DMSBD Tech Tips

DMSBD Final Assembly, Wheels and Tuning Clinic
Written by- Ian Carsten

MSX International, 1426 Pacific Drive, Auburn Hills, MI, Saturday, April 6, 2002

Our Final Assembly, Wheels, and tuning Clinic began with Detroit Metro director, Joe Flynn, announcing that even though next week’s clinic is the last scheduled clinic in this year’s series, we may schedule a single review clinic for latecomers if there is sufficient demand. Joe then commented on concerns for the upcoming Birmingham race to be held either in August or Labor Day weekend. It looks as though both WJR and WXYZ will give the event some coverage. Then, he commented on the progress of the sponsorship package. With reference to that, he said the DADA/Detroit Metro Soap Box Derby poster is at the printers and should be in the Detroit area auto dealerships within the next two weeks. A full size prototype of the poster was on display. It is stunning. It features Lauren Flynn’s beautiful blue-flame-on-white Scottie masters car in a simulated nose-to nose race with her brother, Michael’s, white 2001 All American Masters championship car. All who viewed it were quite impressed. As at the last several clinics, we had the four-pad electronic scales set up for our racers to weigh their cars with the driver in position, place sample weights to attain race weight determine placement for proper balance.

Joe announced that next week’s clinic would focus on race preparation and driving strategy. Also, he reminded the attendees that all the specialized derby tools would be available for our racer’s use at next week’s clinic and at the track on race days if anyone needed to make some last minute pre-inspection adjustments. Regarding today’s topic, he said the 2002 rules now allow us to use clothing dye, such as Rit© dye, to color the cockpit foam to harmonize with the color scheme of our car. Jim Scotti commented that that would be useful to cosmetically restore foam that had faded or discolored due to sun exposure. He said it looks rather ugly when it discolors. Then Joe talked about the proper material and technique to attach the foam to the cockpit. He noted that there is a special concern when using contact cement for gluing cockpit foam onto a derby car that many new builders fail to recognize. The foam eventually deteriorates or is otherwise damaged in use and will ultimately have to be replaced. However, contact cement, when fully cured, is nearly impossible to get off of a derby car’s body. But you have to completely remove the old glue in order to properly cement in new foam when replacement becomes necessary. To avoid the problem, you can first coat the inside lip of the cockpit with something that doesn’t adhere quite so tenaciously to the shell. Then when that coat is dry and hard, you can glue in the foam. In this way, when it is necessary to remove the old foam and glue, scraping and/or the appropriate solvent, should fairly easily strip off the undercoat from the shell taking the layer of old contact cement with it. Mr. Gullet suggested a layer of silicone rubber sealant as is often used to caulk and seal around bathtubs and so forth. He claimed to have had good result with this product and said it strips away cleanly, carrying the old glue and foam with it. For attaching the foam, Joe said he has had good results with Liquid Nails© brand contact cement. It should be brushed on in a thick coat and allowed to completely dry to the touch. The instructions on the can say it should be dry enough adhere the parts together in about 15 minutes after application. Jim Scotti commented that it is important to take spare foam and contact cement with you to races because the bond sometimes unexpectedly fails or the foam may tear due to deterioration as it ages.

Joe reminded the builders that it is important to have sufficient clearance around the axles, cables, and stabilizer bars. Also, he said the rear of a stock body could be raised to accommodate a larger driver. If you use this, raising the rear of the shell often takes care of any vertical clearance problems around the rear axle and stabilizer bars. He said we don’t want the body to touch the shell because it will dampen the spring of the axles and slow the car. He cautioned the builders to get the body attachment screws driven in square to the edge of the board. Otherwise, the screw heads could stick out slightly and increase air drag. Ted Schafer commented that you should be careful and work methodically, since it takes time to get the body-to shell fit correctly. Then Joe said it is a good idea to get all the body screws tightened equally. He cautioned that if you use a power screwdriver or drill motor to install the screws, you should try to use one of the models with a variable-torque clutch set to a modest level so that you don’t strip the screw holes in the board. Then he offered advice for anyone who has stripped a body mount screw hole. He said that you could drive in one or more hardwood toothpicks coated with strong glue to plug such a hole. After the glue has cured, you should be able to put a screw in and it should hold well.

Then Joe mentioned that the shell of a stock car can be made quite a bit smoother than by just waxing it, by first buffing it out with a mild abrasive paint polish, such as Mothers California Gold polishing compound. Also, this smoothes out minor scratches that the stock shells are prone to get. Just be sure you get polishing compound and not the much stronger rubbing compound. You will probably want a coat of wax on top to finish the job and make your shell really slick. Next Joe mentioned that any appliqué should be kept to a minimum from the cockpit to the nose. He feels that any stickers should be kept to the rear part of the car where he believes it will produce less drag. He mentioned that we had some copies of the DerbyTech article on painting a superstock car. We also have this article available on the kids site at www.dmsbd.org. It has some useful advice for obtaining a proper paint job on the unique shell material the superstock body is made of. Ted Schafer said most auto paint shops know how to do this since it is just like painting a plastic auto bumper. Also, he said he had seen an unusual means to finish a superstock that did not involve painting. He said he saw a car that was covered in appliqué then coated with a number of layers of floor wax that had been buffed to a high gloss.

Next, Joe reviewed airfoil mounting. He suggested using a couple of small c-clamps to hold center the air foil vertically on the axle and use a 3/16-inch drill to transfer the screw hole locations into the airfoil, ensuring a perfect fit. Also, he suggested sanding the transition ridge left by the cutter that produced the radius on the airfoil. This is done so the air can make a smooth transition from the radius to the flat sides of the airfoil and axle. But be careful not to change the radius that forms the leading edge of the airfoil since this is one of the many things the inspectors at Akron look for. It is important to keep your car Akron-legal so that you can get the VIP sticker should you race there. And that also pretty much ensures that your car will pass muster at any other track you race at. Next, he showed how to mark a rear airfoil for radius rod clearance if needed on a stock car. However, he warned the builders that the floorboard might not be modified in any way. For a superstock, Joe noted that the front airfoils would have to be trimmed to match the contour of the shell. He suggested using 1 x 2-inch stand-ins to get the trim and overall length correct prior to cutting the airfoils. This prevents you from ruining your airfoils by initially cutting them too short. It is better to make any mistakes on the stand-ins, which are cheap and readily available at your local lumberyard. The 1 x 2 lumber is sold as firring strips. For a stock car only, Joe said many racers are mounting their shell to space the nose of the shell 1/4-inch away from the nose of the floorboard. Since the nose of the shell rests against the starting gate, this pushes the rest of the car 1/4-inch further up the ramp and is a definite advantage over a car not so configured. Since 2002 rules allow it and so many stock cars have been set up this way, you might as well do so too. Otherwise, you’ll be racing at a slight disadvantage. Note: any spacer used to establish this 1/4-inch gap must be removed prior to inspection and racing. However, please pay particular attention to the following if you race a superstock. Any floorboard-to-shell gap is expressly prohibited on a superstock. Don’t try this on a superstock; it will be inspected and disqualified if present.

The next topic discussed involved wheel and spindle lubricant. He said policies vary depending on which track you are racing at. Generally, you may lubricate your wheel bearings and spindles before pre-race inspections if you choose. However, no further changes are generally allowed after inspection. In a wheel swap race, coming up with a faster wheel set is of no advantage. But having slippery spindles may help the wheels squirm about more freely. Joe suggested using a dry lubricant because, in his experience, oily, greasy spindles tend to attract dirt, which, if it gets between the spindle and wheel bearing, increases friction, defeating the purpose of polishing and lubricating the spindles. Ted Schafer commented that it was a rather moot point since, in a wheel swap race, you will constantly be transferring oil and grease from other racers wheels to your spindles. Joe then made some comments about how this differs for racers who are successful enough to get to race at Akron. He said at Akron, about the middle of the week, you are allowed about 15 minutes to clean and lubricate the bearings in the wheel set you are issued. He believes that any lubricant you use will partially dry and thicken before race day and that it might attract dirt, any of which could increase rolling resistance. That would be detrimental to your car’s acceleration, especially in the critical first few seconds of travel. Instead, he recommends using a volatile solvent such as lighter fluid to wash out any dirt, grease, or oil from the bearings. Then he says you should blow them out with a can of compressed air. The spindles could be lubricated with a dry lubricant. He also mentioned that although the champ wheel sets are supposed to be tested so that each box of four has approximately the same total rolling resistance, the boxed sets are almost never equal in rolling resistance because the wheels vary too widely in manufacture. Jim Scotti said that his son, Kyle, had one very bad wheel, which he brought to the attention of the officials. They agreed and allowed him to exchange the bad wheel for one that rolled more normally. Kyle went on to win second place in stock division. It was then suggested that each of your wheels be tested to determine if it has a heavy spot. If so you can mark it with an ink marker. Then, when you set your car against the starting gate, you can orient the wheel to take advantage of the heavy spot to help the car accelerate in the critical first few inches of travel.

Next, we used Maddie Klein’s white stock car to demonstrate the problem most new drivers have getting into proper racing posture. Several rather small drivers tried and were only partially successful. Ted Schafer said that it is very important for the drivers of stock and superstock cars to exercise regularly prior to and during the racing season to maximize their range of motion relative to racing posture. Then, Detroit Metro racer, Alyssa Schafer, who is currently 5’ 2’’, demonstrated the stretching routine she does for several minutes to limber up her muscles and ligaments prior to getting into a stock car. After warming up in this fashion, she slipped into Maddie’s stock car and into a very low racing position with only the top of her head just barely above the cockpit. She made it seem effortless. She commented that gymnastic and ballet students were frequently the best at getting into racing position in a sit up and lean forward type derby car since their exercise regimen keeps them particularly agile.

Then we broke up into independent work groups as in previous weeks. Several racers took advantage of the time to check the triangulation of their rear axles square to the centerline of their cars. Others used our four-pad electronic scales to determine weight requirements to attain race weight and balance. Theresa Young conducted a drawing for the drivers in attendance. This week’s lucky winners and their prizes were:

  1. Alyssa Schaffer     7 foot Jump Rope

  2.  Jordan Barkus      #19 Yzerman Bear Collectable

  3. Justin David          US Off Shore Race Boat

  4. James Gullett        '01 Centennial Hot Wheels

  5. Sally Guimond      #24 Jeff Gordon Bear Collectable

  6. Khristina David      Tech Kart

  7. Josh Barkus          Dave Voelker BXS Series Diecast Bike

  8. Tillie Bergmeier      US Flag Kite

  9. Maddie Klein          Jay Eggleston BXS Series Diecast Bike

  10. Jeffrey Lukacs        Hyper Glide Disk

  11.  Tori Balogh            Double Jump Rope

  12.  Devin Gullett          #2 Rusty Wallace Nascar Framed Print

  13. Kyle Scotti             #88 Dale Jarrett Nascar Framed Print

  14. Alexa Johr              Hyper Glide Disk

  15. Kelsea Klein           Potpourri Pot

Next week’s clinic will focus on Race Prep &  Driving Strategy.

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