The intent of the rule was to keep Super Stockers from being “slammed” to the ground and looking like a full tube chassis-type car. It helps maintain the identity of a Super Stocker compared to a Super Gasser or such, I suppose. Even still, a modern day Super Stocker will sit pretty low and have the rear tires sucked up into the body a fair amount. I personally prefer the Super Stock “look” because it looks aggressive and yet unassuming.
The housing and wheels and tires were placed on jackstands and carefully moved into position for determining the front 4 link bracket installed height. Also, you can see the dropped 2x3 crossmember is lined up with the tailshaft of the transmission, not the center of the car.
So, the first thing that gets installed is the new rear frame rails and 4-link/frame cross member (#C3061). I originally planned on trying to use the Competition Engineering Universal frame rails (#C3060) for a quick start and just modify the area of the rails that kicks up above the rear-end housing to fit the floor height rules. But, upon trial fitting and measuring, it quickly became apparent that it would be better to build rails from scratch instead of completely cannibalizing the pre-bent units.
I prepped the inside of the factory rocker boxes where the new dropped cross member was going to be welded. You absolutely do not want to just weld the cross member to the flimsy sheet metal rockers unless you enjoy making repairs later when the metal cracks and the cross member comes loose. In my opinion, this first step is one of the most important steps in the entire process.
First, I made some measurements of the general area I figured the cross member would be located, based on the finished length of the 4-link bars and brackets. Then I made two plates, one each side, out of 1/8” wall 6 in. x 2 in. tubing. I cut the tube in half lengthwise and made the pieces 8 inches long. With a little trimming I was able to fashion a couple of “L” shaped pieces out of the tubing that fit nicely over the top and side of the rocker panels.
 Here is the rocker panel reinforcement plate that I drilled a series of 3/8" diameter holes in for a better weld penetration. Once all the holes are filled with weld the outside edges of the plate were welded solid. If I tear these off something went horribly wrong! |
I then drilled a series of 3/8” holes in the plates to facilitate “plug welding” them to the rocker panels along with welding the perimeter all the way around. Plug welding or “rosette” welding greatly increases the bonding of the plates to the rockers, and isn’t that hard to do. Then I ground the surface of the plates flat and clean, knocking off the high spots of the rosette welds, and cut the ends of the mandrel bent 2x3 dropped cross member (#C3061) to be a nice snug fit from side to side.
One thing to remember is that some cars such as the Mustang have the driveshaft offset 1 inch to the passenger side of the car. So, when you cut the cross member you must trim the ends accordingly to position the center part of the dropped part of the member in the center of the drive tunnel, not the car. Next, I tack welded the cross member into the car in the position I had previously measured out, and made sure to level it with the car. How I determined the position of the cross member front to rear in the chassis was by taking the dimensions from the instruction sheets (imagine that, I read the instructions!) of the length of the 4-link bars and brackets from the center of the housing and used a plumb bob dropped down from the center of the wheel opening.
I had previously determined that the wheels were in the approximate center of the openings and marked with a felt marker on the fender lip. The instructions want you to measure and find all the centers of the car before you start cutting and make marks on the shop floor but my floor is not nearly nice enough to accomplish that. More than one way to get ’er done, I guess! The NHRA SS rules do not specify how far apart the new rails need to be, so I decided mine would be 22 inches apart measured from the outside to outside. That is as narrow as I think I can be and still have enough spread between the shocks and 4-link bars side to side to still be able to control the car.
I also had previously set the rear wheels and tires I’m using for mock-up purposes under the car in the approximate locations I desire and measured between the wheel mounting flanges to determine the rear end width, axle flange to axle flange. Keeping the rear end as narrow as possible by using the least amount of offset in the rims (in my case a 15 in. wide rim with a 4 ½” backspace) will allow the axles and housing to weigh less. That is all un-sprung weight and in the case of the axles it is also rotating weight so it’s all good being narrow as possible.
Getting back to the frame, I purchased some 8-foot lengths of 2”x3”x.090” wall tubing and went to work. The first pieces I made were the uprights that the Magnum 4-link chassis brackets weld to. The brackets weld to the backside of the tubing and I didn’t want to make the uprights any higher than required to go above the top of the brackets because I need to make sure the over-all frame height stays within the SS-legal floor height requirement. Clear as mud, right? The pictures tell the story.