Mechanical Modifications (Part 3 of 5)

Types of Mechanical Modifications:

  1. Functional – modification to make something behave differently
  2. Structural – modification to make something stronger, lighter

General guidelines:

  • Golden rule: Nuts and Bolts are better than Welds!
    • Welding is a better option if done by a high quality OEM type welding process. If done at a local fabricator then it WILL break in the field. Therefore, whatever you want to make, use nuts and bolts instead. These allow lots of flexibility and can be quickly replaced in the field if broken.
    • Use Liquid Thread Lockers: Nuts have a tendency to get loose due to weathering and vibrations. Non permanent liquid thread lockers like Loctite 242 Blue are best for modification applications as they for a non permanent bond which will not get loose due to vibrations. Its very easy to use and we sell one here.
    • Use Nylock nuts: These nuts have a nylon (plastic) ring at one end, which prevents them from getting loose. We sell high quality Nylock nuts here.
  • Load distribution:
    • e.g.: A top rack to install a top case or luggage box
      • Consider G Forces: The material used for the rack frame must be of the correct thickness. Thickness must be calculated by identifying the static and dynamic loads. Static load mean say you plan to carry 20Kg of luggage. Dynamic load means the 20Kg will become 80Kg when going through pot holes or corners at speed due to G forces. So design must be done for 80Kg load bearing structure and thickness must correspond to this design.
    • As a general rule, round pipes are better suited for such structures. But flat metals can also be used.
    • TIP: Specialized softwares can show before hand how a design will work, the strains and stresses at various points so if possible do this. If not add some afe tolerances to the design. This means having a design which helped complete your ride back home in 1 piece vs troubleshooting in the field.
  • Golden rule: Loads should not extend beyond any of the axle’s.
    • Especially the top box or rear luggage should not extend too much behind the motorcycle. If done, this will hamper the stability in sharp turns and heavy braking; the rear will tend to go faster than the front leading to a slide. Conclusion is Front heavy, light rear.
    • Its better to extend equally on the sides.
  • Golden rule: Keep the CG low and centered
    • Side luggage and panniers should be as low and as inside as possible. This will help ensure better Center of Gravity
  • Golden rule: Torque them all!
    • Anything you do to the structure (stock parts like chassis), remember to torque the nuts and bolts to the specified torque values. Not doing so can not only be hazardous but will also hamper motorcycle performance in the long run. Use torque wrenches available at service centers or buy inexpensive kits.