86-96 C4 No Flex Frame Stiffener Bar System

Suspension - Front
25 lb


Below is a link to a magazine article in Auto Enthusiast, that featured our product



C4 No Flex frame stiffener bar system Benefits

  • Will work on both the coupe and the convertible
  • There will be noticeably less body twist and roll when driving
  • Makes the frame more solid so the front end will not flex when driving on curves
  • Body will be just as solid with the top on or off
  • The No Flex system does not hang below the body so there are no ground clearance issues like the convertible x-brace 
  • The No Flex system does not block the undercarriage so drive shaft and transmission removal is not blocked so there is no reason to remove the No Flex system
  • The No Flex system does not require any body modifications to install. The system bolts to existing mounting holes with the supplied hardware.

The basic theory behind the stiffening system designed by Gordon Killebrew is that it puts the frame rails in compression and does not allow them to flex under load. Putting the frame rails in compression can be accomplished by using a piece of cable instead of a bar system, if desired, but will not have the same effect. A cable will only prevent the frame from flexing in one direction, up under load, whereas the stiffening bar prevents the frame from flexing both up and down under load. The stiffing bar does not become a structural member, like the frame rail, but is a stabilizing or stiffing member, that works as a unit keeping the whole frame system stiffer by not allowing it to flex under load.

A good example of this is a prestressed concrete beam. Concrete has very little strength in tension, but has extreme strength in compression. The way that concrete beams for bridges are constructed is that a form is built and cables are put inside the form and pulled tight so that when concrete is poured into the form and cured, it is under compression when the form is removed. If the cables were not there the beams would be in tension and would not be able to support their own weight across the span.

The X-brace accomplishes a similar effect by bracing one frame rail against the other. This method distributes the load between the two rails and adds quite a bit of rigidity to the rail system, but it has one major drawback. It blocks all access the underside of the drive train, if you want to remove the transmission the X-brace must be removed first. I don’t know the full  details that went into GMs decision to use an X-brace for stiffening the frame system for the convertibles, but I would guess that it was cost. It is much cheaper to stamp out a piece of steel than to fabricate brackets, and add all the other components required for the Gordon Killebrew solution. Plus GM would have had to pay him close to $100k for his idea. The X-brace apparently did not function properly for the Corvettes that were raced because they turned to Gordon's System for the solution to the frame flex problem on the Tommy Morrison challenge car and had extremely good results with it. We have had customers with convertibles order our system to replace their x braces. They have called with nothing but good feedback in the difference between the two. 

Regarding the durability of the system, we have used the basic design, that Gordon designed for racing and have made a few modifications to move the bars further away from the body, but retain the same stiffening affect. This type of bar and bracket system has been used in racing and aftermarket modifications for many years. The rod ends are rated, by the manufacturer, as being capable of a load of 11532 pounds each, it is unlikely that normal street use will ever exceed that load.

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