Sandy Gross Puzzle Pan
A replica 1968 alternative design chassis by Steve Okeefe
There's more than one way to stop tire chatter...
Historical Background
In the summer of 1968, during the first few months after Gene Husting’s Anglewinder revolutionized pro racing chassis design, Sandy Gross, Bob Emott and one or two other east coast pros journeyed out to southern California, where the anglewinders first appeared.
Perhaps they were looking for ways to improve the breed, because although anglewinders were clearly superior to inlines, the design was not without its early “teething pains”. One of the more frustrating problems that builders and drivers were grappling with that summer was rear tire chatter.
Instead of sliding smoothly through turns, the rear tires would tend to begin bouncing up and down very slightly, but at a fairly high frequency... literally chattering across the track. Chattering reduces traction to almost nothing, resulting in the car becoming completely uncontrollable.
It is now generally accepted that too much flexibility in the motor box and motor mounting bracket was the culprit, allowing the motor and rear axle tube to shake and vibrate. A simple brace between the rear axle tube and motor fixed the problem in most cases, but in the summer of ‘68 this was still something of a mystery.
While in California, Sandy decided to try something different in an effort to put a stop to the chattering. What he came up with was a design concept using mechanically interlocked pans instead of main rails that was worlds apart from anything else anybody was building or driving. He built only one example, and it was promptly dubbed the “Puzzle Pan”.
After returning to the east coast, Sandy entered a car using this chassis in the First Cobra Invitational race at Buzz-A-Rama Raceway in Brooklyn, New York on August 24, 1968. To say the least it created quite a stir because in addition to being so utterly different, Sandy made the main with it and took fifth place overall.
Also seen for the first time during that race were the first examples of the "Plumber's Nightmare"; what later came to be known as the plumber hinge. These created quite a stir too, because there were at least four cars sporting plumber hinges, and two of them, driven by Jerry Brady and Pete von Ahrens (PVA), took first and sixth respectively in the main.
As things go I was at that race, and although I was just another geeky-kid "face in the crowd", I managed to get a glimpse of Sandy’s chassis for about 30 seconds while it sat on his pit bench. I tried desperately to memorize what I was looking at and, without daring to touch it, figure out how it went together. Then Sandy picked it up and it was gone; I never saw it again.
A few weeks later, Sandy loaned his one and only Puzzle Pan chassis to his best friend and Cobra Racing partner Howie Ursaner, who entered it in the First Fall/Winter New York Car Model race at Buzz-A-Rama on September 21st. Howie took Top Qualifier and was leading by a slim margin in the main until the closing seconds of last heat, when he de-slotted and lost by a single lap to Mike Tango. ike was driving a Tony P designed and built (as you may have guessed) lumber hinge chassis.
So the new-idea Puzzle Pan chassis got beat twice in its irst two outings by the new-idea plumber inge chassis, but only just barely n the second time out.
The plumber hinge, in various flavors, went on to become art of pro racing chassis “standard design”, but the Puzzle Pan concept ventually fizzled out, even though at least two other pro builders (Bob Emott nd Tony P) built their own versions.
Sandy’s ne and only original Puzzle Pan chassis was unfortunately stolen, and has thus isappeared into slot racing history. If anybody out there has it, or nows where it is (and only you would know who you are), please see it returned to its rightful owner (not me!) I'll even pay for the shipping...
Sandy himself went off to college and never built another Puzzle Pan, so there is no original chassis to work from, no other examples from the original builder, and only one fuzzy photograph published in Model Racing Journal (MRJ) in October 1968. Very nearly a “Mission Impossible”, just the way I like it!
In June of 2008 Sandy Gross posted a few messages on Slotblog. I sent him a private message through the message board, introducing myself and asking him if he would help me piece together a drawing of his original Puzzle Pan chassis. Sandy agreed, and we started with the one fuzzy photograph and added in everything he could remember.
This is one replica I’d been waiting a very long time… about 40 years… to build.
Piecing Together the Design
Using Photoshop ™ I cropped the scanned photo from MRJ and rotated it 90 degrees, saving it as a JPEG. Then I pasted it onto some "electronic graph paper" in Microsoft Excel ™.
Next, I re-sized the photo until the main pan was exactly three inches wide on the graph paper and adjusted its position until the rear axle was perfectly lined up with the zero line:
Then, with Sandy’s irreplaceable help we began to reconstruct the design on paper.
First, the main pan, motor plate and drop arm:
Next, main pan details:
Now the one piece motor box, motor bracket and rear axle tube assembly:
The built-up motor plate:
Front axle tube mount and side pans:
Putting it all together overlaid on the photo:
Now remove the photo and we have a master drawing:
Piece of pie; easy as cake!
Next up: Building the Puzzle Pan... (Click here)
