Sidewall_Tester

Gecker Sidewall Stiffness Tester Instructions

Thank you for purchasing the best value in a tire tool. Knowing your tires is the key to chassis handling. Our new sidewall stiffness tester will provided you with the knowledge needed to make the right tire decision at a fraction of the price of other sidewall stiffness testers. Please read below to properly use your new Gecker Sidewall Stiffness Tester.

1. Unpack The Tester

-Unpack your new tester and confirm that all the parts are included. The following parts should be in the box: 1-Dial indicator, 2-Springs, 1-Test fixture, 1-Hub with bolts and nuts, 1-Bottle Jack with jack lever, 1-axle nut and 1-spacer

-If all these parts are not in the box, call us at Gecker Motorsports Products.

2. Assemble The Tester

-Assembly of the tester will only take 5 minutes following our instructions. Remove the bottle jack and install it below the plate where the scale sits. There is an adapter mounted below the scale surface plate where the top of the bottle jack will slip into. Make sure that the bottle jack is installed into this adapter properly and the jack is sitting squarely on the bottom surface of the tester.

-Next, Install the springs to the bottom of the scale pad mounting surface and hook the spring into the spring “hook” at the bottom of the tester near the bottom of the jack. Wear eye protection at this stage as the spring can snap back and harm you. Be very careful when connecting the spring to the “hook”. Install the other spring in the same way.

-Then, install the dial indicator onto the indicator bracket. The indicator bracket hangs down from the platform where your chassis scale pad will sit. Remove the nut from the indicator bracket stud and slide the indicator onto it. Reinstall the indicator bracket nut and tighten. Tighten the indicator bracket nut so that the indicator stem is perpendicular to the bottom of the tester.

-Now, install the wheel hub onto the axle assembly at the top of the tester. The spacer provided can be used, but is primarily used in checking rims with 5” or more of backset. Tighten the supplied axle nut so that the hub can still turn and has little drag and little play.

-Mount a tire onto the axle/hub assembly. Make sure to tighten the wheel nuts to eliminate the potential for incorrect readings. The outside of the tire as it is mounted on the kart should face you.

-Take your scale pad and set it between the tire and the scale platform on the tester. Install a sheet of paper between the tire and the scale pad. Jack the jack up until you can just pull the sheet of paper out. This will be your starting point on all stiffness measurements.

-Adjust your dial indicator via the thumb screw on the indicator mount bracket so that the indicator will have sufficient travel of at least .500” as you jack the tire up to take your measurements. You may have to spend a minute to ensure that your indicator has enough travel in order to measure at the proper lift rates. Once you are satisfied with the indicator travel, you are ready to start defining your tire program!

3. How to use your new tester

-Mount the tire and install your scale pad. Install the amount of air you plan to run in the tire. Use the same amount of air each time you are checking the same tire. Position your scale display so that you can see it while measuring the tire. Turn your scales on.

-Jack the jack up with until the dial indicator travels .040”. After the pad has contacted the tire and has traveled .040”, zero your dial indicator. It is at this point you can begin to check the tire.

-Jack the tire with the jack slowly until you reach the desired measurement lift. We check our tires at .250” and .4004 lift. If you plan to utilize these same numbers, jack the tire watching the indicator, until you reach those lift levels. Than read the scales. The number that your scales gives you at each lift level represents the amount of pressure that will be exerted onto the racetrack as the kart goes through the corner.

4. Now What?

-Check all of your tires and label your tires with marking chalk on the outside so that the number is visible from your tire rack. If you mark your tires, you will now know the differences between all of your tires that are the same or different in size. This info is important when you are at the track. This will allow you to make the correct tire decision and allowing you to do testing.

-This tool will allow you to make correct decisions on what the tire is and how it will respond with the other tires. As an example, you do not want to run a stiff sidewall on the right front and a weak sidewall on the right rear if the kart does not handle properly. Start to experiment with combinations until you determine what will work best with your kart and the track conditions you run with. Your best bet is to start out with a stiffness number that is close on the outside numbers (for oval) and close all the way around (for road courses).

Some Notes:

-Check the tire each time you run it as the number will start to fall

-Check your tires at different air pressures to determine how the tire will respond in stiffness so you are prepared when you make air pressure adjustments at the racetrack

-Outside tires (oval) with greater than 8 pounds difference will respond differently on the track

-A weak stiffness rating on the outside and the left rear will cause the kart to get more bite

-Alternate your stiffness on the left rear tire in order to get the kart off the corner better

-Tire preps over time will affect the stiffness of your tires sidewall-Check your tires frequently

-Enjoy! You now have a tool to define your day or racing causing you to not pull out your hair as the kart did something different than what is was supposed to!