What type of bushing is this?

 

Energy Suspension trailing arm insert bushing.

My own opinion about it is. Don't use them. Factory trailing arm bushing is best for a street car.

 

thanks for your help

 

or mugen since there the same.

 

There have been many complaints about these bushings causing snap oversteer. On the street I've had no problems with these bushings, and at autox I have yet to find out what snap oversteer is.

It is quite a large bushing to make so hard though.

 

Snap over steer, best way to describe it is to give an example. Say you're turning and all of the sudden the rear of the car gets a little out. You steer in to correct it and all of the sudden, the rear of the car goes back, and keeps going, eventually going all the way around causings you to be faced in the opposite direction. Thats snap oversteer.

 

Snap oversteer just comes without warning, there is no "gets a little out". Grip, grip, slide too fast to recover, no progressive warning. There's a lot more than just a single trailing arm bushing that causes lack of progressive breakaway though, it's a combination of stiff stuff. If you have stiff coilovers, sway bar, and pretty much all of your bushings are hard, you'll have problems. Make everything unyielding and you'll have no compliance left to keep enough grip. Part of this is also lowering, trailing arm geometry doesn't really take well to being lowered because the roll center of the car changes in the back.