Quote:
Originally Posted by BenFenner
I would also like this information. The bolt itself is part number 21207548052. There are 6 of them that mount the pressure plate/clutch assembly (21212284034) to the flywheel.
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Two different people have told me the pressure-plate-to-flywheel bolts have a (assumed dry) torque spec of
34 Nm (25 ft-lbs). One of them also said to not reuse the old bolts, but I'm still not really sure new are necessary. I'm still researching, but if anyone has the TIS info or other definitive source I'd love to hear it.
Edit: The same person saying not to reuse the bolts is saying new ones come with thread locker on them (which makes sense and seems to be confirmed via parts store
pics online) and to at least apply blue Loctitie if you're going to reuse the old ones. Which certainly makes sense to me...
Edit 2: I got real TIS info and it calls for new hardware. I'm not sure why, but there it is and it is "definitive". Certainly people re-use this hardware, but that is not advised by BMW at least.
If I had to guess, I'd say the bolts are not torque-to-yield but BMW wants new ones each time because the factory units have a dry thread locker compound applied that BMW wants to make sure is there. Of course we can add back our own wet thread locking compound (medium/blue seems appropriate) but presumably that will change the torque spec and BMW doesn't want to have to contend with that so they just say "replace ze bolts!".
The torque spec is where things get tricky. According to the first screenshot below, it looks like the S65 almost assuredly uses M8 10.9 ZNS-coated hardware (RealOEM supports this as well), and TIS calls for a jointing torque of 15 Nm then a final torque of 25 degrees.
But then the second screenshot shows M8 10.9 ZNS-coated hardware calling for a jointing torque of 15 Nm then a completely different final torque of 90 degrees.
Crazy, huh?
This might be why people just use the non-ZNS-coated spec of 34 Nm (25 ft-lbs) and call it a day...
