DRUM BRAKE ARCING

The difference between winning and losing can come down to something as simple as brakes. Many drum brakes are mushy with poor stopping power.  Race Tech is now offering Brake Drum Turning and Brake Shoe Arcing.  We use to do this “back in the day” and we were “strongly urged” to start offering the service again.

There are two parts to this; first we cut the drum so it's round and flat and then cut the shoes to the new drum diameter. The difference is quite often amazing.

Here's what we need:

  • Complete clean wheel (with or without tire – shipping without it is a lot cheaper).
  • Wheel should be trued with spokes properly adjusted.  (spokes can easily pull a drum egg shaped).
  • Wheel should be clean inside and out.
  • Axle (must be straight) It is essential the axle is straight or it will cock the backing plate causing poor performance. We check it for straightness and we use it in the Arcing process as well.
  • Complete clean and lubed Backing Plate.
  • Good brake shoes (nothing oily or worn out). 

This service costs $200. Our current turn-around is about 4 working days but give us a call to make sure.



INSTALLATION PROCEDURE - (all drum brakes)

  • Mount the Front Wheel on the Forks. Before you tighten the axle, spin the wheel and grab the front brake lever. While keeping the lever held firmly tighten the axle. This centers the backing plate.
  • There are two major types of front axle systems; Full Width Spacers or Axle Pinching Type. Full Width Spacers are commonly on less expensive or older models. The Axle Pinching Type typically tightens into the left hand leg while the right side allows the fork tubes to be parallel.
  • For the Axle Pinching Type take the bike off the stand and pump the forks with the axle pinch loose. This aligns the fork legs. Tighten the axle pinch clamp.

NOTES:

  • If you've followed this procedure and the front brake lever action feels positive before you tighten the axle but feels mushy afterwords you either have a bent axle or the surface of the fork leg or backing plate is not square to the axle.
  • If you have dual or quad leading shoes do not adjust the tie-rod between the brake cams after the shoes have been arced.
  • Early Magura levers were cool but they didn't have a very good leverage. Honda or Yamaha levers had much better stopping power.

Good luck and good stopping,
Paul Thede

YZ465 Brake Arcing

racetech.com