SPRINT CAR PROJECT
This one is a little out of my normal comfort zone being a 1/43 scale. But a recent forum group at Home Racing World has put together a Proxy race series with these little beasts. 1/43 scale cars fall in line just between HO scale & 1/32 scale. They run in size usually around 3"- 4" in length as compared to HO @ about 2-1/2" & 1/32 @ about 6-1/2" This deal caught my attention mostly because it required building a car within a set of rules. And we all no what's great about a set of rules, how they are interpreted, and how far can they be bent. ; ) So with that said let me begin.
The rules
1. Resin body must be purchased from Ranch Design
2. After market wheels can be used but must be1/43 scale and be available to everyone
3. Motor must be Goldmine 9330
4. Must use the Artin 1/43 chassis, gear, axles.
5. Top wing can be lowered to the top of the roll cage.
The parts that must be used
First things first the chassis that I have to use must be adjusted. Sinse these Proxy races will only be on ovals with left turns, the chassis will be built with as much of the weight as possible shifted left. My first interpretation of the rule that I must use a Artin chassis. Didn`t say how much I had to use. As much of the right side of the chassis as possible was removed and trimmed to just the single strip shown, and glued back together.The bottom was removed to allow the motor to set flush with the bottom of the chassis.
The following 2 pictures show where the right side of the chassis was moved over to the left to rest against the motor. Notice the gap that is pictured at left. Also you can get a idea of the outside contact areas for the tires. This also will aid in adding to the left side weight transfer. Aluminum wheels by Ranch Design
A brass plate was then cut to fit the bottom of the chassis also to help get the weight lower and to the left a bit more. I guess by now your asking yourself why all this stuff about left side weight, why not just add a magnet. Well just hold on a bit, there will be magnets soon. But these cars are also going to run on just as many wood tracks where the magnetic forces will be nada. So my idea is to get this dude set up as well as possible then add the mags. And yep you guessed it the magnets will be on the left side only.
The brass chassis pan has also been fitted with brass rear axle towers that were mainly to reduce the slop, but also they were drilled 1mm higher than the stock Artin chassis to get the weight lower. Look closely at the right picture and you`ll see the brass bolt and nut just behind the front axle. There are 3 of these 2 in the rear that hold the brass pan to the plastic Artin chassis. They will also be glued together.
Brass tubing was used to make a sleeve that keeps the crown gear in check. But it was also used as a stabilizing point for the front axle. Sinse there was no room left in the plastic Artin chassis to re-drill and lower the front end. Piano wire was used to make a arm that connects the rear axle sleeve to a sleeve for the front axle. This allows the guide pin to get deep into the tracks slot. The front axle has some float also so the car has a tripod type setup. On the right a piece of styrene 1/4" angle was glued to the plastic chassis. This acts as part of the body to help cover the plastic chassis that hangs out under the body. Also a nice compartment for that pieces of lead shown to be glued inside.
Here`s the real fun part for me, I just dig building with brass. This is basicly "THE" chassis, the only thing the Artin chassis is used for is a place for the motor to rest, and a braid guide pin holder. The side nerf bars also act as the body mounts as you will see later.
Here you can see how the Artin chassis has been relieved of the stock axle mounts, which actually was a necessity for the crown gear to be moved over far enough to match up to the left sided motor. In the right picture, you get a idea of just how the Artin chassis fits.
As you can see in the following 2 pictures, the brass chassis is a stand alone roller
Now to the body, sinse this body was just a re pop of a diecast car, it wasn`t meant to fit what I have here. So some butchering was needed. This is by no means a strike against Ranch Design, they did a super job of reproducing this in resin.
Here you can see that a mounting post was added to the rear, this will probably be removed as it was a first design before the nerf bar mount. But the stub in the front is a centering point for the body. The styrene you see inside the body was just a backing for the resin I added to fill in the side of the body. Also the front has been whittled away a bit to clear the front axle.
These 2 shots show what was changed on the side body panels.
All the major components come together.
The centering stud, and the front body mount. The body just slides under the brass rod and is locked in place with the stud. The body is not a solid fixture as it floats on the chassis.
In these 2 pictures, you can see where the nerf bars are inserted into the body sides to secure it from dismounting itself. Notice the holes are a bit larger then the rod to aid in the body float.
Everything all together now and ready for a bit of test fitting.
After installing the motor, I found that there was a big clearance problem that I missed while fitting things together. With as low as I got the body, it seemed that the motor was hitting the body just at the center of the hood/scoop area. The only way to remedy this at this point was to start butchering again. So the hood/scoop area was removed which left a big hole. This was repaired with a little styrene and glazing putty.
It`s a little hard to see but there is now enough clearance for a regular size motor on its side. I kinda like the looks of the new hood line.
While the putty was drying I decided to get the chassis cleaned up and painted. The headers were made from 1/16" brass rod, this was a little tougher than the solder headers I`m used to using. But the solder was just to big in diameter for this scale car. They were also painted white at this time. Also I removed the body mounting tab from the rear of the chassis because of the new nerf bar mounts.
Another little detail item I put together was this carburetor breather. As you can see it was made with 4 different size brass tubing and some micro screen. A small deflector was also made from styrene.
Body and wings painted
Chassis finished
With a few 1/32 & HO decals, and a little detail brush painting it`s finished. A big thanks to Steve at Ranch Design for a great body, a hot little motor, and some beautiful rear wheels & tires.
