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Discussion Starter #1
I can't find it on here, I can't find it on the web in general. I know I've seen it in a service manual somewhere. For some reason I'm thinking a hilux book which I don't have any more.
Japanese automotive bolts have numbers in the heads. I have a bolt which is broken with a 9 on the head. I just want to make sure an 8.8 is equivalent or better.
 

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Previously known as twodiffs
1991 GQ Safari.
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Good question that...i've got plenty of containers with bolts and they have 7's 9's etc.
I'm doubtful they will be better than 8.8 as they aren't high tensile.

FMIK they are just standard automotive bolts and nothing special...looking forward to more answers.
 

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thats for the dipsh#ts on the production line the number on the top represents the torque the bolt gets done up to so they dont have to keep checking the manual
 

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BORDERTREK 4X4 & FABRICATION
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MikeH in the workshop manuals those numbers correspond to the specific torque they have to be for the thread size given. You have to make sure the two match up as some bolts have the same numbers but different size threads with different torque settings.
So yeah, nothing to do with tensile grading of the bolts. Most are medium tensile at the least and many are high tensile, some greater than 8.8, depends what they are used on.
Cheers, sudso
 

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Discussion Starter #7
These links only show the american bolt grading (6 radial dashes for grade 8 for example) or the metric 8.8 10.9 etc etc.
Yes there's heaps of that on the net and I know enough about those to get by.

They do not show the JIS grading which is what I'm looking for.

Specific example: M8 pressure plate bolts have a 9 on them. You can tell its a 9 not a 6 because it's back is straight not curved.
Which should I use - the old 9 bolts which may or may not be stronger or the 8.8 bolts I have on the shelf?

Rattle a handful of the 9s together they have that same dull clatter than 8.8 bolts have. They are high tensile of some sort.
 

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Rattle a handful of the 9s together they have that same dull clatter than 8.8 bolts have. They are high tensile of some sort.
wow i've never thought of checking bolts like that it has to be the most accurate way around
 

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You could set up a simple test with a lump of steel with a hole in it and a nut on the other side. Tighten a couple of each bolts to failure with a torque wrench and compare what torque they fail at... not the most scientific way of doing it without monitoring angle / clamp load measurements but better than rattling a couple of them against each other.

If the nut is failing rather than the bolt you may need to tap a deeper thread into a piece of steel.
 

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wow i've never thought of checking bolts like that it has to be the most accurate way around
Yeah well I chipped a tooth so I cant use them and my wit isn't as sharp as yours so I cant use that either.

Ever heard of using a magnet to check if something is bogged? also helps tell the difference between different types of stainless too. Seeing what colour mark is left when you rub it on on bare porcelain is another one for helping identify materials.
You'd be surprised what sort of odd sounding things give you useful information about unknown materials.
 

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Specific example: M8 pressure plate bolts have a 9 on them. You can tell its a 9 not a 6 because it's back is straight not curved.
From the service manual.
The only marks listed are 4, 7 & 9 relating to grade 4T, 7T & 9T

For your example, Grade 9T, M8
Tightening torque (non lubricated) is;
29Nm for a Hex Head Bolt with Pitch = 1.25mm
31Nm for a Hex Head Bolt with Pitch = 1.00mm
35Nm for a Hex Flange Bolt with Pitch = 1.25mm
37Nm for a Hex Flange Bolt with Pitch = 1.00mm
 

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BORDERTREK 4X4 & FABRICATION
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Also says 22-29Nm for pressure plate bolts
 

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Discussion Starter #13
we put the 8.8 bolts in. Known quantity. I also know how the vehicle was and will be driven. I'm glad it has a cast steel bellhousing.

I'll see if I can find that section from the toyota manual and scan it into here. someone might need it one day.
 
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