Thursday, January 19, 2012

Single vs Double Shear Explained

We know the rear toe link joint is a weak point in the Elise/Exige - mostly with track driven cars.  There is a misconception that the toe link is weak - it is actually the joint where the stock balljoint meets the subframe.  This blog entry discusses how we reinforce the joint, with our new DSbrace and RTD2brace, by placing it into Double Shear.  
The easiest way to explain the differences between Double & Single Shear is to think of when you were a child and fighting over a stick or piece of wood with a friend.  He grabs one end, trying to pull it out of your hands, the stick starts to go back and forth, you can hear it starting to crack and then you grab the other side of the stick putting his hand in the middle of your hands. He keeps pulling as hard as he can, but you have full control and there is no more tension on the stick. His force with one arm is now dominated by the strength of your two arms. Now, replace the stick with a bolt, and you and your friends arms are metal rods. The same applies to the bolt as it would the stick. 

The strength of a Double Shear joint is effectively double of a Single Shear joint.  Here is a picture that helps illustrate the shearing actions:

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