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Thread: flywheel bolt torque...please read

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Posts: 11-20 of 34
2011-08-14 18:12:52
I would get new bolts. Or buy the ARP ones that are not torque-to-yield so they are re-usable. Or inspect like cotrim said.

However, my bolts have been through 5 engines. They are on their 5th engine now. And they've been torqued 6 times I believe, and this last time they were torqued way too high. Maybe they are about to fail. Maybe they will be okay.
Just letting you know what to expect out of those bolts as far as longevity.
2011-08-14 18:25:34
yeah my flywheel bolts have been reused about 6-7 times now without problems reving to 8700. I never use a torque wrench on mine either. I just put a breaker bar with adapter for my 3/8 socket and tighten them till tight without overdoing it. Usually in the range of 65-75 ft-lbs from what ive checked with a torque wrench. Ive gotten a good feel for torques.

But im replacing my flywheel bolts this time around just because they have been used soo much. Just getting some oem ones. Never had one break or come lose so no reason to go with anything other than that.
2011-08-14 18:27:26
Thank you sirs! Y'all have always been some of the more trusting sources of mine over the years and always hope you respond in my distress threads :-) amongst others but since '05 on these forums, ive found all 3 of you are certainly some of the more experienced and informative. Thank you
2011-08-14 18:34:38
Torque to yield require angle torquing. 61-69lbft doesn't sound torque to yield to me. Head bolts are TTY and require several steps in the FSM to torque properly, on top of using specified angles during the final torque sequence.

It's my guess, but I don't think the flywheel bolts stretch into the plastic zone. A lot of times you see where the bolts have stretched...but I've never seen that on the flywheel bolts tbh.
2011-08-14 18:49:29
the only flywheel bolts I have seen stretch were over torqued. Usually you damage the threads in the crank before you stretch the bolts.
2011-08-18 22:02:38
^^^agreed... theyre so fine pitched and relatively strong that if you manage to stretch them you did something crazy.

Unless youre doing something huuuuge, you can normally reuse them..(it's not cheap to replace them ). The torque itself is based on the material properties of the specific bolts (cross sectional area, etc). So if its a DE bolt, you use the DE spec like everyone said, regardless of output.
2011-08-18 22:28:16
I'm with Coheed here. Torque-to-yield bolts require you to torque to a specified amount, then turn a certain amount of degrees, kind of like most head bolts. I don't believe flywheel bolts are TTY since you don't turn like 90 degrees to stretch them. I've reused mine multiple times with no loctite and they have never backed out or stretched or broken.
2011-08-18 23:38:35
Here is what can happen when things go wrong.

2011-08-19 00:38:52
flywheel bolts are not torqued to yield.
2011-08-19 00:50:06
Originally Posted by jRod
flywheel bolts are not torqued to yield.

Very true. I just liked the pictures of the carnage.
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