Thanks guys. Am I right that if I use a gasket, I don’t need to use RTV?
I know how to source bolts, it’s a simple google search. I’d just prefer to not get Toyota ones. It’s difficult because Toyota doesn’t use typical markings for the grade of the bolt. So it’s not like I can go to the store and get the same bolt with four dots on it, you can only get those from Toyota. So I had to find the standard and determine that it’s a 8.8 bolt.
So Toyota Class 8T bolt is equivalent to ISO 898-1 8.8 bolts. It’s a shame that this information is so hard to find online. It forces people to get bolts directly from Toyota. But now I can get any 8.8 bolt/nut/stud, of the same length that is already on the car and not have to worry about using a bolt that is of less strength than what was originally there. I know that in this application, using a weaker bolt is probably not that big of deal. I don’t know the mechanical engineering behind it either. The engineers who selected which type of bolt would be appropriate to get the appropriate clamping force, tensile strength, etc chose 8.8 bolts for a reason, why I don’t know? But the math behind it, doesn’t look to simple at all. I’m not a mechanical engineer, and looking at how the clamping force is calculated based on the length of the bolt, grade of the bolt, etc isn’t a simple calculation. So I just want to use the same quality bolt because I don’t know what I’d be changing by using a weaker bolt. But I’d be scared of using a bolt of less strength. I’m also unsure how the appropriate torque is calculated for these bolts, so I just reference charts and the maintenance manual.
Another interesting thing I heard, is that in some cases, weaker bolts are used on purpose for failure scenarios. Meaning while a stronger bolt will work just the same of course, weaker bolts are picked by engineers in some cases so non-critical parts fall apart to indicate a problem with other parts. So the less critical part brakes first, and when you go inspect that part you see the more critical part is starting to fail. Or something like that. I don’t know.
Fastener theory is a bit interesting and complex. Since I’m not familiar with all the math and engineering behind it, I just want to use the same length and grade of fasteners.