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Plenty of photos around of the C7 coupe frame, but I can't find any showing the C7's convertible frame.
Can you post up some photos that show the additional horizontal structural cross member and rear bulkhead that the C7 convertible frame has and the coupe doesn't?
This is what GM says on the matter....."...... the Corvette Coupe and Convertible both use an identical rigid aluminum frame structure. Designed as an open-top vehicle from the outset, no additional reinforcements are required."
PS-I'm not "picking" on you, just correcting wrong information that you posted, again.
Really, Joe? I never said it was for "additional reinforcement," I said there is a comparable cross-member to the coupe hoop. The rear bulkhead, while not part of the frame, is well-documented and one of the reasons the convertible is much quieter than the coupe because rear tire noise is isolated from the cabin.
So I drove a Grand sport convertible and coupe... personally didn't notice much of a difference in road noise to warrant grabbing a convertible.... but the grand coupe is pretty amazing so I'll be keeping my eyes open.... isn't a z06 3lz package the same as a grand sport 3lt package without the super charger ? if so how can they have the same price ?
Really, Joe? I never said it was for "strengthening," I said there is a comparable cross-member to the coupe hoop. The rear bulkhead, while not part of the frame, is well-documented and one of the reasons the convertible is much quieter than the coupe because rear tire noise is isolated from the cabin.
Too bad that you don't know the difference between a molded plastic part that attaches to the molded plastic tub that is glued to the aluminum frame, and the aluminum frame itself.
This is what you said....."The convertible has a horizontal structural cross-member and rear bulkhead to replace the hoop on the coupe chassis...."
The chassis is the frame, is it not? Is the plastic part you show part of the chassis? NO!!!!!!!!!!
You said 'structural' and you were implying that the additional "structural" cross member and bulkhead in the convertible was a "structural" part of the frame that makes the convertible stiffer/stronger than the coupe. You said it replaced the hoop in the coupe, on the chassis. No it doesn't. The plastic part you show functions to separate the folding top compartment from the trunk area and to provide an attachment point for the trunk lid hinges and a seal for the trunk lid. It does not replace the hoop on the coupe.
As I pointed out, there is no difference in the frame of the convertible vs the coupe. You implied there was by referencing the "structural" plastic part you showed to the aluminum hoop on the coupe which is attached directly to the aluminum frame. I might also argue, that the aluminum hoop on the coupe does act as a "structural" member on the coupe and does help stiffen the coupe's frame, where as the plastic part you are talking about does nothing to stiffen the convertible's frame.
BTW, where is the additional "bulkhead" that you say the convertible has that you imply is a "structural" member? Are you talking about the removable partition that is between the soft top compartment and the trunk compartment? Is it a "structural" member that adds to the stiffness of the convertible that the coupe doesn't have?
Your reply(post #26) was about chassis flex, not cabin quietness(your post #41). Deflect much?
Are you sure that's not your imagination because your mind is telling you to expect it a convertible? The convertible has a horizontal structural cross-member and rear bulkhead to replace the hoop on the coupe chassis, and which is open in the rear.
I notice no difference between coupe and convertible in terms of chassis flex. In fact, I notice no chassis flex in the convertible or coupe.
There's no way the removable targa top, that's simply latched in provides any additional significant structural rigidity, although it may creak and rattle as many have reported on this forum.
Not sure where to get the C7 specs on chassis rigidity, but the C5 Corvette had these numbers published in SAE SP-1282. The C5 also has a metal-framed latching-in targa roof panel, like the C7. The higher the chassis resonance, the stiffer it is:
C5 Convertible = 20Hz
C5 Coupe without the Targa roof installed = 20.5Hz
C5 Coupe with the Targa roof installed = 22Hz
C5 Fixed Roof Coupe = 24Hz
Similarly, I would expect the C7 Targa Coupe to be stiffer than the C7 Convertible.
Last edited by ersatz928; May 30, 2017 at 01:44 PM.
Fact: C7 convertible weighs 64 pounds more than coupe (that's direct from GM, search it if you're so inclined). Spring rates and shock damping specs are IDENTICAL on ALL variants of C7 coupe/convertibles (ex. Z06 Coupe/convertible have the same shocks/springs) which speaks volumes of how close the 2 cars are in terms of chassis rigidity. Obviously, many convertibles are considerably heavier than their coupe running mates....as an example, The BMW M240i coupe weighs 3,499 pounds verses the M240i convertible which weight 3,788 pounds (289 pounds difference). Or a 2SS Camaro coupe at 3,685 pounds verses the 2SS convertible at 3,956 (271 pounds different). In both examples, most of this weight is structural reinforcement where the 64 pounds in the Corvette is the motor and plumbing for the power top.
Opinion: I own a C7 convertible and have driven a friend's C7 coupe extensively. I cannot tell ANY difference in chassis stiffness between the 2 cars. I do THINK that the coupe is a little stiffer, but MY seat of the pants CANNOT tell any difference. Driving the 2 cars over the same roads, neither exihibits any cowl shake, windshield header shake, or rear view mirror flutter. The coupe does have a great deal of buffeting with the top out that the convertible does not have, and without question, when both cars are closed up, the convertible is quieter inside.
Fact: C7 convertible weighs 64 pounds more than coupe (that's direct from GM, search it if you're so inclined). Spring rates and shock damping specs are IDENTICAL on ALL variants of C7 coupe/convertibles (ex. Z06 Coupe/convertible have the same shocks/springs) which speaks volumes of how close the 2 cars are in terms of chassis rigidity. Obviously, many convertibles are considerably heavier than their coupe running mates....as an example, The BMW M240i coupe weighs 3,499 pounds verses the M240i convertible which weight 3,788 pounds (289 pounds difference). Or a 2SS Camaro coupe at 3,685 pounds verses the 2SS convertible at 3,956 (271 pounds different). In both examples, most of this weight is structural reinforcement where the 64 pounds in the Corvette is the motor and plumbing for the power top.
Opinion: I own a C7 convertible and have driven a friend's C7 coupe extensively. I cannot tell ANY difference in chassis stiffness between the 2 cars. I do THINK that the coupe is a little stiffer, but MY seat of the pants CANNOT tell any difference. Driving the 2 cars over the same roads, neither exihibits any cowl shake, windshield header shake, or rear view mirror flutter. The coupe does have a great deal of buffeting with the top out that the convertible does not have, and without question, when both cars are closed up, the convertible is quieter inside.
Both the C5 and the C6 were designed from the beginning to be open air cars(Targa and convertible) with the exception of the Z06 and the ZR, so it's not a design feature that is unique to the C7.
The 1998 C5 convertible(manual top) weighed one pound more than the coupe.
The 2005 C6 convertible(manual top) weighed twenty pounds more than the coupe.
Neither the C5 nor the C6 nor the C7 convertibles had any additional "structural cross members and bulkheads" added to stiffen them up vs the coupe.
Most old line Corvette owners are well aware that the modern Corvettes (C5 on), were designed as open air (convertible) cars, with no need for structural rigidity additions as most convertibles need. They also know that the C6 Z06/ZR1 aluminum frames did not have the torsional rigidity necessary to deal with the higher output engines AND removable tops/convertibles, hence the bolted in Targa roof and no convertible option. This is the reason the C6 427 convertible had the steel frame from the "normal" C6's and also why it (427 convertible) was not labeled as a "Z06".
Most old line Corvette owners are well aware that the modern Corvettes (C5 on), were designed as open air (convertible) cars, with no need for structural rigidity additions as most convertibles need. They also know that the C6 Z06/ZR1 aluminum frames did not have the torsional rigidity necessary to deal with the higher output engines AND removable tops/convertibles, hence the bolted in Targa roof and no convertible option. This is the reason the C6 427 convertible had the steel frame from the "normal" C6's and also why it (427 convertible) was not labeled as a "Z06".
Very true, and the C6 aluminum frame weighs 37 pounds less than the C7's aluminum frame. Back in 2006 GM said that they estimated it would require 44 pounds of additional bracing to the Z06's aluminum frame to make it an "open air" car.
The C6 Z06 aluminum frame was designed at the same time as the C6's steel frame and GM's intent was that the Z06 would be a lightweight "supercar" and GM wasn't interested in adding weight that was not required when the magnesium frame of the Z06's roof bolted to the windshield and the B pillar with ten bolts would do the job. 44 pounds saved, when they were not intent on making a heavy Z06 GT cruiser convertible.
Thus a "beefed up" C6 aluminum frame would have weighed only 7 pounds more than the "beefed up" C7 aluminum frame.
The C7's frame would have saved 7 pounds over the C6's aluminum frame if the C6's frame had been modified, yet the C7 stingray picked up 99 pounds over the 2013 C6 Z06. Even with the C7's hollow cast suspension parts and hollow cast cross members that weighed less then the C6 and the C7's body panels that weighed less than the C6's, the C7 picked up fat.
So, even if GM had put that additional 44 pounds in the frame of the C6 Z06 to make the 427 Convertible a Z06 convertible, the car would have still weighed less than the C7 StingRay coupe, and approximately 92 pounds less than the steel framed 427 Convertible.
That late into the C6's lifecycle(last year of production), GM didn't' want to spend the money/time "upgrading" the Z06's aluminum frame for the 427 Convertible, so they raided the parts bin and used the C6's steel frame. GM also didn't want a C6 Z06 convertible/targa top with an aluminum frame and 505 HP stealing the limelight from the C7 convertible/targa top with it's aluminum frame and only 460 HP, that would still be coming down the assembly line after the first 2014 C7 started in production.
Sorry to the OP. ^^^^^^^
To reiterate: From my EXTENSIVE driving time in both a C7 coupe (a friend's car) and my own C7 convertible, I can not tell ANY difference in the way they handle, or perceived chassis rigidity (pulling into driveways at an angle, etc...).
Are you sure that's not your imagination because your mind is telling you to expect it a convertible? The convertible has a horizontal structural cross-member and rear bulkhead to replace the hoop on the coupe chassis, and which is open in the rear.
I notice no difference between coupe and convertible in terms of chassis flex. In fact, I notice no chassis flex in the convertible or coupe.
There's no way the removable targa top, that's simply latched in provides any additional significant structural rigidity, although it may creak and rattle as many have reported on this forum.
Honestly, no. We have way too much frost heaved/poorly patched roads to not notice. I will admit I'm "tuned into" this kind of stuff more than the average motorist. But, it is not just in my head. I know of certain curb cuts that are very severe and my vert does flex a bit going slowly over the hump on an angle. I can hear it - very minor creaks. The coupe made no such noise. Still, for what the car weighs, the structure is quite impressive.
A bit of information on stiffness...Corvettes, for weight reasons, are not the stiffest out there. Numbers in Nm/degree
I consider myself pretty "tuned in" to such things as well, as are many others who have weighed in here. Having owned dozens of convertibles over the years, I know what chassis flex feels like. Your opinion seems to be in the distinct minority regarding perceptible differences in chassis flex in C7s. In fact, I think you're the only person in this thread to make that observation, while plenty of others have said the opposite.
However, here's the latest in a long series of coupe chassis flex threads:
That's not accurate with regard to cooling the e-diff.
The convertible, Z51, GS, and Z06 has the cooling ducts at the bottom front of the rear wheels wells on both sides to replace those on top of the fenders of the coupe.
oh wow. I thought they were still in the fender liners. I wonder if this gets more/less or about the same airflow? my bad.
Last edited by BrunoTheMellow; May 31, 2017 at 01:05 AM.
They never were in the fender liners. That's a picture from my '14 Z51 convertible.
I could see that there actually might even be more airflow in the lower location, since air is channeled under the car with less turbulence than the upper rear fender location.
Well, as I said, my Z51 convertible is a 2014, and I don't have those vents, just the ducts in the picture.
So maybe I stand corrected as well. Maybe there have been changes over various MYs. I also wonder if the ducts are also there in addition to the vents on later MYs. You have to get flat on the floor to even see them.
I was thinking of possibly trading in my coupe for a convertible... are there any differences in performance due to the convertible top? also can you fit golf clubs etc... in a convertible ?
Thanks,
Dan
The differences are negligible for daily driving. Stick with the coupe for track use.
Last edited by airforcex; May 31, 2017 at 03:33 AM.
Full set of clubs, regular size cart bag and shoes, no problem. I don't track my car's and would never want anything but a convertible. Of course I live in Central Florida. T-top's are ok but no match for the feel of a convertible in MHO. I have had both over the years.
Good luck with whatever you chose and as they keep repeating on this site, to each his or her own......
