miss was how useless the Nav system is.

 

[GrimSurfer]

Actually, you're correct about the test drive miss. I didn't intend for it to be a tight-curves car, and it drove so nicely on the roads I did test it on, that after about 45min or so I just said I'll buy one. I didn't realize how compromised it was until last summer, and then on a challenging road in our new location I was appalled. As I suspected by my look underneath with the car lifted, Audi experts I consulted said essentially nothing was adjustable. I made the decision not to do any parts swapping or mods, since the architecture of the car is so compromised. Another test drive miss was how useless the Nav system is.

The car isn't compromised, unless it has been in a serious collision. It's just performing according to the nature of its masses (which is certainly good enough to work with in your case),chassis, components, and settings.

The thing that's hardest to overcome before expecting good handling is chassis stiffness. Just as you cannot build a solid house on a bad foundation, you can't expect a suspension to perform in any consistent way unless the chassis has a good level of torsional stiffness. I've seen nothing to suggest Audi hasn't done a reasonable job in this regard... I mean there's to say it is as bad as the Fox chassis used in the last generation of Mustangs, which rendered those cars untunable without first doing something about the soda-straw structure.

Most cars suspensions lack the adjustability of, say, a Formula Ford racing car. But they are, indeed adjustable... camber, toe at the very least.

Otherwise, one wouldn't ever need alignments, would they? (And most manufacturers specify periodic *four wheel* alignments for their AWD models, with very good reason.)

There is considerable adjustability in today's suspensions. Not all of these are appropriate or advisable. There are also lots of OEM parts, specifically made for cars but not always fitted to cars in certain markets, that can change handling.

The trick is understanding how these parts and adjustments work as part of the system, and making appropriate choices to get the handling you want while avoiding characteristics that would make the car dangerous at the limit.

 

[Montucky]

While we discuss physics and driving dynamics, another million bland crossovers just sold. Makes me want to cry. You guys may not agree on some of these technical aspects, but we should all at least appreciate the fact that at least SOME people out there care enough about this stuff to argue about it, and that gives me a glimmer of hope that not all is lost. Debate away.

 

[Irvrobinson]

I mean there's to say it is as bad as the Fox chassis used in the last generation of Mustangs, which rendered those cars untunable without first doing something about the soda-straw structure.

Hmmm... I thought an expert like yourself would know that the Fox platform hasn't been used in Mustangs since 1994. ;-)

 

[GrimSurfer]

While we discuss physics and driving dynamics, another million bland crossovers just sold. Makes me want to cry. You guys may not agree on some of these technical aspects, but we should all at least appreciate the fact that at least SOME people out there care enough about this stuff to argue about it, and that gives me a glimmer of hope that not all is lost. Debate away.

I don't think there's much of a debate going on. Irv has repeatedly stated that I don't know what I'm talking about. But he's got a problem with his car's handling that he currently can't solve. A clue has been offered, a reading list provided.

Irv's continuation means one of two things: he's using this thread to amuse himself while waiting for Amazon to deliver some books about automotive suspension design and setup OR he thinks his posts will lead me to tell him exactly what he needs to do.

The first premise is unlikely. As for the second premise, it conflicts with Irv's contention that I don't know what I'm talking about. As for me volunteering anything to help a guy who has called me a liar, this is a good time to turn the mike over to Dana Carvey:

 

[GrimSurfer]

Hmmm... I thought an expert like yourself would know that the Fox platform hasn't been used in Mustangs since 1994. ;-)

Yup. Mustang II. I used it as an example because it is considered the worst platform ever to be used in a unibody chassis.

 

[Irvrobinson]

I don't think there's much of a debate going on. Irv has repeatedly stated that I don't know what I'm talking about. But he's got a problem with his car's handling that he currently can't solve. A clue has been offered, a reading list provided.

Irv's continuation means one of two things: he's using this thread to amuse himself while waiting for Amazon to deliver some books about automotive suspension design and setup OR he thinks his posts will lead me to tell him exactly what he needs to do.

Irv does indeed think you don't know what you're talking about. Irv doesn't care to solve the understeer problem with his S3 because he has consulted people who are experts in Audi modifications, there isn't a good fix due to the transverse engine architecture, and Irv thinks his money would be better spent on a better car, if neutral handling is the objective. Irv hasn't decided what to do yet, but the M2 Competition is calling his name, but unfortunately so are the Cayman GTS and the 2020 911 S. Irv has obviously not completed his decision process.

 

[GrimSurfer]

Irv does indeed think you don't know what you're talking about. Irv doesn't care to solve to solve the understeer problem with his S3 because he has consulted people who are experts in Audi modifications, there isn't a good fix due to the transverse engine architecture, and Irv thinks his money would be better spent on a better car, if neutral handling is the objective. Irv hasn't decided what to do yet, but the M2 Competition is calling his name, but unfortunately so are the Cayman GTS and the 2020 911 S. Irv has obviously not completed his decision process.

I think Irv is a guy who would have great difficulty hearing anybody but himself in a crowded room, much less seek the council of others.

What Irv isn't understanding is that practically all manufacturers calibrate their suspensions to deliver terminal understeer up to the point of departure.

So Irv can buy his M2 or Cayman under the misguided view that they will handle better because they don't have a transverse engine (I guess this rules out any hope that Ferrari, Lambo, etc will ever handle to Irv's high standards). He'll then try to hide the error of his ways by seeking oversteer with the throttle pedal. When that happens, Irv's car will be operating on the ragged edge of the envelope and he may get a good spanking by Sir Issac Newton, whose laws of motion are absolute and final.

Hopefully, Irv's exploration of his car's friction circle will not lead to injury (himself or others). It would be a high price to pay for pride and ignorance. But "such is life", as Ned Kelly said as he faced hanging.

One way or another, I wish Irv the best. May he get favourable loan terms and insurance rates. May the inventions of wizards at Bosch save him from meeting his maker.

Sigining off this thread, Irv. You're on your own, bud. Say hello to Sir Issac Newton for me when you meet him.

 

[Irvrobinson]

Say hello to Sir Issac Newton for me when you meet him.

I've already met Sir Issac, in the summer of 2001. I had a BMW Z3 M Coupe. We lived in a place with some high hills and curvy roads nearby, a sports car lover's dream, actually. My teenage son was in the car with me. We were driving on a road on a hillside, with a canyon to my left. My son kept egging me on to go faster, and heading into one tight turn I overcooked it and we spun. There was a guard rail, and I didn't hit it, but I scared the hell out of both of us, and Newton asked, "WTF are you doing, Irv?" After that incident and a lot of research, I significantly upgraded the suspension and the wheels and tires, and when I was done the handling was much better, but drivability suffered (mainly from the coil-overs and lowering). I wasn't really enjoying the Z3M after the mods, and after tweaking for a few years in an attempt to regain the fun, I finally sold it in 2005. It was the most idiosyncratic car I've ever owned, and not BMW's finest work either, IMO, as they used the old and controversial E30 M3 rear suspension for the Z3M, which was a significant compromise. But it was fun for a while.