Why grade 8 for pulling flywheel ??? confused on this

[kodibass]

Was reading the GREAT post for changing coils and points, kinda confused as to using hardened grade 8 bolts in the flywheel puller. if something went bad and stripped out wouldn't it be better for it to be the bolt threads and not the flywheel threads? & if the bolt snapped off in the flywheel I don't think you could drill it out, I'm sure I'm missing something here please set my me straight...:thanks

 

[dwco5051]

Re: Why grade 8 for pulling flywheel ??? confused on this

That is sort of like packing the eggs on the bottom of a grocery bag. That way when they break they don't run over the rest of the groceries.

Actually the chances of a grade 8 bolt breaking is a whole lot less than using a bolt with less strength. Plus if one would break backing it out would not be a big problem as the threads would not be rusted or siezed regardless of which grade bolt was used. The length is important because you want to get maximum thread engagement without bottoming out.

 

[1946Zephyr]

Re: Why grade 8 for pulling flywheel ??? confused on this

Also, grade 8 bolts are less likely to stretch under the usual pressure required to pop a flywheel loose.

 

[OptsyEagle]

Re: Why grade 8 for pulling flywheel ??? confused on this

Once you start tightening down that center bolt to pull a flywheel you will know right away why you need very, very, very hard bolts. Anything less would be like trying to pull it with silly puddy.

 

[NoEcm]

Re: Why grade 8 for pulling flywheel ??? confused on this

Cheap insurance.

Better to buy 3 Grade 8 bolts up front than to have to by an EZ Out later.

 

[Tim Frank]

Re: Why grade 8 for pulling flywheel ??? confused on this

Once you start tightening down that center bolt to pull a flywheel you will know right away why you need very, very, very hard bolts. Anything less would be like trying to pull it with silly puddy.

Hardness is pretty much irrelevant....little difference between grade 1 and grade 8. In fact, "very, very, very hard bolts" are what you don't want....then brittleness creeps in.
It is tensile strength that counts, and the difference between grade 2 and 8 is a factor of more than 2x....which is exactly what you do want.

 

[losnbama]

Re: Why grade 8 for pulling flywheel ??? confused on this

this is why plain and simple...normal bolts are to soft and will retain the shape when twisted to far. hardened bolts wont twist much when pulling a flywheel if the right bolts are used.hence the flywheel will pop off before the bolts twist

 

[kodibass]

Re: Why grade 8 for pulling flywheel ??? confused on this

Very well put Tim, I have many grade 8 bolts of the right length/size laying around, Just wasn't sure cause I have broken a few bolts off in my day, and I hate trying to drill the stainless that is often used in outboards. So thought I'd ask...now I get it.