Re: bolts to pull flywheel
I just wanted to stress the importance of using the correct bolt. I've pulled threads out in the past, and I hate having to make a repair just to do a job twice- cheers!
I completely agree but I am worried that this thread is possibly getting to the point where it might be passing on bad or confusing information.
We are starting with a presumption that grade 8 bolts are required for this.
As a former T&D Maker, that makes some sense to me, although I would suspect that it might be belt and suspenders.
Where did this Grade 8 requirement originate?
As far as using or not using a grade 8 bolt....there is
nothing inherent in a grade 8 bolt that will make it pull threads out. A grade 8 bolt is simply a very strong bolt and generally less likely to break than a lower grade. If you bolt up a wheel puller to a flywheel and start tightening, if the flywheel does not "pop" and you keep tightening, something will give. Either a bolt will break, or tear out of the tapped hole in the flywheel. If a bolt breaks under the amount of tension that a wheel puller can exert, it can become a projectile ~ hence why a higher grade might be a good idea. If you use a higher grade bolt it is more likely to strip out of the threaded hole.
It was suggested that most OMC flywheels are threaded UNF ~ fine thread. That certainly makes a lot of sense. Fine threads are more resistant to tear-out. Personally, I have no idea what thread series OMC actually has used, but what I can say uncategorically is that the metal used in the OMC flywheels that I have seen is soft enough that there would be little difficulty in most cases in turning a coarse thread steel fastener into a fine thread hole. You would actually form a kind of messed up hybrid thread which might hold....or... as R.Johnson says, maybe "it will pull in two".
The moral is, find out what thread is in play before "trying to see whether what you buy will thread in". It might, even though it would have been better if it hadn't.
There was also a statement that shoulder bolts/ stripper bolts are required? For what purpose? It is claimed that "this bolt will not put all of the stress on the threads." Where else
could a bolt put stress?
The only reason to use these is if there is a clearance issue and thread penetration limitation is required. I don't see it.
Of course, if you had some on hand, there would certainly be no reason NOT to use them.
