RE: Born slippy: All about limited-slip differentials

RE: Born slippy: All about limited-slip differentials

Author
Discussion

NickGibbs

1,247 posts

230 months

Wednesday 29th February 2012
quotequote all
Gorbyrev said:
Thanks Nick - superb article, really interesting, more please! Wonder how many XR4x4's are left out there! Not many I would wager.
Love the idea that the Beemer test pilots are all chuffed with the predictable shift to oversteer in an E60 while the rest of us mere mortals are laying down with the rear tyres. Heres to the guys who make sure we don't kill ourselves unnecessarily !

Edited by Gorbyrev on Wednesday 29th February 13:33
Thanks for the thanks. Heinrich had some great tales from the nerdy end of LSD engineering. Like that Audi quattros were all Torsen, yet when Hans Stuck went DTM racing in the Audi V8 (with quattro writ large on the outside), they had to switch to speed sensing LSD because of the kerb riding problem he described. Not dinner party chat, I grant you, but I enjoyed it!

MECHAN1C

2 posts

156 months

Wednesday 29th February 2012
quotequote all
Pingman said:
anything fast said:
That car was the first FWD roadcar ever to have LSD with a viscous coupling system.
I didn't know this smile

Wonder what the first RWD car with an LSD was, off to Google I go! smile
How 'early' was mine? In Oct '87 I factory ordered LSD (amongst other goodies...) on Jan '88 reg'd BMW 325i - it didn't diappoint, especially in snow (altho' aided by paving slabs in boot; a lesson learned from 3000GXL days...)

s m

23,164 posts

202 months

Wednesday 29th February 2012
quotequote all
MECHAN1C said:
Pingman said:
anything fast said:
That car was the first FWD roadcar ever to have LSD with a viscous coupling system.
I didn't know this smile

Wonder what the first RWD car with an LSD was, off to Google I go! smile
How 'early' was mine? In Oct '87 I factory ordered LSD (amongst other goodies...) on Jan '88 reg'd BMW 325i - it didn't diappoint, especially in snow (altho' aided by paving slabs in boot; a lesson learned from 3000GXL days...)
I think LSDs were available many, many years before 87

Marquis Rex

7,377 posts

238 months

Wednesday 29th February 2012
quotequote all
s m said:
MECHAN1C said:
Pingman said:
anything fast said:
That car was the first FWD roadcar ever to have LSD with a viscous coupling system.
I didn't know this smile

Wonder what the first RWD car with an LSD was, off to Google I go! smile
How 'early' was mine? In Oct '87 I factory ordered LSD (amongst other goodies...) on Jan '88 reg'd BMW 325i - it didn't diappoint, especially in snow (altho' aided by paving slabs in boot; a lesson learned from 3000GXL days...)
I think LSDs were available many, many years before 87
Of course they were. American muscle cars of the sixties had them, GM called it posi-traction and Mopar called it 'Suregrip'.
I'm sure that wasn't the first appearance of them, the question is- was it in the sixties or even before that?

The Black Flash

13,735 posts

197 months

Wednesday 29th February 2012
quotequote all
s m said:
The Black Flash said:
Gorbyrev said:
Thanks Nick - superb article, really interesting, more please! Wonder how many XR4x4's are left out there! Not many I would wager.
Most of the ones which are left get turned into kitcars, the xr4 rear LSD is highly sought after.
I should imagine a lot of them are approaching 'open' operation after 25 years usage!
They're a viscous type, so I don't know how/if they wear. Plenty of places rebuild them anyway.

MECHAN1C

2 posts

156 months

Wednesday 29th February 2012
quotequote all
Marquis Rex said:
s m said:
MECHAN1C said:
Pingman said:
anything fast said:
That car was the first FWD roadcar ever to have LSD with a viscous coupling system.
I didn't know this smile

Wonder what the first RWD car with an LSD was, off to Google I go! smile
How 'early' was mine? In Oct '87 I factory ordered LSD (amongst other goodies...) on Jan '88 reg'd BMW 325i - it didn't diappoint, especially in snow (altho' aided by paving slabs in boot; a lesson learned from 3000GXL days...)
I think LSDs were available many, many years before 87
Of course they were. American muscle cars of the sixties had them, GM called it posi-traction and Mopar called it 'Suregrip'.
I'm sure that wasn't the first appearance of them, the question is- was it in the sixties or even before that?
mmm... 'apologies! I'd somehow limited(!) myself to UK/EU RWD roadcars!! I was aware (& tried in '78 in US) LSD'd Firebirds/TranAm's and in '81 bought in UK a (made for UK!)'78 TransAm (403 Olds).

NickGibbs

1,247 posts

230 months

Wednesday 29th February 2012
quotequote all
Marquis Rex said:
s m said:
MECHAN1C said:
Pingman said:
anything fast said:
That car was the first FWD roadcar ever to have LSD with a viscous coupling system.
I didn't know this smile

Wonder what the first RWD car with an LSD was, off to Google I go! smile
How 'early' was mine? In Oct '87 I factory ordered LSD (amongst other goodies...) on Jan '88 reg'd BMW 325i - it didn't diappoint, especially in snow (altho' aided by paving slabs in boot; a lesson learned from 3000GXL days...)
I think LSDs were available many, many years before 87
Of course they were. American muscle cars of the sixties had them, GM called it posi-traction and Mopar called it 'Suregrip'.
I'm sure that wasn't the first appearance of them, the question is- was it in the sixties or even before that?
Posi-traction. My Cousin Vinny brings limited slip diffs to a mainstream movie. Great scene! http://video.mail.ru/mail/fairyv/308/312.html

cptsideways

13,535 posts

251 months

Wednesday 29th February 2012
quotequote all
Cars came with LSD's in the 30's -- nothing new!!

s m

23,164 posts

202 months

Wednesday 29th February 2012
quotequote all
The Black Flash said:
s m said:
The Black Flash said:
Gorbyrev said:
Thanks Nick - superb article, really interesting, more please! Wonder how many XR4x4's are left out there! Not many I would wager.
Most of the ones which are left get turned into kitcars, the xr4 rear LSD is highly sought after.
I should imagine a lot of them are approaching 'open' operation after 25 years usage!
They're a viscous type, so I don't know how/if they wear. Plenty of places rebuild them anyway.
They do gradually lose their properties through heat/work cycles - like you say, they can be rerated/uprated/replaced ...although a lot of people don't bother

Harris328i

358 posts

172 months

Thursday 1st March 2012
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Amazing work guys, cheers

cptsideways

13,535 posts

251 months

Thursday 1st March 2012
quotequote all
This is what a foobarred centre viscous coupling looks like, from a 4x4, its basicly burnt out the fluid, caused by odd tyres being fitted front to rear.


enneffo

24 posts

145 months

Thursday 1st March 2012
quotequote all
More of this sort of thing :-)

I for one would really like to see some exploded diagrams of the various types of LSD, easier to figure out what's going on with a picture.

legalknievel

352 posts

196 months

Thursday 1st March 2012
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wst said:
legalknievel said:
I am surprised at how much I understood of that. I'm off to hit my head with a hammer until the clarity has worn off.
Here is also a pretty handy guide to how the basic open diff works, if you're still feeling intelligent. Though really this one puts it in such pleasant terms that everyone can follow it.
That is surprisingly useful, and yes a bit noddy but nothing wrong with that. Thanks. I was, however, a bit surprised when neither Laurel and Hardy nor Charlie Chaplin had bothered to do so much as slip on a banana skin.

Seriously, though, that video is a good find.

teabagger

723 posts

196 months

Thursday 1st March 2012
quotequote all
How would one go about checking the state of his viscous LSD?

I know of the jack the rear end up, spin one wheel and the other should rotate in the same direction technique but how do you check its actualy fit for purpose and working correctly under driving conditions?

Anyone know of a good place to have a viscous LSD stripped, serviced and setup?

El Guapo

2,787 posts

189 months

Thursday 1st March 2012
quotequote all
cptsideways said:
Cars came with LSD's in the 30's -- nothing new!!
yes IIRC Auto Union came up with idea originally.

s m

23,164 posts

202 months

Thursday 1st March 2012
quotequote all
teabagger said:
Anyone know of a good place to have a viscous LSD stripped, serviced and setup?
Bara and C.T.S. are two places

pacman1

7,318 posts

192 months

Thursday 1st March 2012
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My MV6 has an LSD, but only works correctly if I turn the TC off!

dvs_dave

8,581 posts

224 months

Saturday 3rd March 2012
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Mark Benson said:
450Nick said:
Great to see some technical articles from PH, more of this please on other vehicle systems - very interesting read!
This, PHers are a broad church and this is the sort of thing that helps broaden it more.
+1. Very interesting article! More like this from vehicle system experts explaining the various differences how they work would be greatly appreciated.

HowlerMonkey

106 posts

168 months

Saturday 3rd March 2012
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1980 amc eagle had viscous diff.

1986 nissan milano X1.

Ihavcndygetinvan

23 posts

164 months

Thursday 15th March 2012
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A brilliant read!!! one of the best articles I've read on here in a long time. My understanding of LSD's has increased ten fold... ha!