Reassembling a brake system

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Updated Jul 16, 2015

Below are tips from Haldex’s new Tech Tip series on brake system reassembly. For tips on disassembly, please CLICK HERE.

  • It is important to note:
    • a. Select the proper friction material based on your type of loads, application, duty cycle and operating terrain. Consult your supplier if you have any questions.
    • b. Many shoes look alike, especially the new extended service design. Therefore, be sure to install the same shoe that is removed.
  • Always replace all shoe attaching parts, anchor pin bushings, cam bushings and oil seals. All parts being reused should be cleaned with solvent, rinsed and dried. Replace s-cams, bearings and cups, as necessary.
  • Lubricate anchor pins, brake rollers and bushing area of camshafts. Never lubricate the face of the roller (contact point with the s-cam). Only lubricate the bearing area of the roller that contacts the shoe web.
  • Install new drums, if necessary. Do not mix light- and heavy-duty drums as this will result in uneven brake shoe wear.
  • Lubricate axle spindle to insure bearings slide on easily. Slide hubs on to the axle far enough to be able to install the inner and outer bearing and inside axle nut. Never slam the hub onto the axle. Adjust bearings to manufacturer’s specifications. Install spacer/lock ring and outer nut (if applicable) and new hub cap gasket. Ensure proper hub oil or bearing grease, depending on the type, is applied.
  • Always adjust all brake adjusters on all wheels of the vehicle. Adjust all manual brake adjusters for .015 drum clearance. Automatic brake adjuster drum clearance is .018-.025 (check manufacturer’s specifications for proper setup). Follow the same procedure for each brake adjuster on the vehicle.
  • Inspect all brake hoses leading to chambers, replacing if cracks are found.
  • Inspect all spring brakes for center seal leakage, replacing if needed.
  • Check brake release. If slow on the trailer, install a quick release gladhand on the service side of the trailer to speed air exhaust.
  • Inspect spring brakes for proper installation of rubber dust plug in release tool hole.
  • If you replaced any brake chambers, ensure you did not mix sizes. Never mix long stroke with standard stroke chambers on the same vehicle.
  • If relining a trailer, replace both gladhand seals.
  • Always road test after reassembly to check for satisfactory brake performance. Automatic brake adjusters are typically backed off half turn from lining contact. Final stroke will not occur until brakes are cycled and lining is “burnished in.”
  • Re-examine wheels for excessive end play.
  • Re-check brake adjusters and chambers for proper and equal stroke.

(Editor’s note: This article has been updated this article to remove chamber from the headline above, which was inadvertently added by Truck Parts & Service. These maintenance instructions are for entire brake system service.)

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