this, and probably this only as far as aftermarket. stock from a dealership would also be fine. the head is shallower, and i believe the shoulder may be more precise (thats how the wheel is located on the crank). also stronger than regular cheap grade 8 stuff (that should never be used in any part of the rotating part of the drivetrain period)
you may have gotten flexplate bolts instead of flywheel bolts, they are different (flexplates are thinner).
I agree with the above. I have a disdain for hardware store bolts and their ratings ane don't trust them. If it's a critical bolt, I'll just pay the $10 per bolt for an OEM if it's something like a flywheel where if the bolts sheared, it would be a bad day
There is a serious problem with use of very high strength threaded fasteners, often overlooked. With Grade 8, for example, the material hardness, which primarily determines how much it can stretch or deform before breaking, is pretty high. The higher the hardness, the less strain, or deformation, can the material withstand before failing. The reason for this is that as alloying becomes higher, the Yield Strength gets closer and closer to the Ultimate Tensile Strength. That means the bolt will break when stretched past the yield point more quickly with higher alloying.
Some race car designers prefer Grade 5 over Grade 8 for this reason. So, what's commonly done, is use a larger diameter Grade 5 instead of a smaller diameter Grade 8. Here is a chart showing the relative differences among bolts made of steel. Note the smaller and smaller difference between yield and tensile, as bolt grade increases. imp
https://www.boltdepot.com/fastener-information/Materials-and-Grades/Bolt-Grade-Chart.aspx
Some race car designers prefer Grade 5 over Grade 8 for this reason. So, what's commonly done, is use a larger diameter Grade 5 instead of a smaller diameter Grade 8. Here is a chart showing the relative differences among bolts made of steel. Note the smaller and smaller difference between yield and tensile, as bolt grade increases. imp
https://www.boltdepot.com/fastener-information/Materials-and-Grades/Bolt-Grade-Chart.aspx
You are overthinking this. Though it takes less deformation to break a bolt with a higher tensile strength it also takes a considerable amount of additional force. The ratio is not 1 to 1.
The larger threat in either case is a flaw in the material. Furthermore, applications like a fly wheel do not benefit from hardware that is easier to deform. As a matter of point since we decided to go off into the weeds. There are few places in the drive train that experience more vibration than the fly wheel.
Shear-bolts are another matter altogether and would be really getting down into the weeds.
While I was digging around looking for a head bolt today I found several flywheel bolts and noticed that there is a portion of the threaded bolt that is not threaded. Just a little nipple at the end, I pretty sure they were factory bolts. That may account for the difference in length.
Begging your pardon, but I was taught to "overthink", apparently, while studying Strength of Materials, and similar courses. Fact remains that if you tighten a given bolt in a fairly rigid structure, a "soft" one will stretch and stretch after yielding, that is, becoming plastic, beyond elastic, for a long ways before breaking. A high alloy bolt such as Grade 8, will be felt under similar tightening conditions, to fail suddenly only a short way beyond yield. This is due to the yield and ultimate strengths being much closer together in value.
We are not concerned directly with the value of the tensile force in the various types of bolts, as it's understood that their breaking strength in tension depends on the type of material they are made of, heat treatment, alloying, aging, etc.
No need to beg. Good luck making that happen with your grade 8 bolt and automotive application. If you're that inept with a torque wrench, you probably shouldn't wrenching.
Show me where this is a problem in the automotive industry. I know this isn't a ongoing problem on aircraft unless perhaps it's an R&D project and undersized bolts are being tested specifically for an application.
The REAL problem is 1st: Operator error and 2nd is material deficiencies (cheap bolts from China and elsewhere).
Let me know if find a Grade 8 flywheel bolt (9600 lbs per bolt clamping force) that fails and I'll show you someone that doesn't know how to use tools or follow instructions.
On the other hand, perhaps you should pull all the grade 8 bolts from your vehicles and reinstall grade 5. They (the ones who drew the specification) probably don't understand the problem as well as you do.
I ended up getting ARP 1 inch, installed the pilot bearing, flywheel, clutch and pressure plate saturday. Now waiting for the clutch fork to come in this week. Hopefully figure out my wiring and get this thing started soon