Talk:Understeer and oversteer

message: these are for discussion only, as I can't give a source for them.
Car        	My figure	Swedish mag	
Nissan 350Z	35.0     	19         	
Focus  ST  	34.8     	33         	
Corvette   	60.4     	28         	
WRX        	64.3     	37         	
http://www.edccorp.com/pdfs/WP2004-3.pdf#search=%22%20%22understeer%20gradient%22%22
for some more examples
As you can see the Swedish measurements seem to be way off base. There are good reasons to believe that the 350Z could not be so low. I don't know how to resolve this.
Greglocock 02:52, 11 September 2006 (UTC)
thread_title: More values

message: I've added an external link to a graph on my website. If it is inappropriate delete it. It is sort of original research, but more accurately a demonstration of a well known equation. Greglocock 05:33, 25 September 2006 (UTC)
replies: text: Hi Greg - not sure if anyone without some serious technical knowledge would understand this one, think this section needs to be simplified where possible Driver sam (talk) 15:46, 26 May 2008 (UTC)
replies: text: Aye, mediocrity will always defeat excellence. Greg Locock (talk) 04:18, 27 May 2008 (UTC)
thread_title: External Link

message: Go on, tell me why the reference to Carroll Smith was removed? Most articles I write get pinged for not including references Greglocock 21:46, 27 December 2006 (UTC)
thread_title:  Removing references 

message: Not very happy with the "Common Practice" section. Fitting new tyres to the front doesn't increase understeer, it usually reduces it. The potential safety problem is that it can induce lift-off oversteer. -- Ian Dalziel 16:25, 1 January 2007 (UTC)
replies: text: Indeed - but that isn't an answer to my point, it's agreeing with it! Fitting new tyres to the front does NOT increase understeer, so the item is completely wrong, reference or no reference. The reference doesn't mention understeer, by the way. -- Ian Dalziel 06:39, 1 February 2007 (UTC)
thread_title:  Tyre placement 

message: There's a citation in "Understeer values" but it doesn't link to anything.  Disappointing, as I've like to know where the numbers came from...
: They came from the sports car magazine Automobil, but the link will do no good since the list is only published in the paper version. // Liftarn
I concur - deleted the section. Somebody can bring it back if they have a real understanding of the understeer coefficient. The section as-is is pretty much nonsense; a quick google search turns up nothing when looking for "understeer value" and "understeer rating", and the maths for "understeer coefficient" are much more complicated than implied by the headline of the section.  — Preceding unsigned comment added by Sniper1rfa (talk • contribs) 13:44, 24 December 2010 (UTC)
thread_title:  Understeer values citation? 

message: Hi - I was reading this article and it seems to have quite an engineering focussed style of definition. I've done a but of research and found a few external references which may be useful for the reader with less of a physics / maths based background. There doesn't seem to be much out there but:
http://news.bbc.co.uk/sport1/hi/motorsport/formula_one/car_behaviour/default.stm - a BBC explanation of understeer and oversteer
http://www.drivingfast.net/car_control/understeer.htm - a dedicated article on understeer
Driver sam (talk) 11:57, 26 May 2008 (UTC)
replies: text: Well I guess it depends on whether you want a schoolkid's encyclopaedia or a more generally useful one. The first article is too simplistic by far, the second one is confusing and unhelpful (it could be summarised as find what you are doing that causes the underster and then stop doing it). But it does at least suggest that things are not straightforward. Greg Locock (talk) 04:15, 27 May 2008 (UTC)
replies: text: Many people use wikipedia as a first port of call when looking up automotive terms such as understeer and oversteer (probably including schoolkids!). Such terms, although commonly used in engineering are also useful for driving enthusiasts and anyone interested in motorsport. I'm sure you have an engineering background, but launching straight into relatively complex terminology doesn't help most people unless they have a residual knowledge on these topics. I'd welcome your suggestions on an external link which might help provide a more basic explanation, or I think it would be beneficial to have a 'dummies guide' to understeer at the start, same for the oversteer section. I'm not suggesting rewriting the article, but simply adding some more beginner friendly info. What did you find confusing in the second link, do you think there anything which could be re-written for this section? Would be interested to see what others think, or am I way off the mark here? Driver sam (talk) 16:17, 27 May 2008 (UTC)
replies: text: I'm going to add the latter of the two articles primarily due to the decent illustrations. But as Greglocock has suggested, I do think there may be better links around so please feel free to suggest some. May do the same for oversteer, but would be great if someone could come up with a decent image for wikipedia on these topics. Driver sam (talk) 16:01, 10 June 2008 (UTC)
thread_title:  Possible links? 

message: In racing there are several sorts of understeer: straight line linear range understeer, understeer on entry to the corner (under trail braking), understeer at the apex, and understeer on exiting the corner, due to throttle. Until you know which one you are talking about then things will be very confusing. Greglocock (talk) 02:54, 8 May 2009 (UTC)
thread_title: Racing Understeer

message: The concepts of understeer and oversteer have been around for many decades, and they're much simpler in concept than the two wiki pages indicate. The US Society of Automotive Engineers (SAE) has published a standard for terminology J670 that covers the topics in a few sentences. The definition in J670 from 1976 has been kept in the updated version (2008?) and is also in the new ISO 8855 standard on vehicle dynamics terminology. They're also in any textbook I've seen covering vehicle dynamics. Certainly Gillespie's "Fundamentals of Vehicle Dynamics" textbook (referenced in the Oversteer page) presents the concept succinctly.
==== Summary of the Definitions ====
The concept is that a car making a turn with non-slipping tires has front-wheel steer equal to the arctangent of the quotient of wheelbase divided by the turn radius. This is called the Ackermann steer angle. If the lateral acceleration increases due to increased speed on a constant-radius track, or decreased radius at a constant speed, or any combination, there is a gradient of steering wheel angle vs. g's that would be obtained with Ackermann steering (Ackermann's name is always used for the reference neutral steering).
The real measure is the difference in gradient (real - Ackermann). If the difference is greater than zero, it's understeer. If less than zero, it's oversteer.
Different companies and organizations have slightly different test procedures for establishing the gradient. It's normally done under quasi-static conditions in which either steer or speed are increased very slowly. Results do depend on the test, so just giving a deg/g number is not sufficient; you also have to indicate the type of test used.
In more transient maneuvers, such as racing turns or stability control tests, the names understeer and oversteer are also used by engineers to indicate that the steering needed for the maneuver is more (understeer) or less (oversteer) than some reference. 
==== What Next ====
I'm new to wikipedia editing, and have no clue about how to merge pages. To make sure this is seen, I'm pasting it into the talk pages for both topics.
If they are merged and redone, I can contribute if needed to ensure that the descriptions match the SAE and ISO definitions.
Mikesayersskier (talk) 18:34, 12 June 2010 (UTC)
thread_title:  Understeer and Oversteer should be one topic 

message: I'm new to wikipedia editing, and have no clue about how to merge pages. To make sure this is seen, I'm pasting it into the talk pages for both topics.
If they are merged and redone, I can contribute if needed to ensure that the descriptions match the SAE and ISO definitions.
Mikesayersskier (talk) 18:34, 12 June 2010 (UTC)
thread_title:  What Next 

message: Article merged with Oversteer: See old oversteer talk-page here — Preceding unsigned comment added by Mikesayersskier (talk • contribs) 03:08, 18 May 2011 (UTC)
thread_title:  Merged with [[Oversteer]] 

message: I have moved these comments here because the first time I removed them, they were simply reinserted.
:"An old bit of racing humor says that an understeering car goes through the fence nose first, an oversteering car goes through the fence tail first, and with a neutral-steering car, both ends go through the fence at the same time. In the same vein, horsepower is defined as how fast the fence is hit and torque as how far the fence is taken by the car."
The fact remains that they are not about understeer, oversteer, or steering at all and so have no place in this article. If I am mistaken, please explain how. -AndrewDressel (talk) 18:52, 18 July 2010 (UTC)
thread_title:  Comments on horsepower and torque 

message: I have renamed the article. I wasn't sure about the title, but eventually settled on this after doing a google test: "oversteer and understeer" gives 231,000 hits, "understeer and oversteer" gives 364,000 hits. Cheers, theFace 14:27, 25 September 2011 (UTC)
thread_title:  Move to "Understeer and oversteer" 

message: How does one classify the following situation?
A car approaches a corner at a rate of speed that, even with max braking, cannot slow the car down enough to clear the corner without understeer. During braking, one of the rear wheels gets too light and starts to lose traction, putting the car in a slide. The car misses the corner and plows outwards, albeit with its rear end coming around at the same time.  — Preceding unsigned comment added by 174.47.162.2 (talk) 19:08, 28 April 2014 (UTC)
replies: text: I think your description is a good summary in itself. To be honest if the driver keeps the brakes on, or uses the handbrake, to try and get the rear sliding and bring the nose round then that is a perfectly valid technique, good fun in the snow and on gravel. Understeer is when the front slip angle is greater than the rear, or the yaw velocity is less than it should be for a given lat acc, oversteer the opposite, you have more or less made the car more neutralGreglocock (talk) 01:24, 29 April 2014 (UTC)
thread_title:  Understeer and Oversteer at the same time 

message: I know nothing on this topic, thus my looking it up.  I did note one spelling inconsistency between "Ackermann steer", found in the section titled Vehicle dynamics terminology and "Ackerman angle" in the section titled Related measures.
Seeing now that the link goes to a page called "Ackermann steering geometry," it is very likely  the link's spelling of the family name is correct, but I will still let someone with more knowledge on the topic correct the spelling inconsistency, for it could go either way. Lytzf (talk) 00:07, 29 April 2015 (UTC)
replies: text: I'll vote for nn see http://www.wolfgang-pfaller.de/landespa.htm   Greglocock (talk) 01:47, 29 April 2015 (UTC)
thread_title:  Two spellings of "Ackerman(n)"