Oval vs. Round lower control arm bushings
 

I think most, if not all of us are aware that they used 2 different bushings (round or oval) on the rear bushing on the front lower control arm. My 66 GTO has oval bushings.

My question is, is there any rhyme or reason a particular car would get one vs. the other? Is it year specific, plant specific, or completely random?

Just curious....

Importsmasher

Ooh. good one.

Common sense says which, direction the torque is forcing the axis (pivot bolt) needs more rubber to cushion the force as well as wear longer.

If you've replaced as many bushings over 5 decades as I have, they always break down on one side. The round bushings will first compress, then wear away the broken down rubber until the center sleeve is loose in the rubber, and the bond breaks down. The longer it is driven like this, the more play happens to the pivot joint, until there is just the sleeve bouncing around inside of the outer shell.

Just a guess that possibly the more severe the usage (stick shift cars) that the engineers would opt for a bushing with more rubber for isolation, and longevity.

Years ago, before there were urethane bushings racers used to hammer finishing nails into the bushings to stiffen the joint to stop wheel hop, this actually made the durometer readings increase on the rubber bushings, and stopped the wheel hop. The rubber hardness, and thickness plays a big role in how the joint acts under severe stress.

On front suspension, the bushings also figure into spring rates because of their resistance to movement. Certain suspension options may use the bushings to fine tune the end spring rates.

Just some observations over the years of working on mostly GM cars, and building race cars over the years.

:2cents:

I would say random.

Depending on what they had on hand they’d use on the assembly line.

I’ve heard of cars built with both types, one on each side.