Need help with bolt size

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junkout

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I have a predator 212 non-hemi. I bought a China torque converter for it and the bolt to mount it to the motor are the wrong size. The head of the bolt that won't fit reads 8.8. Thanks in advance!
 

JTSpeedDemon

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I think what Pearl111 meant, is that it means grade 8.8, which is used to designate a metric fastener. SAE fasteners don't use the term and marking grade 8.8.


So you're both right, the said bolt is metric.
 

itsid

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yes bolt grades on metric fastener..
in front of the dot
the tensile strength (times 100 N/mm²)

.X is a multiplier to denote the
yield strength for bolts 6.8 or lower (times 10N/mm²)
(so 6*8*10 N/mm².. aka MPa)
or proof stress for bolts 8.8 and higher (again same math)
(so 8*8*10N/mm²)

metric units to calculate.

So an 8.8 would have a tensile strength of 800MPa or better (~ 116000 psi)
and a proof stress limit of at least 640MPa ( ~93000 psi )

many online sources unfortunately miss the swap at eight and continue to calculate yield strength for bolts of grade 8.8 and bigger, instead of proof stress which it should be.
that way the bolt grade looks inferior to what it is most of the time..
but since that doesn't cause a prematurely failing bolt (in fact the opposite) no one cares enough ;)

please, proceed as normal ;)

'sid
 

pearl111

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This is all true but I could never understand why most of all the nuts and bolts (hardware) are metric and a couple of side cover ones and clutch shaft are US, SAE sizes. Anyone know?
 

itsid

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well it's a chinese engine so everything's metric.

It's made for the american market,
so everything that the end user has to add
is made for their convenience iimperial.
(PTO and PTO flange)

'sid
 
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