54 F100 Sub-frame Project

I stumbled on to a set of PICs I thought I had lost ... I can turn this into a "Makin' Progress" story with lots of PICs.

Some might find it interesting and it might do me good to go over some of it again anyway. I'll make it flow a little at a time and show what we did.

Disclaimer: This is work which was actually done several years ago and the "brain-trust" and #1 Fabricator for this job (Jim Davis) is now dead, so we are down to just me on any technical questions about this project.

This was the starting point ... a Factory Ford style front axle. This one is actually a "drop front axle" which lowered the front of the truck about 3 to 4 inches




From there we went to a 78 Pontiac Trans AM front clip seen below. I purchased this for $175.00.

I decided to go with the Trans AM front clip on the F100 because it has some of the best suspension and steering geometry that was available in that era and parts are plentiful. It was also a graft Jim had done many times so we knew it could be fit to the frame without problem.

Here is a closer shot ... that 1 1/4" front sway-bar is pretty appealing as well especially since the truck would be sporting a 460 BB and C6.



Here is the front clip after dis-assembly, sand blasting, repainting and rebuild. It's all prepared for "the knife" well, actually tourch

Nice stuff.

Bring on the pics.~

The drop front axle was unbolted and was sold on eBay to a guy in So. Cal. for about $550.00. The front disc brakes makes it a fairly desireable and valuable piece

In this frontal view you can see (at the center of the large front crossmember) the mounting point for the core support which is also the mounting point for the entire front end of the truck body ... It becomes a key part of the job at a certain point in the process. Obviously the T/A front clip won't have anything resembling this.

Jim was the guy with all the spec knowledge regarding "distance" and "angles" ... all of which is very important in insuring the suspension functions correctly and that the wheels are positioned properly in the wheel well and the ride height is what we want it to be.

We planned this one out to move the front wheels a couple of inches forward in the wheel well. Jim convinced me this gives the truck a little more of a "Trick" look <--- copping a word from Jim there

Jim had me set the truck on jack stands at whatever height I wanted it to ride at when finished ... he took it from there using measurements and specs which Jim always had on the top of his head and at the tip of his tounge.

What you see right here is the truck frame on stands at 10" to the bottom of the frame rails ... this would be "finished ride height"

After Jim defined his reference points, made his measurements and did some math ... this was the line for the first cut ...






This is Jim making the first cut in the frame of the Old Effie.





Passenger side is shown cut through with Jim making the cuts on the driver side as I shoot PICs




Here we are with both sides cut through ...

Now in the interest of "Full Disclosure"

I have to fess up. As soon as we butted the T/A subframe up to this cut and made one quick measurement it was obvious something was askew. Jim did some quick re-running of the numbers and determined he had failed to subtract one number in the equation ... this cut was in the wrong place




This ... was the right place

Here is the Trans Am sub frame butted up to Old Effie




As you might guess ... this is an incredibly important part of the process.

We had to insure the angles at the control arms was perfect ...

The height from the floor was perfect ...

And the distance (front to back) from Jim's reference points between the two sections was perfect.

This is where we simply had to keep tweaking and shimming and measuring ... tweaking and shimming and measuring ... Over and Over and Over again til FINALLY like an act of God ... everything checked out perfect at the same time.

Actually it came together fairly well ... Jim was surprised that we nailed it as quickly as we did.

That's Friggin swell work!

Sorry you lost your friend.


FE

This shot is the passenger side with the first tack welds to hold the two pieces together for us. This shot also shows the triangle or "pie slice" cut in the T/A frame rail which will be utilized in the next PIC



The next two PICs switch to the driver side, but show the next step

The outer edges of the two frames do not line up ... the T/A frame is wider by about two inches than the Effie frame ... so we cut that "pie slice" out of the T/A frame so we can "FLOW" the frames together.



Here in the top view you can see how the T/A frame rail was fabricated (bent in) to make the outer edge flow smoothly to the Effie frame.

These are the first secure and solid connectioins between the two pieces. The inside of the frame rails lines up very well so no "flowing" is necessary on the inside.



Here is the passenger side welded ... Note: the spring perches and crossmember you see in these PICs will be scarfed out. The crossmember will no longer be needed and the spring perches are actually going to be in the way during the next step.

With the project now secure enough for us to be certain things were not going to move on us, we now need to provide the required stability to the joint needed to make the Effie safe on the road.

This was accompliished with gussets made of 3/16" steel plate. I purchased a 20 foot length 6" wide for this job.

We made cardboard patterns for each gusset, transferred the pattern to the steel, torch cut the steel plate and ground the edges to make them clean for welding.

Below is the Driver Side inner plate cut to follow the contour of the A-arm bracket in the front. This plate "boxes in" the frame on the inside. The plate visible on the floor is the gusset we will be using in the next step



Below is the Passenger Side inside plate shown from the outside of the frame. You might now notice the crossmember and spring perches are gone.