cheseroo wrote:No reason for a leaf spring car to have a panhard and OP edited post to say it doesnt have one. IIRC, roll center on leaf spring axle is set by shackle bolt locations. If I had to make an uneducated guess, I'd say rear CG in truck is lower than a car.
I have added panhard bars to all my leaf spring auto-x and race cars, they help immensely with keeping the rear of the car where you want it, and make it predictable. Those that have driven my cars will tell you how well they handle, but please note that I do lots of other things too.
Even with a panhard bar, leaf springs WILL twist and flex, and that flex WILL change the geometry of the rear suspension of the vehicle (roll-over steer and roll-understeer), however it will be significantly reduced with a properly installed panhard bar. Flex will be amplified with lowering blocks and/or longer shackles.
Question: Why do people swap to poly (bearings) in the front end? Answer: To help keep the geometry correct. Why should the rear of the vehicle any different??
If there is no panhard bar the centerline of the axle is the roll center, if you add a panhard bar, where the panhard bar IS becomes the roll center. Ideally the panhard bar needs to be as long as you can make it, as level as you can make it, as centered as you can make it, and its distance above or below the centerline of the axle will effect the handling; you can use this to help tune the suspension.
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Bill
2020 I.O.E. CT #36 The Rootes Of All Evil,1958 Sunbeam Rapier Convertible (YES 1958!!) & 2019 Judges Choice NJMP
2016 Thompson Speedway #36 Sabrina Duncan's Revenge, IOE Trophy, 5th Place 'C' Class 1977 Ford Pinto
2009 Stafford Motor Speedway #16 Team Teflon, 11th Place (overall) 1997 Saturn SL2