Diff LSD or POSI ??

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Zippys
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Post Mon Apr 30, 2012 4:17 pm

Does BMW offer a true POSI Diff.?
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DHFiS
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Post Mon Apr 30, 2012 8:44 pm

Whats a true POSI diff?
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kam-325i
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Post Mon Apr 30, 2012 8:51 pm

Zippys wrote:Does BMW offer a true POSI Diff.?
"POSI" as in GM's POSItive TRACking diff ?????

If so, its just another name for the same thing, a Limited Slip Differential.

So the answer is Yes, BMW call it a LSD.
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Zippys
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Post Mon Apr 30, 2012 10:39 pm

DHFiS wrote:Whats a true POSI diff?
No clutches, geared for both wheels to spin.
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Zippys
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Post Mon Apr 30, 2012 10:43 pm

If BMW lists their Diff "open vs. LSD" and LSD is in fact a POSI then all is well and I need to check on what I have. Thanks.
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DanThe
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Post Mon Apr 30, 2012 11:26 pm

Standard LSD has clutches, same as all standard LSD's :mad:

No clutch ie gear locking diffs are named Torsen
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Brianmoooore
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Post Mon Apr 30, 2012 11:33 pm

DanThe wrote: No clutch ie gear locking diffs are named Torsen
And are available in E30 fitment on a Z3 2.8.
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Zippys
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Post Mon Apr 30, 2012 11:43 pm

Thank you, need to remember "Torsen" Diff for 1990 325i
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Brianmoooore
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Post Tue May 01, 2012 12:19 am

Z3 2.8 diff. has a 3.15 ratio though, so is unsuitable for use with the normal E30 gearboxes with their overdrive top gears. Need to be used with a direct top gear box, such as the ones that come attached to M50 and M52 engines.
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DanThe
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Post Tue May 01, 2012 8:42 am

No E30 ever came with a torsen diff, only Z3 AFAIK
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