1969 Frame Off Restoration
I am doing a frame off on a 1969 convertible. Getting ready to refinish the differential casing and have a question on the finish on the 8 bolts that attach the rear cover to the differential. I can not tell if the bolts are natural or blackened? Any information?Steve
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Re: 1969 Frame Off Restoration
Hi Steve,
The bolts on my 71 differential casing showed the remains of a dark finish.
Can't say if it was black oxide or manganese phosphate.
I redid them in the manganese phosphate.
The lock washers are quite thick compared to regular lock washers of that size and had a dark finish too.
Regards,
Alan71 Coupe, 350/270, 4 speed
Mason Dixon Chapter
Chapter Top Flight October 2011 -
Re: 1969 Frame Off Restoration
Thanks for the reply.SteveComment
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Re: 1969 Frame Off Restoration
Steve-------
The bolts, GM #3843384, were a phosphate-organic finish. These appear like a "slightly shiny" or "lightly oiled" finish. They appear slightly brown. It's a virtually impossible finish to re-create. However, if you use gray phosphate finished bolts, I don't think anyone will know the difference.In Appreciation of John HinckleyComment
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Re: 1969 Frame Off Restoration
All------
I can't edit the post now, but I was incorrect on the GM part number for the differential cover bolts. The 3843384 are the same thread size and length but they have a short, unthreaded shank and are SAE grade 8. The cover bolts are full thread and SAE grade 5. I believe that they were both of the same phosphate-organic finish, though.In Appreciation of John HinckleyComment
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