Project Muscrate… the quest continues

Hi everyone and welcome back! Spring time is here and the 2009 racing season has begun! Business is good (can’t keep up), and I have been working until exhaustion “after hours” to keep Project Muscrate headed towards completion. On to the ‘taters.

Last month I left off with the beginning of the front cross member modifications I am doing to allow easier oil pan removal for intermittent bearing inspections and, more importantly, to allow for a deeper, wider, custom oil pan to be fitted.

The NHRA Super Stock rules allow for the stock cross member to be removed for clearance as long as it is replaced with a new permanent or removable cross member of similar material and strength. It is also allowed to use an aftermarket “Pinto” style manual steering rack, which will free up even more room compared to the stock Mustang unit and shave some front weight as well.

Out with the old. Man, was this thing a dirty pig. Amazing what 15 years of service will do!

The pictures show the design pretty well. After making some measurements at strategic locations and writing them down I used a electric “sawz-all” to remove the center section of the cross member. As I finished cutting the first side, the remaining section “sprung” about 1/16” towards the back of the car, demonstrating that there was a bind in the cross member.

My measurements, however, showed that the critical areas between the frame rails had not moved. I then put my thinking cap on and started looking at the possible loads that will be placed on the cross member and decided that the most stress it will see is when the front end touches down post wheelie. I was trying to decide if the cross member would see a “pull” or a “push” in this situation and I decided it will actually try to pull apart because the front wheels are the contact point and the lower control arm is working against the struts at the spindle. There is no upper control arm to “leverage” inward on the cross member.

The sway bar mounts were directly in the way and not needed. Drill a few holes, "tap" with a "BFH", no more brackets!

Clear as mud, right? Trust me, I’m what they call a professional. I guess we will all find out eventually!

So, I decided to maximize the available oil pan clearance and minimize the intrusion on ground clearance by using 1”x4” rectangular tubing instead of round, as is more common. It is 3/16” wall and will be plenty strong. It also allowed easy placement of the new Pinto style rack mounts.

The first thing I did was fabricate four 1/8” thick plates that are form fitted to the ends of the remaining stock cross member. I welded two of them, one per side, to the cross member inside and out and flush ground the welds for a finished look. I then used c-clamps to hold the other two plates, one per side, to the welded units and drilled three 7/16” holes through both plates and secured them with bolts. The new 1”x4” tubing was cut to length and welded in between the plates. I then added two small gussets per side to help triangulate and spread the load on the ends of the new cross member.