Talk:Limited slip differential

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Contents 1 howstuffworks.com 2 Fixed Differential - Spool 3 Changed explanation of dilatant fluids 4 reversion of large edit 5 Needs Diagrams 6 plagarism 7 Viscous LSD revert 8 Mechanical LSD Description 9 Viscous LSD Description 10 "Electronic LSD" 11 Generic Name

[edit] howstuffworks.com

Has anyone gone to visit howstuffworks.com's differential section lately? It is quite clear. - Robert Turner 05:27, 9 September 2006 (UTC)

[edit] Fixed Differential - Spool

I removed this: " Compare this behavior to that of a fixed differential, where there is never a speed difference between the shafts". To my mind this is confusing on two counts. The linked article doesn't exist, so one cannot make the suggested comparison; and the description is odd, because it says that there is never a speed difference - if so, then how is it a differential? Perhaps the writer simply means a crown wheel and pinion gear(?) - this is not a differential. I also removed one of the section headings - it seems superfluous given that there are already numerous subheadings in what is quite a short article. Graham 00:50, 27 Jul 2004 (UTC)

It is somewhat common to call a simple (crown wheel and pinion, etc.) gearing a "fixed differential" in discussions of differentials. One would not normally use the term elsewhere, but it is proper here. AlbertCahalan 01:36, 20 May 2005 (UTC)

If it's a fixed crown wheel and pinion, it's not a differential at all, by definition. If some people call it that, then that's there ignorance - it shouldn't be propagated as a fact in an encyclopedia. Graham 03:03, 20 May 2005 (UTC)

Language is how people use it, so, yes it is a differential. Perhaps you'd prefer "null differential", but that's not the term people have settled on. In other news, "zero" is a number. AlbertCahalan 05:04, 20 May 2005 (UTC)

Not really - "differential" implies "difference" - in this case in the speed between its output shafts. If there is no difference (and there can't be here since they are joined rigidly together) it cannot be a differential. And yes, zero has always been a number, it just took man along time to realise it. I don't see the analogy. Graham 07:32, 20 May 2005 (UTC)

Ah, but it does allow a difference in speed! Of course, that difference is zero. AlbertCahalan 08:06, 20 May 2005 (UTC)

Although it is strictly incorrect to call a basic crown and pinion gearset a differential, that term has expanded to cover even this non-difference differential today. Back in the day (the early part of the century), "differential" always meant a gearset that allowed a speed differential, but this implication has pretty much gone by the wayside as the crown and pinion disappeared. --SFoskett 12:54, May 20, 2005 (UTC)

The word I know it by is "Spool". I wondered if it might be just an Antipodean word, but I checked Carroll Smith, and he uses it, so it's definitely North American as well, don't know about the UK. The traditional spool has a solid shaft connecting the rear wheels, i.e. no diff centre at all, and just a pinion/ring gear. Obviously that can only be used on live axles, but now there's spools where the solid shaft extends only to the uni joints for IRS. There's also the mini-spool which is the most popular in terms of sales because it's cheap and easy to fit (don't have to remove hubs/axles). The mini-spool keeps the existing axles, but just replaces the diff centre with a simple pinion/ring gear. I'm not sure whether a mention of the spool would be in order or not, because it's not a diff, and it's not limited slip, but it's used by similar people for similar purpose. RB30DE 10:07, 5 June 2006 (UTC)

[edit] Changed explanation of dilatant fluids

Previous version described a dilatant fluid as "one whose viscosity varies as the inverse proportion of an applied force". This explanation is wrong. A dilatant fluid becomes MORE viscous as force is increased, not less. Also, this relationship is not linear (ie. not proportional). See Power-law fluid. Ryanrs 06:54, 10 November 2005 (UTC)

[edit] reversion of large edit

I reverted a big tract of added text, contributed by anon. There is some useful info in what was added, but on the whole it was more confusing than useful. IF such details are worth including (debatable, in an encyclopedia) then it needs to be much, much, much better written. As the contributor freely admitted, it was a cut and paste job from an online forum, where writing standards are different. In addition, it cut what was already a decent section of text clean in two. Can I suggest to the contributor in question that a little more experience of WP is gained before trying to put it back in, so you know what we are looking for. Graham 01:13, 22 December 2005 (UTC)

[edit] Needs Diagrams

If this page had some clear diagrams like the page on Differential (mechanics) I think it would have given me a much clearer picture of the device and how it worked.

Amen to that! Anon is right [and should sign his/her postings]. These phrases particularly beg illustration:

• "A 1-way notch is cut like an upside down triangle"
• "A 1.5-way notch is like an upside down triangle with a half triangle on top of it."
• "A 2-way notch is shaped like a diamond."

--Nil0lab 17:02, 2 April 2006 (UTC)

[edit] plagarism

Parts of this article are almost literal cut and pastes from a few forums. I'm sorry to say, forum or not, the copyright is still held by someone. I'm going to be pulling this stuff promptly.--Oni Ookami Alfador^Talk|@ 02:33, 2 June 2006 (UTC)

Proof: http://www.drifting.com/forums/showthread.php?t=6800 October 16 2004 was the date of the post on the forum. This content was added after that.--Oni Ookami Alfador^Talk|@ 02:41, 2 June 2006 (UTC)

I believe that the author of those forums re-used his own text here, so it is probably OK from the copyright point of view. However, I do feel that much of the added text is quite inappropriate and overdetailed for an encyclopedia article- so if you ditch it on that basis I for one would support that. Graham 05:18, 2 June 2006 (UTC)

I found nothing in the edit summaries that supports that, but I could have missed it. In any case, yes its not very encyclopedic, but it is good info and all pretty much correct to the best of my knowledge. I'm rewriting a paraphrase version now that will work well in the encyclopdia and maintain all the key info with less of the manual/guide aspect.--Oni Ookami Alfador^Talk|@ 04:33, 3 June 2006 (UTC)

[edit] Viscous LSD revert

I deleted the reference to changing the fluid in VLSD centres, which has since been reverted. This is incorrect. The Nissan R200 VLSD centre is sealed and not serviceable. The differential housing itself contains gear oil which can be changed, but the cartridge in the centre is quite separate from this. When they start open wheeling, the only way to fix it is to replace it, usually with an aftermarket clutch pack, because Nissan charge a ridiculous price for the insert. If you disassemble your diff you will see quite clearly what I mean. RB30DE 09:18, 4 June 2006 (UTC)

Sorry, not really reasonable of me to expect you to take the back off, I tried to find some images showing a viscous diff. Actually I found some photos labelled "viscous diff" that were not, so people don't necessarily know what is in their housing. Anyway - Autozine Technical School - pretty decent site overall, new to me, also very good explanation of Torsen diff. Visco-Kupplung - German page with excellent photo of cutaway diff. Physics Of Car Racing - another good photo of cutaway diff. RB30DE 12:22, 4 June 2006 (UTC)

Oooh found a picture (in book) of a racing viscous diff which looks like it can be disassembled! I'm wrong! But still no passenger car VLSD that can be, hacksaws only to date. RB30DE 03:09, 6 June 2006 (UTC)

Fixed it. Why be distructive and remove info when all you have to do is clarify for the few people who're not going to get it? ask any mechanic and they will tell you about Changing differential fluid/oil meaning the fluid in the housing. Its just a generic speaking term but I do see where it might cause confusion.--Oni Ookami Alfador^Talk|@ 03:50, 6 June 2006 (UTC)

Aiyo. Please do call my edit destructive, I'm trying to improve the article. I think you've understood that the oil in the diff housing is not the silicone fluid in the chamber that forms the outer of the VLSD. There are two entirely separate enclosures. The chamber that contains the silicone fluid is inside the oil filled diff housing and is separated from it by seals. But you haven't understood that you do not service a VLSD by changing the housing oil, you throw the VLSD away and start again.

This is the sentence we've got now - "However, they are less prone to breakdown as long as the housing fluid is changed regularly.". Whatever you do with the housing oil, if you run mashed bananas and sawdust in there, it has no effect on the VLSD centre. Changing the housing oil does not extend the service life of the VLSD. The VLSD will expire at its own convenience, and it will expire sooner than a mechanical LSD. They are more prone to breakdown, not less, and they are unaffected by oil/fluid changes. Why remove "info"? Because it's false. You keep reinserting these errors - is an incorrect statement better than no statement at all? Why would you do that? I'm baffled. If I come up with a more encyclopaedic paragraph that covers servicing and service life, replacing the sentence that's there now, are you going to continue reverting? 210.0.100.153 03:17, 8 June 2006 (UTC)

[edit] Mechanical LSD Description

Current description is kind of a mish mash of characteristics of several different diff types, doesn't make sense. If talking about clutch type LSDs, it's not a difference in axle speed that activates the cam action which compresses the clutch packs, it's drive shaft input torque. The centrifugal rotor thing doesn't apply to clutch/cone/viscous/torsen diffs, the only design I'm aware of that it fits is the Detroit Locker / Lokka (tm) diff (possibly Weismann locker), which is an on/off design, either open or locked. Perhaps either the article should be a lot longer, or a lot shorter. Also if Detroit Lockers are going in, perhaps air lockers & hydraulic lockers come with them? There's a whole lot of other motorsport LSDs that passenger cars rarely see which could possibly get a sentence each down the bottom or something. RB30DE 03:09, 6 June 2006 (UTC)

Expanded the clutch LSD bit. Removed the part about centrifugal rotors etc. The other little fly in the ointment is I've only just become aware there are (at least) two kinds of clutch LSD. There's the type I've described, and there's a type where the clutches are compressed by springs(?). In my part of the world, that kind of friction-surface-mated-by-springs LSD is a cone LSD, not familiar with the spring loaded clutch type. I was going to write a cone LSD description, but that needs to encompass spring loaded clutches as well now I think. RB30DE 22:08, 21 June 2006 (UTC)

[edit] Viscous LSD Description

Changed the mechanism description a bit. Moved the Gerotor paragraph out of that position, it didn't make sense there. I can't understand the Gerotor description too well, I don't know anything about them, can someone who does expand that a bit? Who uses them? RB30DE 00:10, 16 July 2006 (UTC)

[edit] "Electronic LSD"

I removed the entry for "Electronic LSD" as this is not an example of a LSD at all ( Note: LSD = Limited slip differential) this was an explantation of how traction control systems work and while some of the outcomes of both are the same they reach their goals in entirely different ways.

You are right, a system that uses brakes to limit slip, without affecting the differential, is not an LSD. But there are electonic differential locks, that electronically affect how the differential function, and we should cover it. For example, latest Skoda Octavia TDI PD 170 VRS, uses something that they market as "Electronic Differential Lock (EDL)", and we should probably cover it. Personally me don't know exactly how this Skoda's unit works. I've augmented the section about worm-gear-based LSDs, please review this section. Thanks: --Maxim Masiutin 11:54, 26 January 2007

It is a form of speed sensitive limited slip differential - look for a definition of differential. That is what it does. No doubt about it. The fact that it is using a brake on the end of the axel, not a clutch inside the differential gear housing is irrelevant - that is NOT an "entirely different way", it is pretty much exactly the same thing. That is how it is used and that is how it is marketed (see Toyota's ATRAC, Nissan's ALSB, etc.). Other articles (such as Jeep Wrangler) refer to this entry as that is what they sell on their vehicles. Leaving it out is confusing. I have reverted that omission fo rthis reason. 66.248.222.34 21:16, 20 June 2007 (UTC)(UTC)

[edit] Generic Name

The article says that LSD is commonly called "posi" (and the like), but I think this may only be true in the US. In England, at least, its commonly known as E-Diff, and this may be true for most other countries in Europe also. But, somebody more knowledgeable than I might want to check this out... Krea 21:00, 28 September 2007 (UTC)