This beautiful yellow C4 was posted at the Cohort by chrisjcieslak , under the title “Did they make a ZR-1 convertible?”. That’s actually a very interesting question and one which I decided to find an answer to. As it turns out; yes. A couple of them, actually.
There have actually been several ZR-1 convertibles across the four Corvette generations with such a model on their lineup. Pedantry forbids me from including the C6 and C7 ZR1’s thanks to the lack of hyphen in the name. But the older C3 models had a ZR-1 package if you decided to opt for the LT-1 engine between 1970 and 1972. Eight people added infinite headroom to the heavy duty suspension components, power brakes and a heavy-duty manual transmission. Should make up for the lack of air conditioning. And the unencumbered V8 rumble should make an adequate substitute for the radio.
Compared to the 53 C3 ZR-1s ever made, 6,939 C4 ZR-1s rolled off the assembly line in Bowling Green. I’ve gone on record saying that the C4 is my favorite of all the Corvette generations. A completely new design after the evolutionary C3, it set the design template from which all future Corvettes were built. And yet, it was unmistakably a product of the decade that spawned it.
Sure, the digital gauges were a bit unfortunate. And nowadays they carry an air of…middle age about them. Doesn’t matter, they have remained my favorites since I’ve got memory. And out of all the C4s, the ZR-1 is my favorite of all. Twice the price of a normal Corvette with only wider wheels, upgraded suspension, steering and brakes, a unique rear end (which stopped being unique after the 1991 facelift) and a small badge to distinguish it visually, as most of the changes were done under the hood.
Thanks to the 375 horsepower V8 (designated LT5, designed by Lotus and assembled by Mercury Marine), the ZR-1 could crack 60 in 4.4 seconds. Today that is the domain of the Camaro SS, but back in the 1988, a mormal Corvette would run 6.1 to 60 (According to either C&D or R&T). The ZR-1 gave some much needed bite to the corvette. 4.4 Seconds was reserved for 911 Turbos and Lotus Esprits at the time. The Testarossa would do it in 5, which means it could be out-dragged by a good driver on a turbo V6 Pontiac Firebird.
And thanks to the brake and suspension upgrades done in collaboration with Lotus, you could keep going at transcontinental speeds even if the roads got twisty. There were only two compromises. The price, and the fact that you would have to make due with the coupe and its targa top. GM discovered that the convertible body just wasn’t stiff enough to handle the power of a ZR-1.
And how did they discovered that?
With this! Meet the Corvette DR-1, the only GM backed C4 ZR-1 convertible. DR stands for Don Runkle, then Vice-President of Advanced Engineering and the man who requested that this convertible ZR-1 was built. Naturally, after he had discovered that production of a ZR-1 convertible would not be viable, he took it upon himself to discover the long term effects of LT-5 use in a convertible by using it as his personal car. Truly a man who thoroughly validates his work. Last we heard of it, it was sold at a 2009 Barrett-Jackson collector car auction for a not-inconsiderate $265,000.
So that was it for convertibles made by GM themselves. However, ASC also decided to have a go at it. Their result is this, the ASC ZR-1 Spyder. is a much more involved affair including a chopped windshield. Originally presented in silver with a yellow interior, it picked a coat of purple paint and a red retrim before making its way to the Bowling green Corvette museum.
Then that sinkhole kicked in.
Do not let the horrifying image scare you though. It’s okay now, back on the plinth where it was supposed to be.
Finally, there is this, a 1991 C4 done by Metalcrafters, an outfit in Fountain Valley, California. The vehicle was originally done for Dr. Larry Bartschi. He also decided to send the engine for some custom work which bumped it up to 475 horsepower. It has gone through three owners and at least 175,000 miles.
And…that’s it, there have indeed been several C4 ZR-1 convertibles. But this particular one, I’m afraid, isn’t one. It’s just a very well kept Corvette C4 convertible being enjoyed on a clear night. It’s the best time to have the roof down anyway.
The C4’s are a neat design, but boy do they fall short in a lot of places.
’84s had the trashy Crossfire injection, early cars had the clunky 4+3, LT1 cars had the loathsome optispark system. Not to mention all of the cars had interiors that rattled like a rubber maid container full of lego bricks. And lets not forget rigidity, or lack thereof. Drive a C4 with the roof off over some railroad tracks and you’ll find it’s as floppy as a bloodhound’s ears.
None of this is to impugn the performance of the cars themselves, least of all ZR1, which, besides the ’84 models, was quite good for the times.
They remain cheap for a variety of reasons, not the least of which is how tricky they are to get in and out of, putting them out of the realm of ownership for many Corvette enthusiasts; elderly gentleman in so many words.
That said, when properly equipped (TPI & 6 speed), they are fun to drive, and posses more 80s flair that most any car of the era short of a Countach, making anyone feel like the brash Miami coke dealers that undoubtedly bought them new.
Saying they are challenging for their prospective owners to get in and out of brings back memories of my late father. He bought a bronze metallic 1986 Corvette brand new when he was 45. It was his present to himself for making partner at the accounting firm. In the course of his ownership, he managed to break off the directional/wiper stalk at least three times by snagging it in the cuffs of his suit trousers getting into the car. A rather large gentleman, he also had trouble getting out. Much to his teenage children’s amusement.
I had the opportunity to drive it three times. Steering, brakes, clutch all required heavy inputs.
From new, the car squeaked and rattled. But it sure could go like stink.
If the right C4 came around, I’d buy one in a heartbeat.
I don’t get all the hate for Opti-spark. I think this is just internet lore that has made it such an evil system. The opti-spark ignition system was considerably more accurate than a traditional distributor it replaced. The early models had inadequate venting, but this was later fixed with better venting and a vacuum line. It’s not hard to retrofit the early systems. The only other issue was water intrusion, which could happen if the water pump failed, or it was submerged.
When I worked at a GM dealer these were a lot of money to replace, parts and labour, but that was 20 years ago. Prices have come down, and they are not hard for a DIYer to replace. The key is, use quality parts, and make sure you change the water pump when you do the opti-spark. Personally I’d much rather have an LT1 and deal with the opti-spark over having a TPI engine.
I couldn’t disagree more. The LT1 is the awkward middle child of the GM small blocks. All the disadvantages of the Chevy Small Block and the LS family, with a fraction of the aftermarket support. I just don’t think the 60ish horsepower is worth the hassle of a hokey ignition setup, especially with how cheaply a conventional 350 can be modified.
Optispark reeked of a NIH alternative to distributerless ignition that was the clear future, which came with the LS. The LT1 had some good things going for it, but optispark was as much of a dead end as feedback carburetors
Opti-spark was simply the final incarnation of the distributor, nothing more. GM had DIS before the introduction of opti-spark. Yes, they half assed it and should have used DIS, but at least it improved the distributor technology. It was nothing really new, just an optical distributor and it was moved to the front of the engine. This was done to improved clearance and to improve accuracy due to camshaft deflection when the distributor is at the back of the engine. The TPI engines weren’t exactly GMs finest engines either, with lots of intake sealing issues.
All I am saying is that fixing opti-spark isn’t all that difficult or expensive to fix anymore. There is still decent aftermarket support, I including a number of complete hi-po replacement distributors. I have worked on them and I never understood all the fear of the system, that’s all.
I’ve had four b-bodies with LT1’s and have never had an optispark go out (knock on wood). Perhaps my time is coming, but Ive had good experiences with the engines. No other significant problems, either.
I remember when a ZR-1 seemed to grace the cover of at least one mainstream car magazine every month, involved against “awesome” and “groundbreaking” comparison tests against supercars of various sorts.
I have come to admire the clean lines of the C4, but have read enough about its shortcomings that I would head towards a later C3 if I were in the market for an affordable Vette.
Gerardo, what a great surprise to see this pic up on the site today!
I found this particular like-new C4 in front of the hotel I was staying at in Bloomington-Normal, IL. I actually have an article about the rental I drove down there that I need to finish…
The ZR1 was the Cosworth Vega done right.
I had a giant poster of all year Corvettes on my childhood bedroom wall, and right dead center was a facelifted ZR1, so these are a bit nostalgic icons to me, even if the C4 isn’t my favorite generation, even then(I drooled over the C1s and C3s on it mostly). The convertible is the greatest form of C4 IMO, the roofline is what makes them look dated and without it you can actually notice some Ferrari Daytona Spyder influence in the profile. I’m not a convertible guy either, but make my C4 this way, even if that means I can’t get the fantastic DOHC small block
How memories of malaise can cloud the waters. The C4 was the beginning of the Corvette as a supercar in all aspects except name, and that includes the maligned ’84. Quality issues were real, but the car’s performance spoke loudly even if they don’t sound impressive today. Motorweek’s test of the ZR1 is on YouTube, the launch in Switzerland wasn’t ignored by anyone. Starting with the C4, you won’t beat the performance without spending 2x or more MSRP, a trend that continues today. Post an article on the 924 and its joy and performance will be inflated or excused. Having spent considerable time driving an ’86 automatic C4, I can tell you it still feels fast in traffic (300 ft-lbs. with little mass will do that), and the crisp, svelte lines have aged very well to me.
Great write-up! I remember in 1989 or 90 our local Chevy dealer had got a black ZR-1 in the show room. There was a big ad in the paper and it garnered a lot of attention. Dad and I went down to the show room to check it out and it was an impressive machine. It was probably the last time I remember a new car garnering so much attention at a dealership.
I think C4 Vettes are pretty underrated these days. They do have lots of flaws, but they were a massive improvement over the C3’s, which was very long in the tooth by 1982. While it’s chassis ridigity wasn’t the best, but it had a good suspension (after it was sorted out), good performance, and made the Corvette a real sports car again, probably for the first time since the early 1970’s. The ZR-1 was the pinnacle of this generation, but it too was flawed. Today, I’d worry about getting parts for that 5.7L LT5 engine. A Lotus design, it shares nothing with traditional small block Chevys. Good thing it has proven to be a fairly robust engine.
Here’s an easy tell for the ZR-1 vs regular 1991-96 Corvette. The ZR-1s are actually considerably wider in the back end (for the larger tires), so they use a unique tail section, despite looking identical to a base Corvette. The easy to spot difference is in the CMSL. The base Corvettes have it integrated into the tail section, between the tail lights. The ZR-1’s have it mount on the roof, above the rear window.
Good info!
Hi my late father owned a zr1 convertible from that era while in Saudi Arabia. She came from California originally and with some kind of body kit also. Probably one of the prettiest cars I’d seen at the time with the exception of the f355. I still have video footage of it including the 6 shift manual zf box so I know she was a real zr1. And I can confirm the handling with the top chopped off was truly horrifying. He ended up climbing a couple of juvenile palm trees in her at about 60mph sideways sadly. He was fine, but the car sadly was not. If I get you some screen shots do you think you maybe able to help me identify who did the original build?