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02-12-2008, 10:12 PM | #46 | |
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Re: Whats the point of Front Wheel drive?
The more I read this, the more I agree with Nereth on one thing:
For ultimate performance, RWD is better than FWD. But that was estrablished right at the start of this thread. From there things get a little lost. Nereth you seem to be always arguing from the point of ultimate high performance. Where it is valid and accepted that RWD is better. What the rest of us are pointing out, is that it is not always better under less demanding circumstances, and in the average road car, FWD can be preform just as well as RWD, and sometimes better. You don't need a degree in engineering to understand that, you simply need to go out and drive a few cars, or even read a few magazine reviews to see real world examples.
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02-12-2008, 10:15 PM | #47 | ||
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Re: Whats the point of Front Wheel drive?
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You did nothing of the sort. You insulted him, and used his choice of car as your reasoning. Do it again, or call anyone else here ignorant and I will ban you for a week.
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02-12-2008, 10:24 PM | #48 | ||||||
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Re: Whats the point of Front Wheel drive?
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60/40 front to rear and a front natural frequency of 1.5 and rear of 1.6, given that natural frequency=sqrt(spring rate/mass) yields a front spring rate of 135 and a rear spring rate of 102.4. Roll hardness from the springs, assuming equal track front to rear, will be directly proportional to that. This means the rear end takes less of the lateral load transfer, and also is lighter. Quote:
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Lets take our earlier example car. 900kg front 600kg rear (60:40), with 1.5hz body frequency front, and 1.6hz rear. Toe and camber will be set to 0, and we assume the car doesn't roll, for simplicities sake. Wheelbase will be 100 inches, track will be 60. CGH is 20 inches. We will assume a perfectly rigid chassis. Using the springrates calculated earlier (front 135, rear 102.4), the TLLTD is 56.7% front, 43.3 rear, without swaybars. In this configuration, the car understeers at 1.093 gees. If the TLLTD=50:50, the car understeers at 1.103 Trial and error reveals neutral lies at approximately TLLTD=45.74% front, where the car understeers at 1.1071 gees. For a bit of spare drive traction for turn exit, lets pretend that equals 0.46 (it pretty much does, for the accuracy of this program :P). Anyway, to get the 56.7:43.4 to 46:54, the minimum rear swaybar hardness is 23.16 units. Considering that is more than half of the current rear spring rate, I think that is significant. Anyway, I don't know if you will accept that analysis, since you don't have any reason to trust the program or numbers, but at least it makes me feel a bit more confident. Quote:
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02-12-2008, 10:27 PM | #49 | |
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Re: Whats the point of Front Wheel drive?
Jesus, I hate this kind of "my $500 car is better than your $500 car" BS
With skill, tools and knowledge, I can make ANY $500 car absolutely kick ass in any category. I am so NOT impressed if you prefer one over another for some arbitrary reason You really think an Iroc can't handle? Do you know where the "iroc" name came from? thats to slideways, btw
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02-12-2008, 10:37 PM | #50 | |||||
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Re: Whats the point of Front Wheel drive?
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02-12-2008, 10:38 PM | #51 | ||
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Re: Whats the point of Front Wheel drive?
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I can tell you from experiance it works, and it works very well. That experiance both driving a FWD car, and chasing one on a race track. Your quoting a lot of theory, and lovely results from computer models, but theory can only ever take you so far. At the end of the day there are always variables involved that a computer model can not test for, all allow for in a realistic way. I spent the other weekend at the Taupo round of the A1GP, and got to spend a bit of time talking to some of the teams engineers. They have all sorts of data logging, computer modeling, degrees and experiance to work with. Yet most of their chassis work was done the same way its been done since people started racing cars. Tweak, drive it, and see what happens.
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02-12-2008, 10:44 PM | #52 | ||
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Re: Whats the point of Front Wheel drive?
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Nothing wrong with your theory, just your application of it If you want to be a really great engineer, then the first thing you need to understand is when and where to apply your theories, and how much to apply them. You also need to understand that a theory is not a fact, and so is open to being proven false at any time. Then you need to understand how those theory work out in real life, and just how realistic they are. An alien with no knowledge of automotive engineering could easily conclude that FWD was better than RWD because there are more FWD cars produced that RWD one's, and be correct in his theory.
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02-12-2008, 10:48 PM | #53 | ||||||||
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Re: Whats the point of Front Wheel drive?
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Allow me to quote myself a few times, in chornological order, and with a few bolded parts to help make my point: Quote:
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02-12-2008, 11:05 PM | #54 | |||
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Re: Whats the point of Front Wheel drive?
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The chief advantage of them here is that they simplify the model down so that you can look at FWD versus RWD without including a bunch of irrelevant extras. By using the theories, I got to remove the effects of different suspension geometry, aerodynamics, wheelbase, track, tyre compound, road quality, etc etc. If the opening question had been 'is a [FWD car] better than a [RWD car]', then the complicating factors become relevant, and the theories at my level become a lot more useless. |
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02-12-2008, 11:14 PM | #55 | |
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Re: Whats the point of Front Wheel drive?
at this point all i really have to say is...
does it really matter that much? the original question was asked by a NOOB and we are now all sitting here aruguing with more NOOBS who enjoy knocking heads... lol |
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02-12-2008, 11:18 PM | #56 | |
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Re: Whats the point of Front Wheel drive?
but as for lift off oversteer, it IS a big factor.
any idiot knows that once your tires are sliding as opposed to rolling, they have less grip. once you get your rear tires sliding slightly a larger radius than the optimal line of the front tires, you can begin to "drift" although you arent applying any opposite lock. btw, drifting in a powerful FWD car seems fun. smack a "stupidly stiff" sway bar on the rear, disconnect the front one, and go. if you get out of control, floor it and it will tighten up your line. much easier than RWD drifting possibly |
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02-12-2008, 11:55 PM | #57 | |||
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Re: Whats the point of Front Wheel drive?
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It's a major mistake and one that shoots down completely every other assumption you've made on the topic. This quote sums it up quite succinctly. Quote:
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02-13-2008, 12:37 AM | #58 | ||||
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Re: Whats the point of Front Wheel drive?
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It's something I picked up somewhere along the way. I had no reason to doubt it and no feasible way to check it. Quote:
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You are also assuming that because one FWD car can outperform one RWD car, FWD is better. I have been posting disadvantages of FWD cars compared to RWD... most of the replies comes down to 'its not that bad', which is really quite a weak argument. I would like it if you people could then tell me some of the advantages it has? Moppie seems to be the only one who understands I am talking in terms of high performance/racing situations. It would be nice if everyone else could understand that before replying as well. |
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02-13-2008, 12:40 AM | #59 | ||
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Re: Whats the point of Front Wheel drive?
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BTW all calculations based on a faulty assumption quickly become worthless. I suggest you reread my posts, your interpretation of my comments is not accurate. |
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02-13-2008, 01:02 AM | #60 | |||
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Re: Whats the point of Front Wheel drive?
Quote:
I have stuck my head under cars before. It isn't as easy as you say to eyeball RCH, especially considerin the difference front to rear of the RCHs is only a few inches. What about with strut type suspensions? Are you claiming you can eyeball a line out a couple of meters perpendicular to a strut? And then intersect it and a couple of other lines and points? And do all this within a few inches of accuracy? And then, moreover, while lying upside down, and with a bunch of other components in the way? I can barely fit my head under the couple of stock-ride-height cars we have over here, and even if I do, there are fuel tanks and the like in the way. Quote:
I would rather you start naming the performance advantages of FWD though, as I asked in my last post. |
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