1970

me personally i don't want to grease up my bushings my driveway is 3/4 mile gravel and that dust sticks to everything i figure if i'm not racing it ill take quiet and soft

67mustang302

Then the suspension will never move the way the geometry is intended. Yeah, dirt is an issue (I live in the land of corral dust and gravel), but as long as you don't over lube and wipe off the excess on the outside where it's not needed it should be fine. It's actually pretty hard to get dirt inside the moving surfaces on the rear suspension because of how tight everything is.

But lubing makes a rather large difference in suspension function. It works without lubing it, but it causes the bushing surfaces to not be able to move, so as the suspension articulates the bushings twist...almost like a tiny plastic torsion bar. The job of the spring is to be the spring, the job of the bushing is to locate the spring and provide some pliability to allow for spring twist during body roll and to absorb road harshness.

Lubing the bushings everywhere lets the surface slide inside the contact points, so the bushing doesn't twist. That way the spring does all the work and the suspension can articulate through the total geometric range. It makes for a noticeable difference over rough roads and under cornering on rough surfaces. Matched with a correctly tuned spring/shock combo, you'd be amazed what a leaf spring suspension can do when it's allowed to move.

Leaf spring suspensions have some inherent drawbacks in the way they function, they need all the help they can get. Most of the harshness and lack of control in leaf suspensions comes from all sorts of binding.