Rear Floor and Cross member Coating/Painting Discussion

[J_Speegle]

Rather than add this response to another thread on a somewhat related but different focus I thought I would respond to a question asked there in this new thread out of respect for the OP in the other

Original thread - https://www.saacforum.com/index.php?topic=21640.30

Now the question

Jeff, I should have asked a question of you when I posted. I posted pics of my friends original boss9. That "purple" color can be seen pretty much front to back underneath in my pics. My question is would that "purple" also transcend up to the rear cross panel since it is on the vertical trunk drop offs? If so would a car that had a black underside(batch) possibly also have that black up to some degree behind the rear valance? ............................

Will try and keep this short since the thread focus is a bit different. Remember that the jets applying were attached below the moving unibody so as far as we know they did not tilt or move during the application. This would have limited access or at least reduced it in some areas, pockets and cavities. Also, would depend on how the triggers for this application were adjust that day. Were they adjusted to stop before the rear cross member or later. Possibly creating issues with  application of the color onto the following body. Application and the process was not perfect so we find examples with little, light or no paint in the rear pockets while in other cases better coverage And of course if the spray was directed at an angle or straight upward  that would affect what we're seeing today also.  So yes, in some cases I've documented some cars with some spray, from below on the bottom edge (horizontal) of the rear cross member while others light if it was there originally. But it would likely only have a little if any overspray form this application on the vertical rear facing surface of that cross member of the floor color. This is possibly the reason they galvanized this piece also since a fair amount might be exposed with no coating.

As far as "behind the rear valance" that was not on the car when the floor color was being applied the above description should address that for this discussion


Here are two extremes First one where the jets were adjusted to stop well before the spray reached the rear of the floor and cross member. Bare metal for maybe the last 10 inches or more. Floor and rear frame rails were treated differently so that is the reason one likely developed surface rust while the other remained fairly fresh looking surface though the surface details have altered since new

This car had the typical dark grey/blueish floor color application. Exterior color a blue.




And a second where the jets appear to spray at a slight reward angle so they reached into the rear cross member pockets so they almost reached the interior/frotn surface of the rear cross member. Notice the arrows and bare metal surfaces. This angle would insure that no paint from this application would get on the vertical surface of the rear of the cross member. This example used the red oxide colored epoxy primer sealer  floor color. Exterior color was a green



The two pictures above are from different years and plants but used to illustrate the range of possibilities and the day to day practices. Allot of unrestored cars don't look this clean nor are the details as clear as these two and for that reason they were chosen for this purpose. Top picture is of a 69 while the lower is a 68 if your wondering

[shelbymann1970]

Thanks as always Jeff. I'm sure you have seen this pic but I'll post it again for some who may not. My vert on May 6th at Dearborn they had a clogged sprayer as you can see. In the first pic you see paint running into a bare metal spot. Notice the factory candy apple red on the floor ribs also.
The second pic the 69 B9 April built  shows what you are saying about a lack of paint at the rear from the sprayers. I wonder how the trunk drop offs have the "purple" paint  but the frame rail appears to have the factory black jade paint on it. Car was a S&C car until a collector got a hold of it. My friend bought it in 1996 out of Mn. Ed Meyer will confirm how original this car is. The rear valance seems to have been repainted buy my friend actually bought an original paint rear valance for it from Ed. Funny in that he has an original paint 67 Corvette with added side pipes.  Someone changed out the rear valance to a side pipe car valance. At a local swap meet he finds a rear valance with original paint  with exhaust cutouts for his car. Buys it and brings it home. Matches perfectly to his paint. Pretty sure that was the valance that came off of his car which never left our area from new. What are the odds? Lyndale blue metallic paint. Last pic the B9 and 67 Vette together.

[J_Speegle]

Thanks as always Jeff. I'm sure you have seen this pic but I'll post it again for some who may not. My vert on May 6th at Dearborn they had a clogged sprayer as you can see. In the first pic you see paint running into a bare metal spot. Notice the factory candy apple red on the floor ribs also.
The second pic the 69 B9 April built  shows what you are saying about a lack of paint at the rear from the sprayers. I wonder how the trunk drop offs have the "purple" paint  but the frame rail appears to have the factory black jade paint on it.

Pretty simple - we see this all the time and notice you will see some of this on the examples I posted.  At the rearward area the body color, after the the floor (including the trunk drop offs) was coated and rear valance was added the body color overspray and direct spray could be introduced into this area in the gap between the rear valance (left hanging) and the back lower end of the  quarter panel, through the back up lights but the angle often just created paint in a localized spot on the rear frame cross member and or from painting the lower edge and pinch weld on the lower edge of the quarter panels. This is common on all years and plants just depended on how tall or short, older or younger, making more effort to bend lower or not of the painter that was painting the exterior of the particular car

Car was a S&C car until a collector got a hold of it. My friend bought it in 1996 out of Mn. Ed Meyer will confirm how original this car is. The rear valance seems to have been repainted buy my friend actually bought an original paint rear valance for it from Ed. Funny in that he has an original paint 67 Corvette with added side pipes.  Someone changed out the rear valance to a side pipe car valance. At a local swap meet he finds a rear valance with original paint  with exhaust cutouts for his car. Buys it and brings it home. Matches perfectly to his paint. Pretty sure that was the valance that came off of his car which never left our area from new. What are the odds? Lyndale blue metallic paint. Last pic the B9 and 67 Vette together.

[J_Speegle]

A few examples to illustrate what I was referring to above and in relationship on the introduction of body color, applied over undercarriage color, in the area of the rear frame rail behind the wheel well

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[shelbymann1970]

Thanks Jeff for posting those great pics.