The J-bar tends to get rid of the tight -loose problem that the long panhard bar usually causes. The lond bar puts a lot of load against the outside edge of the RR tire, causing a tight entry. The J-bar moves the rear roll center to the left, which helps gain side bite by allowing the car to get on top of the RR tire. Typical handling of a J-bar is free to snug entry (depends on center of gravity height, shocks, springs and bite) to snug to tight exit (depending on same things above)