What are the radius arms and where are they located? 

Radius arms are part of beam axle or solid axle suspension systems.  Solid axles and radius arms are found most frequently on trucks and SUVs.  The radius arm is a piece of stamped steel that connects the axle to the chassis to control the forward and back motion of the wheels.  It helps to keep the steering under control.  The radius arm attaches to a bracket on the chassis and a bracket on the axle by the shock absorber.  There is one radius arm for either side of the solid axle.  Each radius arm has rubber bushings at each end to protect it from the kind of damage that results from metal striking metal. 

How do I know if my ­­­­ radius arms need to be replaced?            

It’s more than likely that you’ll have to replace the radius arm bushings than the radius arm itself.  Like all suspension parts, the radius arm and its bushings get exposed to the elements.  The bushings also get worn from their near constant movement.  If they wear out, the radius arm may start to clunk against the brackets, which is often audible inside the truck cabin.  The sound will come from underneath the floorboards.  You may also notice that the steering becomes loose or sloppy.  Loose steering poses a danger to yourself, your passengers, and other drivers, so if your radius arm bushings reach that point, it’s time to replace them.  If you suspect you have a problem with your radius arm bushings, you can visually inspect them for wear or cracks.  You can also jack the car up, so the wheel is off of the ground, and then have someone try to move the wheel in and out. While they are moving the wheel check the radius arm for play, if it is moving you probably need to replace the bushings.

If the bushings get too far gone, the clunking of the radius arm against the brackets can crack the brackets and wear on the radius arms.  This poses an even bigger threat to your steering control.  You should visually inspect these parts if you are replacing the radius arm bushings. Replace the bracket or the radius arm itself if it shows cracks, corrosion, or other signs of damage. 

Can I replace the radius arms myself?  

Replacing the radius arms is about as difficult as replacing any other suspension part.  If you need to replace your radius arms, odds are that their bushings need replacing too.  This can be done while the radius arm is off.  Unfortunately, if you want to replace the bushings alone, you’ll still have to replace the entire radius arm. 

First, you’ll have to raise and secure the vehicle.  Then support the suspension with a jack to take some of the pressure off of it.  Then you’re going to want to disconnect the coil spring from the axle.  Then you can disconnect the radius arm from the axle.  If you are just replacing the bushings, you may choose to do so now by simply sliding out the old bushing and sliding on the new one.  Then, you could reconnect this end of the radius arm, and then work on the other end.  Otherwise, continue by disconnecting the radius arm from the chassis bracket.  Again, here you can replace the bushings.  If you’re installing a new arm, put the bushings onto it, put it into place, and bolt it on.  Then you can reconnect the spring.  As with any other suspension part, you’ll want to replace both radius arms (or both sets of bushings), left and right, at the same time.  You’ll also want to have your suspension professionally aligned following this job.