1971 Coupe: Part Identification Help

[Ray K.]

Found this foam part in the back of a 1971 Coupe.
Have no idea what it is or where it's supposed to be located.
I couldn't find it in the 1971 AIM either . . . . .
It's solid foam and at it's widest and longest it measures about 8" long, 8" wide and 1" thick.
Anybody have a clue?
Ray K (#43777)

'71 Vette - Foam Part TBD - 14Apr25.jpg

[Patrick H.]

Found this foam part in the back of a 1971 Coupe.
Have no idea what it is or where it's supposed to be located.

Probably supposed to go where you found it.

It goes over the wheelwell and behind the pillar trim on each side, sort of lateral to where the shoulder belt reels are.
I'm at the office currently but can send you a picture later tonight if no one else puts one up.

[Owen L.]

I think it's in an AIM unusual location, at least for the '72 AIM. It sits on top of the carpet, so that's where I'd expect to find it called out, but nope:

Screenshot 2025-04-14 at 2.07.38 PM.png

[Ray K.]

Pat & Owen,
Thanks a bunch,
Before my post I looked thru my AIM, primarily in UPC 1 (carpet and rear trim) and couldn't find it either!
Never thought it would be in UPC 1 the bolt weld section!!!

Need your help in figuring out how it "sits on top of the carpet" though.
Can either one of you post a picture of it in its correct location?
And, is this pad supposed to be on both sides of the car?
Ray K

[John S.]

Ray, here’s a couple shots of the foam pads installed on my ‘73, placed on top of the carpet and on both sides just behind and above the seat belt reels. Hope this helps.

97043BF6-9BD4-42A5-8870-99771E349FCA.jpg B3433712-D586-4A49-915A-A974BDE2AD44.jpg

[Ray K.]

John,
Your pictures are great. Thanks for posting.
Very interesting to see the pads in their locations.
It makes me wonder what purpose they actually served.
I also tried to find them in the 1970-1972 Technical Information and Judging Manual and couldn't find any mention of them in there.
Hopefully someone can chime in . . . . . .
Ray K

[Owen L.]

John,
Your pictures are great. Thanks for posting.
Very interesting to see the pads in their locations.
It makes me wonder what purpose they actually served.
I also tried to find them in the 1970-1972 Technical Information and Judging Manual and couldn't find any mention of them in there.
Hopefully someone can chime in . . . . . .
Ray K

Agreed, those are very good pics of the foam pads.

I've no clue what they are supposed to do - they just sort of seem to be stuck there with no obvious purpose. Convertibles have them too, just a different shape. Right behind where they sit are the rear vent drain tubes...

[Terry M.]

John,
Your pictures are great. Thanks for posting.
Very interesting to see the pads in their locations.
It makes me wonder what purpose they actually served.
I also tried to find them in the 1970-1972 Technical Information and Judging Manual and couldn't find any mention of them in there.
Hopefully someone can chime in . . . . . .
Ray K

RAy

I am not sure which edition of the 1970-72 TIM&JG you are looking at, but for the 6th Edition see page 19, Figure I 2.13.

As for the reason: just a WAG, but sound deadening might be the reason. I agree that is a stretch given the other ways the early C3s are primitive - especially as compared what we are used to today in C8s.

[Ray K.]

Terry,
I have the 6th edition, same as yours.
Figure I 2.13 is a convertible says it’s a styrofoam part not a foam part like the coupe. Which begs the question of foam on the coupes and styrofoam on the convertibles? Or was there a change in material sometime (without changing the part number)???

Agree that these parts are strange. It would interesting to see how many are still in the rear compartments…….
Ray K

[Terry M.]

Ray
I believe Styrofoam is a miss-statement. I think either coupe or convertible are the same kind of foam -- even if different shapes. I can tell you both coupes I have access to (1970 & 1971) are foam. My 1969 coupe is less accessible, but given the long term (maybe months) I'll check that one. I have less access to convertibles, but will put it on the list to check. Perhaps readers with early C3 convertibles can check the composition on the material in their cars.

[Ray K.]

Terry,
I went back and took another look at figure I 2.13 and to me that surely looks like a piece of "white" styrofoam.
Hopefully someone from the C3 Interior technical and/or judging team can chime in . . .

Also noticed that it seems that this part (GM# 3947939) is not being reproduced.
Ray K

'71 Vette - Foam Part - Figure I 2.13 -16Apr25.jpg

[Patrick H.]

Ray,

That's in the back corner of the rear compartment. Note the rear wall of the compartment and the hinge for the rear window tray.
The foam is in the front corners, as we've described previously and shown in pictures.
Two different locations and two different parts.

I've added a red arrow to the AIM drawing to show where the styrofoam would go on a convertible.

[Terry M.]

I was wrong on my earlier posts. I had to do some more digging. Everyone was on the right path until I threw a curve ball into the discussion. My apologies. I hope the following summarizes and clarifies the situation.

There are two different foam pieces on each side, as Patrick has pointed out. The red arrow in his post above points to where the white Styrofoam (shown in the TIM&JG) goes. The white Styrofoam piece goes back near the hinge for the rear window storage compartment. That white Styrofoam piece is not shown in that AIM drawing, but it goes about where Patrick has indicated.

John S, in post #5, shows where the gray flexible foam goes - just behind the shoulder harness reel -- the blue arrows in the AIM drawing that Owen posted in post #3, and Patrick reposted, point to that piece (#11 & #12 in the parts list).

We do not show the gray foam piece in the 1970-72 TIM&JG. We will have to add that to future editions.

[Ray K.]

Terry & Pat,
Thanks for your further clarification.
Do you know if the styrofoam part was used on the coupe also? If so, do you know what the dimension are?
Ray K

[Mark F.]

Styrofoam burns fairly well...and with toxic pyrolysis decomposition products when that happens...

Do you think GM would have put styrofoam inside the passenger compartment fuselage ?
and/or would DOT have allowed it as a safety issue ?