N52 Flywheel Bolt Torque Spec

Krorez · 12-14-2025, 07:24 PM

Hey everyone,
Currently helping a friend replace the motor in his 128i with a donor N52 from a Z4. I was gonna put the flywheel on, but saw on ISTA that the bolts were one time use and it also talked about aluminum bolts, but his bolts aren't aluminum. The picture on ISTA also shows a completely different flywheel with 8 bolts instead of 6 bolts. It's an automatic with a 6 hexagon, not torx, bolt flywheel that are definitely not aluminum (they're magnetic). So, I'm just a little confused. Do I need to replace these bolts and what's the right torque spec? Also do these go in dry or lubed?(might be a dumb question) Definitely do not want to end up with righty-loosey flywheel bolts. Any help is appreciated, thanks!

Attached are pictures from ISTA.

cerealwars · 12-16-2025, 04:01 PM

All bolts that thread into the block are TTY, because of the block's aluminum/magnesium construction.

These bolts go into the crank, so that rule doesn't necessarily apply. I'd bet they are reusable, but you definitely need the right torque spec. Go around twice with the wrench. They won't stretch much because of the short grip length.

When I did my clutch and SMFW conversion, I bought new OEM bolts. Not certain I needed to, but it wasn't something I wanted to mess with. Sorry i don't have a more straightforward answer for your question, just tossing in my 2 cents.

12-14-2025, 07:24 PM	#1
Krorez Registered 0 Rep 1 Posts Drives: 2010 BMW 128i Join Date: Dec 2025 Location: USA iTrader: (0)	N52 Flywheel Bolt Torque Spec Hey everyone, Currently helping a friend replace the motor in his 128i with a donor N52 from a Z4. I was gonna put the flywheel on, but saw on ISTA that the bolts were one time use and it also talked about aluminum bolts, but his bolts aren't aluminum. The picture on ISTA also shows a completely different flywheel with 8 bolts instead of 6 bolts. It's an automatic with a 6 hexagon, not torx, bolt flywheel that are definitely not aluminum (they're magnetic). So, I'm just a little confused. Do I need to replace these bolts and what's the right torque spec? Also do these go in dry or lubed?(might be a dumb question) Definitely do not want to end up with righty-loosey flywheel bolts. Any help is appreciated, thanks! Attached are pictures from ISTA. Attached Images
	Appreciate 0 Tweet Quote

12-16-2025, 04:01 PM	#2
cerealwars Riffraff 688 Rep 480 Posts Drives: 128i 6M, 1UZ S13, '62 C10 Join Date: Apr 2023 Location: Detroit Metro Outskirts iTrader: (1) Garage List 2010 BMW 128i [0.00]	All bolts that thread into the block are TTY, because of the block's aluminum/magnesium construction. These bolts go into the crank, so that rule doesn't necessarily apply. I'd bet they are reusable, but you definitely need the right torque spec. Go around twice with the wrench. They won't stretch much because of the short grip length. When I did my clutch and SMFW conversion, I bought new OEM bolts. Not certain I needed to, but it wasn't something I wanted to mess with. Sorry i don't have a more straightforward answer for your question, just tossing in my 2 cents.
	Appreciate 0 Quote