Motor mount to frame bolt size?

[RITTER]

I used standard 3/8" grade 8, 1" in length with flat washer on each side and the oblong lock nut.

Metric 10.9 is like a mid-grade bolt. The 12.9 is more of a Grade 8 equivalent

 

[81GrandPrix383]

I used standard 3/8" grade 8, 1" in length with flat washer on each side and the oblong lock nut.

Metric 10.9 is like a mid-grade bolt. The 12.9 is more of a Grade 8 equivalent

That sucks. I thought grade 10.9 would have been better than grade 8. (number is higher)

Thanks for the info.

 

[RITTER]

My bad, I just looked it up in my Rockford book here and it looks like 10.9 is equivalent to Grade 8 SAE

8.8 - 120,350
10.9 - 150,800
12.9 - 176,900

5 - 120,000
8 - 150,000

That is Min. Tensile, PSI

 

[81GrandPrix383]

My bad, I just looked it up in my Rockford book here and it looks like 10.9 is equivalent to Grade 8 SAE

8.8 - 120,350
10.9 - 150,800
12.9 - 176,900

5 - 120,000
8 - 150,000

That is Min. Tensile, PSI

Thanks RITTER, I'm happy with Grade 8.
I appreciate the follow up.
I may even call Part Source and let them know because no one there had a clue. .....Nah, nevermind.

 

[pontiacgp]

My bad, I just looked it up in my Rockford book here and it looks like 10.9 is equivalent to Grade 8 SAE

8.8 - 120,350
10.9 - 150,800
12.9 - 176,900

5 - 120,000
8 - 150,000

That is Min. Tensile, PSI

I think you were right the first time..

10.9 M5-M20 medium carbon steel, quenched and tempered

the grade 8 is a carbon alloy steel....

Grade 8
Medium Carbon Alloy Steel, Quenched and Tempered

the grade 5 is like the 10.9, a medium carbon steel...

Grade 5
Medium Carbon Steel, Quenched and Tempered


The bolts I used for the body mounts were also a 10.9 grade which I was told was equivalent to the grade 5 by the bolt retailer I bought them from.

 

[81GrandPrix383]

Ha Ha Ha, full circle.

 

[81GrandPrix383]

I just found this on the internet so it must be true. LOL.

Some details on conversion guidance between metric and inch based strength grades is given in section 3.4 of the standard SAE J1199 (Mechanical and Material Requirements for Metric Externally Threaded Steel Fasteners).

Metric fastener strength is denoted by a property class which is equivalent to a strength grade. Briefly:

Class 4.6 is approximately equivalent to SAE J429 Grade 1 and ASTM A307 Grade A

Class 5.8 is approximately equivalent to SAE J429 Grade 2

Class 8.8 is approximately equivalent to SAE J429 Grade 5 and ASTM A449

Class 9.8 is approximately 9% stronger than equivalent to SAE J429 Grade 5 and ASTM A449

Class 10.9 is approximately equivalent to SAE J429 Grade 8 and ASTM A354 Grade BD

For information there is no direct inch equivalent to the metric 12.9 property class.