'E69 Underbody Insulation - looking for your opinion

[Kevin S.]

Good Morning,

I have installed new reproduction underbody insulation panels on my early 1969. Bought and installed about 4 new retainer clips to replace some that were rotted out and tabs missing. I took the liberty of installing two additional insulation retainer clips along the upper LH side of the tranny tunnel where the 4-speed shift linkage is located to make sure that the insulation does not come into contact with the linkage and tear up the insulation.

My heart is telling me to stop here and leave the underbody insulation alone because what I have done so far is closer to what was done at the factory for NCRS judging purposes. My head is telling me to close in the gap areas along the tranny tunnel and just take the point deductions for over restoration. Reasoning: to both provide additional cooling inside the cabin area and to provide more sound deadening in the cabin by closing up the gaps. See photos below.

Looking for your opinions. Leave it as is, better for juding points. Close the exposed areas and take the point deduction(s). My OCD and perfectionist tendancies tell me to close it all up and provide as much insulation and noise reduction as is possible.

Kevin

[Leif A.]

Re: 'E69 Underbody Insulation - looking for your opinion

Kevin,
IMHO, you've done a very nice job of installing the insulation...leave well enough alone, at this point.

[Kevin S.]

Re: 'E69 Underbody Insulation - looking for your opinion

Hi Leif,
Thank you for your input. I was (still am) concerned about the proximity of the exhaust pipes running through the two openings in the center crossmember and the lack of underbody insulation in those locations adjacent to the exhaust system.

Kevin

[Patrick H.]

Re: 'E69 Underbody Insulation - looking for your opinion

Remember, later cars have none of this insulation. so you’re already ahead of it.

If you drive the car so much after judging that the small openings really make your feet hot, fill them in at that time.

[David H.]

Re: 'E69 Underbody Insulation - looking for your opinion

Kevin

Underbody heat shields are 3 points Originality and 3 points Condition. If they were completely missing - 6 point deduction.

Your situation: You cover those empty spots. CDCIF: Configuration & Installation deductions. Or 40% of 3 or about a SINGLE point deduction.

There are 4500 points in Flight Judging. i.e. Doesn't matter. Do what you want.

Dave

[Kevin S.]

Re: 'E69 Underbody Insulation - looking for your opinion

Hey Dave,
Thank you for those details and the CDCIF breakdown. Very helpful and just what I was looking for.

Well, that is it. I am going to leave it alone. Thank you Leif, Patrick, and Dave for your very valued input and recommendations.

Kevin

[David M.]

Re: 'E69 Underbody Insulation - looking for your opinion

I installed the high quality self adhesive sound deadener under the carpet where no one can see it unless they pull the carpet back.
Day and night difference with reduced heat and sound.

You all correct me if I'm wrong but I thought our 68 had the neg cable routed under the insulation between the floor and the insulation...or is my memory that shot? I dont have the AIM or the car handy at the moment. Did it 10 years ago.

The insulation was original never removed as far as I could tell. Again it was an April build 68 roadster...with the lovely non removable cross member. Made installation of the insulation impossible with out slightly bending he back side and if course I creased it.

Ill look at it again for my own sanity.

[Kevin S.]

Re: 'E69 Underbody Insulation - looking for your opinion

Hi David,
The old aftermarket side post battery and side post negative battery cable were on the outside of the insulation when we bought the car in 2009. As part of this resotration, I change the battery back to a NCRS correct top post and also changed the positive and negative battery cables back to top post a couple of years ago per my 6th edition TIM&JG based on my early build date.

Attached is a photo of the AIM showing the positive battery cable routing. I looked at the exploded View A in the upper left corner of the page and concluded that the rubber coated clips were on the outside of the underbody insulation...looking at it closer now I guess that is the fiberglass tranny wall cutaway and not the insulation.

Sheet! I may have messed up and put the negative battery cable on top of the underbody insulation.

Kevin

[David M.]

Re: 'E69 Underbody Insulation - looking for your opinion

Kevin,
Thanks for that pic of the 69 AIM. I have yet to dig out my 68 nor examine the car. Busy weekend and car is off site.
I'm 99.9% sure my tunnel insulation and neg cable were what the car was born with.
Would make sense to isolate the drive train heat from the cable.
If I'm right sorry to make you rework the great work you've done.
Dave

[Kevin S.]

Re: 'E69 Underbody Insulation - looking for your opinion

Update 11-3-2024,

I finally got around to relocating my positive battery cable from on top of the underbody insulation to under the insulation next to the fiberglass as suggested by David Morland. David, you were right! I did check a couple of additional sources to confirm the correct routing of the positive battery cable. Not that I did not believe you. Just that it is a pain to redo and I wanted to make sure and only redo it one time. Finally did it, moved the battery cable, did not tear up the underbody insulation too bad, also did not break any of the fairly brittle insulation retainers. Was VERY happy about that.

Thanks everyone for you advice and helpful suggestions. On to the next tasks.

Kevin

[Terry M.]

Re: 'E69 Underbody Insulation - looking for your opinion

Update 11-3-2024,

I finally got around to relocating my negative battery cable from on top of the underbody insulation to under the insulation next to the fiberglass as suggested by David Morland. David, you were right! I did check a couple of additional sources to confirm the correct routing of the negative battery cable. Not that I did not believe you. Just that it is a pain to redo and I wanted to make sure and only redo it one time. Finally did it, moved the battery cable, did not tear up the underbody insulation too bad, also did not break any of the fairly brittle insulation retainers. Was VERY happy about that.

Thanks everyone for you advice and helpful suggestions. On to the next tasks.

Kevin

I don't want to throw do do in the story at this point, but I hope it was the positive cable you installed under the insulation (labeled as number 1 in the AIM sheet shown. The positive cable is long and goes to the starter solenoid. The negative cable is shorter and goes to the frame (labeled as number 2 in the AIM sheet shown). The AIM sheet shows a side terminal battery. Early 1969 (prior to SN 22,081 according to the 1968-69 TIM&JG, 6th Edition) Corvettes had a top terminal battery. I hope you consulted the TIM&JG before you began your work. I have come to this thread lately, so I hope I have missed something.

[Kevin S.]

Re: 'E69 Underbody Insulation - looking for your opinion

Good Morning Terry,

I edited and corrected my post(s) to correctly reflect number 1 in the AIM to describe the positive battery cable routing that goes from the solenoid to the top post of the battery. I have VIN number 6479 (October 31, 1968 build) and would be an early car as you correctly pointed out, prior to SN 22,081. I do have the 6th Edition TIM&JG which is how I knew that someone installed the wrong side post battery in this car when we bought it in 2009.

Thank you, Terry. I appreciate getting the right information.

Kevin