Greetings, Does anyone know if there was originally any insulation on the interior side of the firewall on a 68 coupe L-79 ? If the answer is yes, what was the composition thereof and is it currently available from anyone? Thank you in advance, Kurt Bunting
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Re: 68 Firewall insulation? ( Interior)
Kurt,
Unless someone else has information to the contrary, I was under the impression that interior firewall insulation (both upper and lower) was standard on all 1968 production Corvettes, regardless of engine option. My 68 L89 had it, which I replaced (upper and lower) at the time I did my main dash harness. I couldn't stand for the "crumbling" mess it was making anymore.
I can't tell you the "name" of the stuff, but it appears to have been a composition of cloth fiber and "other" materials that was glued (?) to a hard outer surface (How's that for specifics). Originally mine looked reddish-brown color.
I found reproduction 1968 upper and lower interior firewall insulation available at several of the larger catalog parts suppliers. But a better question would be if it is available anywhere "as original" and with the correct color. I didn't exhaust my resources but only found the upper available in green. The reproduction lower insulation was a greenish-blue-black, and glued with the sweat of Hercules to a bullet-proof, black, plastic coating. I got it to fit, only after alot of pushing, pulling, swearing, and "break-taking" (and that was with the entire contents of the interior removed). There may not BE, but if there is better "as original" stuff out there, I would suggest to try to find it. Best wishes. Tom #24014 -
Re: 68 Firewall insulation? ( Interior)
Kurt,
Unless someone else has information to the contrary, I was under the impression that interior firewall insulation (both upper and lower) was standard on all 1968 production Corvettes, regardless of engine option. My 68 L89 had it, which I replaced (upper and lower) at the time I did my main dash harness. I couldn't stand for the "crumbling" mess it was making anymore.
I can't tell you the "name" of the stuff, but it appears to have been a composition of cloth fiber and "other" materials that was glued (?) to a hard outer surface (How's that for specifics). Originally mine looked reddish-brown color.
I found reproduction 1968 upper and lower interior firewall insulation available at several of the larger catalog parts suppliers. But a better question would be if it is available anywhere "as original" and with the correct color. I didn't exhaust my resources but only found the upper available in green. The reproduction lower insulation was a greenish-blue-black, and glued with the sweat of Hercules to a bullet-proof, black, plastic coating. I got it to fit, only after alot of pushing, pulling, swearing, and "break-taking" (and that was with the entire contents of the interior removed). There may not BE, but if there is better "as original" stuff out there, I would suggest to try to find it. Best wishes. Tom #24014Comment
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Re: 68 Firewall insulation? ( Interior)
Tom, You scare me when you say "entire interior removed" Does the dash cluster have to be removed? Steering column? What else? I am hesitant to mess with the dash as I know there will be a loose wire or something when I am done and I don't want the electrical problems. Also, your post seemed to indicate Upper & Lower??? Is what you have "pre-shaped" or do you cut it to fit? Thanks for the help. Kurt Bunting NCRS 26406Comment
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Re: 68 Firewall insulation? ( Interior)
Tom, You scare me when you say "entire interior removed" Does the dash cluster have to be removed? Steering column? What else? I am hesitant to mess with the dash as I know there will be a loose wire or something when I am done and I don't want the electrical problems. Also, your post seemed to indicate Upper & Lower??? Is what you have "pre-shaped" or do you cut it to fit? Thanks for the help. Kurt Bunting NCRS 26406Comment
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Re: 68 Firewall insulation? ( Interior)
Kurt,
I'm sorry, calm down, just take this as one thing at a time. Your perception is right, this is a big endeavor. There is an "upper" and "lower" firewall insulation for 1968. If you have the 68 AIM see page H92. If you don't have the 68 AIM then you'll need it, and DON'T attempt this without it. You will understand below:
The upper is commonly called "dash insulation" or "sound deadener", and the 68 AIM shows it as "Insulator - plenum panel". It is in two sections (LH and RH), overall about 6"-8" wide, is "cut to form", and glued in place. In place: approximately where the top of the interior firewall meets the underside forward edge of the dash, on down. The upper is the "cloth-strand-composite" that I mentioned, and has no "hard" backing. My original color was reddish-brown.
The "lower" firewall insulation is shown in the 68 AIM as "Mat assembly". It is the same "cloth-strand-composite" glued to a hard (outer) backing. The reproduction "Mat" differs from the original in that the hard backing is now a thick, but pliable plastic (what I jokingly called "bullet-proof"). This lower insulation is molded-to-form in one entire piece (approximately 12" wide) and reaches from the left kick panel (wall) to the right. It is held in place with 9 or 10 rubber "plugs", as well as the heater core housing on the right.
Also, there are three pieces of insulation (composed like the "upper") that are under the radio, the front console, and the rear console assembly (AIM page H129). These are cut in unusual shapes and I wasn't able to find a replacement for them (so I re-glued what I had in place).
Replacing the lower is less complicated than the upper. There will be plenty to do, but you should be able to do it without removing the entire (upper) dash. I happened to include both with all else that I was doing, which centered around replacing my main dash harness. Just for your info: I would also like to meet, shake the hand, and get the autograph of the guy who says he did either (correctly: as original) WITHOUT removing "a something". The firewall insulation was in place before all else (dash) and common replacement "short cuts" are to slice or alter the insulation. If you want to do the job "correctly" then my suggestion is to remove all that you need to (not to cut or make "little slits"). You will be working around everything dash-related so basically take a look at the AIM.
Doing upper and lower together is time consuming (you'll have to plan to take your car out of commission for a while) but component removal is not completely difficult OR impossible. The most difficult thing I encountered was getting the new plastic-backed lower insulation in place, which was how I described previously.
Even though I replaced my main dash harness, I probably "cleaned up" more other electrical stuff or eventual problems than I would have created. The best I can say is that if you are looking for a way to "bond" with your car, then this is surely one way to do it. Just ask if you want or need more info. Tom #24014Comment
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Re: 68 Firewall insulation? ( Interior)
Kurt,
I'm sorry, calm down, just take this as one thing at a time. Your perception is right, this is a big endeavor. There is an "upper" and "lower" firewall insulation for 1968. If you have the 68 AIM see page H92. If you don't have the 68 AIM then you'll need it, and DON'T attempt this without it. You will understand below:
The upper is commonly called "dash insulation" or "sound deadener", and the 68 AIM shows it as "Insulator - plenum panel". It is in two sections (LH and RH), overall about 6"-8" wide, is "cut to form", and glued in place. In place: approximately where the top of the interior firewall meets the underside forward edge of the dash, on down. The upper is the "cloth-strand-composite" that I mentioned, and has no "hard" backing. My original color was reddish-brown.
The "lower" firewall insulation is shown in the 68 AIM as "Mat assembly". It is the same "cloth-strand-composite" glued to a hard (outer) backing. The reproduction "Mat" differs from the original in that the hard backing is now a thick, but pliable plastic (what I jokingly called "bullet-proof"). This lower insulation is molded-to-form in one entire piece (approximately 12" wide) and reaches from the left kick panel (wall) to the right. It is held in place with 9 or 10 rubber "plugs", as well as the heater core housing on the right.
Also, there are three pieces of insulation (composed like the "upper") that are under the radio, the front console, and the rear console assembly (AIM page H129). These are cut in unusual shapes and I wasn't able to find a replacement for them (so I re-glued what I had in place).
Replacing the lower is less complicated than the upper. There will be plenty to do, but you should be able to do it without removing the entire (upper) dash. I happened to include both with all else that I was doing, which centered around replacing my main dash harness. Just for your info: I would also like to meet, shake the hand, and get the autograph of the guy who says he did either (correctly: as original) WITHOUT removing "a something". The firewall insulation was in place before all else (dash) and common replacement "short cuts" are to slice or alter the insulation. If you want to do the job "correctly" then my suggestion is to remove all that you need to (not to cut or make "little slits"). You will be working around everything dash-related so basically take a look at the AIM.
Doing upper and lower together is time consuming (you'll have to plan to take your car out of commission for a while) but component removal is not completely difficult OR impossible. The most difficult thing I encountered was getting the new plastic-backed lower insulation in place, which was how I described previously.
Even though I replaced my main dash harness, I probably "cleaned up" more other electrical stuff or eventual problems than I would have created. The best I can say is that if you are looking for a way to "bond" with your car, then this is surely one way to do it. Just ask if you want or need more info. Tom #24014Comment
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Re: 68 Firewall insulation? ( Interior)
Tom, Thanks for the excellent reply. I just looked in my AIM and you are 100% correct. Looks like everything out before installing is the way to go. (Haven't calmed down yet though) Seems like a job and a half. Where did you get the mats you were able to find? Probably to old for Chevrolet dealer's parts dept. How about the fasteners to hold it in place? Any adhesive used? Thanks for your input. Much appreciate it. KurtComment
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Re: 68 Firewall insulation? ( Interior)
Tom, Thanks for the excellent reply. I just looked in my AIM and you are 100% correct. Looks like everything out before installing is the way to go. (Haven't calmed down yet though) Seems like a job and a half. Where did you get the mats you were able to find? Probably to old for Chevrolet dealer's parts dept. How about the fasteners to hold it in place? Any adhesive used? Thanks for your input. Much appreciate it. KurtComment
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Re: 68 Firewall insulation? ( Interior)
Kurt,
I don't have access to my receipts or shop right now but will give you what I can.
Reproduction upper and lower insulation has been available from the larger catalog parts suppliers, and for what I considered, are fairly expensive or "pricey". I don't recall exactly which supplier I used. Also, I didn't research enough to see if it was still available through GM, or if "as original" is supplied SOMEWHERE. After 3 or 4 "tries" of asking different sales reps to ask their stockman/Tech for a color and description I gave up, assuming I would continue to run into the same stuff everywhere. Look around "it" may be out there.
I do remember having to go back and re-order the 9 or 10 rubber "plugs" for the lower. The sales rep told me they were included but weren't, and again, they were pretty "pricey" for what I considered. Something like $2-$3.00 EACH.
If you want to be 100% correct for original you'll have to use the 68 AIM to determine the EXACT TYPE of adhesive used for the upper. I used a "GM General Purpose Trim Adhesive" (spray) that I applied to both surfaces then put in place (upper, radio, and consoles only). I don't remember the part number, but it's available at the same suppliers.
As a side note: I did clean the original factory glue away since it was dry, "flakey" and wouldn't provide a good adhesive surface. Adhesive Spray Remover can do it, but I also used a spray can of "carb cleaner" that after a couple minutes "rubberized" and loosened the dried glue. I worked small areas at a time, and be careful using those items in a confined and "enclosed" area. The last thing you want is a mini-flash fire to remove the "satisfaction" you will be achieving.
It would also be a good idea to have one or two of the different "service manuals" on hand. You'll be removing components like (what you dreaded) the steering column, heater core/blower box, etc. Some new firewall seals/grommets may be in order, and get a heater box seal kit. Try to avoid the tempting "short-cuts". Correct instructions for component removal/replacement make the job just as easy, and as I mentioned wasn't off the scale of difficulty.
Finally, some last things: Keep a box of zip-lock baggies, 3x5 cards, and a pen at your side. Use them to keep track of screws, items, etc. that will greatly aid their replacememt (The AIM will only show you were they go, not necessarily what you have, scattered loosely). Above all, BE PATIENT, take as many breaks as you need (do it once/do it right). Also: I took pictures.
Even though my 68 had a (quality) restoration 10 years before I got it, they left the original interior (wiring, dash, and all) intact and some "unmolested". I had far more things to restore/replace and worked them into one huge project, which you might want to consider as well. I'm satisfied with the good job I did (heck, it all works correctly and I didn't break anything) which makes me know that POTENTIALLY it won't need to be gone through again for maybe another 30 years. You can never have enough information. Tom #24014Comment
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Re: 68 Firewall insulation? ( Interior)
Kurt,
I don't have access to my receipts or shop right now but will give you what I can.
Reproduction upper and lower insulation has been available from the larger catalog parts suppliers, and for what I considered, are fairly expensive or "pricey". I don't recall exactly which supplier I used. Also, I didn't research enough to see if it was still available through GM, or if "as original" is supplied SOMEWHERE. After 3 or 4 "tries" of asking different sales reps to ask their stockman/Tech for a color and description I gave up, assuming I would continue to run into the same stuff everywhere. Look around "it" may be out there.
I do remember having to go back and re-order the 9 or 10 rubber "plugs" for the lower. The sales rep told me they were included but weren't, and again, they were pretty "pricey" for what I considered. Something like $2-$3.00 EACH.
If you want to be 100% correct for original you'll have to use the 68 AIM to determine the EXACT TYPE of adhesive used for the upper. I used a "GM General Purpose Trim Adhesive" (spray) that I applied to both surfaces then put in place (upper, radio, and consoles only). I don't remember the part number, but it's available at the same suppliers.
As a side note: I did clean the original factory glue away since it was dry, "flakey" and wouldn't provide a good adhesive surface. Adhesive Spray Remover can do it, but I also used a spray can of "carb cleaner" that after a couple minutes "rubberized" and loosened the dried glue. I worked small areas at a time, and be careful using those items in a confined and "enclosed" area. The last thing you want is a mini-flash fire to remove the "satisfaction" you will be achieving.
It would also be a good idea to have one or two of the different "service manuals" on hand. You'll be removing components like (what you dreaded) the steering column, heater core/blower box, etc. Some new firewall seals/grommets may be in order, and get a heater box seal kit. Try to avoid the tempting "short-cuts". Correct instructions for component removal/replacement make the job just as easy, and as I mentioned wasn't off the scale of difficulty.
Finally, some last things: Keep a box of zip-lock baggies, 3x5 cards, and a pen at your side. Use them to keep track of screws, items, etc. that will greatly aid their replacememt (The AIM will only show you were they go, not necessarily what you have, scattered loosely). Above all, BE PATIENT, take as many breaks as you need (do it once/do it right). Also: I took pictures.
Even though my 68 had a (quality) restoration 10 years before I got it, they left the original interior (wiring, dash, and all) intact and some "unmolested". I had far more things to restore/replace and worked them into one huge project, which you might want to consider as well. I'm satisfied with the good job I did (heck, it all works correctly and I didn't break anything) which makes me know that POTENTIALLY it won't need to be gone through again for maybe another 30 years. You can never have enough information. Tom #24014Comment
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Re: 68 Firewall insulation? ( Interior)
there are around $264. I believe Dr.Rebuild has them, I'll check also. jcComment
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Re: 68 Firewall insulation? ( Interior)
there are around $264. I believe Dr.Rebuild has them, I'll check also. jcComment
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Re: 68 Firewall insulation? ( Interior)
Thank you gentlemen for the excellent and very helpful input. I agree, I might as well do it once and do it right. Regards, Kurt BuntingComment
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Re: 68 Firewall insulation? ( Interior)
Thank you gentlemen for the excellent and very helpful input. I agree, I might as well do it once and do it right. Regards, Kurt BuntingComment
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