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Discussion Starter #1
this is specific to the single mass flywheel cars; I’ve heard that for the NA ‘93 cars clutch weight was reduced? On realoem the part numbers are just for the entire pressure plate and clutch disk set. I’m doing a clutch on my 11/90 M5 and it’s got a Sachs race engineering pressure plate ending in part number 647. There is also a Sachs 765, 238 and 208. I don’t hear a lot of discussion on how they are different and which ones were OE per the build date. I want to make an informed decision whether or not to keep with the 647 or to change to something else.
 

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Different numbers indicate models that differ by diameter and calculated torque handling capability. 765 being the most capable of the bunch.

Below is a quote from www.race.fi:

"Sachs SRE 763
SRE number: 883082 999763
Disc diameter: 228 mm
Torque cap with organic disc: 430nm
Torque cap with sintered disc: 505nm

Sachs SRE 765
SRE number: 883082 999765
Disc diameter: 240 mm
Torque cap with organic disc: 590nm
Torque cap with sintered disc: 700nm

Sachs SRE 707
SRE number: 883082 999707
Disc diameter: 240 mm
Torque cap with organic disc: 520nm
Torque cap with sintered disc: 615nm

Sachs SRE 645
SRE number: 883082 999645
Disc diameter: 228 mm
Torque cap with organic disc: 420nm
Torque cap with sintered disc: 500nm

Sachs SRE 731
SRE number: 883082 999731
Disc diameter: 240 mm
Torque cap with organic disc: 360nm
Torque cap with sintered disc: 520nm

Sachs SRE 785
SRE number: 883082 999785
Disc diameter: 240 mm
Torque cap with organic disc: 545nm
Torque cap with sintered disc: 640nm

About torque caps
The toque caps are listed when using a Sachs SRE disc, and a regular steel surface flywheel in normal conditions. The exact break torque is hard to calculate so these numbers have an approximate 10 % margin on the safe side. Proper shimming and installation is essential for getting the most out of any clutch kit."
 

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Discussion Starter #3
I found another database that lists the 647 @ 296ftlbs and the 765 @ 437ftlbs, both with a stock disk. It seems like the 765 is pretty overkill for a B36, and I can’t find a 647 for sale statewide.
 
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