C4 Info needed

[Thomas B.]

I am getting my 1993 Coupe ready for judging at the chapter level. It's a relatively low mileage example for its age ... just 17,500 miles. It is not the anniversary model. I am going through the technical manual and have a couple of concerns.

The manual says:
. the rubber boot around the gas cap should say 'Made in the USA SAE1 PA 66T', around the outside.
. I can't find this on mine.

. the taillight lens the part number is GM 16509625 MR 2F.
. My right rear light has the complete correct number. The other 3 end with '1F'.

. the emblems are chrome.
. Mine are black.

. the window washer fluid reservoir cap has a small vent hole in the center with blue lettering, 'Washer Fluid Only' and a windshield washer symbol. The manual shows a picture of a ZR1 cap.
. Mine has no lettering with a windshield washer symbol in white and a small vent hole, just below center.

. there are 2 Belt Installation Labels.
. I have one that says, 'Accessory Belt Routing and Printed in the USA'. Depending on how you read the guide, could one of these be for a 92 and the other for a 93? Or could one be for a ZR1? OR should there be 2 labels on the car?

My car was built in May of 1993.

Could any of these been part of a mid-year production change, or did another owner change something along the way?

Any info is appreciated.

[Joe L.]

Re: C4 Info needed

I am getting my 1993 Coupe ready for judging at the chapter level. It's a relatively low mileage example for its age ... just 17,500 miles. It is not the anniversary model. I am going through the technical manual and have a couple of concerns.

The manual says:
. the rubber boot around the gas cap should say 'Made in the USA SAE1 PA 66T', around the outside.
. I can't find this on mine.

. the taillight lens the part number is GM 16509625 MR 2F.
. My right rear light has the complete correct number. The other 3 end with '1F'.

. the emblems are chrome.
. Mine are black.

. the window washer fluid reservoir cap has a small vent hole in the center with blue lettering, 'Washer Fluid Only' and a windshield washer symbol. The manual shows a picture of a ZR1 cap.
. Mine has no lettering with a windshield washer symbol in white and a small vent hole, just below center.

. there are 2 Belt Installation Labels.
. I have one that says, 'Accessory Belt Routing and Printed in the USA'. Depending on how you read the guide, could one of these be for a 92 and the other for a 93? Or could one be for a ZR1? OR should there be 2 labels on the car?

My car was built in May of 1993.

Could any of these been part of a mid-year production change, or did another owner change something along the way?

Any info is appreciated.

Thomas------


The rubber fuel boot on my original-owner 1992 has no marking visible with the boot installed in the car. I would expect the same for 1993 but it's possible a feature like this could have been added at some point. I would be extremely surprised if your boot were not original to the car.

The known-original rear lenses on my car end in "1 F" for both the left side lenses and in "2 F" for the right side lenses. They have the same part number as yours.

For 1993 the 40th Anniversary Edition used chrome emblems, front and rear, whereas the standard used black. So, yours are as they should be.

My washer fluid reservoir cap is as described in your manual. I would expect the same for 1993 but it's possible there was a change. I can tell you that the GM part number for 1992 and 1993 cap was the same----GM #22101158. Of course, it is possible that features like you mentioned might have changed within that part number.

1992 and early 1993 used a serpentine drive belt with ribs on both sides. Later 1993 used a belt with ribs on only one side and smooth on the other. Just when the changeover occurred I do not know. I would expect different labels for the different configuirations. My 1992 has just one label associated with the belt and is mounted on the left (driver) side of the fan shroud. It shows the belt routing and advises to use the correct dual-sided belt.

[Pat F.]

Re: C4 Info needed

Folks, the rear lenses on my 1995 August 4, 1994 build have MR2 for the inboard and MR1 for the outboard.

Have information on another 95 with the same combination. Have another 95 with MR2 on both left hand lenses and MR1 on both right hand lenses.

The 1994-96 NCRS Judging Manual calls for rear lenses of 16509625 MR2 F.

I have sent to the 90-96 National Judging Chairman photos of numerous observations of various combinations of MR1 and MR2 on the rear lenses.

Hope this helps.

[Thomas B.]

Re: C4 Info needed

Thank you .. any info is a BIG help

[Joe L.]

Re: C4 Info needed

Folks, the rear lenses on my 1995 August 4, 1994 build have MR2 for the inboard and MR1 for the outboard.

Have information on another 95 with the same combination. Have another 95 with MR2 on both left hand lenses and MR1 on both right hand lenses.

The 1994-96 NCRS Judging Manual calls for rear lenses of 16509625 MR2 F.

I have sent to the 90-96 National Judging Chairman photos of numerous observations of various combinations of MR1 and MR2 on the rear lenses.

Hope this helps.

Pat------


I do not think that the suffixing "MR 1" or "MR 2" has anything to do with establishing which positions the lenses are installed in. While, I don't know what they do denote, the fact of the matter is that GM parts are defined by a part number, not a part number + suffixing code. If you were to purchase a lens from GMSPO for ANY position for a 1991-96 Corvette (except ZR1), you would purchase a GM #16509625, the same part number that's on the lens.

[William C.]

Re: C4 Info needed

Very likely a Mold Cavity ID so that if a defect is observed the toolmaker can go quickly to find the problem. Most of out molds had shutoffs that allowed one (or more) cavitys of a multiple cavity mold to be shut off and the others would be used to build sufficient inventory to allow the tool to be "pulled" from the molding press for repair. Pretty standard practice in the Molding business. As to numbers/location in the vehicle looking at the (what are likely) mold cavity ID on the lenses, someone might have a vivid imagination.

[Pat F.]

Re: C4 Info needed

Joe, again, thanks for the input.

I will pass on the information discussed in this thread concerning the rear lenses suffix to the National Team Leader for consideration in the next revised manual, as it stands the 94-96 Judging Manual solely designates a MR2 after the rear lens number. As you state and I have in my data base, the MR1 and MR2 are interchangeable.

As always I thank you for your time and effort to help us understand the C4 and it components.