The Layout and Wiring of a Drag Strip

by Bob Herrick

One of the most important aspects of a strong Scale Drag Racing program is the building and wiring of the racetrack. We thought we would discuss the key points of proper track building.

Surface:

First we would like to touch on the surface, surface quality, and mounting height of a top quality track. For the top surface we recommend you use ¾ to 1" particleboard at a minimum, with 1” to 1 ¼” being preferred. The track should be located not higher than 36 to 40 inches from the floor. You must sand it smooth before painting using an orbital sander with 220-grit paper (we prefer wet or dry sandpaper for all sanding procedures). One thing we can not over stress is the importance of the track and slot being smooth, flat and straight. We also fold a piece of sandpaper several times and sand the slot thoroughly, by walking up and down the track, sanding the slot as you go. After the slot is smooth, we paint the slot (the whole length) using a small paintbrush. This helps the cars performance, for obvious reasons, and prevents cleaning solvent, and braid juice from penetrating the unprotected track material, causing it to swell over time, with permanent damage resulting to your track.

On the tracks that we have been involved in the construction of we have chosen Sherwin William's Industrial Floor Enamel (black or light grey) as the final finish. We have found this paint to be the best for traction, and very durable. Another thing to take into consideration is that this paint does not have an obnoxious odor while applying (follow all manufacturer instructions for use of this paint, and providing proper ventilation, on the side of the can). We prefer to thin the paint with common enamel reducer (probably best to buy this along with paint) and apply using an automotive type spray gun. We apply three coats, with the first one being thinned more to allow the first coat to thoroughly penetrate the surface (we do not use a primer). After the first three coats are dry, take your orbital sander, with 220 grit paper and sand the finish to remove all traces of orange peel in the painted surface. Then we apply three more even coats and allow drying. If you still have considerable orange peel, repeat the previous procedure.

After 30 days or so we clean the track thoroughly and take the orbital sander with 320-grit paper and take the shine off the track for about the first six feet. This gives the track the appearance of a chalkboard. This is done to allow the glue to attach to the track much like water sticks to an unwaxed car. When a car has a coat of wax, it causes the water to bead up on the surface. The glue on a shiny track has the same effect.

Shiny surface, (glue beads and you must use more glue for your car to get traction).

Chalkboard finish, (glue does not bead on the track and takes much less glue to give your car traction).

The method of making the braid joints is also very important. We have found the best way to do this is to drill a series of 1/16" holes the width of the braid and then chisel out a smooth rectangular slot. This helps the cars not arc over the joints by allowing a smooth even braid joint (this should be done on circuit racing tracks too).

Braid:

The braid area should also be recessed before installation so that the braid surface is approx. .010" below the track surface. The layout of the drag strip is quite simple. The first two feet at the beginning of the track should be the stage/start area, so the staging sensor should be located at least 18" from the beginning of the track. This will be the starting line. Your first braid joint should be at 20 feet from the starting line to allow you to replace the starting line braid (the starting line is where the most braid damage occurs) this also provides a convenient place to make a power tap. 55' from the starting line is where the finish line sensor is located. This is the finish line. The mile-per-hour sensor location varies by manufacturer, so check the documentation that came with your timing equipment. The final braid joint where the power cuts off should be 1 foot past the finish line sensor to allow the cars to pass the finish line under full power. This brings up the issue of stopping the cars. An adequate shut down area should be planned before construction and at least 20 feet should be used to prevent damage to the racecars. Don't forget the scale 1/8-mile (27.6') tracks, which only needs 15' for shutdown, and 1000' ft (41.8') tracks, which should have 20' for shutdown. These tracks are great for locations that can not provide adequate shutdown length for a 1/4-mile track!

Wiring:

The wiring of the track is quite simple but there are a few areas that need to be covered, such as the type of wire used. This should be THHN nylon jacketed wire because this wire is oil and gas resistant. This type of wire also is double jacketed with nylon, which is good for safety reasons. All connections should be soldered to insure good electrical contact.

One thing we can not over stress is the importance of neatness, and soldering every connection.

Pay special attention to cleaning the adhesive from the braid before you attempt to solder it to your power wires.

Be sure to use high quality rosin core electrical solder for all wire connections.

At the great risk of being misunderstood, we are going to explain our method of wiring a Slotcar Dragstrip. Read carefully, and if you have any questions, contact us and we will work with you on your project.

We will start with the controller stations located at the staging area. We prefer to use either copper or brass 5/16" machine screw's to hook the controllers to. First decide where to locate the controller stations, keeping in mind that two people at a time will be trying to get their controller hooked up at the same time. Naturally if you have a free standing track you would put them on opposite sides. In the real world of wall mounted tracks, it is best to have one on the exposed side of the track, the other one being located on the end of the track. It also is good to have the controller hookups where the racers can reach their cars, and most controllers do not have very long leads. Once this is decided drill two 5/16" holes about three inches apart at each location. On each screw we first install a nut and screw it on far enough so that you will have about 1" exposed thread on the shoulder end of the screw. Next put a washer on then insert the screw into the hole and finish by putting a washer, then a nut and tighten. You will notice that we did not say how long a screw to use, but we are not sure how thick your sidewalls are on your track. They need to be long enough so you have about 1" exposed on both sides of the sidewall. We also like to leave the head of the screw exposed to the outside of the track as it helps prevent ripped pants, and nasty scratches in the heat of the race!

Now we can begin the installation of the power wires. First you need to decide on what kind of wire you wish to use. For all wire sizes up to 10-gauge we would use THHN as described at the beginning of this article. Make no mistake 10 gauge wire can and does make a lot of cars go fast. However recent developments in motor technology have seen the amperage requirements go though the roof in the Open Motor Classes. We personally have seen one AA/FC car pull 225+ amps on the launch, we have not measured it with two cars at the same time. No reason to expect it to be any less than double this amount! So some of the raceways have been going up in wire size. The last track that we wired we used ultra fine strand 4-gauge welding cable for the power wires. The cost can be a factor using this size cable when you consider that you will need around 250' to wire a 1/4-mile track. If you do not run Open Motor Classes. Save your money and go with the 10-gauge THHN wire. We are going to explain how to wire one lane of the track, repeat for the other lane.

First you must determine the positive side and the negative side of the lane you are going to wire. Looking down the track from the starting line (in the direction the cars will travel), the positive side is on the right-hand side of the slot, negative on the left-hand side of the slot. Now go to the finish line and starting with the positive side clean ALL ADHESIVES from the braid that will be soldered to the positive cable. Strip back about two inches of the insulation, then wrap the braid around the cable and solder using high quality rosin core solder. Next route the positive power cable to the braid joint located twenty feet from the starting line. Now skin the insulation from the positive power cable about three inches long, then wrap both pieces of the positive braid around the positive power cable and solder. Now route the positive power cable to the controller station for the lane that you are working on and solder on a ring terminal of the proper size and attach it to one of the screws that you installed previously using another nut, to hold it in place. Now take a piece of power cable and strip and solder it to the positive braid where it comes over the end of the track at the starting area. Now route the cable to the SAME TERMINAL at the controller station. Use another ring terminal to attach the positive power cable to the controller station. Remove the nut holding the other positive power cable that you installed previously and attach both wires and tighten. Now for the other terminal at the controller station (the one with no wire attached to it), if they both have a wire attached. STOP. GO BACK AND READ the paragraph again! The other controller station terminal will attach to the positive side of the battery. Use a ring terminal on both ends. We like to use marine type battery terminals since they were designed for use with ring terminals. Do not connect the Positive power cable to the battery yet.

Now go to the finish line and starting with the negative side clean ALL ADHESIVES from the braid that will be soldered to the negative cable. Strip back about two inches of the insulation, then wrap the braid around the cable and solder using high quality rosin core solder. Next route the negative power cable to the braid joint located twenty feet from the starting line. Now skin the insulation from the negative power cable about three inches long, then wrap both pieces of the negative braid around the negative power cable and solder. Now route the negative power cable to the negative side of the battery. Solder on a ring terminal of the proper size and attach it to a marine type battery terminal to hold it in place. Now take a piece of power cable and strip and solder it to the negative braid where it comes over the end of the track at the starting area. Now route this cable to the negative side of the battery and attach. When you are ready for testing you will need to hook up the right and left lane, positive power cables to the positive side of the battery. These are the wires coming from both of the controller station.

This completes the proper wiring for one lane. Repeat the previous steps for the other lane. YES YOU MUST USE A SEPARATE NEGATIVE POWER CABLE FOR BOTH LANES. If you do not, you will find that when two cars run at the same time it will affect the times of both cars! If you desire to use a coin-op on your dragstrip, use it to control the timing system, not the track power. We know that the manufacturers claim that their track power relays are sufficient. We also have burned the contacts out of the relays that they provide! You be the judge! If you have to have a power relay, use a heavy-duty contactor or motor starter. Contact us for details.

Track Power:

On the question of track power we believe that the best source of power is from two 12-volt 8d batteries (dump truck, diesel truck, batteries). These come in different cold cranking amps; we prefer the 1175 CCA model to the larger 1300+ CCA models. They provide a faster discharge rate and will help the initial launch of the cars, not to mention they are also less expensive. We also recommend using a commercial type battery charger (Schumacher Model # SE-6030 is our favorite) set on 12v slow charge for most of the time except when a large number of people are using the track running group 20 and up cars. Under these conditions we will turn up the charger to 12v fast charge. We never have seen the need to set the charger on 12v-engine start, as this will definitely ruin the batteries. The maximum power allowed under the major sanctioning bodies is 16-volts maximum. We are aware that some tracks are trying to use two 8-volt batteries to reach this figure and it is not possible to maintain a maximum of 16v using any type of charger that we have seen. If you use more voltage to power the track you will create more than one problem.

1. You will have to use more glue to gain traction, which will cause your car to bog.

2. You will find that your controller will have a very short life span.

3. You will create an arcing condition on your commutator that will cause a drop off in performance and a shorter life span of your armature and motor brushes.

4. Any ET or M.P.H. That could qualify as a record, would not be recognized.

5. When you are going through the learning curve of drag racing a loss of traction can occur and a severe over revving of your car can result in tires coming off the rim and also can cause armatures to let go causing a near total destruction of your expensive motor. Most all the fast times you may have read about in the magazines have been attained on the type of track power that is outlined above.

We have just touched on the most important areas of track building, but if you take your time and work slow and precise, y’all can have a fine track too!

This document is provided for informational purposes only. The information contained in this document represents the current view of Drag Racing Specialties on the issues discussed as of the date of publication. Because Drag Racing Specialties must respond to change in market conditions, it should not be interpreted to be a commitment on the part of Drag Racing Specialties and Drag Racing Specialties cannot guarantee the accuracy of any information presented after the date of publication. INFORMATION PROVIDED IN THIS DOCUMENT IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND FREEDOM FROM INFRINGEMENT. The user assumes the entire risk as to the accuracy and the use of this document. This document may be copied and distributed subject to the following conditions. 1) All text must be copied without modification and all pages must be included. 2) All copies must contain Drag Racing Specialties copyright notice and any other notices provided therein. 3) This document may not be distributed for profit.

© Drag Racing Specialties 1990-2017