24 September 2014

Behind the Seen

I know that the grammar isn't proper, but I want to make a point: in the world of panel replacement the quarter panels, doors and fenders are the rock stars, but what about the out-of-sight, out-of-mind lowly panels behind them? It's these “behind the seen” panels that allow for proper panel alignment and attachment.

The subject for this article is the cross rail for the second generation Camaro, and while it isn't one of those panels that add to the sleek look of these cars, it is a true work horse with more than its fair share of shape.

Thanks to our friends at Auto Metal Direct, this often overlooked and abused panel has finally been reproduced. Take it from a body man that has repaired his fair share of these cross rails — it ain't easy. Let's consider the design aspects of this seemingly inconsequential little panel, or more accurately, three panels: a center section with two end pieces. What exactly does a cross rail do? It plays the irreplaceable role of tying the back of the car together. Follow along as we look at all of the areas that this panel aligns and most importantly, holds in place.

Rear-end damage leads to cross rail trouble.

It may be hard to judge from this photo, but a close inspection reveals a Camaro that was rear ended and had the tail panel replaced. It wasn't that long ago when repairing these cars correctly involved most of the body man’s skill set, hammer dolly work, welding and shrinking. The person that repaired this Camaro simply gave up and didn't attach the lower tail panel to the cross rail.

The new cross rail ready for installation.

A good look at the cross rail reveals why this little part is hard to return to its proper shape after an impact. Notice that it’s made in three separate parts, and the ends allow for some variance at the trunk drop offs.

Without a cross rail, there is no support in the rear.

With the tail panel out of the way you can see just how many areas the cross rail completes. It completes the structure; it's a sheer panel tying the trunk floor, gas tank braces, rear of the frame rails, trunk drop offs, and lower tail panel together.

The cross rail is set for install, with holes drilled for ease of welding.

Knowing the proper welding methods is required of any cross rail repair. Using a MIG welder, the plug-weld method is an industry accepted practice.

Here is a welding tip that will save you time and produce a stronger car: With the cross rail clamped in place for a test fit, scribe the gas tank braces, frame the rails and the small ends of the cross rail onto the cross rail. Then drill the cross rail, allowing the welding to be done through the cross rail. With this method, everything on the underside will be finished without any grinding and the non-ground welds will be stronger. Naturally the welds on the tail panel mating surfaces must be ground flush.

The fuel tank is one of the most important things that a cross rail supports.

While looking at the fuel tank braces, you must take into account how much a full tank of gas weighs, and how motion effects the weight distribution. The trunk floor is able to control most of the back-and-forth and side-to-side motions because the braces are welded to the trunk floor, but don’t forget about the up-and-down motions. The shape of the back of the tank acts as a brace, and when welded to the cross rail it completes the box. The cross rail then controls the up-and-down motion.

A closer look at the cross rail in action.

This little cross rail isn't done working yet. Notice how close the spring shackles are to the end of the frame rail. Once again, the cross rail comes to the rescue. Not only must the up-and-down and side-to-side energy be controlled, but consider the amount of twist that can be applied through tight corners.

Auto Metal Direct did their homework; not only are all of the contact points correct, but the gage of the metal is spot on. The installation of the new cross rail is up to you, but thankfully no one should be struggling to repair another bent and rusted 2nd Gen Camaro cross rail again.

The finished product.

Here we are at the finish line and the cross rail is once again “behind the seen”. But that's a good thing; I'm content letting the tail panel be the rock star. I can sleep better knowing the new cross rail is doing its job and another car in history is saved.

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