Bolt Grade

Royse · Jan 31, 2023

Anyone recognize the grading on this bolt?
It's the shear bolt out of my 3 pt snowblower. I picked up a rock and broke the bolt.
Should be an easy fix but I don't want to replace it with something too hard.

J Hamilton · Jan 31, 2023

I'm not seeing a picture. But a shear bolt is normally a grade 5

Royse · Jan 31, 2023

Not sure why the pics didn't load. Trying again.

wore out · Jan 31, 2023

That is metric bolt grade. (Must be a metric bolt.)

Metric bolt grade 6.8 is similar to a Grade 2.

''The higher the ISO numbers are, the stronger the bolt. A metric bolt designated as ISO class 6.8 roughly corresponds in strength to an SAE Grade 2 bolt. Bolts of ISO class 8.8 and the slightly stronger class 9.8 roughly correspond to an SAE Grade 5 bolt. An ISO Class 10.9 bolt roughly corresponds to an SAE Grade 8 bolt.''

R Geiger · Jan 31, 2023

I would never use a grade 5 bolt as a shear bolt! Grade 2 is what I use!

Royse · Jan 31, 2023

wore out, I assume it is metric. Roughly the same size as 5/16.
The snowblower is a Meteor brand made in Canada.

stevieb49829 · Jan 31, 2023

Royse, I can't tell. Was there a weak spot engineered into the bolt? Try a grade 2 first. If it shears too easily, go to a grade 5. But I'd file a notch around the grade 5, just to make sure it comes apart where you want it to.

stevieb49829 · Jan 31, 2023

Wore Out, how did you get quotation marks to work in your response?

wore out · Feb 1, 2023

(quoted from post at 22:11:16 01/31/23) Wore Out, how did you get quotation marks to work in your response?

Quotation marks don't work with the outdated software here, but two apostrophes work to make a quotation mark.

Tim PloughNman Daley RIP · Feb 1, 2023

This post does not show your picture but other pix looks like and older style bolt, B4 they started marking the grades. I'd say marks are just the manufacturers' logo and
part ID number. Shear bolts are softer grades so they snap off as intended but you already know this. A Grade 2 or 5 bolt should be OK.

Tim Daley(MI)

Jim.ME · Feb 1, 2023

Meteor has some operator/parts books for the snow blowers online, you might check for your model there. The couple I looked at show shear bolts in fractional sizes and #2, which would indicate grade 2 to me. I would agree with wore out, that your old bolt is a 6.8 metric bolt.

This post was edited by Jim.ME on 02/01/2023 at 03:29 am.

TheOldHokie · Feb 1, 2023

(quoted from post at 21:09:21 01/31/23) Not sure why the pics didn't load. Trying again.

Metric fastener and ISO grade markings are more informative than SAE. First number is yield strength and second number indicates ratio of yield to tensile strength.

6.8 is not a standard grade but maybe a special. I initially read that as 8.8 which is standard and roughly equivalent to SAE grade 5.

TOH

oldsarge · Feb 1, 2023

I'm wore out,but not'' Wore Out''. I use apostrophe twice and it comes thru the machine as quotes (shrug)

Dave G9N · Feb 1, 2023

It may be that the head die was worn and it really is an ISO grade 8.8. You aren't likely to find a 6.8 anywhere. They bang these things out in lots of 100,000 so a little wear on the head marking is not unlikely.

The metric grade does indicate strength. The first number(s) are the tensile strength in 100s of MPa and the number after the period is the yield strength expressed as a percentage of the ultimate strength. 8.8 indicates 800 MPa uts and 640 MPa ys. The actual spec is 830/660 if you're splitting hairs. (120/96 in ksi).

SAE Grade 5 is 120 ksi uts, 92 ys up to 1 inch diameter and 105/81 from 1 inch to 1 1/2 inch.

ASEguy · Feb 3, 2023

That's what I use.

TheOldHokie · Feb 3, 2023

(quoted from post at 09:11:51 02/03/23) That's what I use.

You can insert special characters using the standard HTML escape sequence which is &# followed by the numeric ASCII code for the character followed by a ;. Just type it as a string with no embedded spaces and it will display the desired character. The ASCII code for quote is 34.

Displayed as:

"

TOH

showcrop · Feb 3, 2023

(quoted from post at 00:03:51 02/01/23)

(quoted from post at 22:11:16 01/31/23) Wore Out, how did you get quotation marks to work in your response?

Click to expand...

Quotation marks don't work with the outdated software here, but two apostrophes work to make a quotation mark.

Nothing wrong with the software here. Quotes work just fine in modern view. The problem is outdated old pharts insisting on using the old view.

Royse · Feb 5, 2023

Just wanted to follow up on this post. I found the original part
number and ordered a replacement. Not cheap, but they are
indeed M8x50 cl 6.8 bolts and the snowblower is back in service.
Thanks for the help!!

TheOldHokie · Feb 6, 2023

(quoted from post at 22:18:32 02/05/23) Just wanted to follow up on this post. I found the original part
number and ordered a replacement. Not cheap, but they are
indeed M8x50 cl 6.8 bolts and the snowblower is back in service.
Thanks for the help

A 5/16 x 2 grade 2 bolt is dirt cheap.

This post was edited by TheOldHokie on 02/06/2023 at 04:36 am.

Royse · Feb 6, 2023

(quoted from post at 08:26:09 02/06/23)

(quoted from post at 22:18:32 02/05/23) Just wanted to follow up on this post. I found the original part
number and ordered a replacement. Not cheap, but they are
indeed M8x50 cl 6.8 bolts and the snowblower is back in service.
Thanks for the help

Click to expand...

A 5/16 x 2 grade 2 bolt is dirt cheap.

This post was edited by TheOldHokie on 02/06/2023 at 04:36 am.

Agreed. And that would have worked fine. Except no local store had one so I was ordering online anyways.

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