Which bolts are stronger. Grade 8.8 or stainless?

According to a site I just Googled for:

"Stainless components have a strength typically 87.5% of the same size fixing of grade 8.8 steel"

What usage are you planning for these bolts? In *many* applications, 8.8 metric bolts (or Stainless, even at 87.5% of 8.8) are more than sufficient. A lot of the bolts (hex head capscrews) that I've pulled and retained from the previous two 240Z's that I owned are graded "7" or lower.

FWIW, according to www.lawsonproducts.com which is where I buy my metric fastners, since they offer most of them (non stainless anyway) in the proper (for Nissan) even mm wrench size:

An 8.8 hex capscrew in size M8 X 1.25 X 25mm has a rating of 830 MPa (120,000 PSI) minimum ultimate tensile strength.

An "A2 Stainless" Metric Capscrew in the same size has a rating of Minimum tensile strength 689.5 MPa (80,000 PSI)

An "A4 Stainless" Metric Capscrew in the same size has a rating of Tensile strength 700 MPa (101,000 PSI)

I'm not sure stainless is really a grade of bolt.

An excellent book on this topic is Carroll Smith's "Nuts, Bolts, Fastners and Plumbing Handbook".

Originally posted by Mark Schue

I'm not sure stainless is really a grade of bolt.

An excellent book on this topic is Carroll Smith's "Nuts, Bolts, Fastners and Plumbing Handbook".

Right, "Stainless" isn't a "grade" of bolt. It describes in general terms the material the bolt is made of. There are different grades of Stainless Steel used to make bolts, hence the A2 and A4 variants of bolts made of Stainless steel that are sold (in the case of my post, by Lawson ).

All of Carroll Smith's books are great resources to have and refer to. He was one helluva smart man. Sadly, he passed away recently.

I'm looking to replace the old rusty bolts in the suspension components. For example; the T/C rod to A arm bolts, crossmember to frame, steering rack to crossmember, and so on. For these high stress areas I want to use a high grade bolt that won't rust over time. Either I can replace with OEM type bolts that are plated or stainless. I'm sure that new plated ones could last another 30 years but, I was thinking about stainless in certain areas.

For the uses that you mentioned, *FOR ME*, I'd stick with new 8.8 rather than Stainless, but that is just one persons opinion.

Thanks Carl, by the way what are you doing up so early? 4am 4u

Originally posted by Ed

Thanks Carl, by the way what are you doing up so early? 4am 4u

Ed: I don't sleep so good. (for long time periods anyway) About 4 hours max and I wake up. Just checked email and the site, watched a bit of TV, now going back to sleep for a few more hours. Talk to you later!

Carl

Thanks Michael, I went shopping around today, looking for either stainless or yellow zinc metric, boy they are hard to find. I think I'm gonna give Chloe a jingle. Can you post her number?

Oh, one more thing, I purchased the two front control arm to crossmember bolts from Victoria B. and I got the right size bolt but the coating on it is black. Is this black oxide or something?

Here ya go Ed