Alternator brace GM #3881816: where are the two bends to create the offset?

[David L.]

Re: Alternator brace GM #3881816: where are the two bends to create the offset?

Gary,
The bend at about 1 1/4" more or less is somewhat obvious but the bend at 7 1/2" more or less is hardly noticeable. I used a 24" aluminum 2" wide ruler to determine the bent points and they are very approximate. The thinkness of my 3881816 brace and my 3884640 brace measures 0.21". I believe that the 3884640 brace on my 1966 has the "B" stamping. When I get a chance I will check and measure the thickness as well.
Dave

[Gary B.]

[Gary B.]

Re: Alternator brace GM #3881816: where are the two bends to create the offset?

Gary,
The bend at about 1 1/4" more or less is somewhat obvious but the bend at 7 1/2" more or less is hardly noticeable. I used a 24" aluminum 2" wide ruler to determine the bent points and they are very approximate. The thinkness of my 3881816 brace and my 3884640 brace measures 0.21". I believe that the 3884640 brace on my 1966 has the "B" stamping. When I get a chance I will check and measure the thickness as well.
Dave

[David L.]

Re: Alternator brace GM #3881816: where are the two bends to create the offset?

Gary,
When I lay the 3881816 brace on a flat table and push down hard on the curved slotted area the end with the hole lifts up. I measured the offset at about 0.24"+/-.
When I lay the 3884640 brace on a flat table and push down on hard the curved slotted area the end with the hole lifts up. I measured the offset at about 0.34"+/-.
Why didn't I think of measuring the offset this way...........maybe just old age.
I would assume the offset must be different because they use different alternator pulleys.
Dave

[Gary B.]

[David L.]

Re: Alternator brace GM #3881816: where are the two bends to create the offset?

Gary,
My 1966 & 1967 Chevrolet Parts Catalogs in Gr. 2.317 list 17/64" (0.265") as the offset for both the 3881816 & 3884640 braces. I guess my 0.24" and 0.34" offset measurements using a flat table top were a bit off but were at least in the "ball park" (maybe Fenway Park).

As per Chevrolet & GM Parts History (for service parts):
GM # 3881816 was replaced in 1975 +/- by GM # 361491 (offset unknown) which was then replaced in Sept. 1977 by GM # 460754 (2" offset).
GM # 3884640 was replaced in Dec. 1971 by GM # 3826928 {63-65 PASS. (409), 1 3/16" offset}.
My 1979 & 1981 Corvette Parts Catalogs (June 1979 & Nov. 1981) in Gr. 2.317 has the following note:
"Original equipment braces may be replaced by service braces which will require drilling of attaching hole and forming."
Dave

[Gary B.]

Re: Alternator brace GM #3881816: where are the two bends to create the offset?

[David L.]

Re: Alternator brace GM #3881816: where are the two bends to create the offset?

Gary,
I have a NOS 3868882 brace (as well as a used one) for 1965 Corvettes {(P/S w/Sp. H/Per. w/hyd. lifters)(327)(exc. C.A.C.)} that actually has "very slightly indented straight lines" which are barely visible where the bends were made. My measurements of the brace agree very closely with those shown in my 1965 Chevrolet Parts Catalog.

NOTE: This 3868882 brace is almost identical to the 1963 Corvette brace with the stamped letter "V", GM # 3825462, which is the same shape, variable width, and thickness except that the 3825462 brace is about 3/8" shorter in length.
Dave

[Don H.]

Re: Alternator brace GM #3881816: where are the two bends to create the offset?

I can see those tiny barely visible straight lines in Gary's photo of his brace in post #6

the brace on my 64 pretty clearly has a couple bends in it. And has the B.

fullsizeoutput_224e.jpg

fullsizeoutput_224c.jpg

[Gary B.]

[Don H.]

Re: Alternator brace GM #3881816: where are the two bends to create the offset?

tiny marks are out on the edges about 1/2" below the B

[Gary B.]

Re: Alternator brace GM #3881816: where are the two bends to create the offset?

Don,

Yup. I see them now.

Gary