I’m Not An Engineer, But I’ll Do My Best To Describe This Issue. A Stress Riser Is A Sharp Edge, And A Sharp Edge On Any Stressed Part Can Lead To A Crack. The Threads In The Rod Ends Used In Most Of The Control Arm Designs Are Stress Risers. The Worst Thing You Can Do To A Stress Riser Is Put It Under A Bending Load. Particularly In The Rear Of The Z, This Is Exactly What We Are Doing. The Farther The Rod End Is Extended, The Wose The Bending Load Is. The Bending Load Tries To Spread Open The Threads And “Continue” The Crack. If The Crack Does Propogate, This Is Going To Result In A Snapped Rod End, Which Results In Sudden And Violent Toe Change Which Most Likely Will End With The Other Rod End Letting Go, And From There An Accident. You Need To Decide Whether That Risk Is Acceptable And What Kind Of Maintenance And Inspection Schedule Is Appropriate For These Parts.

Since Rod Ends Have No Insulating Property, The Vibrations In The Control Arms Will Be Transferred To The Chassis. This Makes The Cabin More Noisy, But There Is A More Serious Factor At Work. The Lack Of A Bushing Means That Sudden Impacts To The Suspension Will Also Be Transferred To The Chassis And These Can Lead To Weakening Of The Structure Of The Mini Cooper, Weakening Of The Control Arm, Or Both.

Camber Bushings Are Available For Our Mini Cooper As An Alternative To Adjustable Control Arms, And These Have Limitations That Are Often Overlooked. When One Adjusts The Camber The Toe Changes As Well. The Bumpsteer Also Changes. The Bushings Don’t Adjust Camber Very Much (About 1 Degree Total Adjustment) And They Necessarily Bind The Front Suspension. As The Front Control Arm Moves Up And Down, The Tc Rod Pivots With It. The Tc Rod Pivots On An Arc, And This Arc Wants To Make The Control Arm Forward Until The Tc Rod Is Parallel To The Ground, Then Back Until The Suspension Bottoms. The Camber Bushings Don’t Allow For This Swing Since They Are Made From Very Hard Delin And Aluminum, So This Stress Is Taken Up Jointly By The Tc Bushings And The Crossmember. Stock Rubber Bushings Will Flex To Allow This Sweep, Although Commonly Used Polyurethane Is Also Fairly Stiff And Increases The Stress On These Parts. A Rod End On An Adjustable Control Arm Allows For This Movement With No Increased Stress At The Crossmember Or The Tc Rod. The Suspension Is Free To Travel Its Natural Arc Without Any Binding Or Increased Friction.