C1 rear spring front saddle bolts

[Al C.]

I've pulled my rear springs, and 8 of 8 subject bolts broke (rusted in). The Paragon catalog sells "grade 2", and Dr. Rebuild has "grade 300". I was under the impression that Corvettes only used high-grade hardware?
Should I use the grade 2 replacements from Paragon?
... Al '58 #378 245hp NCRS SACC

[Joe L.]

Re: C1 rear spring front saddle bolts

Al-----

I assume that the "grade 300" shown in the Dr. Rebuild catalog refers to GM 300-M grade bolts. This is equivalent to SAE grade 8 (6 lines). Those are the ones that I'd use.

[John H.]

Re: C1 rear spring front saddle bolts

My '57 has the original 8 bolts in those locations, and they are indeed plain heads with no marks; this is about the only application I've seen where less than a Grade 5 bolt was used. If you look at the design, however, there is virtually no stress on them - all the forces from the front eye of the spring are taken directly into the welded bracket on the frame, and the 4 bolts per side just keep the loose bracket for the front spring eye from falling out.

[James F.]

Re: C1 rear spring front saddle bolts-Al

Al,
I believe you'll find the lower two bolts longer than the upper two because of the added thickness of the lower support plate. Regards,