The Old Weird Herald -the most dangerous 'zine in slot car racing!

Vintage Euroscale Plus

From Toy to Serious Race Car

With a Little Help From Proslot, Plafit, and Company

by Bob Ward

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Pennzoil Porsche936

 

Warning: If you're a purist collector or a box-stock absolutist, read on at your own risk, because I'm going to revel in forbidden fruit, technological crimes guaranteed to give you at least a case of the vapors, if not cardiac arrest. This article is not for the faint of heart or the politically correct. Just by reading it, let alone doing what it describes, you may be taking the first deadly step down the slippery slope from mint boxed scale virtue to wing cars, cobalt magnets, thingie bodies, and 30 more years of slot racing dark ages. You have been warned: beyond here there be monsters.

Have you ever looked at a Euroscale car, like a Scalextric, and wondered what you would get if you could combine its scale accuracy and detail with some of the bad-boy performance of those terrible commercial raceway cars - those "Lexan doorstops" raced by "speed-crazed morons"? I did. But I didn't just look and wonder. I actually did it - took a prime collectable and mated it with a cheetah and (gasp) a demon!

It all started when I acquired, in a trade, a Carrera (of Germany) Porsche 936 body ...

If there is one name in racing that has become famous for winning the 24 Hours of LeMans and other major endurance races it's Porsche. Beginning with the legendary 917 in 1970, Porsche has won more LeMans races than any other manufacturer.

Perhaps the least well-known of Porsche's LeMans winners, at least in the United States, is the 936. Introduced in 1976, it won the 24 Hours in its first year and went on to win the event two more times, in 1977 and 1981, using several different bodywork, engine and gearbox combinations over its six-year career.

The 936 has some of the most eye-pleasing aerodynamic lines ever put on a race car. Carrera, a German home racing set manufacturer, did an outstanding job of capturing those lines on one of their 1/32 scale home set cars. The body was gorgeous, or would be with some TLC. But then, I discovered that the chassis that was supposed to go under that voluptuous body was...well, hopeless.

The body, as I acquired it, was complete and in good condition except for a missing chrome headlight insert and driver's head, a rough coat of black paint, and some slight warping. All it took to remove the warp was to hold the body under the bathroom sink faucet with the water running full hot and gently twist it until it was straight. With no immediate prospect of replacing the missing headlight insert I removed the other one and filled the cavities in the front fenders with body putty. After rough shaping with an emery board I wet-sanded the areas smooth with 600-grit paper. A little more wet sanding smoothed out the rough paint and removed minor surface flaws. I cut off the body mounting posts. Then it was time to build a chassis.

936 Porsche - Modified Demon Chassis

 

Any body this aggressive looking cries out for a chassis and motor with performance to match. At almost 2 1/2 inches wide, the 936 has plenty of room for any chassis layout one could want, including an anglewinder. Proslot's #PS310 Demon chassis is an anglewinder designed to compete with Parma's I-32. The Demon is a strong, simple stamped chassis that has been used successfully in Lexan-bodied 1/32 cars for several years. It lends itself readily to being adapted for hard-bodied cars. Since I had several of them around my workshop I decided to use one in the 936.

The Demon chassis needs some alteration to fit the Porsche body. Most of the needed changes are at the front end and involve shortening everything. The guide lead shrank from 3 1/2" to 3 1/8" to fit under the relatively short nose. The easiest way to do this was to cut the center section about 1/2" back from the base of the guide tongue and solder the front part in place on top of the main part as shown in drawing #1. I had to flatten out the guide tongue so the guide would ride deep in the slot without requiring a stack of washers. This increased the guide lead slightly, so I had to take that into account when soldering the two parts of the center section together.

Drawing #1

 

The wheelbase went from 3 1/4" to 3 1/16". It was also necessary to allow for an increase in front wheel diameter from .625" to .6875". Simple L-brackets and a U-shaped bracket with extensions soldered to the center section located the front axle tube (see drawing #1). Because the wheelbase and guide lead are so close the guide nut is right under the front axle. To provide access to the nut I cut out the center part of the axle tube between the brackets after everything was securely soldered in place. When the front axle is removed the guide nut can be reached with a nut driver.

At the back of the center section I cut off the motor bracket. This allows a better motor position, farther aft and more centered on the chassis. I also soldered in the rear axle oilites, using an axle for alignment. The center section is also bent up slightly just aft of the motor location to accept the .800" diameter rear tires while maintaining .060" clearance under the chassis.

On the stock Demon there is a lot of space between the center section and the pans. This allows a great deal of movement between the pans and the center. This is fine with a Lexan body but with an injection-molded scale body, some of that movement must be taken out or the tires will rub on the body in all the corners. To take up the space I soldered .063" steel wire alongside the center section as shown in drawing #3.

Drawing #2

 

The pan assembly had to be shortened and the fingers cut out to clear the wider and larger-diameter front wheels. Drawing #2 shows the portions of the pan assembly that were removed with a Dremel Moto-Tool. When the cuts were completed the outer edges of the pans were the same length as the body sides between the wheel openings.

Because the injection-molded Porsche body is heavier than the vacuum-formed bodies the chassis was designed for, some extra weight on the pans helps to get the center of gravity back down where it belongs. I soldered a strip of .063" brass onto each pan, set in about 1/16" from the outer edge.

Drawing #3

 

The pan unit attaches to the center section with two .063" wire hinges as shown in Drawing #3. The hinges have a slight bend in them, exaggerated in the drawing, so most of their length lies flat on top of the inner edge of the pan finger, giving adequate surface area for strong solder joints. With the pan unit mounted on its hinges, I drilled a 1/16" hole on the car's centerline just aft of the pan unit's crosspiece. I soldered in an L-shaped upstop for the pan unit, leaving room for about 1/16" of upward movement as shown in drawing #3.

The body clears the tires and the nose clears the track perfectly when the body sides sit on top of the outer edges of the pans. With the .063" brass strips soldered in place a test fit of the body showed it to be properly aligned and centered on the chassis. I then soldered the body mounts in place as shown in drawings 3 and 4, with the ends of the brass rods even with the outer edges of the .063" strips.

Drawing #4

 

From this point, mounting the body was simplicity itself. I drilled four 1/8" diameter holes in a sheet of .080" styrene and cut out four rectangles with one of the holes in the center of each. I placed one on each body mount as shown in drawings 4 and 5. Then I liberally coated the inner sides of the body and the outer face of the four styrene rectangles with liquid plastic cement. I slid the body down over the mounts and carefully positioned it so it sat flat on the pans and the wheels were aligned with the wheel openings. After letting everything dry for an afternoon I sprung one side of the body outward and the body popped right off the chassis. It stays snugly mounted but is easily snapped on and off with no pins, screws, or Velcro needed.

Drawing #5

 

Porsche originally used 5-spoke alloy wheels on the 936. The Cox 1/24 Ford GT wheel, except for having 6 spokes, looks quite similar, so I decided to use a set of them on the car. Whenever I use Cox wheels on one of my cars I adapt them to set screw mounting by grinding out the original threaded mounting from the back of the wheel center and pressing an aluminum set screw hub into the rim.

The Cox 1/24 scale Ford, Ferrari, Lotus, and BRM magnesium wheels measure out to a scale diameter of 13 to 14 inches. In the years since the 60's, as racing tire profiles have become lower and lower and wheel diameters have increased to 16, 18, even 20 inches, the 1/24 Cox wheels have become just the right diameter for many 1/32 scale cars. With my set screw inserts I can get tire widths up to .625", which is what I used on rear of the 936. The front tire width is .375". The Ford wheels, with Sonic black sponge rubber on the rear and solid rubber on the front, look every bit the part of late 70's racing wheels on the Porsche.

In choosing a motor for my vintage Porsche, I looked once again to the hardware used in our race program for Lexan-bodied 1/32 cars. The motor that is taking over 1/32 and entry-level 1/24 classes in the Puget Sound area is the Plafit Cheetah. The Cheetah and its lower-powered twin, the Fox, come as close to being universal slot racing motors as anything yet seen. They have proved to be the perfect motors for low-cost box-stock racing. They are inexpensive, only $8.95, and they are very difficult to tamper with on the sly. This makes a box-stock motor rule close to self-enforcing. In our I-32 races, the Cheetah -powered cars are faster than the 16-D's over the length of a race because of their lighter weight, better handling due to improved weight distribution,, and better drivability. The 936 project was the ideal opportunity to try a Cheetah in a vintage car.

Based on experience with the Cheetah in I-32 cars I chose a gear ratio of 10:40, using a Sonic 64-pitch pinion and a PSE Slot Sprocket spur gear riding on a 3/32" drill blank axle. I installed the rear axle, spur gear, and completed rear wheels and tires, spacing everything out to the maximum width of the body and placing the spur gear as far outboard as possible. I slipped the pinion onto the motor shaft and test-fitted it, placing it so the gears meshed properly and the end of the motor just cleared the right tire. To position the motor as far to the left as space permitted I had to cut a small amount off the end of the shaft. I soldered the pinion onto the shaft, set the motor back in place on the chassis and lightly clamped it down, being careful not to bend the can. I soldered the motor along both edges of the chassis and also used a V-shaped wire brace to attach the rear side of the can to the chassis just above the right axle oilite.

All that remained was to install the front axle and wheels, a set of silicone lead wires and clips, and a jet guide and braid, and the car was ready to test. Before putting the car on the track I placed a drop of Parma bushing oil in each motor and axle bushing and in each end of the front axle tube. I turned my track power down to 6 volts and disconnected the brake wire. I ran the car for about 100 gentle break-in laps, checking it every few laps for binding, rubbing, and motor heat. The only problem turned out to be a slight bit of warp left in the nose, which caused one corner to scrape in the turns. A little more gentle twisting under hot running water soon cured that.

With the power back to a full 12 volts and the brake on, I set out to explore the car's performance. As the tires broke in the lap times came steadily down to a best time just a tick over 6 seconds. This compares with the Lexan-bodied I-32 lap record of 5.05 seconds. The Cheetah gives plenty of controllable power. Brakes are excellent without any adjustment on the controller. The Porsche's handling is very driver-friendly. Its only vice is just a slight tendency to tilt rather than slide at the limit. Further work with weight distribution should take care of the problem.

Initial testing completed, it was on to painting and detailing. At the time, I was completing two other cars in Pennzoil colors, so I decided to make the 936 a Pennzoil car, too. The Porsche is finished entirely in Testor Model Master colors applied with a Binks Wren airbrush.. For details on the car's paint and decals, see my article, "Big Car Decals For Little Cars" on this same web site. The Carrera body and Cox wheels really don't need much in the way of additional details. The only one I added was a set of centerlock nuts, taken from a Matchbox Porsche 917-10 static model, painted red, and epoxied to the centers of the wheels.

No one ever raced a Porsche 936 in Pennzoil colors, but if someone had, it almost certainly would have looked much like my model. It's easy to imagine some wealthy Pennzoil executive running a 936 painted in the company livery in today's 1/1 scale vintage races. The purists would wince, but he'd have the brightest car on the track, and what an advertising writeoff!

My three anglewinder hardbody vintage cars, two modified Demons and one with a completely scratchbuilt chassis, also make purists wince, bit I love 'em. The Demons, at least, are easy to build, because Proslot has already done all the hard part. On my non-magnetic polyurethane-surfaced track they will utterly blow the doors off any of my other 1/32 hardbody or vintage cars. More important, I can run them and race them to my heart's content because everything under the body is readily replaceable and inexpensive. Also, being hybrids, my 936 and its siblings have no collector value, so I am not putting a fortune at risk every time I take them out of my display case. Above all, they're FUN, and, after all, isn't that what vintage slot racing is supposed to be all about?

By the way, the 936 project was made much easier by the invaluable help of the good people at Fantasy World Toy and Hobby in Tacoma, Washington. They stock one of the biggest selections of Euroscale cars, sets, parts, and accessories to be found anywhere. If you don't have a local retailer who carries 1/32 supplies, give them a call at (253) 473-6223. They do mail order and you can use your VISA, Mastercard, American Express, or Discover card.

Oh, and one more thing... This same car, with a Fox instead of a Cheetah, a Parma home set guide, and different rear tires also works on a plastic track. And if you care to, there's plenty of room to stick in a chassis magnet. A car for all tracks, anyone?

Wow, I'm really far gone on the road to model car racing perdition. There is at least one person, very prominent in the world of Euroscale, who most likely wants to drive a stake through my heart just for writing this article. If I disappear, don't bother calling the police. They'll never find me. I'll be one of the X-files. But until the black helicopter guys get me, I'll have more fun than anyone should be allowed to have with my politically incorrect Porsche/Demon/Cheetah. And for my next project in applied Demonology...how about the new Fly Joest Porsche WSC when it comes out this summer? Do I dare?

Bob Ward mailbobward@oldweirdherald.com <- (flame retardant, bomb-proof mail box)

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