Sub-frame connectors... Please build them correctly!

For what it's worth. Not more than a few years ago, I saw a test done on the net somewhere. It was essentially a static load test to evaluate body torsion. If I remember correctly, the rear frame rails were anchored to the test bed at about the axle location. A fulcrum was built of steel and the K-frame rested on it. The apparatus was elevated such that the tires were not resting on the floor. The techs then began hanging weights from one corner of the front frame rails. They measured frame rail deviation between right and left sides with every weight that was applied.

They did the first test with a unibody car without frame rail connectors. The second test was with front-to-back frame rail connectors (welded). The third test was with connectors also welded to the floor sheet metal.

They graphed the results. The amount of twist in a normal unibody was ridiculous. (Twisting the body absorbs energy from the drive train.) Second best results came from the end-to-end connectors - the results were dramatic. The third test with the welded-to-floor connectors showed a further improvement.

I just wish I had the sense to save that test at the time.


Here is an interesting thread by some road racers:

http://www.pro-touring.com/threads/23278-What-do-sub-frame-connectors-really-do