68 under-body heat shield Installation

[Patrick N.]

Hi All,
I am at the stage of re-installing the under body fiberglass around toe kick panel and under body. My March 7th 68 is equipped with the fiberglass insulation, plastic toe-kick panels and the unique triangular shaped shields but no drill holes under the transmission cross brace or evidence of the having the square metal under body panels.

I have some questions with the installation process and components as my AIM has no information:

1. In the TIMJG service bulletin section it shows "C" shaped clips on the ends of the bent tabs labeled as "existing bracket" that are riveted to the under body fiberglass and which the plastic toe pan shield is fastened to. Are those clips just typical bent metal clip nuts?

2. Were all plastic toe pan shields "Pop Riveted" with washers to the fiberglass at the top RH & LH side? TSB shows washers on left side only.

3. I assume battery cable is installed under the tunnel insulation- correct? AIM shows cable installation later in the book and neither procedures reference the other component location.

3. Is there any benefit to adding the square metal panels if the car did not come with them? If so, would there be any deduction in points for doing this?

As always- Many Thanks!
Pat

[Gene M.]

Re: 68 under-body heat shield Installation

Pat,
I have a very early 68 so I can only help you with #3. The battery cable on mine was between the fiberglass tunnel insulation and the floor. As far as all the other sheet metal, plastic and insulation never had any. Was more like a C2 than a C3 in early 68's.

My advice is don't add anything that wasn't there originally.

[Patrick N.]

Re: 68 under-body heat shield Installation

Thanks for confirming batt cable, I figured that was the right order but not sure.

I was considering adding the other pans because I read in other posts the pans further help minimize heat entering the passenger area. As a TSB update to 68's I was thinking it would not get dinged when judged - I could simply add heat barrier under my carpet and call it a night.

Thanks again
Pat

[John C.]

Re: 68 under-body heat shield Installation

Pat

Are you trying to restore it back to the way it was originally built or just something you can drive comfortably. When your car was built only the insulation and the triangle shields were being used. The large square protection panels for the insulation came later. The plastic toe panels also came later and replaced the triangular shields. No car should have both.

Many cars were retrofitted with the square shields and plastic toe panels through service bulletins that came later to reduce driver compartment heat, but they are not original to cars built before approximately May 1968.

John

[John C.]

Re: 68 under-body heat shield Installation

Pat

Are you trying to restore it back to the way it was originally built or just something you can drive comfortably. When your car was built only the insulation and the triangle shields were being used. The large square protection panels for the insulation came later. The plastic toe panels also came later and replaced the triangular shields. No car should have both.

Many cars were retrofitted with the square shields and plastic toe panels through service bulletins that came later to reduce driver compartment heat, but they are not original to cars built before approximately May 1968.

John

[Patrick N.]

Re: 68 under-body heat shield Installation

Hi John-

Back to the way it was for flight judging as priority, but also would like a comfortable ride as I do plan to drive it.

Regarding the pans / Toe pan shields. I thought I was clear after reviewing my car, reading the past threads on this and the TIMJG but perhaps not. Althought the white toe pan was added late 68, I thought that was in conjunction with the triangle shaped pans and only removed when the second set of heat shields were added: updated TIMJG states " ...A TSB of 17 December 1968 recommends the removal of the triangular heat shield on early 1968 cars and the addition of the rectangular heat shield as described above." I have not installed anything as of yet, so thank you for helping me clear this up.

[John C.]

Re: 68 under-body heat shield Installation

Pat

The current JG still doesn't do a good job on describing the changes during the 1968 model year that that took place in regards to the underbody insulation and associated shields.

The triangular shields were used in production from day one. They actually make the interior heat problem worse as the hold the hot air up against the firewall. I don't use them on my car and it make a big difference.

The first attempt to solve the problem was through the addition of the insulation. With the triangular shields still in place this must not have been very successful. The insulation was also not protected under the seats and left it very vulnerable to road debris.

The second attempt was to drop the triangular shields and add the plastic toe shields that direct the hot air down under the car. I also believe that this is when the square shields were added during production to protect the insulation. Although they may help some with heat insulation the main reason the square shields were added is to protect the insulation.

The service bulletin of Dec 17th in the appendix of the JG brings early cars up to what was last in production. It has you discard the triangular shields when both the plastic toe panels and square shields are added. It's get confusing because the pages that go with this bulletin are not shown in order. An April 22nd bulletin dealing with the same issue is placed in the middle.

John

[Patrick N.]

Re: 68 under-body heat shield Installation

I think my installation just got a heck of a lot easier. Prior to this thread, I thought the white plastic parts were used on my car with triangles + insulation. At this point, triangular metal pans will go back on as well as the fiberglass insulation and that will be the configuration.

Thanks for the help on this one John.

Best,
Pat

[Dale C.]

Re: 68 under-body heat shield Installation

Pat, I put mine (Mar 8th) back the way John described and the way you are going. I did add insulation under the carpet. (Paragon). It's an A/C car and still get too darn hot. Best option is to let the top down on a hot day. By the way I'm having my door panels fixed by a car trim guy. I'll let you know how they turned out. Dale

[Patrick N.]

Re: 68 under-body heat shield Installation

Pat, I put mine (Mar 8th) back the way John described and the way you are going. I did add insulation under the carpet. (Paragon). It's an A/C car and still get too darn hot. Best option is to let the top down on a hot day. By the way I'm having my door panels fixed by a car trim guy. I'll let you know how they turned out. Dale

Yes, I'm glad I posted on this. I will be putting the insulation in tonight. I'm not ready for the interior yet but I have heard these cars can get toasty and will most likely add the heat barrier. My kids are so excited to go for rides if I ever get this darn thing completed and I don't want to fry them

Please send pics or let me know how the doors come out.

Also since I got you on the post Dale, out of curiosity, can you let me know if your emission sticker was placed on the top of the firewall near the Master cylinder or on the top of radiator? My photos of my car (Mar 7th) when I got it does not show it in either location so it was lost or removed at some point.

Regards,
Pat

[Terry M.]

Re: 68 under-body heat shield Installation

Also since I got you on the post Dale, out of curiosity, can you let me know if your emission sticker was placed on the top of the firewall near the Master cylinder or on the top of radiator? My photos of my car (Mar 7th) when I got it does not show it in either location so it was lost or removed at some point.

Regards,
Pat

Pat,
Often there is a "ghost" of the adheisive used to hold the emission label in place, of course if the areas have been refinished that idea won't work.

[Patrick N.]

Re: 68 under-body heat shield Installation

Pat,
Often there is a "ghost" of the adheisive used to hold the emission label in place, of course if the areas have been refinished that idea won't work.

Hi Terry, I did not think to take detailed photos or event think about the label before I started the restoration and I do not have a photo of the radiator location. So now I am kicking myself for missing that. Here is the best shot I have of the fire wall area before I started the project -maybe a better trained eye can see a clue
Right Firewall.jpg

[Terry M.]

Re: 68 under-body heat shield Installation

Hi Terry, I did not think to take detailed photos or event think about the label before I started the restoration and I do not have a photo of the radiator location. So now I am kicking myself for missing that. Here is the best shot I have of the fire wall area before I started the project -maybe a better trained eye can see a clue
[ATTACH=CONFIG]48591[/ATTACH]

Nothing I can see, but a shot a little more outboard would include more likely area. Looking at this is like looking at engine pads. The internet just destroys all fine detail.

You are doing the best you can by asking other owners and mimicking their cars.

[Dale C.]

Re: 68 under-body heat shield Installation

IMG_6960.jpgIMG_6961.jpgPat, The photo on the right is Corvette America's copy of the AIM and shows the emission sticker on the radiator in view "B". The photo on the left is my copy of an original AIM and shows that view "B" being removed, change #6 on 1-16-68 and the sticker moved from radiator to firewall. Don't know for sure but it looks like our Mar cars had it on the firewall. That's where mine is. By the way that dang sticker is a bucket of worms on the 427 A/C cars. There was a Feb service change that changed the sticker from 3927744 F to a new # 3940925 and procedure (with??? letter) and I sure would like to just see one of those.

[Patrick N.]

Re: 68 under-body heat shield Installation

Thanks Dale and Terry. All things equal, I'll base my decision on the info in your original AIM Dale and the fact that our cars are hours apart when made and place on the firewall. I recall you were looking into that AC label- sounds like another 68 unicorn. I hope one turns up.

Thanks again guys!
Pat