C1 Aux Hardtops

[Bill B.]

Re: C1 Aux Hardtops

At this point, we have essentially covered the tops from 56 to 58 (#6400). In an effort to simply, following is my effort to summarize:

1 - narrower header (painted or unpainted) or wide front header with 3-piece stainless trim
2 - rear "Y" stainless clip
3 - early drip rails with a "sharp" top edge and an extended rear tail and later a drip rail with a "smooth" top edge and an extended rear tail.
4 - all used the same rear lower outer exterior 3-piece stainless trim (long center and straight sides)--actually, all the exterior stainless trim is the same excluding the header used and all the interior stainless trim is the same except for the interior upper side trim which had no holes and clipped to the drip rail interior flange until 57 (3300). The later trim looks the same but had 3-screw holes to secure it to the flange.
5 - all used the same 3-piece spotwelded rear lower main weatherstrip stainless channel assembly
6 - rear and side window glass is identical but they were all date coded
7 - the front vertical quarter window channel is the same
8 - the top diagonal quarter window channel assembly is the same. This assembly has a small rectangular stamped stainless plate spotwelded near the rear lower end. Two rivets secured a "side hold down bracket" to the channel then four rivets attached the total assembly to the rear lower 3-piece main stainless weatherstrip channel. The "side hold down brackets" and "center rear hold down bracket" were all chrome plated cast.
9 - all used the same rear window/weatherstrip upper main channel. Just a caution--later upper main channels are not interchangeable.

I just want to make sure that we also remember what we still don't know:

1-when in 56 the narrow header changed to wide? Odds are we may never know.
2-how the narrow header is secured to the roof panel?
3-when did the "sharp" edge drip rail change to "smooth/crimped over"?
4-is the 58-60 TIM/JG correct for early 58 tops?

I am still thinking about how to explain the 58(#6400) to early 59. And then from early 59-60. We will eventually get to headliners and glass and ...at the very end.

[Larry C.]

Re: C1 Aux Hardtops

Hey, Bill,

Back in 1970, I purchased a basket-case 1956 Corvette, serial #352, built in Feb 1956. Have since sold the car.

The front aluminum header, with only about 1 inch showing, was attached to the fiberglass skin of the top from the "outside" with about 5 or six phillips head screws that screwed into the aluminum header and were countersunk in the fiberglass skin just enough to be eventually filled over. This was evident since the previous owner had removed the h/t paint. There was some evidence that the holes were filled in at the factory with some type of body filler, sanded down and then painted over.

You and others have often referred to the "Y" s/s molding that covered the gap at the lower, rear corner of the side windows. One clip was missing on my hardtop but the other was not a "Y". It was a 45 degree angle clip that covered the gap, not a "Y". This 45 degree clip was identical to the 90 degree clips used at the upper corners of the rear h/t window. From all indications, it was factory installed as the lower window molding was rounded over, not sharp cut, and butted up against the front of the 45 degree clip. I surmise that sometime after this, the factory started using the "Y" clip, but I have no proof. The 1956 GM photo I mention below also seems to show a 45 degree clip, not the usual "Y" clip.

A bit of side note, I have a GM photograph (actually published as a centerfold in an early Restorer issue) taken either late 1955 or early 1956 showing a Venitian Red 56 on which the h/t header was painted Red as the rest of the h/t. The are no signs of the attaching screws that I mentioned above as these would have been all filled in and painted over. In the photo, however, you can make out a slightly distinctive line where the header meets up with the fiberglass skin. Assume some type of body filler was used in this gap and painted over.

Also, in this same photo, the normally chrome-plated headlight bezels were also painted red like the body on the outer portion of bezels. Inside the bezels, adjacent to the headlights, chrome is showing This particular 56 may have been an introduction and promotional car with changes made before the actual production run began, but there could have been some 56s delivered with body painted header and headlight bezels.

On my 56, there was no evidence of it ever having been painted. Also, the header was anodized and it would seem unlikely that GM would have anodized and then painted it body color.

This is all I can think of at the moment. Hope this information is useful.

Larry

[Bill B.]

Re: C1 Aux Hardtops

Larry,

I know the info you provided is very appreciated by others and especially by me! No wonder Chevrolet "improved" the top design by going to the wide header. The "45" versus "Y" rear clip is nice to know existed too. At least if someone sees one they will know it could be on an early 56 top. Happy New Year to a Great Texan!

Bill

[John H.]

Re: C1 Aux Hardtops

Bill & Larry -

We'll probably never know what the "factory" did on hardtops (except by forensics), as all C1 hardtops were built and painted, ready to install, by an outside supplier in Toledo, Ohio, and shipped to St. Louis in racks; all St. Louis did was to take the top out of the rack and bolt it on the car.

[Bill B.]

Re: C1 Aux Hardtops

John,

Gives me some comfort to know that you have scanned through my thread. I want to apologize for mispelling your last name earlier but my fingers where moving a lot faster than my brain at the time--and I don't ever proof read things. With a last name like mine, you can butcher anytime you like. I was also hoping that maybe the factory was a little more involved than just trying to keep drawings current as best they could. Really helps me understand a little better. My youngest son is a design engineer and accurate drawings from a historical perspective is one of his biggest complaints--especially if they have to build another identical part for an old generation subsea tool. Thanks

Bill

[Bill B.]

Re: C1 Aux Hardtops

Just found some bracket pictures that I had which should help some folks. The left is the early style bracket (chrome plated cast) and channel arrangement used with 3-piece spot welded rear lower main channels. Center is a later bracket (stamped stainless) used with the 1-piece rear lower main channel. However, according to the 58-60 TIM/JG the early cast bracket is found till 59 then the stamped bracket used through 60. I don't agree with this and will discuss further once I get to the 58 (#6400) to 60 top. Right is bracket (stamped stainless) which was used on 61-62 tops. Note the absence of the hold down bolt portion.

side brackets.jpg

[Bill B.]

Re: C1 Aux Hardtops

Sort of learning how to post pictures you can see. Redid the brackets styles so you can more clearly see the differences. Far left is the early chrome cast bracket and channel assembly with spotwelded bracket attachment plate. This is an assemby with PN 3729393 & 3729394. The example bracket below the channel assembly still has a plate riveted to it but the bracket PN is 3728421 & 3728422. Center is the later channel assembly with stamped stainless bracket welded to channel. This is an assembly and had a its own PN 3757795 & 3757796. Being able to identify these brackets will assist in understanding what period the tops belong to and are really important to changes prior to and after 58 (approx serial #6400).
side bracket assemblies.jpg

Still organizing my thoughts on the 58 (#6400) to 60. I believe this period could be the most controversial.

[Gary C.]

Re: C1 Aux Hardtops

Rich Mauser provided this photo and requested its posting - Sterling manufacturer's label from his C1 hardtop.

C1hardtop 012acrop.jpg

[Bill B.]

Re: C1 Aux Hardtops

Thanks Gary and Rich. I have a copy of that stamping which is on the underside of your roof panel. Interesting as my 60 top has nothing of the sort but does have "TURQ" written in crayon and some pencil numbers which I cannot make out. You should all be aware that the rear lower main weatherstrip channel stainless will also have a stamped oval with "ELKART", "INDIANA", AND "XL" logo.

[Bill B.]

Re: C1 Aux Hardtops

The 58-60 TIM/JG describes things this way:

"The outer trim moldings are made of highly polished stainless steel. the front header is covered by a 2-inch (approximately) wide bright stainless molding (2-piece, left and right, with a center escutcheon). The stainless rain gutter for early 58 is a single (sharp) variety. the stainless rain gutter for late 58 (Ser #6400 approximately) through 1960 have a rolled or rounded edge. the underside of the rain gutter contains three truss head rivets on each side and three phillips head screws on each side. The rear stainless around the back and side has ten pieces (early 58 through Ser #6400). late 58 through 1960 has eight pieces. The major difference is the late 1958 through 1960 has no "y" moldings that join the lower stainless with the back side window verticle stainless. (See AIM illustration page 31)

The mounting brackets for all 58 hardtops are chrome plated cast brackets attached to the hardtop lower frame rail with stainless round head rivets. All 59-60 hardtops used stmaped stainless steel mounting brackets except early 59 (tops assembled through Oct, 58) which used the chrome plated cast hold down bracketat the center of the back window only. these brackets were attached with two rivets instead of three like 1958."

The AIM page mentioned contains two illustrations which are essentially the same as shown in Noland's book on pages 268 and 269. One (early 58) is the 3-piece spotwelded rear main lower channel with "Y" clip style top and the other (late 58-60) is the newer style 1-piece rear main lower channel with the "Y" clip eliminated. To me, the most noteable and critical difference is the change from and use of either the 3-piece or 1-piece rear main lower channel. Once the 1-piece channel was used, the "Y" was eliminated, the rear trim changed, and the drip rail changed. Also, the 58 AIM shows this same side window configuration with a "stamped" style side hold down bracket-not the early cast style. The drawing is originally dated 6-23-58 and is subsequently annotated "RELEASED FOR 59, 8-15-58". Paradoxically, the other 58 AIM drawing showing the remaining top configuration shows the older 3-piece spotwelded with "Y" clip arrangement. The drawings original date is 8-19-57 and also states it was "REDRAWN" on 5-5-58. The 58 AIM only confuses me and complicates things. And, the TIM/JG just keeps me in "DO LOOP".

When I experimented with trying to retrofit my 60 top from stamped style brackets to the older cast brackets-- the fit was just "hookie" and "ill logical" to me. After many trial attempts, I finally called Matt at Glassworks to see if they could straighten my bent s/s channel and to ask about the assembly configuaration. I explained to him what the TIM/JG stated and he responded with "I have never seen one like that but maybe the rear center bracket could have been found on the first 100 59's. You must be reading the TIM/JG incorrectly." He had never seen a 1-piece s/s channel with cast side brackets. Does anyone have or know of a top that has the single channel, no "Y" clip, and cast side brackets versus stamped stainless side brackets as described in the TIM/JG?

I will wait to see if someone can help here before I continue any further.

[Bill B.]

Re: C1 Aux Hardtops

Just a misc tidbit. Many folks will never see this stamping (ELKHART-INDIANA-XL) unless you have to replace your rear window weatherstrip. You will find it on all (56-62) rear main lower stainless weatherstrip channels. This channel section is a right side front straight piece with the reinforcement spotwelded on the left side and the side locator pin on the underside right front. The locator pin can break off or get bent but replacements are availabe. This particular channel piece is found on the early 3-piece spotwelded channels. That bent up reinforcement section gets spotwelded to the long curved rear channel. As for the battery, IIRC I put that there.

channel logo.jpg

[Bill B.]

Re: C1 Aux Hardtops

58 (approx serial #6400) to 60 Tops.

Based on 58-60 TIM/JG revisions, I know that at a previous point in time the guide described a 58 (#6400) to early 59 top as looking just like the early tops but the side rail changed to "smooth" from "sharp" and it retained the "Y" clip trim. My point, the guide recognized a "smooth" rail existence in early 58. This description made it very simple and easy to understand and to comply with and it gave us a reference point to justify a driprail change from "sharp" to "smooth". Also, later 59-60 tops were then described as having a two-piece bottom rear molding without the "Y" joiner pieces. Again, simple and easy to comply with--if you add a small center clip to the two-piece bottom rear molding. For whatever reason, the TIM/JG with its current revision dramatically changed things for the late 58 top. The late 58 top now would be seen without the "Y" clip trim and a hybrid bracket arrangement. In addition to these changes, we have also lost any reference for the existence of a "smooth" rail and change to it prior to 58 (#6400)-remember, I have one. The guide now only references a "sharp" edge style. At least for stupid me, that darn TIM/JG now has made it complicated and somewhat paradoxical. But, I feel it is right on track and just needs some tweeking. Following is how I am making it make sense for me:

First, recall that the 58 AIM sheet 3 shows a main structure style top with the "Y" clip trim and a sheet 4 side window view with the "Y" clip trim eliminated--the paradox.

Here is how I solved it. The original date in the 58 AIM for this "Y" clip style sheet 3 is 6-19-57 and it was redrawn on 5-5-58. This evolution of the main structure and drawings from 57 through 58 is totally consistent and amounts to minor differences regarding rivet part number changes, nothing significant. But, within 49-days this sheet was again redrawn on 6-23-58. It just never was posted to the AIM. I found it in the 59 AIM. This new sheet 3 is the newer main top structure with the "Y" eliminated. Had it been inserted into the 58 AIM, sheet 3 and 4 would properly show what the newer style "Y" eliminated 58 (#6400) to 60 top looked like. And, I don't think we would have a "HYBRID" bracket situation for the late 58 production period. All late 58 to 60 tops would use the stamped stainless brackets, 1-piece main lower rear weatherstrip main channel, "smooth" driprails with a shortended rear tail, and "Y" clip eliminated style 3-piece rear exterior lower trim. Is is also difficult for me to imagine the center rear holddown bracket being cast instead of the newer stamped stainless at this point.

The exact opposite happened for the 58 AIM sheet 4 which was inserted and dated 6-23-58 illustrating the "newer" style side window with "Y" eliminated and later released for 59. Unfortunately, the older version sheet 4 pages from "sometime" in 57 until 6-23-58 were removed and discarded. Bottomline-we don't know what might have existed for the side window configuration structure and especially the "sharp" to "smooth" driprail change with "Y" style tops. I feel very confident these lost pages would support a "smooth" style driprail and not the "razor" style rail described in the 58 TIM/JG for at least the early 58 cars. However, I still think the 57 AIM shows the "smooth" rails too. You have heard it before, "sometime" in 57 the driprails probably changed from "sharp" to "smooth". We may never know exactly when.

The information I have provided so far is just my view of things-nothing more. Again, if I am in error, lets get it corrected. If you have any helpful details or questions, please get them iposted. Lets face it, the best sources are known documented examples.

[Bill B.]

Re: C1 Aux Hardtops

The 61-62 to Tops. Noland's book, page 369, provides some details on the 61-62 tops. I think the key points he makes is that theses tops only fit 61-62 cars, the rear window has a center "hump" to match the deckllid windsplit, hold down bracket configuratin changes, and around 61 serial number 5500 two screws where added to secure the rear lower center "indented" s/s clip trim molding. If you see that rear window "hump", it is a 61-62.

You should also know that the header bar, front 3-piece exterior s/s trim, and fiberglass roof panel are the same as used since 57. Moving back, the drip rails are unique to 61-62 tops. They are a "smooth" top edge rail. Also, this rail's rear tail is the shortest of all drip rails. That is why the rear and side window plexiglas is different from 56 to 60 glass. The rear main lower s/s weatherstrip channel is a 1-piece channel and it will have the center rear "hump" in it. The older style holddown brackets would now be better decsribed as a side "reinforcement bracket". They are stamped stainless and look just like the 58L-60 brackets except the hold down tang is removed. It is simply a reinforcement now. The rear lower exterior trim is 3-pieces (two long curved sections which are then joined in center with an "indented" center clip). The earlier side locator pins have been replaced with a substantial sized bracket which is spotwelded to the main frame. This bracket is then bolted to the car right behind each door. This is the only top which will have two rear hold down brackets versus earlier a single center hold bracket. The hold down brackets are the same as the 58L-60 center rear thin s/s stamped bracket. It is just that the 61-62 uses two of them and they are mounted inboard from the rear center-there will be no center hold down.

One last point on this 61-62 top, the rear window upper main frame assembly is also unique. Its sides are shorter than earlier frames.

I am going to assume that we have basically covered the main structural differences. I think my next post will be critical to folks shopping for repair/replacement parts. Kinda of a parts interchange aid. Descriptive details so you don't get ripped off on ebay. Some of this stainless and frame stuff is very, very expensive--but most of it is out there somewhere (repo and original). From what I have seen, a lot of it is listed incorrectly. You need to be the smart one.