C4 body question
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Instructor
Joined: Jun 2005
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From: New Milford Ct
C4 body question
Does anyone know how much of the C4's underbody is metal? I know the frame is, but from looking at the GM diagrams, it seems that there are metal reinforcements supporting the main body. Is this right?
Melting Slicks
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From: Milan
Originally Posted by hogs29
Does anyone know how much of the C4's underbody is metal? I know the frame is, but from looking at the GM diagrams, it seems that there are metal reinforcements supporting the main body. Is this right?
-Beppe-
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Originally Posted by grandspt
I'm no expert but I know when the C4 came out I read that the body is glued (with a special adhesive) to the uniframe!
I believe all the body panels are bolt ons with the exceptiion of the upper rear quareter panels
Much if not all of the supporting frame and skeleton is steel or aluminum
alll of the front cross mebers are steel and the rear body support package is aluminum
seeya
Drifting
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From: MA
Originally Posted by jackdaroofer
I respectfully disagree
I believe all the body panels are bolt ons with the exceptiion of the upper rear quareter panels
Much if not all of the supporting frame and skeleton is steel or aluminum
alll of the front cross mebers are steel and the rear body support package is aluminum
seeya
I believe all the body panels are bolt ons with the exceptiion of the upper rear quareter panels
Much if not all of the supporting frame and skeleton is steel or aluminum
alll of the front cross mebers are steel and the rear body support package is aluminum
seeya
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Originally Posted by grandspt
So was anything glued to the frame? Or was it the upper rear qtr. panels?
This sort of supports what the book says
There is a lot of metal in our cars, only the body panels and the front and rear springs are fiberglass
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Originally Posted by 4bblC4
is any of it steel? or all aluminum?
Most everything is galvanized and painted steel. GM and i sort of believe it says the C4 is the first truly rust proof VetteThe quality of the galvanizing and the painting seem very good and there have been few reports, if any of chassis rusting out. This was a problem on C1,2,3
The rear bumber frame assy which bolts to the main frame assy was steel until sometime in 1988 when it was switched to aluminum.
My late 1988 is aluminum, but 88's were supposed to be steel
If you are curious, a magnet will answer your questions. Neither aluminum or fiberglass will attract the magnet.
seeya
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Drifting
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From: Portage Mi
Originally Posted by grandspt
So was anything glued to the frame? Or was it the upper rear qtr. panels?
The firewall and forward section of the floor are fibreglass and are bonded to the frame and to each other.
The rear "tub" is fibreglass and is also bonded to the frame. The upper quarter panels are bonded to the frame and also to the rear tub. The exterior roof halo cover is also bonded to the frame. Also, the lower "dog legs" are fibreglass and are bonded to the frame.
The rear section of the floorpan is steel--the part that the seats sit on--and the vertical wall directly behind the seats is also steel.
One thing of interest I found is that different adhesives were used for bonding FG to FG and FG to Steel.
Linn
edit: Oh yeah, the sill covers are also bonded to the frame.
Last edited by Black 'n Blue; Jul 13, 2005 at 08:13 PM.
Drifting
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From: MA
Originally Posted by Black 'n Blue
The firewall and forward section of the floor are fibreglass and are bonded to the frame and to each other.
The rear "tub" is fibreglass and is also bonded to the frame. The upper quarter panels are bonded to the frame and also to the rear tub. The exterior roof halo cover is also bonded to the frame. Also, the lower "dog legs" are fibreglass and are bonded to the frame.
The rear section of the floorpan is steel--the part that the seats sit on--and the vertical wall directly behind the seats is also steel.
One thing of interest I found is that different adhesives were used for bonding FG to FG and FG to Steel.
Linn
edit: Oh yeah, the sill covers are also bonded to the frame.
The rear "tub" is fibreglass and is also bonded to the frame. The upper quarter panels are bonded to the frame and also to the rear tub. The exterior roof halo cover is also bonded to the frame. Also, the lower "dog legs" are fibreglass and are bonded to the frame.
The rear section of the floorpan is steel--the part that the seats sit on--and the vertical wall directly behind the seats is also steel.
One thing of interest I found is that different adhesives were used for bonding FG to FG and FG to Steel.
Linn
edit: Oh yeah, the sill covers are also bonded to the frame.
Thanks for the info.
I knew I read somewhere that bonding was used on our cars.
Melting Slicks
Joined: Jul 2003
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From: Reno/Sparks Nevada
I recently completely disassembled an '86 down to the frame. As Black 'n Blue mentions alot of fiberglass body parts unbolt such as the doors, fenders, hood, bumpers, etc. The rest are bonded to the birdcage, sills and rear tub. What's interesting about the rear tub is that it sits on the rear part of the frame on pads. It's not directly bonded to the frame. However the attachment points where it is bonded and riveted is the vertical and horizontal areas directly behind the seats and at the door jam pillars where the halo ends. The rear fenders are bonded to the rear top surround and the rear top surround is bonded to the tub. The rear fenders attach to the rear bumper and inner fenders, which are attached to the frame with screws and braces. It's a very elaborate method of attaching the body to the frame. A real pain to disassemble. Glue and rivets. I have some pics. I'll post them when I find them.
Art
Art
Last edited by MrRenoman; Jul 14, 2005 at 08:39 PM.
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Originally Posted by MrRenoman
I recently completely disassembled an '86 down to the frame. As Black 'n Blue mentions alot of fiberglass body parts which don't unbolt such as the doors, fenders, hood, bumpers, etc. are bonded to the birdcage and rear tub. {SNIP}
Art
Art
So do rear bumper and lower rear quarter panelas, wheel wells, etc
I have actually physically unbolted these parts from my car. I am amazed, or rather was amazed when I first did this, that the darn thing would stay together at 140 mph
Is my car unusual?
I know a lot of adhesives were used in C5 and C6and i am sure you are right about "tubs", but at least on mine, everything else un bolts...I have never tried the upper rear quarter panels, so I can't say for sure
Thanks
Drifting
Joined: Aug 2001
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From: Portage Mi
Originally Posted by MrRenoman
It's a very elaborate method of attaching the body to the frame. A real pain to disassemble. Glue and rivets.
Melting Slicks
Joined: Jul 2003
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From: Reno/Sparks Nevada
My Bad...edited
Originally Posted by jackdaroofer
Don't mean to quibble, but on my 88 vert, doors, fenders, hood and bumbers actually un bolt!
Thanks
Thanks
Last edited by MrRenoman; Jul 14, 2005 at 08:39 PM.
Melting Slicks
Joined: Jan 2002
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From: Milan
Originally Posted by MrRenoman
I recently completely disassembled an '86 down to the frame. As Black 'n Blue mentions alot of fiberglass body parts unbolt such as the doors, fenders, hood, bumpers, etc. The rest are bonded to the birdcage, sills and rear tub. What's interesting about the rear tub is that it sits on the rear part of the frame on pads. It's not directly bonded to the frame. However the attachment points where it is bonded and riveted is the vertical and horizontal areas directly behind the seats and at the door jam pillars where the halo ends. The rear fenders are bonded to the rear top surround and the rear top surround is bonded to the tub. The rear fenders attach to the rear bumper and inner fenders, which are attached to the frame with screws and braces. It's a very elaborate method of attaching the body to the frame. A real pain to disassemble. Glue and rivets. I have some pics. I'll post them when I find them.
Art
Art
I'm suspecting that the "C4 ghost driver lean" is related to the wear that can be developped to the pads where the frame is bonded to the frame.
-Beppe-
Thread Starter
Instructor
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From: New Milford Ct
Wow! Thanks for all the answers. I should have been more descriptive with my question. I had no doubts that the frame was metal. My concern is the upper main body shell. On a recent tv show, a Corvette expert talked about the tendency of fibergalss to weaken over time causing cracks and such. He was dealing with a '66 I believe. My C4 developed a crack in the quarter panel behind the driver's door, right at the front-bottom corner of the rear glass. It's about an inch and half long, and has not gotten any longer or wider in the past 5 years when it first appeared. I have patched it with some fiberglass filler, but it came right back. I was wondering if this could be that fibergalss fatigue, or if there were a metal substructure behind it, in which case that would be unlikely. It's the only spot on the car that any crack has developed. The rest of the car is perfect, so I'm kind of concerned as to what the cause is.
