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Old 08-03-2016, 08:07 PM   #1
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1967 Astro I & 1968 Astro II mid-engine Concepts

There are conflicting stories about how this concept came to be, but given that Bill Mitchell and Zora did not like each other, I'll present the most logical (to me) version here. Mitchell was upset that Zora was getting most of the credit for the success of the C2, and then Zora covertly had the rear windpw split removed which sort of sealed the dislike.

Roy Lonberger was working as a design engineer (Mitchell had replaced Harley Earl as the top designer of course) in the Chevy-2 design studio when Mitchell selected a Lonberger sketch to be built as the Astro I. From the beginning, Mitchell wanted a VERY, VERY low stance and he wanted it built across the street at Shinoda's studio (which is why Shinoda sometimes incorrectly gets credit for this concept). This was a practice that was normally used for covert racing concepts. However, the low stance prevented the use of a large V8 and the weird lifting cockpit makes it obvious this was never to be a race car.

Before the full impact of Ralph Nader's Corvair torpedo book, GM developed a Corvair flat 6 with a SOHC on each bank of cylinders, hemispherical combustion chambers and inclined valves. The carburetion came from a pair of prototype GM three-barrel, inline carburetors that used Weber internals. The castings were designed to place the carburetor barrels right over the ports, giving the air-fuel mixture a straight shot at the valves. This was the engine that Mitchell intended to use, but placed directly behind the cockpit as a rear-mid engine, not out back like in the Corvair. Why? Maybe just because it would fit in his sub-36 inch concept, or maybe because he knew Zora never worked with the 6cyl engineers and would not hear about this concept during its extremely short gestation.

Uncharacteristically, Mitchell made zero changes to Longberger's design (no Mitchell fingerprints - this almost NEVER happened) and the fabrication was exceedingly fast. From drawing to show ready took 5 weeks.

The "finished" show car was never a runner. This was partly because of the rush and (IMO) partly because no chassis engineers were involved because of the Zora blackout.

Mitchell, IMO, got what he wanted. The Astro I was a big hit on the show circuit and Zora's name was never (correctly) associated with it.







Although not a runner, Mitchell included plenty of new features ... other than the obvious:
A complete four-wheel independent suspension system. Custom control arms were used at all four corners, as were disc brakes and custom magnesium eight bolt wheels, which featured removable outer rims available in a variety of widths. The two-seater was fitted with 5.5-inch wide wheels in the front and 7-inch wide wheels in the rear. Prototype Goodyear redline tires were used.

BTW, one more reason this was never to be a race car; mentally place yourself behind the steering wheel. Now imagine speeding into a corner and check how close you are to the edge of the track. Ooops, you are so low and the fenders are so high and block such a large area, that you sort of have tunnel vision.
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Old 08-05-2016, 06:25 PM   #2
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1968 Astro II - Rear Mid V8

Apparently, the acclaim for the Astro I enabled Mitchell to excise his dislike/jealousy of Zora - or maybe he knew it was time to get serious about planning a C3 replacement. Regardless, Mitchell's and Zora's teams worked "together" to create the XP-880 Astro II for the 1968 NY Auto Show.

Mitchell's contribution was a body that continued the XP-819 and Astro I evolution - both, of course, were influenced heavily by the Mako Shark / Manta Ray designs. Unlike the Astro I, the XP-880 was to be a preproduction design so there was storage space, doors, pretty good forward visibility, comfortable cockpit, wheel wells that could accommodate performance rubber and a 43" height.

Zora chose to go with a backbone frame, and a 390 HP Mark IV big block feeding a Pontiac Tempest Transaxle. The center backbone actually contained a 20 gal fuel cell. I'm thinking that they could drive this puppy around OK but attempts to break loose the tires had to be verboten, or spend your weekend replacing that rather fragile transaxle.

Unlike the exotic mid-engine sports cars of the day, the Astro II had the radiator out back. The front trunk actually provided luggage storage. There was also enough storage behind the seats to place a collapsible spare tire on one side. The rest of the cockpit included normal instrumentation, exceptional lateral support, and (because of the Tempest Auto) a sliding gear selector.

The rear hood/fenders/hatch/ rear fascia/clamshell started at the rear edge of conventional doors and ended ... well at the rear of the car. Uh huh. I see all you fellow C4 owners / former owners rolling your eyes. Imagine how heavy this Astro II piece would be in production. Definitely heavier than the C4 hood. Regardless, it provided generous access to the storage compartments directly behind the seating area, the suspension, and the drive train. The big block was turned 180 degrees, placing the accessories (alt, water pump, etc.) farther away from the cockpit and the drive to the transaxle at the (former) front of the 427 engine.

The finished XP-880 weighed 200 pounds less than a production 427 - albeit with the fragile transaxle.



Here you can see how much smaller and lower the Astro I is compared to the Astro II. Proportionately, the Astro II also has wider rubber and a more stable / wider wheelbase. These were concessions that Mitchell didn't have to make on his covert, design exercise Astro I.






That's the next installment, the Indy / CERV III, behind the Astro II in this pic.




Why didn't the Astro II lead directly to a production C4?
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Old 12-17-2016, 07:58 PM   #3
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