URO Systems, LLC

URO Systems, LLC Shackle and Suspension Systems

A Proven High Performance Innovative Product with Superior Quality and Reliability

Technical Service Bulletin...

DATE: June 1998

Subject: Front Suspension

To: All ® Suspension and Shackle Bushing Kit Installers

Re: Wear Limits for Rear of Front Leaf Spring Bushings on all vehicles with Multi-leaf and Parabolic Leaf Springs.

DESCRIPTION

The following procedures should be used to determine when Rear of Front Leaf Spring Shackle Bushing service is required.

NOTE: The following bushing wear should be made prior to lubrication, however, ® Suspension and Shackle Bushings require no lubrication.

1. Insert a 24" bar between the spring hanger pin and the rear of the front leaf spring eye from the rear side. Pry in an upward and downward movement until normal shackle movement and flex takes place. Observe the movement of the leaf spring eye while pushing up and down on the outer end of the bar. If the movement (spring pin separation) of the leaf spring eye at the spring pin and the spring hanger pin is greater than .1255 inch (1/8"), proceed to step two. Please note that this measurement is a combination of both the upper spring hanger bushing and the lower spring eye bushing. It should noted that a bar of greater than 24" in length could exert undue force causing the spring, spring hanger and or spring pin to be deformed or unnecessarily show signs of premature service life. It should also be noted that the chemical properties of the polyurethane provide for elasticity, or (flexible movement if you will). There is a distinct difference between elasticity movements that will occur during checking for wear movement. Elasticity movement in ® Suspension and Shackle Bushings should not exceed .060 inch (1/16") and this movement is similar to movement that would occur as the front suspension articulates as it travels down the road.

2. The only accurate measurement of bushing wear requires removing the spring pin from the leaf spring, measuring the outside diameter of the spring pin and the inside diameter of the spring eye bushing. The difference between the two measurements is the amount of clearance between the spring eye bushing and the spring pin. If a measurement of .007 to .012 is noted, the bushing is new. A measurement of .080 to .090 indicates that the bushing will require replacement during the next vehicle service interval; if the measurement is .125 or greater, the bushing should be replaced immediately.