rear control arms

Reply #15 – April 24, 2006, 10:50:52 AM

During body roll, the lower arms are forced to "twist" as the axle stays planted on the ground and the body rotates. This is where the isolator stiffness (or resistance to twist/deflection) comes into play. As the body rolls to the limit, the roll stiffness increases. When it binds, the body stops rolling in relation to the axle and technically the rear axle will want to try and lift due to the twist. When this happens is when you'll lose rear traction. You want to maintain as much compliance as is feasible while keeping body roll down.

The body moving vertcally over the axle (ie over bumps, etc) does not cause this increase in roll stiffness.

rear control arms

Reply #16 – April 24, 2006, 01:38:06 PM

I've installed the CHE adjustable lowers and uppers (non adj.) on my car. I was also quite pleased to be able to get adjustable lowers (& uppers to boot) for less than a set of non-adjustable MM arms - which would have been useless to me as the car sags already and I need to raise it a bit to fit the 28"x10" drag tires when I take it to the track.

I've said this in other posts, but these arms "feel" right on my car. You can feel cracks in the pavement more, but otherwise things are nice & smooth. CHE claims to have picked a urethane with a lower hardness to reduce the binding forces:

"Polyurethane Bushing:
The polyurethane bushing is designed to absorb shock and allows the axle to move through its complex range of motion without harsh binding or torque box damage. Because the poly bushings remain fixed without rotating, there are no annoying squeaks. We carefully select the proper hardness to provide maximum performance and prevent binding and damage.
Our Polyurethane bushings are engineered and manufactured specifically for our products ensuring optimal performance for any driving or racing style. "

I am not sure they are soft enough to limit binding forces that cause the sudden "snap" oversteer, so far so good in my car, though I've had my front swaybar off for a while now as I'm trying to get in one good run at the track. I'll be able to better evaluate the performance in the curves where the "twist-bind" is likely to occur later in the spring.