Magride in Convertible vs Coupe
05-03-2018, 11:02 AM
#1
Le Mans Master
Thread Starter
Magride in Convertible vs Coupe
I was watching a show about a Ferrari last night and they were mentioning how the car wasn't as rigid in roaster form so Ferrari had softened the magride for the convertible.
That brought to mind two things:
1) My Z roadster is so rigid that I can't tell it from a coupe (and it IS that good, I have a BMW M3 that flexes far, far more)
2) The roadster and the coupe must share the same magride calibration since the current update only delineates by FE6/FE7 and so on, and never by body style.
Just an observation, and not a big one, but I hadn't stopped to notice before that they're all calibrated apparently the same!
That brought to mind two things:
1) My Z roadster is so rigid that I can't tell it from a coupe (and it IS that good, I have a BMW M3 that flexes far, far more)
2) The roadster and the coupe must share the same magride calibration since the current update only delineates by FE6/FE7 and so on, and never by body style.
Just an observation, and not a big one, but I hadn't stopped to notice before that they're all calibrated apparently the same!
Last edited by davepl; 05-03-2018 at 11:03 AM.
05-03-2018, 06:19 PM
#3
Moderator
I don't think there is any difference in the calibration between coupe and convertible. From GM press release:
The technologically advanced foundation is an all-new aluminum frame structure that is 99 pounds (45 kg) lighter, and is 57-percent stiffer than the previous-generation convertible. The result is a frame that is so strong, no structural reinforcements are needed for the convertible model. The only changes are limited to accommodations for the folding top and repositioned safety belt mounts.
Compared to the previous generation, which used continuous hydroformed main frame rails with a constant 2mm wall thickness, the new Corvette’s frame features main rails composed of five customized aluminum segments, including aluminum extrusions at each end, a center main rail section and hollow-cast nodes at the suspension interface points. Each segment’s gauge varies in thickness from 2mm to 11mm, tailored – along with the shape – by the simulation software to optimize the strength requirements for each frame section with minimal weight.
The aluminum frame is manufactured using innovative manufacturing processes at GM’s Bowling Green, Ky., assembly plant. The state-of-the-art facility employs several advanced joining technologies to ensure dimensional accuracy within 0.75 mm. Each frame features:
354 spot-welds using a GM-patented process that uses a unique electrode designed specifically for aluminum
188 Flowdrill-machined fasteners, which are installed by a high-speed drill that extrudes the frame material to create a strong, integral collar that is tapped for bolt-on fasteners
113 feet of structural adhesives, used in conjunction with welding and fasteners to increase overall frame stiffness
37 feet of laser welds, which join frame sections via a precise beam of high energy that minimizes heat beyond the weld area for improved structural accuracy.
The frame’s greater strength and lower weight are complemented by chassis elements also designed for low-mass strength, including hollow-cast aluminum front and rear cradles that are approximately 25-percent lighter and 20-percent stiffer than the solid cradles used on the previous structure.
Compared to the previous generation, which used continuous hydroformed main frame rails with a constant 2mm wall thickness, the new Corvette’s frame features main rails composed of five customized aluminum segments, including aluminum extrusions at each end, a center main rail section and hollow-cast nodes at the suspension interface points. Each segment’s gauge varies in thickness from 2mm to 11mm, tailored – along with the shape – by the simulation software to optimize the strength requirements for each frame section with minimal weight.
The aluminum frame is manufactured using innovative manufacturing processes at GM’s Bowling Green, Ky., assembly plant. The state-of-the-art facility employs several advanced joining technologies to ensure dimensional accuracy within 0.75 mm. Each frame features:
354 spot-welds using a GM-patented process that uses a unique electrode designed specifically for aluminum
188 Flowdrill-machined fasteners, which are installed by a high-speed drill that extrudes the frame material to create a strong, integral collar that is tapped for bolt-on fasteners
113 feet of structural adhesives, used in conjunction with welding and fasteners to increase overall frame stiffness
37 feet of laser welds, which join frame sections via a precise beam of high energy that minimizes heat beyond the weld area for improved structural accuracy.
The frame’s greater strength and lower weight are complemented by chassis elements also designed for low-mass strength, including hollow-cast aluminum front and rear cradles that are approximately 25-percent lighter and 20-percent stiffer than the solid cradles used on the previous structure.
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05-03-2018, 06:47 PM
#4
I've owned convertibles of many makes and models for more than 30 years, and my two C7 convertibles are the first and only that I detect zero chassis flex in.
05-04-2018, 08:45 AM
#5
Le Mans Master
The C7 was designed so that the convertible is as rigid as the coupe. The Mag Ride calibrations should be identical.
05-04-2018, 09:06 AM
#6
Melting Slicks
I believe they are the same. The other aspect which has been brought up in here on the frame strength can be summed up by this:
The same frame used on C7 is used across its entire lineup. From base car to ZR1, I think that speaks volumes of how strong it really is.
The same frame used on C7 is used across its entire lineup. From base car to ZR1, I think that speaks volumes of how strong it really is.
05-04-2018, 11:08 AM
#7
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I was watching a show about a Ferrari last night and they were mentioning how the car wasn't as rigid in roaster form so Ferrari had softened the magride for the convertible.
That brought to mind two things:
1) My Z roadster is so rigid that I can't tell it from a coupe (and it IS that good, I have a BMW M3 that flexes far, far more)
2) The roadster and the coupe must share the same magride calibration since the current update only delineates by FE6/FE7 and so on, and never by body style.
Just an observation, and not a big one, but I hadn't stopped to notice before that they're all calibrated apparently the same!
That brought to mind two things:
1) My Z roadster is so rigid that I can't tell it from a coupe (and it IS that good, I have a BMW M3 that flexes far, far more)
2) The roadster and the coupe must share the same magride calibration since the current update only delineates by FE6/FE7 and so on, and never by body style.
Just an observation, and not a big one, but I hadn't stopped to notice before that they're all calibrated apparently the same!
My wife has a BMW M3 ALSO & HAS EVERY THING THAT CAN COME ON ONE. That car rides like a dream & does flex like you are saying to the c7.
Good luck in the car man.. Robert
05-04-2018, 11:40 AM
#9
Le Mans Master
In addition to Mag Shock calibration question....
Is there a difference in Vert vs Cpe transverse spring rate, sway bays, suspension bushings, wheel alignment?
Accepting the Base, z51, GS, Z06, ZR different springs & bars.
Is there a difference in Vert vs Cpe transverse spring rate, sway bays, suspension bushings, wheel alignment?
Accepting the Base, z51, GS, Z06, ZR different springs & bars.
05-04-2018, 12:02 PM
#10
No, convertibles have the identical equipage and specs as the coupe counterpart within models/submodels. Think about it, all coupes have removable roofs.
Last edited by Foosh; 05-04-2018 at 12:02 PM.
05-04-2018, 01:25 PM
#11
Instructor
Exactly, There isnt really a coupe option anymore, its either targa or convertible. The chassis flex has always been the same between the two also. Thats why the c5z and c6z/c6zr1 were FRC cars, this was in order to prevent some of the chassis flex from the roof being removed.
05-04-2018, 03:04 PM
#12
Advanced
The Ask Tadge response to the mag ride update indicates that the MRC is calibrated differently for each vin. I think the tuning is slightly different for stingray, z51, GS, ZO6, ZR1, and targa/vert versions of them. Maybe not very significantly, but definitely differently. Weight distribution, aero, and components like sway bars affect that as well I am sure.
05-04-2018, 04:06 PM
#13
The calibrations aren't different for each VIN, it's just that the VIN is used to determine the correct calibration for each car, and to keep a record of cars that have been upgraded. If I recall correctly from chassis engineer Jim Mero's answer, there are 21 different upgrade calibrations, taking into account MY and model type.
Nonetheless, pertinent to the topic here none of the calibrations are linked to coupe vs. convertible.
Nonetheless, pertinent to the topic here none of the calibrations are linked to coupe vs. convertible.
Last edited by Foosh; 05-04-2018 at 04:15 PM.
05-04-2018, 04:35 PM
#14
Advanced
Ah. I interpreted the VIN part to mean that the calibration was different per vehicle category such as base or Z51. Now I see that while that is the case, the full VIN is also specifically used to indicate which vehicles have had the calibration done.
And yeah I see in the full writeup that coupe vs vert was never mentioned in the calibration discussion. I thought it would make a little bit of a difference, but I guess the body rigidity is consistent regardless of top.
And yeah I see in the full writeup that coupe vs vert was never mentioned in the calibration discussion. I thought it would make a little bit of a difference, but I guess the body rigidity is consistent regardless of top.
05-04-2018, 04:36 PM
#15
It's great to read how state-of-the-art the C7 is, but there seems to still be flex going on since there's a continuous mention from some hatchback/coupe members here of roof creaking. If there were absolutely no flex, then why the reports of roofs creaking?
05-04-2018, 04:39 PM
#16
My 2017 Stingray convertible with MSRC, is one tight ride in Tour mode. Which is fine with me.
05-04-2018, 04:50 PM
#17
05-04-2018, 05:21 PM
#18
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It is just the shocks & the set up on these cars the BMW even the M SERIERS. I think the bmw is made more for a 
woman driving the car. Really the ride in the bmw is just not no where as stiff of a ride as the c7. The bmw is more like it rolls with the feel of the road. The c7 you JUST feel every roll in the road if that make any sense at all. But for sure the c7 is a road course car & feel...
05-04-2018, 05:48 PM
#19
Moderator
Nobody said there was no flex, just that it is rigid to the point that the convertible does not require any additional reinforcement and that it is significantly more rigid that the previous generations.