general ike

Hello all cleaning up my 1972 and I have moved to the rear of the car. I have encountered the following:




So this is right in front of the rear end. Is this stuff 45 year old undercoating? It seems to be, it chips away in chunks. Or is it petrified 45 years of dirt?

I forget, didn't GM do some undercoating? If so where and to what extent? If this is undercoating is it most likely from the dealer?

What areas did GM undercoat (the wheel wells only) and what did the dealer typically undercoat?

Looking to restore the Vette as acurate as I can!!!! So any and all advise would be appreciated!!! Ike

doorgunner

I'm not sure about GM's policy with undercoating. I can tell you that in the late 70s/early 80s many people were having their vehicles undercoated because "it was the thing to do" at the time.

62corvette

Looks like your engine/tranny leaked a lot of oil that blew back and mixed with dirt.

general ike

Agreed Doorgunner and it was usually done poorly and sometimes involved drilling holes which just allowed the car to rust even more!!!!

I am pretty sure GM did some undercoating, I think more for sound proofing then anything else, but I don't know the extent. Ike

Hayes69

joewill

i think that stuff is what you said.. petrified/oily dirt. .is it on just that rear end, or everywhere?

gbvette62

GM did not undercoat cars. The exception was the wheel wells.

Undercoating was applied to the front wheel wells, from the mid point of the front inner skirts rearward, and on the rear ones from the mid point of the rear inner fender, forward. Once the undercoating was applied, all four wheel wells were shot with black out. The only area of the underside of the car, that might have undercoating on it, is the sides of the rear rear storage compartments, which sometimes got overspray on them, when the rear inner fenders were shot. Any other undercoating was either done by a dealer, or a previous owner.

Undercoating was a popular dealer installed option, or more accurately, dealer mark up item, from the 60's and 70's. It's still done today, but not so much by dealers anymore.

general ike

Thanks all I have a feeling it is all the above. There are locations of it in various places. Some, I assume had worn off completely and some partially, There was even a layer on the rear of the spare tire carrier. I thought it was dirt but when I realized that it was too hard to remove and a uniform layer that it most have been undercoating. Then I found it around the rear supports of the diff . It looks like most of it is gone but there are "pockets" of it in a few places. I wonder how difficult it is to remove?


I am glad they sprayed the spare tire carrier. Worked perfectly, not a spot of rust on it!!!!

Ike

gleninsandiego

Yep, I am convinced my car lived for years down a dirt road.
That also had standing water in it.
You wouldn't believe the coating my 69 had

Tom73

Chevy started using a tar like spray on in 73 for sound deading. The Vette was turning into a boulevard cruiser by then and they wanted to try and reduce road noise. It’s use in 73 was mostly in the wheel wells.

Tom...

Alan 71

Hi Ike,
I found that the coating of oily dirt can do a pretty nice job of protecting whatever parts it's on. It sort of depends when it was formed.
So it's not necessarily a bad thing!
Regards,
Alan

C376FL

gbvette62 I believe in 68 when I bought a new firebird I had it undercoated. If I remember wright it was around 75.00 to have it coated. It seemes that was the thing to do back then. My 76 has some undercoating under the rear wheel wells, I am sure one of the po had it done, not when it was new.

Alan 71

Hi,
I believe that typically the sound deadening applied in the rear wheel wells was from about the area of the shoulder belt mount re-inforcement REARWARD.
These are some photos from a quite low mileage and quite untouched 72.
It's NOT pretty!
Regards,
Alan

general ike

Thanks all. The dealer installed undercoating was usually a joke. As I stated they would sometimes drill holes to spray into, which would just let the car rust faster!!!!

I guess GM put the worst painter they had on the undercoating. I think there was alot of overspray. Good photos, as always, to help replicate it. Thanks Alan