240Z Factory Original Undercoating??

[cygnusx1]

What's the real story on the cars and how they came from the factory? Did they come bare underneath, painted, primered, undercoated? Or did the dealers to the undercoating? What was the norm for a 240Z coming off the boat?

Thanks. I am spending a lot of time under my Z inspecting the bottom and I find no rust, thin undercoating, and a few spots where the undercoating scrapes off easily revealing shiny, bare sheet metal. Mostly in the tunnel where a bad trans seal allowed oil to soften the undercoating.

What was the norm if there was one?

Edited December 22, 2009 by cygnusx1

[zhead240]

my zed is painted body color in the wheel wells and front of the floor pans. the bottom of the floor pans could be painted too but there's to much grim on it to tell.

[esprist]

What's the real story on the cars and how they came from the factory? Did they come bare underneath, painted, primered, undercoated? Or did the dealers to the undercoating? What was the norm for a 240Z coming off the boat?

Thanks. I am spending a lot of time under my Z inspecting the bottom and I find no rust, thin undercoating, and a few spots where the undercoating scrapes off easily revealing shiny, bare sheet metal. Mostly in the tunnel where a bad trans seal allowed oil to soften the undercoating.

What was the norm if there was one?

Many cars that were shipped to East Coast had black under coating.

Many others for West coast did not receive any.

Here is one from Wast coast. I hope this will help you little.

[d240zx2]

My Z was received at the Port of Houston in late March/early April of '70. It has no undercoating, just paint with 40 years of road grit embedded. I tried a power washer to clean it off.... didn't even give me a glimmer of hope....

Frank

[JohnnyO]

I recently stripped my car to bare metal. What I found under the floor pans and in the wheel wells was that it had a coat of thin black undercoating but it looked more like black paint. On top of that was zinc oxide primer then light grey surfacer then the finish coat of 920 applied kind of thin but enough to hold up for 39 years.

I asked this question a while back in a paint thread I started and I think I received a reply confirming what I had found and that it was typical.

Hope that helps.

[Mike B]

Many cars that were shipped to East Coast had black under coating.

Many others for West coast did not receive any.

Here is one from Wast coast. I hope this will help you little.

Are you talking about factory undercoating or additional undercoating applied by dealers? I wouldn't doubt that many dealers in rust prone areas added additional undercoating, as much for additional profit as for any protection it provided, but I have never heard of the factory undercoating cars differently based on which coast they would be sold on. I doubt it was even known which coast the cars would be sold on when they were on the production line.

Based on what Terry Vollnogle relayed from Carl Beck, the only difference was that very early cars (1969 and early 1970 production) only had undercoating (which was then covered with paint) in the wheel wells, while later cars also had undercoating (also covered with paint) on underside of the floors, etc. http://www.classiczcars.com/forums/showpost.php?p=303027&postcount=19

This is consistent with what I have found on my three 1969 production cars and my 5/72 car.

-Mike

Edited December 23, 2009 by Mike B

[26th-Z]

I can pretty much confirm what you said, Mike, as well as the reference going back to Carl. We had this discussion a long time ago when it was believed that all undercoating was applied after arrival in the States. The description from Carl and Terry is fairly accurate, showing a rippled texture to a thick paint finish throughout the rear wheel wells and rear deck extending into the transmission tunnel. I have no evidence of the front fenders receiving this treatment; just the front wheel well area of the chassis indicating that this surface was applied prior to application of any mechanical and body components. I think the splash shield in the right rear wheel well is discussed accurately also. No texture, just paint with painted screws. I would not describe the paint finish as "overspray" though. I find a thorough spray applied finish. I have an example of an early car in silver and the paint finish underneath does not contain the metalic luster of the upper body surface. It is simply the grey pigment.

I suspect that the "undercoating" finish was applied at the same time the body seam sealant was applied. The paint finish is obviouosly spray applied and I have noticed thin or non-existant spots underneath the cowl, top, and inside the rear quarter panels. Ther is also a bare strip on the post that braces the rear valance at the center of the car. My cars show no evidence of paint inside the constructed body sections. It seems to be all bare metal in there.

[geezer]

I found the underbody treatment to be the same as typically found on most vehicles of this era. It wasn't until the late '70s that E-coat systems came into widespread use. With an E-coat process, the vehicle would be submerged or partially submerged into the coating and the positively charged current would force coverage inside and out, including any voids or unseen areas. As Chris noted, these cars "show no evidence of paint inside the constructed body sections".

I have taken an interest in the processes used in the production of these cars. I have noted the need to transfer the shells from the metal line carts/carriers to the carts used specifically in the paint shop. This was the opportune time for the coating to be applied, after being lifted off the metal shop cart, but before being set down on the cart that would travel through paint. Separate carts had to be used for many reasons, contamination prevention of the paint being the foremost concern. Even the wheel grease used on a cart could be ruinous to the paint finish when exposed & dispersed by the high temp ovens.

It does appear to be different than the exterior finish paint. When I was stripping this material off the bottom of my car I asked myself several times, "why take it all off?"

It was still well adhered and still protecting the surface. My cars color being silver, had a distinct metalic finish but not so on the underbody. Another thing that is a mystery to me is the composition of the undercoat & paint. I have not been able to determine if what appears to be a heavier black base coat under the silver paint is actually the same coat. Many paint formulations had the characteristic of the color rising to the surface after being sprayed, not like an acrylic that would be color consistant throughout the thickness of the layer. I just couldn't find any evidence of the heavy black undercoat and the silver top coat being sprayed seperately.

Here's a pic of the original coating I found while cleaning off the years of accumulated crud under my Z.

This second pic shows the rear valance reinforcing strip that is void of paint on every S30, that Chris mentioned. I originally thought that was caused by the grounding clamp being attached at this point while in the paint system. I now think it was simply from the placement of a temporary upright support, used to hold the rear hatch open during the painting process.

Edited December 23, 2009 by geezer
spelling

[esprist]

Are you talking about factory undercoating or additional undercoating applied by dealers? I wouldn't doubt that many dealers in rust prone areas added additional undercoating, as much for additional profit as for any protection it provided, but I have never heard of the factory undercoating cars differently based on which coast they would be sold on. I doubt it was even known which coast the cars would be sold on when they were on the production line.

Based on what Terry Vollnogle relayed from Carl Beck, the only difference was that very early cars (1969 and early 1970 production) only had undercoating (which was then covered with paint) in the wheel wells, while later cars also had undercoating (also covered with paint) on underside of the floors, etc. http://www.classiczcars.com/forums/showpost.php?p=303027&postcount=19

This is consistent with what I have found on my three 1969 production cars and my 5/72 car.

-Mike

So the black spray undercoating was applied by US dealers?

I did not know that!

[JohnnyO]

Based on what Terry Vollnogle relayed from Carl Beck, the only difference was that very early cars (1969 and early 1970 production) only had undercoating (which was then covered with paint) in the wheel wells, while later cars also had undercoating (also covered with paint) on underside of the floors, etc. http://www.classiczcars.com/forums/showpost.php?p=303027&postcount=19

This is consistent with what I have found on my three 1969 production cars and my 5/72 car.

-Mike

Yes, that is exactly what I found. I also confirmed this with Carl and Terry. #1366 had black between the steel and paint in the wheel wells, but not the floor boards.

John