You should also remove the quick-connect clevis, if one was attached to the failed slack, and replace it with a standard threaded type. Finally, examine the brake chamber for cracks, excessive corrosion, bent pushrod and egg-shaped clevis pin holes. Also check the S-cam to make sure it is straight and that its bushings and seals are intact. A lot of lining nowadays is marked to indicate when replacement is necessary. Inspect the foundation brakes to ensure the lining is still suitable. By the time a slack adjuster fails, other components in the brake assembly are probably also worn. Parts that have been in service a long time or inadequately greased will often need to be coaxed off with a large hammer, puller or acetylene torch.Ĥ. This damage might not be a problem, however, if you’re discarding the slack being removed. Use an impact wrench, because this task will destroy the internal clutch mechanism found in most automatic slacks. Rotate the manual-adjusting bolt counterclockwise (or clockwise with ArvinMeritor products) to back off the slack adjuster so it separates from the clevis. If you must leave the brakes applied, which would be the case with an unattached trailer, you will need to cage (or manually retract the main spring of) the air chamber attached to the slack adjuster being replaced.ģ. Park your truck or trailer on a level surface and chock its wheels. The followig information applies to drum brakes.ġ. Instructions are also packaged with each new adjuster. Product-specific information is available from the manufacturers’ websites. Usually, the biggest challenge is loosening the old slack’s grip on the S-camshaft. Without difficulties, slack adjusters can be swapped in less than 30 minutes, not counting time spent chasing parts or drinking coffee. The benefits of extended longevity are something to consider the next time a scale master directs you to a waiting inspection lane.ĥ.Ě well-greased 10-spline S-camshaft without the slack. Repeated offences can damage the slack adjuster.“If proper maintenance is routinely done, there is no reason that a slack adjuster shouldn’t last as long as the vehicle it’s mounted to,” says Gary Ganaway at ArvinMeritor. That will allow the adjustment to back off a little each time the brakes are applied. You can do this and adjust them like manual slacks.If the brakes are forced to be backed off without doing this it will strip out the paw. If you want it back the brakes off it needs to be removed or the center stem spraged ( there are tools for that ). They also have a lock paw with what looks like a 3/4 inch bolt head on it. You can check the travel and adjust them up a bit just to keep them tuned up. A 3/8's 12 point will fit them if they are not mucked up. They have an adjustment screw on them that is 5/16 square. Do not want them tighter than a 1/2 inch. You do not want more than about an inch ( brakes cold ) and if it runs on out several inches you definitely have a problem. Put the side of the wrench against the chamber mounting bolt and pry the clevis away from the chamber. One way is to take a 7/8 or 15/16 open end wrench and put it between the clevis and the brake chamber.
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