Interesting Convertible Information/History
02-21-02, 04:46 PM
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Interesting Convertible Information/History
I got this from 'that other mazda convertible' forum.
The post was in a thread gathering infomation about the 'vert in comparison to the Miata. I knew that this person was part of the Miata design team, but didn't know he had a hand in the FC. Anyhow read and enjoy.
quote:
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Actually the 2nd gen RX-7 *was* originally designed to be a convertible
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Not hardly. When we started the sketch program for the FC in November, 1982, the question of a convertible was raised and summarily rejected. It was the first passenger car program I worked on (I got to cut my teeth on the B-series pick-up) and being a bit of a fan of open cars, Yoichi Sato and I pursued the point. At length and to the consternation of some, including our boss.
Engineering was dead set against it and made no accommodation whatsoever towards it, even mandating clamshell doors rather than frameless side glass or doors with discrete sashes to hold an open version at bay. The official reason to go with the clamshells was weight control, yet when the FD was done (a car where they were serious - perhaps too much so at times - about keeping weight in line) doors with discrete sashes were selected for minimum weight.
This decision at the start is why the convertible body in white was as heavy as it was (though they did get good structural rigidity out of the mods) and the reason for the delay in introduction of the car. The convertible wasn't given the go-ahead until the eve of the car's launch, though it was fast-tracked once the approval was granted by The Decision Makers. Still it required a major tear-up of the structure and manufacturing process in relation to the fixed roof P747.
Between the time the convertible got approval and the first mechanical prototypes were done, the program manager for the RX-7 was changed, with Takaharu Kobayakawa taking the top job there. Koby-san shared the disdain a number of us had for the power top with rigid forward section and initiated a study to use a Miata-style soft top (albeit with a glass rear window and lining) instead of the power set-up. Sadly, the fast tracking meant that by the time Koby-san stepped into the hot seat tooling for the top lift mechanism had already been completed, so the simple human-operated top was not to be. This was particularly disappointing to a number of us, since the top and related mechanism - as well as the structural accommodation for same - added about 198kg to the car's weight in comparison to the human-powered top with glass rear window and inner lining.
Still, the RX-7 convertible was a superb boulevard car and was close to being an excellent GT car, with a slight lack of luggage space the only real negative vis-a-vis GT car criteria. Like all FC RX-7s, it had the same trouble-prone (and warranty-intensive) HVAC system. Surprisingly, the quickly engineered top lift system proved to be reasonably trouble-free.
I was always fascinated by the fact the convertible was sold in North America solely in normally-aspirated form while in Japan you could only get it with the 13B Turbo.
bwob
__________
The post was in a thread gathering infomation about the 'vert in comparison to the Miata. I knew that this person was part of the Miata design team, but didn't know he had a hand in the FC. Anyhow read and enjoy.
quote:
--------------------------------------------------------------------------------
Actually the 2nd gen RX-7 *was* originally designed to be a convertible
--------------------------------------------------------------------------------
Not hardly. When we started the sketch program for the FC in November, 1982, the question of a convertible was raised and summarily rejected. It was the first passenger car program I worked on (I got to cut my teeth on the B-series pick-up) and being a bit of a fan of open cars, Yoichi Sato and I pursued the point. At length and to the consternation of some, including our boss.
Engineering was dead set against it and made no accommodation whatsoever towards it, even mandating clamshell doors rather than frameless side glass or doors with discrete sashes to hold an open version at bay. The official reason to go with the clamshells was weight control, yet when the FD was done (a car where they were serious - perhaps too much so at times - about keeping weight in line) doors with discrete sashes were selected for minimum weight.
This decision at the start is why the convertible body in white was as heavy as it was (though they did get good structural rigidity out of the mods) and the reason for the delay in introduction of the car. The convertible wasn't given the go-ahead until the eve of the car's launch, though it was fast-tracked once the approval was granted by The Decision Makers. Still it required a major tear-up of the structure and manufacturing process in relation to the fixed roof P747.
Between the time the convertible got approval and the first mechanical prototypes were done, the program manager for the RX-7 was changed, with Takaharu Kobayakawa taking the top job there. Koby-san shared the disdain a number of us had for the power top with rigid forward section and initiated a study to use a Miata-style soft top (albeit with a glass rear window and lining) instead of the power set-up. Sadly, the fast tracking meant that by the time Koby-san stepped into the hot seat tooling for the top lift mechanism had already been completed, so the simple human-operated top was not to be. This was particularly disappointing to a number of us, since the top and related mechanism - as well as the structural accommodation for same - added about 198kg to the car's weight in comparison to the human-powered top with glass rear window and inner lining.
Still, the RX-7 convertible was a superb boulevard car and was close to being an excellent GT car, with a slight lack of luggage space the only real negative vis-a-vis GT car criteria. Like all FC RX-7s, it had the same trouble-prone (and warranty-intensive) HVAC system. Surprisingly, the quickly engineered top lift system proved to be reasonably trouble-free.
I was always fascinated by the fact the convertible was sold in North America solely in normally-aspirated form while in Japan you could only get it with the 13B Turbo.
bwob
__________
02-21-02, 08:50 PM
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Originally posted by NZConvertible
That's awesome, cheers. Can I have the link to that vert forum?
That's awesome, cheers. Can I have the link to that vert forum?
.
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02-22-02, 11:41 AM
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Originally posted by 1Revvin7
ah, what is so wrong with it? mine is fine and blow hot air....
ah, what is so wrong with it? mine is fine and blow hot air....
02-22-02, 01:44 PM
#11
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I know why Mazda had an NA only vert - it appealed to a wider variet of buyers.
If they had a turbo - the additional price would have killed sales.
Remember the 1st and 2nd gens were "rotary cars for everyone" and had a wider appeal.
The 3rd gens were nice, but were in the "entry exotic price range & class."
If they had a turbo - the additional price would have killed sales.
Remember the 1st and 2nd gens were "rotary cars for everyone" and had a wider appeal.
The 3rd gens were nice, but were in the "entry exotic price range & class."
02-22-02, 08:50 PM
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bwob revisited the thread and had even more info about the development 
. If my 'vert would have weighed 300lbs of the line, I'd probably still own it.
Here's the text:
quote:
--------------------------------------------------------------------------------
So if it had a manual top, it would have weighed about the same as the coupe?
--------------------------------------------------------------------------------
Close to the coupe's weight. I miscalculated the difference between the car as built and the alternate hand-operated top version which was briefly studies. The 198kg figure did not take into to account the replacement top frame, cover and glass rear window (which could have been marginally larger than the one fitted to the production car). With those essential components factored in, the weight disparity would have been about 140 to 150kg, still a considerable amount.
quote:
--------------------------------------------------------------------------------
I heard it from different sources (one of them being from the RX-7 club magazine). I wonder why they were mis-informed
--------------------------------------------------------------------------------
You'd obviously have to ask the sources you'd mentioned, but there weren't any members of the RX-7 owners club peering over our shoulders while we were doing the car.
As a complete aside, the P747 (FC or second-generation RX-7) had a fascinating design evolution. Four design themes were produced by Mazda against four done under contract by Bertone, with complete interior proposals for the lot along with full-scale fibreglass models for each used in a customer clinic held in La Canada, California in 1983.
Additionally, the winning proposal as originally approved for production didn't have the vestigial fender bulges worn by the production FC. Which made it look considerably less Porsche-like. But somebody in the food chain thought they'd be a good idea.
As a general rule of thumb, a car which is destined to be offered in convertible form (and was engineered that way from the start or was protected in the engineering phase to make a convertible easier/simpler/smarter will not use clamshell/panel doors. Such cars usually feature discrete (applied) door sashes or frameless side glass. In the case of the BMW E36, four-door sedans has clamshell doors while the two-doors used sashless doors to make a convertible a simpler engineering proposition as well as to share costs on the doors and door hardware, a very expensive portion of body engineering.
While clamshell doors and the apertures for same can be cut or altered with a die insert at the pressing stage, this results in additional manufacturing process not shared with other cars and as a result drives prices up. Also, when developing open cars from closed ones, nobody in their right mind would start out with a hatchback if they had given any thought to the idea of a convertible being pulled off the same structure. With that big hole in the back to fill up (and no web or upper crossmember between the rear wheelwells), considerable re-engineering must go into making the structure properly rigid in each axis.
bwob
__________
If you can't go fast with 90hp, 900hp won't help you
. If my 'vert would have weighed 300lbs of the line, I'd probably still own it.Here's the text:
quote:
--------------------------------------------------------------------------------
So if it had a manual top, it would have weighed about the same as the coupe?
--------------------------------------------------------------------------------
Close to the coupe's weight. I miscalculated the difference between the car as built and the alternate hand-operated top version which was briefly studies. The 198kg figure did not take into to account the replacement top frame, cover and glass rear window (which could have been marginally larger than the one fitted to the production car). With those essential components factored in, the weight disparity would have been about 140 to 150kg, still a considerable amount.
quote:
--------------------------------------------------------------------------------
I heard it from different sources (one of them being from the RX-7 club magazine). I wonder why they were mis-informed
--------------------------------------------------------------------------------
You'd obviously have to ask the sources you'd mentioned, but there weren't any members of the RX-7 owners club peering over our shoulders while we were doing the car.
As a complete aside, the P747 (FC or second-generation RX-7) had a fascinating design evolution. Four design themes were produced by Mazda against four done under contract by Bertone, with complete interior proposals for the lot along with full-scale fibreglass models for each used in a customer clinic held in La Canada, California in 1983.
Additionally, the winning proposal as originally approved for production didn't have the vestigial fender bulges worn by the production FC. Which made it look considerably less Porsche-like. But somebody in the food chain thought they'd be a good idea.
As a general rule of thumb, a car which is destined to be offered in convertible form (and was engineered that way from the start or was protected in the engineering phase to make a convertible easier/simpler/smarter will not use clamshell/panel doors. Such cars usually feature discrete (applied) door sashes or frameless side glass. In the case of the BMW E36, four-door sedans has clamshell doors while the two-doors used sashless doors to make a convertible a simpler engineering proposition as well as to share costs on the doors and door hardware, a very expensive portion of body engineering.
While clamshell doors and the apertures for same can be cut or altered with a die insert at the pressing stage, this results in additional manufacturing process not shared with other cars and as a result drives prices up. Also, when developing open cars from closed ones, nobody in their right mind would start out with a hatchback if they had given any thought to the idea of a convertible being pulled off the same structure. With that big hole in the back to fill up (and no web or upper crossmember between the rear wheelwells), considerable re-engineering must go into making the structure properly rigid in each axis.
bwob
__________
If you can't go fast with 90hp, 900hp won't help you
02-22-02, 11:06 PM
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I know why Mazda had an NA only vert - it appealed to a wider variet of buyers.
Actually, the only reason the T2 Vert wasn't imported (and thinking about this always makes me mad) was due to the Gas Guzzler tax. The T2 Verts lower gas mileage dragged down the whole line in that respect, so had to be restricted away to stay above that line. 
Left hand drive T2 Verts were produced, but they only made it to Europe. I bought a factory brochure from a guy in Belgium that proves it. Best darn looking 2nd Gen in my humble opinion.
Leave it to good ol' government (Read... Ralph Nader) wisdom to mess up a good idea.
At least the retro-fit option is there to bridge the gap.
Left hand drive T2 Verts were produced, but they only made it to Europe. I bought a factory brochure from a guy in Belgium that proves it. Best darn looking 2nd Gen in my humble opinion.
Leave it to good ol' government (Read... Ralph Nader) wisdom to mess up a good idea.
At least the retro-fit option is there to bridge the gap.
Last edited by HOZZMANRX7; 02-22-02 at 11:11 PM.
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