FWD vs. RWD

[RTz]

You can't make a race car out of a pig, but you sure can make a damn fast pig.

[JMortensen]

Preparation wins races. To be even more nit-picky, nothing we do is science. Its just application of technology. Science is that whole Theory, Experiment/Observation, Document, and Publish thing.

To be nit-picky, if you're good at setting up a car, it's likely because you use the scientific method. It's not the publishing that makes something scientific.

 

http://www.sciencemadesimple.com/scientific_method.html

The steps of the Scientific Method are:

Observation/Research

Hypothesis

Prediction

Experimentation

Conclusion

 

Maybe I've read your previous posts wrong and you don't work in a scientific manner. Perhaps you do an understeer dance and sacrifice a hamster before a race, I don't know. I kinda doubt it though.

[johnc]

Its a chicken, not a hamster. Not enough blood in a hamster.

 

My method is:

 

1. WTF?

2. Why did I do that?

3. Hope no one finds out.

4. Better fix it.

5. That worked.

6. Better just leave it alone from now on.

[tube80z]

I actually wasn't aware of the weight penalty for running RWD and AWD cars, so thanks for pointing that out to me. In addition to this weight penalty I believe BTCC gives a weight penalty to the top 4 or 5 cars that win a race, though the exact details about how that works isn't as clear to me. This additional weight penalty seems like it would compensate for if a certain car was clearly superior to the others (for example, if the weight penalty to RWD cars made FWD vastly superior)? I dont regularly follow this series so please correct me if I'm wrong

 

I don't really want to get into a FWD/RWD battle but BTCC is interesting. If you watch much of it you can see the BMWs often make up a ton a places on the start and then struggle until about mid race where they get strong again. The FWD cars are much harder to get off the line and then are often very quick but seem to lose pace towards the end of the race. And certain tracks are seem to favor certain configurations.

 

At least in this series the different configs use the tires at different rates and that often has a lot to do with the outcome. And in single lap qualifying there's often very little difference between the two even when you figure in ballast.

 

Cary

[tube80z]

To be nit-picky, if you're good at setting up a car, it's likely because you use the scientific method. It's not the publishing that makes something scientific.

 

The steps of the Scientific Method are:

Observation/Research

 

I think most people never make it past step one.

[Nigel]

To be nit-picky, if you're good at setting up a car, it's likely because you use the scientific method. It's not the publishing that makes something scientific.

 

http://www.sciencema...fic_method.html

The steps of the Scientific Method are:

Observation/Research

Hypothesis

Prediction

Experimentation

Conclusion

 

 

Exactly! A race track is like a giant laboratory. Every time you change spring rates, adjust camber, check tire temperatures, etc. you're experimenting and observing and gaining knowledge.

 

As I said before, it's a simple fact of physics that you can't have a tire dedicate 100% of it's traction to acceleration and to cornering at the same time. It doesn't mean a FWD car CAN'T win in a race with a RWD car. It's just one factor among many others that has an influence on the outcome. And you don't win races by being ignorant of those factors. Experimenting, observing and gaining knowledge about them allows one to make intelligent decisions about their application or influence and consequently improve his or her chances of winning.

 

Nigel

Edited June 10, 2011 by Nigel

[Leon]

As I said before, it's a simple fact of physics that you can't have a tire dedicate 100% of it's traction to acceleration and to cornering at the same time.

 

What's your point, exactly? In a corner, all four tires are dedicating their grip for cornering, the outsides more so than the insides, whether a car is front or rear wheel drive. Two wheels, either front or rear, also dedicate some grip to acceleration when the driver is on the throttle. The advantage of rear wheel drive comes in where upon acceleration, weight shifts to the rear, loading the rear tires and unloading the fronts.

 

It has nothing to do with the so-commonly stated, "FWD sucks because the front wheels steer and drive the car."

[19762802+2]

What's your point, exactly? In a corner, all four tires are dedicating their grip for cornering, the outsides more so than the insides, whether a car is front or rear wheel drive. Two wheels, either front or rear, also dedicate some grip to acceleration when the driver is on the throttle. The advantage of rear wheel drive comes in where upon acceleration, weight shifts to the rear, loading the rear tires and unloading the fronts.

 

It has nothing to do with the so-commonly stated, "FWD sucks because the front wheels steer and drive the car."

 

Well I was under the impression that people argue that point because with the FWD platform there are some troubles with handling because of certain things that a FWD has such as different length CV axles causing torquesteer and the wheels to turn different speeds then one another, also the weight directly over the drive wheels, granted anything can be fixed or made better with time and money but most street driveable FWD cars have problems with understeer for various reasons. This can be different in a Race car but FWD cars just have a different battle to fight when it comes to overcoming certain problems as opposed to RWD cars, doesn't make them any better or worse just a different way to approach it. I believe a lot of the FWD sucks compared to RWD comes from Drag racing since FWD can have issues with Weight transfer and traction loss at takeoff.

Edited June 10, 2011 by 19762802+2

[wheelman]

What Nigel is referring to is the traction of the front tires on an FWD car is providing the acceleration and turning force at the same time, only a portion of that traction can be dedicated to each of those activities. A RWD car can theorectically put 100% of the traction of the rear tires to acceleration and 100% of the traction of the front tires to turning.

 

My personal opinion about the FWD vs RWD vs AWD debates found on the internet is that they are mostly pissing contests by boys trying to defend their choice of car.

 

I prefer a RWD platform but thats because it's what I'm most comfortable with, I have no illusions about it being the "best" layout in all situations.

 

 

[JMortensen]

What Nigel is referring to is the traction of the front tires on an FWD car is providing the acceleration and turning force at the same time, only a portion of that traction can be dedicated to each of those activities. A RWD car can theorectically put 100% of the traction of the rear tires to acceleration and 100% of the traction of the front tires to turning.

Not really. Since a corner requires effort from the front AND rear tires (although less from the rears), you can't really separate out the turning to the front and the acceleration to the rear. There is always going to be some unused portion of available grip. Rear drive leaves front grip on the table, front drive leaves rear grip on the table. An AWD car can drive the fronts and rears, and having a little drive to the front, since weight transfers to the rear, is going to be faster than driving just the rears.

[johnc]

And then there's the braking loads on the tires. The front tires do a lot of work even on a RWD car. On a FWD car they do even more work. As long as the total amount of work they are asked to do is with the capability of the tire, there's really no disadvantage to FWD. When you exceed the tire's capability then you have problems - which is also true for high horsepower RWD cars. F1 on the new Pirellis is a perfect example of how rear tires go away on a high horsepower RWD cars. Watch how quickly the rear tires grain in a race, especially the super softs.

 

Its really hard on a high horsepower RWD chassis to get the fronts to do enough of the work. On my old race car the biggest focus was on getting the fronts to do as much work as possible because the rears would go away towards the end of the session. Its the same problem the FWD racers face, just on a different end of the car.

[Leon]

What Nigel is referring to is the traction of the front tires on an FWD car is providing the acceleration and turning force at the same time, only a portion of that traction can be dedicated to each of those activities. A RWD car can theorectically put 100% of the traction of the rear tires to acceleration and 100% of the traction of the front tires to turning.

 

My personal opinion about the FWD vs RWD vs AWD debates found on the internet is that they are mostly pissing contests by boys trying to defend their choice of car.

 

I prefer a RWD platform but thats because it's what I'm most comfortable with, I have no illusions about it being the "best" layout in all situations.

 

That's exactly the fallacy I spoke of earlier. What you describe is physically impossible.

 

And then there's the braking loads on the tires. The front tires do a lot of work even on a RWD car. On a FWD car they do even more work. As long as the total amount of work they are asked to do is with the capability of the tire, there's really no disadvantage to FWD. When you exceed the tire's capability then you have problems - which is also true for high horsepower RWD cars. F1 on the new Pirellis is a perfect example of how rear tires go away on a high horsepower RWD cars. Watch how quickly the rear tires grain in a race, especially the super softs.

 

Its really hard on a high horsepower RWD chassis to get the fronts to do enough of the work. On my old race car the biggest focus was on getting the fronts to do as much work as possible because the rears would go away towards the end of the session. Its the same problem the FWD racers face, just on a different end of the car.

 

Precisely!

 

If you have a car with a heavy rear weight bias, the rears can actually be doing more work than the fronts in a turn. John points out very clearly how whether it's front or rear wheel drive, you are compromising lateral traction for acceleration on one set of wheels. It all comes down to adapting what you have to the intended use. You can make a FWD handle well and you can make a RWD handle well. People who don't understand vehicle dynamics love to make up things and perpetuate fallacies like "RWD rules because the fronts can turn and rears can accelerate" or "FWD always understeers." It's knowing what you have and how you can make it do what you want it to do that will make a car handle properly.

[VenomousType]

eh.. **** FWD.

[kiwi303]

 

[JIM73240Z]

All cars are not equal. Even in spec classes, the rules are set up to level the playing field, car set up can make a huge difference in the outcome with equal drivers. The Nasa Director here in AZ had a civic that he would be hanging with vettes and vipers all day long in a certain class. That thing was suprisingly fast. Then there is Chris Rado with his Scion. He was smashing course records. FWD, RWD, AWD, if you are smashing records, that is a fast car. He had that big ass ugly wing on the front of the car that was pure function over form. Not arguing that it was ugly, but YOU cannot argue that it did not work.

 

Jimbo

[Michael]

For a while there I was wavering, but now I've mustered resolve: I'm going to convert my Z to FWD. I'll use the reverse of the JTR mounts to position the engine maximally forward, for better loading of the front tires.

[260DET]

Quick impression of that video was that most of of the cars did not have rear aero and were struggling for grip on the long sweeping bends that characterise that circuit. Also the Honda was not slow in a straight line compared to a lot of the cars he passed. On that circuit I'd suggest that a front jiver would be comparatively easy to drive, just wind more lock on in those sweepers whereas most bum draggers (FWD) find very slow corners tough, particularly on exit. With a powerful rear driver on that circuit you would need a lot of high speed rear grip, aero, plus have confidence in the car and be able to drive it well. Not easy for most of us.

 

Having said all that Hondas are a damm fast circuit car, obviously the car and driver in the vid are good too.