Grade 5 Nuts and Washers?

[Rob M.]

When Grade 5 bolts are specified on a C2, did Chevy always use Grade 5 nuts, plain washers and lock washers with those Grade 5 bolts? Same for Grade 8 bolts? Thanks!

[David B.]

Re: Grade 5 Nuts and Washers?

A short version (answer) to your question.
GM Engineering Standards specifies:
1. "GM 286- M steel: Nuts of this material are intended primarily
for assembly with bolts conforming to GM 280-M steel, or bolts of lesser strength".
2 "GM 301-M steel: Nuts of this material are intended primarily
for assembly with bolts conforming to GM 290-M or GM 300-M steel".
3. "GM 456-M corrosion resistant steel: Nuts of this material are intended primarily
for assembly with bolts conforming to GM 455-M".
Since all fasteners (nuts,bolts,washers) have a part number their material make up can be verified.

[Rob M.]

Re: Grade 5 Nuts and Washers?

Thanks for responding. These are probably dumb questions, but here goes:
1. Is there an easy way to translate part numbers from my Assembly Manual into their material make up (GM 286-M, etc.)?
2. Is there an easy reference guide to what Grade steel the various material make up designations correspond to (for example, does GM 280-M steel mean Grade 5)?
Appreciate the help!

[Michael G.]

Re: Grade 5 Nuts and Washers?

1. No. You need the GM drawing of the fastener
2. GM 260-M = Grade 2
GM 280-M - Grade 5
GM 300-M = Grade 8

Search for any of those on google and you'll find all the info you need.

[Rob M.]

Re: Grade 5 Nuts and Washers?

Thanks Mike!