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Another controversy on the door glass code on my 82. The last line of the mark on the drivers side on my car is "DOT 15 M75". The vender I am working with for replacement glass thinks it should be "DOT 15 M74". Anyone with original glass in their '82 able to help on this? Mike? By the way can someone decode the line? As always all help is appreciated.
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Re: C3 Door Glass Codes
Scott, To answer your question
DOT 15 translates to DOT (Department of transportation), 15 (Libbey Owens Ford the maker of the glass)
M74 or M75 is the numbered assigned by LOF when they submit their glass design to the DOT for approval of this specific construction...being a door light there will be three things stated in the construction. Thickness, color, temper...in this case, I am assuming you have a door lite made of green tint glass, its tempered, just use a micrometer to measure the thickness, somewhere in the 3-5 cm range....I am sure the difference will be thickness, it could be color...green tint versus clear.....
By the way ...green tint means the color throughout the piece...many people get confused and look at green glass and think its clear also they get confused on windshields and call tinted windshields clear and the shadeband versions tint...not true...Dino Lanno -
Re: C3 Door Glass Codes
M75 was designated for convertible side windows...M74 designated for coupe side window throughout C3.Tom Russo
78 SA NCRS 5 Star Bowtie78 Pace Car L82 M2100 MY/TR/ConvComment
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Re: C3 Door Glass Codes
Tom
I'm interested in an 82 with M75 as it must be real rare.
LyleComment
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Re: C3 Door Glass Codes
I'm still confused on the M74 vs M75 code. My car is an April 82, 4th week build. The door glass, which I think is original (I'm second owner and have had the car for 21 years) has a GV date(April 82) and the M75 code. The glass is a soft green almost gray tint. My car is of course t-top (no conv in 82). The glass measures 5mm in thickness. By the way I have a pass door glass with a '78 date code. It is M74 and is 6mm thick. So... should my drover door glass be M74 or M75? Anybody with known original glass on an 82 able to come to the rescue on this?Comment
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Re: C3 Door Glass Codes
My records indicate the GV date code was applicable to April 1969 and 1982, M75 indicates convertible and M74 is a coupe. With GV and M75 code on your glass it's entirely possible it was manufactured for a April 1969 convertible.Comment
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Re: C3 Door Glass Codes
Which than makes it an interesting study of originality for an 82...did something happen (break-in) in which glass was replaced or did factory install a dated piece of glass? Or something happen on the way to the dealer, at the dealer or soon afterward and it was replaced with an available M74 without the installers never realizing a bunch of code breakin geeks, Corvette anals from the 21st century would figure out their middeeds?
It's unlikely the factory had a ten-year old piece of glass lying around which therefore leads us to a more likely scenario of replacement in the early days of either transport or ownership. Scott, you may wish to track down the original ownership and tap his recollections of ownership and delivery.
Interesting though keep us posted.Tom Russo
78 SA NCRS 5 Star Bowtie78 Pace Car L82 M2100 MY/TR/ConvComment
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Re: C3 Door Glass Codes
One thing for sure it was never 69 convertible glass as it was never the same shape. Vert. glass won't fit coupes.
LyleComment
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Re: C3 Door Glass Codes
M-74 means the glass is 6mm thick EZI Green (Soft Ray) and M-75 means 5mm thick EZI Green (Soft Ray). This is a fact from LOF....Are the glass shapes different between coupes and convertibles?.....Dino LannoComment
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Re: Yes Rear top 90 degrees on coupe
rear about 110 degrees on convertibleComment
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Re: Yes Rear top 90 degrees on coupe
So the coupe side glass was made of 1mm thicker glass...Glass thickness typically soundproofs the interior...I wonder what other reasons GM could have had in mind when using different thicknesses? I know glass thickness effects channels, mounting hardware, rubber wipe and cat wiskers wipes, also effects the rubber seals around the door glass....why not make the noisy convertible thicker versus the coupe?Dino LannoComment
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Re: Yes Rear top 90 degrees on coupe
OK, bottom line looks like glass should be M74 on an '82 since all were t-top coupes. Thanks to all who responded.Comment
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