- People complain sometimes when they're asked to pay as much or more for a Group 15
Pelletier, Zap, Yeti or other "hand-made" scratch chassis as they did for their
first complete Group 10 car. They haven't been at slot car racing for long enough to
realize that custom made equipment, by its very nature, can be a lot more expensive than
"cookie-cutter" stamped steel chassis which are cranked out by the jillions.
Every track owner, and every racer who's ever driven stamped steel chassis cars for
extended periods of time has experienced one or two which, right out of the box, seem to
handle better than others--perhaps even made by the same manufacturer. This is why smart
shop owners always tell their customers to make certain both pieces (or...in the case of
single piece designs such as the JK 4 1/2" version) are absolutely flat. One or both
pieces might have come from the factory slightly "tweaked" or suffered a small
amount of bending from shipping. Board member Voltaire Yap and others have shown their
racers how to lay a 6" steel rule across the bottom, turning it in every direction to
make sure each piece is level and lays flat on a tech block or a piece of glass. Even a
slight tweak is bad and can affect the handling. No serious racer will keep driving a car
that has hit a wall hard without taking it apart to make sure all points still touch the
- As racers improve, wishing to move up to faster classes, the most logical step is from
stamped steel designs to Box Stock. There are numerous box stock chassis designs from
several manufacturers on the market...from Koford, Parma, ProSlot, Hunter, FX and others.
These designs are basically just pieces of pre-cut brass plate, soldered together with
various lengths of 1/16" piano wire. All USRA-approved Box Stock chassis also have an
axle tube at the rear. But all of these seemingly "scratch-built" designs are
factory-assembled...most of them originating out of manufacturing facilities in South
America. Once the parts have been cut, they are laid onto soldering jigs and held in place
with clamps which hold the pieces together while one assembly worker tins and solders the
finished chassis together. Once completed, these are then cleaned...sometimes
"tumbled" to polish the pieces and remove any flux and dirt prior to packaging.
Like the stamped steel versions, these might also suffer some "tweaking" between
final assembly, packaging and shipping to their final destination...your raceway and your
customers. In order for a manufacturer to a sell one of these chassis at $19.95 retail and
make a profit for his company he must be able to produce it (his cost) in the $5 to $6
range, and make thousands of them while he's at it. At a cost of $5 or $6, and in the
quantities they must be produced, they simply cannot be "lovingly assembled"
one-at-a-time like the American-made versions of a Pelletier or a Zap. Therefore, the
serious racer is going to have to do some "hands-on tweaking" of their own. And
just because it looks shiny, new and pretty once you've taken it out of the package,
chances are 100-to-1 that you can improve the handling by "relaxing" the entire
chassis. Sometimes you'll even find a chassis where the rear axle tube has been
inadvertently soldered on an angle...one side higher or lower than the other. Car won't
handle unless all parts are flat and level, especially the rear axle!
- "RELAXING YOUR BOX STOCK CHASSIS FOR RACING"
- This can be done using just a good chassis block that you use to solder motors in and
out of cars...so long as it's large enough for the entire chassis to sit flat on the
surface. (Do not use your BR 102 lexan body mounting block!) It will take a good Ungar
soldering iron with a 4033-S tip, acid flux, small paint brush, a an old pair of oilite
bushings and a straight 3/32" axle, pair of set of Camen "jig" wheels for
the rear axle tube, and your other small tools such as a good pair of needle-nose pliers.
Another indispensable item is an old wire braid brush. Be sure to wear some type of safety
glasses or goggles to prevent any solder which might sling off the pieces.
- Start at the front of the chassis by unsoldering the joint which holds the piano wire to
one side of the brass plate nose piece. If there was any tension applied when the pieces
were originally soldered together, it might go "SPROING" and the wire will move,
separating from the nose piece. If that happens, you'll have to unsolder the wire from the
back end (take it loose from the rear axle tube) also. Carefully bend the wire with the
pliers until it sits flat where it belongs and you can resolder it into position without
forcing the pieces together. Hold the wire in the middle with one finger; apply a small
amount of acid flux using the tiny paint brush; then resolder the wire to the nose piece
and rear axle tube. DON'T GO CRAZY WITH THE SOLDER! We've seen many people
"glob" solder onto joints and never achieve a good, solid joint. This is why you
have to use an iron that gets hot enough. The solder should "flow" between the
pieces...not just sit on top of them. Experienced racers who do a lot of this type work,
or scratch-build their own chassis sometimes use a mini-torch, but you have to be very
- Once you have completed one side, and checked the solder joints for good connections,
and you're satisfied that the pieces are now flat, repeat the process on the other side.
All these chassis utilize pin tubes for body mounting. Many times you will find these have
been cut with diagonal side cuts and are crimped on one end, so the pins won't go all the
way through. Besides that, they have been soldered right on top of the side rails which I
find are too low for good body mounting. (That low means bodies can be torn off easily in
crashes.) I prefer to move the pin tubes up at least 1/16" by either soldering a new
pin tube on top of the original, or by doing the following: first, remove the original pin
tubes; then soldering a piece of 1/16" piano wire or tube to the side rail (or, if
possible, one on each side of the brass nose piece and put pin tubes forward of the front
wheels) and then solder new pin tubes on top of those. This allows the pins to be pushed
through the body 1/8" from the bottom and allows the use of Slick 7 "Ninja
Stars" or other type of body mounting reinforcing material.
- There are a couple of additional reinforcing techniques that can be done, but you first
need to check the rule book you'll be using. Neither the USRA or Parma Challenge Cup rules
will allow these two modifications. They are allowed under ASRA rules since they only
strengthen the chassis and do not make the car go any faster.
- Tie Wires. These can be used to reinforce the connections between the piano wire and the
rear axle tube. You can purchase a small roll of thin, malleable steel wire from any
hardware store. It usually comes on a red, wooden spool. This isn't a difficult task, but
might be tricky the first time or two you try it. Unroll about 6" to 8" and cut
with diagonal sidecuts. (We've used scissors, but it's hard on them). Polish the wire by
running it a few times through a piece of folded over sandpaper. Carefully wrap it around,
over, under and through the piano wire uprights and the rear axle tube. After doing both
sides, reinstall the rear bushings, axle and jig wheels. Set flat on block; apply acid
flux and solder using either rosin or acid core. Once solder joint has "set"
(but is still hot), use your old steel braid brush and "brush" the joint. This
will remove any slag or solder residue.
- One of the weakest features of any stamped steel or Box Stock chassis is the front end
where the guide flag is located. If this gets bent--either up or down--during a wall shot,
the car can turn into an instant "pile." This is an area that needs checking all
the time, even when you first take it out of the package. Hold the chassis sideways at
eye-level and be sure that this area is flat, or has one or two degrees of
"uptilt." Our "racer-friendly" ASRA rules allow the installation of a
Slick 7 or other steel nose piece on top of the original and soldered together for
additional strength. Once together, this area will never bend again! You just have to be
careful to properly align the holes in the two pieces so the flag post will rotate freely
once the two pieces are soldered together. We clamp the two together using a couple of old
alligator clips, then solder with acid flux and silver solder. Once cool, brush with old
braid brush, then do any clean up needed with a Dremel cut-off disc or small, flat files.
We also keep a tapered reamer handy and run it a couple of times through the flag post
hole, both from the top and bottom to be sure there is no solder there to hinder the flag
from turning. On some tracks--especially bumpy ones--just the small amount of added weight
from the additional nose piece will aid in handling.
- If you're completely satisfied that the chassis has been "relaxed" and the
parts adequately resoldered together, take it to the kitchen sink (don't let your wife see
you do this!) and scrub it thoroughly using an old tooth brush and some scouring powder.
We've also used Brillo pads. Once clean and polished, dry it thoroughly and spray it
lightly with WD-40. If you're not going to assemble it immediately, wrap it in a plastic
sandwich bag and store it flat.
- When you decide to build the finished car using the new "relaxed" chassis,
we've found the following tips make everything work a bit smoother. We use Backtrack's
guide flag post threader to run the threads all the way down before we install the flag.
The guide flag should turn very easily from side to side, but there should never be any
"slop." Using your thumb and index finger, hold the blade of the flag. There
should never be any side-to-side or up and down (front to back) movement. Use as many
teflon or metal spacers as needed between the flag and the chassis to maximize braid
contact, depending upon the height of the braid on the track that you're going to race.
Some tracks have braid that is recessed a few thousandths more than others. After a
chassis is completely assembled (and before you install the body) place it on the track
and press down on the guide flag. The rear tires should not lift off the racing surface.
If they do, add sufficient teflon spacers until it sits flat when you push down on the
flag. "Loop" the leadwires in such a manner that the guide flag will
"self-center" once you push it from side to side. If the flag hangs up on either
side, something is putting it in a bind and needs to be "tweaked" until it turns
freely, returning to the center on its own.
- For Pro-Wire 12s or Box Stock classes, first try a body that doesn't have a lot of
"kick-up" at the rear...one that's fairly flat. Use 5-mil side dams and a 7-mil
rear spoiler. Most serious winged car racers prefer to "wing-up" their own bods.
If you don't know how, or don't want to take the time, Aero and several other companies do
very neat work. Just make sure to mount the body as low, straight and square on the
chassis as possible. Once mounted, reinforce the holes on the sides where the pins hold it
to the chassis. Install a good set of tires for your individual track and driving style,
slap on some numbers, a few sponsor decals, and go blow away your competition. You'll love
the way the car handles!
- RONNY BURNETT MAKES SUGGESTION ON TWEAKING BENT STAMPED STEEL CHASSIS THAT HAVE BEEN
REINFORCED WITH PIANO WIRE AT BACK Those of us who dearly love to race stamped steel
chassis know that the addition of a pre-bent piece of piano wire, soldered securely
between the rear axle uprights, will add much needed durability to almost any design. The
purist and extremely dedicated enthusiast will almost ALWAYS completely disassemble a
stamped steel chassis car after an eight-heat race...then check it on a flat surface to
make certain the pieces still lie flat and are not tweaked in any way, shape or fashion.
What Ronny has found it that once a chassis has been bent or even slightly tweaked as a
result of a wall shot or rear end collision...even though it has a piano wire rear
brace...cannot be adequately straightened UNLESS you reheat/resolder the piano
wire/uprights. Ronny says, "If you try to straighten a stamped steel chassis, and DO
NOT resolder the reinforcing piano wire, the next time the car hits the wall it will
easily return to the same bend it had after the first crash. Every time I reheat those two
solder joints (between the uprights and the piano wire) I hear a "sproing." This
tells me I have properly relieved the tension and the straightened chassis will again be
as strong as it was originally." Try this on one of your stamped steel cars that has
been bent from a crash. Ronny thinks you'll like the improvement in performance. Thanks
for the tip, youngun!