Re-use flywheel torque to yield "stretch bolts"

[CrankyOldMan]

Originally Posted by sorka

Cost $2.71 each...

Just a quick cost vs risk assessment.

New bolts:
$16.26 + tax
Waiting one day to get them.

Grenaded clutch/flywheel repair (cheapest aftermarket I found in 10 second search):
$63 Replacement brand clutch kit
$50 Luk brand flywheel/flex plate
$16.26 for a new set of bolts (old ones will probably not be salvageable)
Hours/days downtime tearing out engine/trans to replace

Even if you skip the OEM clutch and flywheel and go super low quality, you're out at least a weekend to pull everything apart. Investing the $20 while you've already got it apart seems to be a no-brainer to me.

That said, I agree that elastic deformation bolts can be re-used, plastic deformation cannot. But without a length spec in the manual to verify against, or a good understanding of what a plastic deformed bolt looks like, it's a crap shoot.

[CoryM]

Originally Posted by CrankyOldMan

Just a quick cost vs risk assessment.

New bolts:
$16.26 + tax
Waiting one day to get them.

Grenaded clutch/flywheel repair (cheapest aftermarket I found in 10 second search):
$63 Replacement brand clutch kit
$50 Luk brand flywheel/flex plate
$16.26 for a new set of bolts (old ones will probably not be salvageable)
Hours/days downtime tearing out engine/trans to replace

A flywheel has a huge amount of inertia. If the bolts were to suddenly shear at 6500rpm you would need a new car.

https://www.youtube.com/watch?v=n0TxZFDLa3w

This is why it is not something to play around with.

Cheers.

[CrankyOldMan]

Originally Posted by CoryM

A flywheel has a huge amount of inertia. If the bolts were to suddenly shear at 6500rpm you would need a new car.

I was thinking more of a single head shearing off and tumbling around inside, but yes, a total failure at redline would be catastrophic for everything around it. That's why real racecars are required to have a shroud around the flywheel that protects the driver and bystanders.