Topic: undercarriage should be bare metal at backend

[carm]

I have heard that the backend of the undercarriage remained bear metal as the application of primer stopped about two inches from back edge of the car. I guess they didn't want to have the primer spraying freely into the shop floor once it reached the back of the car.
 But does anyone have any pictures of this end result and can anybody tell me more specifically where do I measure those two inches from?
Thanks for your help, Carmine.

[bullitt68]

I have heard that the backend of the undercarriage remained bear metal as the application of primer stopped about two inches from back edge of the car. I guess they didn't want to have the primer spraying freely into the shop floor once it reached the back of the car.
 But does anyone have any pictures of this end result and can anybody tell me more specifically where do I measure those two inches from?
Thanks for your help, Carmine.

Hi Carmen not sure what year car you have or where it was built. This makes a difference as there were 3 different plants. FYI my San Jose 1968 car is original paint underneath and the primer goes all the way to the back of the car with no bare metal showing. I have not hear that before, but I am sure that someone can comment factually to that point

[carm]

Good morning and thank-you for your response. My car is an  April 69 built Dearborn car.
I'm pretty sure about this 2" as I have heard about this before on CMF. I just needed more specific instructions on this detail and pictures say more than....

It's interesting to find that your San Jose 68 car is primered all the way to the back. It was news to me too, when I found out about this 2" from the back detail. (all this detail, where do these guys get this stuff.) But in my head I was thinking that we would have the primer jets start 2" form the back and stop  underneath the front of the firewall and then no more. Why then did I find traces of the same primer underneath the front clip apron lips practically past the shock towers. (I have posted a picture)
Then I found another another blog where someone (much more knowledgeable than myself, and it makes more sense) mentions that the cars advance forwards on the assembly line. So I deducted that the primer jets don't stop completely or may be leaking at the time or they start up a second before reaching the firewall and left those trace of primer on the front clip. Then they spray the cars undercarriage and finally shut off just before reaching the back end of the car.

What do you think? 




 

[J_Speegle]

I have heard that the backend of the undercarriage remained bear metal as the application of primer stopped about two inches from back edge of the car. I guess they didn't want to have the primer spraying freely into the shop floor once it reached the back of the car.
 But does anyone have any pictures of this end result and can anybody tell me more specifically where do I measure those two inches from?
Thanks for your help, Carmine.

Yes have described that many times here and on other forums. Since the spraying was automated and any paint reaching past the rear edge of the undercarriage would rain down on the following car the jets were suppose to stop spraying before that.  Sure the measurement was not exact as the triggering mechanism was fairly primitive, no laser or motion detectors applied back then for this purpose.  And since its a spray the edge would not be a sharp one but instead on the original car, a soft one as the overspray would have been produced along the end of the spray.

The rear cross member was galvanized so it not getting completely spray was not a big deal in the short run but the pockets formed way at the rear where the floor, rear frame rail and rear cross member came together made it difficult to get more than a thin coat, if that, in those pockets. Its fairly typical to see rust develop there on the surfaces on even the nicest of unrestored cars. Same thing can be seen, very very thin paint to almost nothing, along some vertical surfaces such as the sides of the frame rails on some original cars

[J_Speegle]

Good morning and thank-you for your response. My car is an  April 69 built Dearborn car.......

What do you think? 

On your example your looking at the front of the car where the primer layer would have been applied by human painters so your kind of comparing apples and oranges IMHO.

In those areas the lower facing surfaces didn't, sometimes, get allot of paint, if the painter didn't reach or direct the spray gun to cover that area well 

[carm]

I understand that the front clip was painted manually and that it should be painted in red oxide, but we could not find any evidence of any red oxide anywhere on this cars front end. Personally I would of preffered if it was red oxide. I think it would look better. The cars with the red oxide shock towers and red oxide undersides on the front clips often look like works of art in my opion. But unfortunately, mine is not red oxide.
Jeff, the places which I point to in the picture are not red oxide, they are exactly the same shade of slop as on the undercarriage.

My shock towers and underside front clip are black and show up blueish under a camera flash.

My undercarriage is painted with a pinkish slop primer. It is similar to the underside of Feb 69 Shelby convertable in the unrestored picture thread which you started. I will enclose a picture where we can clearly see the difference between the slop and this weird strip of red oxide that goes along the pinchweld. This red oxide is only along the passenger side. The driver side got a similar strip but in grey oxide, I don't know why.

[J_Speegle]

I understand that the front clip was painted manually and that it should be painted in red oxide, but we could not find any evidence of any red oxide anywhere on this cars front end. Personally I would of preffered if it was red oxide. I think it would look better. The cars with the red oxide shock towers and red oxide undersides on the front clips often look like works of art in my opion. But unfortunately, mine is not red oxide.
Jeff, the places which I point to in the picture are not red oxide, they are exactly the same shade of slop as on the undercarriage.

My undercarriage is painted with a pinkish slop primer..............................

OK let me try and confirm (get it right in my head) what I'm hearing from you.

In reply #2 the areas identified with the arrows in the first picture is not a rd oxide but a pinkish finish similar or same as what your finding on the floor pans?

In the second/lower picture the color of the paint/primer sealer under the fender lip of the inner fender panels is the same as the arrow surfaces?



As mentioned in prior threads and the article related to undercarriage finishes there were a couple of time periods in 69 at Dearborn when the plant painted the front wheel well areas first with the same or very similar paint as the floors as they would transition to in 70 production. Not sure why they switched back in forth any more than we understand why they switched between batch based or red oxide colored base for the floor (firewall rearward) section of the undercarriage.

[carm]

Yes and yes...

[J_Speegle]

Think that the pinkish color may be a red oxide epoxy primer sealer based batch color. really doesn't make much difference for us as we only need to reproduce what the final look was/should be

We see allot of the various versions of "red oxide" in earlier years of San Jose production as an example or as a comparison