Factory undercoating?

[Steve F.]

I have been cleaning the underneath of my 70 (thank God for the lift) and have been pleased with what I am finding under the dirt and grime. Frame still has a fair amount of the paint and all of the metal is either clean or surface rust only.
When I was working on the front section there seems to be a layer of a built up coating on the back side of the inner fender well - where the tire would spin stuff up from the road. The top area has less and the front has none. When I started to scrape at it I can see that it isn't just a dirt accumulation but it looks like something was applied. What has me wondering is that it is only on the back side and I thought if Bubba had done it he would have put a thick coating on the whole area. It also looks like it would offer some slight protection from small rocks flying off from the wheel.

Question - did GM put any type of coating in the area behind the front wheel in the inner fender or should it be clean fiberglass/plastic like the top and front?

[Edward J.]

Re: Factory undercoating?

Steve,The factory did put a heavy type undercoating in a few areas in the wheel wells front and rear. generally behind the wheels front and rear a some at the tops of the wheel opening, if the car has shoulder harnesses they coated the re-inforcement plates that are at the mounted under the rear wheels. Its was not a full coverage. I would leave whats left there, as its hard to duplicate. just clean with soap and water.

[Patrick H.]

Re: Factory undercoating?

Here you go - factory undercoating on my 72:

184154.jpg

[Steve F.]

Re: Factory undercoating?

Thanks, that's what it looks like. Fortunately I didn't take much off before stopping. I will just clean it up as suggested.

[Monte M.]

Re: Factory undercoating?

Ed and Patrick,
A few months ago I pulled my 72 out of the storage she has been in for the past seven years. I was working on another project. I was reading this thread and thinking about how much undercoating my car has.
It is in the fender well, but it also covers the spare tire carrier, the back of the rear spring and a number of other places.
Even where there is no coating the car barely even has surface rust on it.

My question is: Have you seen many other cars with this much undercoating, or do you think this was something done after it left the factory.
had followed the ownership back to the original owner, but he passed away a few years ago. The other owner know nothing about it.
The reason I question this is, the car was originally sold in Utah. A place that might put extra undercoating on, but then the owner moved out here to California in 1974.
Any input or thoughts might help.
Thanks,
Monte

[Edward J.]

Re: Factory undercoating?

Monte, all the cars I have seen the undercoating was a sprit here and a sprit there. no two cars got the same coverage. I believe that the spring was not on the car at the time of the undercoating. Patrick will surely know for sure.

I can tell you that my 72 has most of its factory undercoating left with a few exceptions of the front wheel area. The areas that were covered were-
Above the wheel wells front and rear, directly behind the front and rear wheels, and If your car has shoulder harnesses, The retainer plates on the inner wheel house left and right sides were coated, and sometimes when they coated those plates it will extend to the battery box area and storage compartment area. and thats about it. The coating was very thick and is hard to duplicate.

I have not noted any undercoating on the spare tire carrier before (I don't think the body was mated to the frame at the time of undercoating) , I do know that when the car were blacked out there was sometimes minor overspray on the carrier.

[Steve F.]

Re: Factory undercoating?

I was thinking the undercoating was more to protect from debri off the tires as there is nothing to rust at least where it is located on my car. If it was for rust I would think they would do the rocker channels and body mount areas before applying it to fiberglass?

[Monte M.]

Re: Factory undercoating?

Thanks for getting back to me. From the old days of Corvettes when I was a kid, when I bought my first Corvette, I was 23. It was a 350/ 350, 4-speed, A/C car. The guy I bought it from had owned a number of Corvettes before the 69 he was selling me.

He explained the reason the undercoating was there was to prevent the rocks from flying up and chipping the paint from the inside.
Over the years I have seen a number of cars with those up-chips, and for the most part, they were cars with the undercoating removed.

I am going to have to get my car up on a hoist and take a better look. I have no plans on restoring the car. Partually because it is so original, but I also have my 63 to finish.

But, I sure would like to take the spare tire carrier out and clean it up. It is not too hard to get off, thank goodness. A heat gun with a plastic scraper, then a plastic bristle brush, then a little solvent on a paper towel takes it off pretty easily.

Maybe clean it up enough so it looks good from behind?

Thanks,

[Edward J.]

Re: Factory undercoating?

Steve, you are correct it is for debis protection when its on the fiberglass. I guess GM never thought about protecting the metal parts, who would have ever figured these cars would be around as long as they have.

[Kurt G.]

Re: Factory undercoating?

When I bought my '72 coupe 7 years ago I found out the original owner of this Chicago area car had it under coated to protect the metal parts. Last year I spent over 40 hours under the car and 6 cans of undergone getting it all off, except for the stuff behind the tires in the wheel wells. The only good thing is I found lots of chalk and crayon markings that were protected by the undercoating. If its not in the wheel wells, it doesn't belong on the car, and that includes the spare tub, springs, etc.

[Paul J.]

Re: Factory undercoating?

When I bought my '72 coupe 7 years ago I found out the original owner of this Chicago area car had it under coated to protect the metal parts. Last year I spent over 40 hours under the car and 6 cans of undergone getting it all off, except for the stuff behind the tires in the wheel wells. The only good thing is I found lots of chalk and crayon markings that were protected by the undercoating. If its not in the wheel wells, it doesn't belong on the car, and that includes the spare tub, springs, etc.

All of you may remember that undercoating was a big deal in the 60's and 70's and was offered both by dealers and aftermarket suppliers. It was ADP (Additional Dealer Profit) to the dealers and I've seen several cars with this. If you think that all dealers would'nt make the mistake of undercoating a fiberglass body, I can tell you about the Toronado that the dealer put snow tires on the rear wheels.

[Edward J.]

Re: Factory undercoating?

All of you may remember that undercoating was a big deal in the 60's and 70's and was offered both by dealers and aftermarket suppliers. It was ADP (Additional Dealer Profit) to the dealers and I've seen several cars with this. If you think that all dealers would'nt make the mistake of undercoating a fiberglass body, I can tell you about the Toronado that the dealer put snow tires on the rear wheels.

I worked for a Chevrolet dealer for a lot of years 70's 80's and must say we undercoated quite a few cars here in the Northeast, corvettes also and basicly it was done from top to bottom, inc.s Corvettes fiberglass floors, metal floors came along later. When the cust. looked under the car they wanted to be sure there was full coverage.

[Ron G.]

Re: Factory undercoating?

Steve,

Just an FYI - I replied to a post regarding undercoating that included when it was applied, where it was applied, and who was the supplier of the undercoating itself. It was a couple of months ago. Perhaps Patrick can tell you what post it was and how far back it was. It was a lot of info. Thanks - Ron

[Patrick H.]

Re: Factory undercoating?

Steve,

Just an FYI - I replied to a post regarding undercoating that included when it was applied, where it was applied, and who was the supplier of the undercoating itself. It was a couple of months ago. Perhaps Patrick can tell you what post it was and how far back it was. It was a lot of info. Thanks - Ron

This one?

https://www.forums.ncrs.org/showthre...441#post620441

[Monte M.]

Re: Factory undercoating?

Kurt,

Is "undergone" a real product. The reason I ask is you say that whatever you were using even left the chalk marks.

My car has undercoating on the frame rails and the whole rear section. Most of the floor panel area do not have any undercoating at all. This should help a bit in getting it off.

My intent was to use solvent as I have in the past. It does a pretty good job without removing paint or much else. My guess is it would mess up the chalk marks a bit.