Underbody Mounting Plate Finishes for AOS Bodies

[Gary B.]

Re: Underbody Mounting Plate Finishes for AOS Bodies

Bill,

Based on your photo I would have guessed that's a St. Louis body, not AOS. I thought the long, front seat reinforcements on AOS cars were unequivocally believed to be zinc chromate.

Gary

[Bill H.]

Re: Underbody Mounting Plate Finishes for AOS Bodies

Bill,

Based on your photo I would have guessed that's a St. Louis body, not AOS. I thought the long, front seat reinforcements on AOS cars were unequivocally believed to be zinc chromate.

Gary

Gary, I put this on another post because I felt the same about the chromate after doing a search.
thought it was interesting.
But they are black.
Sorry for the bsd pic of the plate, and the seat reinforcement:

[Bill H.]

Re: Underbody Mounting Plate Finishes for AOS Bodies

I did a little scraping on the seatbelt anchor. It's hard to see but the dark gray in the pic is plating. It won't come off with laquer thinner at all and there's bare metal underneath.

[Gary B.]

Re: Underbody Mounting Plate Finishes for AOS Bodies

Gary,

I have wondered about that photo each time I see it. That is either an exceptionally well-preserved underbody, or the photo is of a restoration in progress....

Scott,

I contacted John Hinckley about that photo and he checked his records and he said:

"... that photo ... was taken in October, 2005; don't recall where. Must have been a restoration, as the seat belt reinforcements are shown incorrectly - they should be zinc-plated. The rear seat plates should also be natural, and the zinc chromate on the sills is too dark."

In a follow-up e-mail John told me that the seat belt reinforcements came zinc plated from the supplier, so both AOS and SLT cars would be the same in terms of the seat belt reinforcements.

So, I guess I have to figure out how to get a poor quality zinc plating done for those reinforcement, since the consensus seems to be that the zinc plating was not showcase quality.

Gary

[Scott S.]

Re: Underbody Mounting Plate Finishes for AOS Bodies

Gary (and John),

This is great information, thank you for the follow-ups :thumbsup:

Together with all of the earlier posts, this is a very helpful Thread, multiple questions have been answered now

[Gene M.]

Re: Underbody Mounting Plate Finishes for AOS Bodies

It goes to show ya when obtaining information on restoring one's car it is important to rely on known original cars as ya look for original configuration. Seeing restored cars is only someone else's interpretation of how it was. It is sure nice to have guys that worked at the Corvette plant like John Hinkley and Mike Hanson to recall the way it was.

[Steve A.]

Re: Underbody Mounting Plate Finishes for AOS Bodies

Sorry to resurrect an old thread but perhaps better than creating a new thread. I am at the point of installing my underbody brackets on a 1965 STL coupe. When I removed my hardware it appeared that the long front brackets were black, the seat anchor plates were natural and the inner and outer corner re-enforcements for the seat belts were zinc plated (but very rusted) and no indication of black paint, which is consistent with this thread. However, the 1965 TIM/JG 5th edition only calls out that the seat anchors are natural. Will I get dinged for having the belt anchors as zinc instead of black?

[Gary B.]

Re: Underbody Mounting Plate Finishes for AOS Bodies

... Will I get dinged for having the belt anchors as zinc instead of black?

Steve,

I hope not, but one can't predict what a given set of judges will do. I'm in the same situation that you are, albeit in my case for my '66. I've removed my rusted underbody brackets and restored them and now I need to re-rivet them back on. For a STL car, some are clearly known to be black, like the long front seat bracket, some are clearly known to be natural, like the small rear seat brackets, some should be zinc like the seat belt brackets, and based on an assessment of the originals on my car, a few others should be painted black, specifically the shoulder harness brackets on the inside of the inner rear wheel well. My concern is the '66 TIM&JG is not very helpful about the finishes for some of these brackets, so I don't know what some judges will do given the lack of guidance in the '66 TIM&JG. But I'm going to prep mine to be consistent with what I think came on the car originally. That's the best I can do. And then I'll hope the judges will listen to me if they query me about a specific bracket.

Gary

[Gene M.]

Re: Underbody Mounting Plate Finishes for AOS Bodies

Sorry to resurrect an old thread but perhaps better than creating a new thread. I am at the point of installing my underbody brackets on a 1965 STL coupe. When I removed my hardware it appeared that the long front brackets were black, the seat anchor plates were natural and the inner and outer corner re-enforcements for the seat belts were zinc plated (but very rusted) and no indication of black paint, which is consistent with this thread. However, the 1965 TIM/JG 5th edition only calls out that the seat anchors are natural. Will I get dinged for having the belt anchors as zinc instead of black?

Steve,
If the 1965 TIM/JG 5th edition only calls out that the seat anchors as natural I believe this to be in error. The finish on these should be a real poor quality zinc. Definitely not black paint.

I believe the rear seat mount rectangle plates (4 pieces) are natural steel.

[Gary B.]

Re: Underbody Mounting Plate Finishes for AOS Bodies

Steve,
If the 1965 TIM/JG 5th edition only calls out that the seat anchors as natural I believe this to be in error. The finish on these should be a real poor quality zinc. Definitely not black paint.

I believe the rear seat mount rectangle plates (4 pieces) are natural steel.

Gene,

By seat anchors I was referring to the small (1.5"x3" or so) plates that are natural. I'm not sure what you mean by the finish on "these" being poor quality zinc.

Gary

[Gene M.]

Re: Underbody Mounting Plate Finishes for AOS Bodies

Gary,
Sorry I left out a word. It should read seat belt anchors. If the 1965 TIM/JG 5th edition only calls out that the seat BELT anchors as natural I believe this to be in error. The finish on these should be a real poor quality zinc.
I should proof read better. Sometimes it is easy to read what one's thinking rather than what one typed.

[Gary B.]

Re: Underbody Mounting Plate Finishes for AOS Bodies

Gene,

And what do you think about the body mount brackets riveted to the underbody on STL cars? Cheap zinc as well? I assume the answer is yes.

Gary

[Gene M.]

Re: Underbody Mounting Plate Finishes for AOS Bodies

Gene,

And what do you think about the body mount brackets riveted to the underbody on STL cars? Cheap zinc as well? I assume the answer is yes.

Gary

Gary,
I would say no. Examples taken off originally are mostly rust. But I have found black paint on the inside surfaces once separated from the fiberglass. But realistically the black out such as in the rear wheel well will cover up anything.

My guess is the 4 body mount brackets (two behind rear wheels, two at firewall) were supplied to St Louis and AO Smith all ready black. I've done a few AO Smith cars and have not discovered any green chromate finish on any of these four brackets. Hence my guess that these parts were delivered finished ready to assemble (rivet). But to be sure John Hinckley or Mike Hanson should chime in.

[John H.]

Re: Underbody Mounting Plate Finishes for AOS Bodies

Gary,
I would say no. Examples taken off originally are mostly rust. But I have found black paint on the inside surfaces once separated from the fiberglass. But realistically the black out such as in the rear wheel well will cover up anything.

My guess is the 4 body mount brackets (two behind rear wheels, two at firewall) were supplied to St Louis and AO Smith all ready black. I've done a few AO Smith cars and have not discovered any green chromate finish on any of these four brackets. Hence my guess that these parts were delivered finished ready to assemble (rivet). But to be sure John Hinckley or Mike Hanson should chime in.

Gene -

I'd agree with this assessment, but I'd also defer to Wayne Womble - he's seen more of these underbodies than I have. It should also be noted that it's been a LOOOOOONG time since the '65 TM&JG has been revised, and things have been learned since then.

[Wayne W.]

Re: Underbody Mounting Plate Finishes for AOS Bodies

I might not be much help on this one. Most I have worked on were mostly rust. The coatings were of such poor quality it`s gone. The rears were subject to black out and wouldn't show much green anyway.

I would think the bow-tie judges would have nailed that down by now.