Contact: Rich Kurz   Page content last updated January 12, 2022

They didn't build it...

One of a pair of fully operational concept cars developed by GM under the direction of Bill Mitchell. The GT coupe was built first in '62 and the SS roadster followed in spring of '63. GM outdid the Italian design houses this time. The Testuda pales compared to the GT.

The resemblance to the 63-67 Corvette is obvious - both were penned by Larry Shinoda with the assistance of Tony Lapine. GM considered producing the GT, and clay models and a nonrunning preproduction version of a roadster version were prepared, but bad press from Ralph Nader's book "Unsafe at Any Speed" and the introduction of the Mustang brought things to a screeching halt. It was also feared that it might take sales away from the Corvette, which was near and dear to Mitchell's heart. I know I would have bought one... or two!

And they wouldn't sell it...

Somewhere in my reading it said that a Saudi prince offered $5 million to buy the SS and GM refused. Happily both the SS and GT were placed in the care of the Heritage Musuem along with dozens of other styling prototypes. The cars can still be seen there and from time to time at such events as Amelia Island. But the musuem is private and a visit has to be arranged, usually as part of a tour.

So I'll have to make it!

Here's how I'll do it...Ready?...
  • Take a donor car, cut it down, and add a custom body.

...SIMPLE! (do I detect some hur-rumpfs?)

The Build (On-going Construction Diary)

The Choice (Humble Beginnings)

Two choices were considered: Porsche 911 and VW 411/412. The 911 has nearly exactly the same wheelbase and track as the Monza SS. But the biggest problem seems to be the height of the engine - or rather - the engine fan. It's too tall. The 411/412 has the same track, but has a wheelbase ten inches longer.

My goal is an affordable "commuter" car suitable for weekend trips as well. The 911 is more expensive overall, although would have Porsche performance. The Type4 engine used in the 411/412 has less performance, but still acceptable horsepower (120 and up with performance parts). I also have the help of a neighbor who is a professional welder and builds custom cars for pleasure.

And the winner is...

   VW 411/412.

Published Dimensions  (source: "Road&Track" Aug.'63, "Car Life" Sept.'63)

length o/a:
width o/a:
height o/a:
front overhang:
rear overhang:

Blue Streak Special 6.00/6.50-13

Web Links

A collection of LINKS pointing to vendors I'm using and notable web pages I've searched

The Construction Diary


"Road&Track" puts the Monza SS on its cover plus an article on it inside. The dream begins!


At the Kettering Holiday-at-Home Parade, the Shriners perform formation driving in Monza SS go-karts! I did not know they existed. How could I get one on an allowance of 75 cents a week?


Decide to make my own Monza SS rather than a custom car of my own design.
As I kept noodling and doodling, I kept coming up with more features I wanted to build into a car of my own design. At last I stepped back and realized what I was getting myself into - I who had never pulled an engine. I decided that my custom car would be too ambitious for a first try. The Monza would be simpler.
Besides... I have always loved the styling of the roadster, and if I only build one car, I would be very happy to be driving it!

Pick up Chevy Jr go-kart in TN. Will use body for measurements of full size car. It looks like the fender line matches almost exactly that of the real Monza SS! The go-kart is slightly larger than 1/2 scale at 87"x36" compared to 164.5"x64.5" for the real article.

It's time to get serious about what I will use as the chassis for the Monza SS. I created a comparison spreadsheet of every car that I seriously fancied.
A Corvair seemed the most likely, except that it was too wide in track, rather heavy engined, and generally poor gas mileage (~16mpg). It would take a lot of cutting, but it would be in spirit a duplicate.
The Porsche 911 was nearly right-on in wheelbase(+/− 1 inch depending on the year), track, and overall dimensions. But, oh, the cost! Imagine buying one just to cut off the body!! The front struts were too tall, but coilovers are available. But, oh, the cost!!!
The Sterling custom chassis was considered, but again, it seemed costly and still needed some adapting, being too long.
Surprisingly, the VW 411/412 stood out as a candidate. Certainly it was too long and underpowered, but using the dunebuggy as a metaphor, it could be shortened and souped up. In fact, souped up a lot! And... the rear suspension had been properly designed (think no-swing-axle) and the track was within an inch of desired. True, the front suspension had those horribly tall struts, but other than that, looked to be a good solution. In fact, the Hillman Imp was noted for its handling even though it was rear-engined, and it had about the same type of suspension as the 411 (read it here)!
So I had my choices narrowed down, and here is how they stacked up:

      • 88" wheelbase / 53" track
        • front suspension: double wishbone + longitudinal torsion bars
          • rear suspension: double wishbone + coils and shocks (not coilovers)
            • Corvair engine: 140 hp, 4-barrel (originally), 6-barrel currently
              • Seats fixed, pedals adjustable, steering moves in/out (about 4")
                • too-low Cibie headlights & Corvette-style taillights
                  • non-street legal windscreen
                    • no top, integrated rollbar added in '65

                  1) '65-'69 CORVAIR
                      • 108" wheelbase // 55.5/56.5" track fr/rr
                        + Corvair engine
                          + good rear suspension
                            − requires upscaling SS design 105% to use Corvair rear track
                              − poor gas mileage (15 mpg)
                                − adapt new front suspension?
                                  −> biggest problem: resizing body
                                    −> biggest negative: gas mileage, weight of engine/transaxle

                                  2) PORSCHE 911/912
                                      • 87/89" wheelbase '64/'69 // 53.8/52.8" track fr/rr
                                        + near exact wheelbase & track
                                          + roller available
                                            + 911-specific coilover suspension available (sort of)
                                              − must cut away all but floor pan
                                                − engine too tall because of fan
                                                  − add frame reinforcement (unless a Carrera)
                                                    −> option: mating T4 engine to transaxle & suspension
                                                      −> biggest negative: probably expense overall, front struts too tall, cooling fan too high

                                                    3) VW 411/412
                                                        • 98.4" wheelbase // 54.2/53.2" track fr/rr
                                                          + use existing T4 engine and rear suspension (only 1" wider track)
                                                            + T4 can be rebuilt for 100 to 200 hp
                                                              + T4 engine+trans is 80 lbs lighter than Corvair
                                                                − replace front strut suspension
                                                                  − wheelbase: shorten chassis (10.5")
                                                                    − add frame reinforcement
                                                                      −> biggest problem: new front suspension
                                                                        −> biggest negative: not Corvair-powered like original (not a negative, really)

                                                                      4) CUSTOM CHASSIS
                                                                          + match exact dimensions: body, wheelbase, track
                                                                            − cost: custom design & build
                                                                              −> biggest problem: near complete ignorance of what I am facing this way
                                                                                −> biggest negative: don't know yet

                                                                              −−−−−−−−−− CONSTRUCTION DECISIONS −−−−−−−−−−
                                                                                  • ENGINE: T4 '76 Vanagon rebuilt to 2056cc/127hp
                                                                                    • WHEELS: 13x5.5 aluminum Scirocco
                                                                                      • HUBS: adapt knock-off spinner and back plate
                                                                                        • HEADLIGHTS: Hella 3-1/2" bi-xeon or bi-halogen HID
                                                                                          • TAILLIGHTS: 3-1/2" '58/'61 Chevrolet "beehive tail lenses / '62 F-85 taillight bezels
                                                                                            • WINDSHIELD: custom formed, adjustable height - 5"->12"
                                                                                              • WIPERS: wipers mounted to windshield or convertible top?
                                                                                                • SEATS: bucket, adjustable, back folds down
                                                                                                  • TOP: removable roll bar + top panel (Targa style) or adapt C3 Corvette convertible top
                                                                                                    • STEERING WHEEL: telescopic, tilt, removable
                                                                                                      • PEDALS: adjustable
                                                                                                        • GAUGES: 6 like in original
                                                                                                          • HEAT/COOL: VW 412 gas heater / front vent

                                                                                                        Check out 2014 for more progress!

                                                                                                        Web Links

                                                                                                        Dane Northrup at DI Polishing (on Facebook) - polishes aluminum automotive parts!
                                                                                                        Vince Sprague at Horizon Machining in Berthoud Colorado (970 532-2458) -
                                                                                                        a top-notch machine shop, and car guy as well. Built his own sand rail.
                                                                                                        Orignal Customs (and on Facebook) - engine rebuilder and more!
                                                                                                        Poudre Sport Cars - performance, sports cars, and exotics - repair, track-ready prep, & customer-oriented service; source for transmission & rebuild
                                                                                                        VRBA's in Fort Collins, Colorado (970 484-2011) - air-cooled VW specialist on the north Front Range; service, parts, and source for donor vehicle and engine. It's incredible the details and specs he keeps in his head.
                                                                                                        Mel Francis - car builder extraordinaire! He built a "production replica" of the Monza and is currently working on doing one of Syd Mead's "Sentinels"... and MORE!
                                                                                                        Pat's Vee W-Unlimited in Loveland, Colorado (970 667-3682) - air & water-cooled VW specialist on the north Front Range; service, parts. Very busy cuz he's very good. And a real nice guy, too. He knows his stuff. I walked in once and he was putting a differential back together. He gets that deep.

The Original

1st ROW
(L,C,R) The Monza GT and SS beauty shots
       Note the headlight clamshells on the SS. That indicates the original (and short-lived) headlight solution
2nd ROW
(L) A 3/4 rear view - very windswept. The styling combined creased lines with rounded surfaces.
(C) Circa '67. Note the Cibié headlights now and the integral roll bar.
(R) The Kamm tail was aerodynamic. The fender protruding exhausts were a nice touch.
       But the only muffler on them was a short glasspack between the tip and the exhaust ports. It must be noisy!
3rd ROW
(L) This view gives some sense of how low is the car. It was, after all, designed as a true sports car a la Shelby Cobra.
(C) The original Monza Jr made for Bill Mitchell.
       It was later produced by the Rupp go-kart company for GM marketing and finally for general sales.
(R) Another engineless prototype was created as a study for a production version.
       Note the bumpers, wider doors, and still-creased-but-shallower windshield. I think there was a thin rod at the crease.
       The Kamm tail was not as recessed and flatter, and looked very much like the '65-'69 Corvairs.
(L) Hood emblem
(C) Fender Emblem
(R) Alloy wheel (I think they made a mirrored-image set for left and right)
(R) Cockpit - note the seat cushion apparently sprung up to aid getting in and out.

The Monza Jr

1st ROW
(L) The go-kart on chopsticks...
(C) And lifting it onto the carrier rack of our Caravan. Note the white 2x4s that will block the wheels in place.
(R) In place and ready to wrap. It made for great entertainment for those who got to watch.
2nd ROW
(L) Covering it for the drive from Tennesee to Colorado.
(C) The netting was added to keep the tarp from being windswept off.
       It worked and it even rained on the way home and the go-kart kept dry! The car was a little top-heavy, but only on turns.
(R) How it looked when I bought it. At one point it was used by Pizza Hut according to the license plate.

Research & Comparisons


1st ROW
Spreadsheet (pdf format) comparing different vehicles to determine the best (easiest, cheapest) donor car.
       The Porsche 911 seemed the best, but just try buying one, even as a roller! Labor and time I have, money I don't.
       Buying a kit chassis was seriously considered.
       And of course a Corvair was definitely considered!
       I will be able to tell you if I made a good decision after I'm done.
2nd ROW
(L) Monza SS / 1960-64 Corvair
(C) Monza SS / C2 Corvette / C3 Corvette
(R) Monza SS / 1968 C3 Corvette. SS front view is approximate.
3rd ROW
(L) Monza SS / Porsche 911 long wheelbase
(C) Monza SS / Pontiac Fiero
(R) Monza SS / Monza Jr go-kart. Yellow outline is taken from SS profile.
4th ROW
(L) Monza SS side elevation.
       I scaled up the centerline-to-seat bulkhead and superimposed the wheels & fenders
       according to the published dimensions to get a sense of an side elevation view.
(C) Monza SS / VW 411 fastback sectional view
(R) Monza SS / VW 411 after cutting down. Note the front struts are WAY too tall! My first thought was to replace them with coilovers, but that is easier said than done. The wheel bolt pattern is for the 15 inch wheel, so that would have to be replaced.
       Building a top wishbone and mounting it is daunting to me, and how does one attache it to the wheel? Better to find a front end. The Corvair suggested itself as a good direction, being a complete, non-engine-supporting unit.
5th ROW
(L) Example of perspective reconstruction 3-view, using the wheelbase as my datum line. The photo was reconstructed in Hugin, then the three views placed and scaled in Adobe Illustrator. But deriving dimensions is still difficult. One has to determine a set of points in the same plane.
(C) The base photo used for perspective reconstruction
(R) And here is a work-in-process line drawing based on the reconstructions. There is still lots of work using multiple photos to get a best-average set of lines.

The Donor Vehicle

1st ROW
(L) The VW 412 as I found it after sitting for 20+ years.
(C) (After having it towed home) Driver side
(R) Passenger side - very close to an elevation view
2nd ROW
(L1) 3/4 front view, and just cute enough that my daughter wanted it for her own
(L2) 3/4 rear view
(R1) front view - note the skinny tires
(R2) rear view