I looked at what people had done for a rear suspension on these trucks with them lowered and the vast majority were refurbishing the stock leaf spring setup and using lowering blocks. I saw where one guy disassembled the leaf spring packs and completely rebuilt them with new Teflon pads, new bushings in the eyelets, and media blasting each leaf and using POR15 on each one. Looked really good and other than the springs being worn out a cheap way to go about it. Some have stuck with the 9" and others have opted for the '01 and down Explorer rear end that came factory with leaf springs. Good option for gearing, traclok, and disc brakes with integral parking brake that can be hooked up to the e-brake pedal in our trucks. I saw where Hackster used an 8.8 out of a Coyote Mustang and fabbed up the brackets to utilize the three link which was pretty sweet. That guy is amazing and does it all.
My thought was to use the existing 9" being it was free and we had several old nine inch parts laying around the shop from other projects. I ended up using a spare 3rd member and had it built with 3.73's, new traclok, and a complete builder kit of Timken seals and bearings. My original thought was to leave the rear end the stock length but after some research and talking to guys with tubbed vehicles it was obvious I was going to have to narrow the rear end. That sucked to find out as I had already ordered stock length Moser axles for the rear end. So now that it will be narrowed they will have to go back to Moser to get cut to length and resplined for an additional charge. So now that I had a better plan I had the same guy that set up the gears cut the ends off the housing being he will be the one welding them on and finishing the welds on the four link brackets. He has a jig and will tig weld all fo that. I removed the spring perches and shock mount brackets and then cleaned up the inside of the rear end. I do not think this rear end was ever serviced in its life. The gear oil was the consistency of bearing grease and there was more in the axle tubes that had to be scraped out.
This is what came out of the rear end
So I spent a full day getting the truck level from front to back and side to side to start the process of installing the four link. I laid out the suspension pieces and then started measuring and measuring and measuring some more. I put the rear end under it and the driveshaft loop cross member that the front four link brackets will attach to. I had to open up the ID of the four link rear brackets that slide on the axle tube as they were 3.00" and the stock axle tubes are 3.09". Metal carbide bit, die grinder, and a few minutes took care of that issue.
If it appears that the drive shaft loop cross member is offset to the passenger side you are correct. The 9" is centered in the truck and the center line of the pinion on it is 15/16" to the passenger side so we moved the loop over 1" to the passenger side. The motor and trans have a factory offset of 3/4" to the passenger side and with the motor mounts I am getting I can correct that to 1". Hopefully I can get a straight shot left to right on the drive shaft so the u-joints are only dealing with the up and down.
So with this setup the top of the drive shaft loop cross member is level with the center line of the rear axle. You need to know the diameter of the tire you are going to run to set this up and also know the ride height of the vehicle. From there the back of the drive shaft loop cross member is 25-3/4" forward of the rear axle center line. Once you have all of this figured out then its level the frame up from front to back and side to side and fire the plasma cutter up. We started with the driver shaft loop cross member first:
Plasma cutter in action
Fitment of cross member
Welded it up and then a couple rounds of welding to fill in the gaps and lots of grinding got this
We will add a couple of gussets on the inside of the frame once it is boxed and weld the boxing to the cross member so it should be plenty stout.
From here we moved to the 3" c-notches as the ride height will have the top of the axle tubes 1" from the bottom of the frame and the travel on the suspension is +/- 3". With the notches I have 4" above the axle tube and the top of the rear end will miss the bottom of the bed by 1/4" so bump stops will be mandatory.
Metal prepped and c-notch marked (notice the long dimple on the left there is one on the right as well)
Plasma cutter back in action (you can see the c-notch on top of the frame to the left)
Welding in the c-notch (6.625" x 0.280" pipe that was cut 3-1/4" wide and then split in half all on a band saw)
Back of the c-notch installed
The bottom of the frame in front and back of the c-notch will be cut out as Ford clearanced the frame for the shocks. This was done in a press when the frame was made and we did debate heating it up and just hammering it flat and then thought better of it. Plasma cutter will make short work of it and I will make some templates and transfer those shapes to some plate I bought for this and the boxing work. Should look pretty slick when it is done. I am debating on getting a dimple die set and putting holes in the boxing plate. This would be for looks but also media blasting and getting the powder coat all in there.
Front side with additional welding to fill in some factory dimples
Ground all of that flat and then added some more filler weld and ground that down and then hit it with some 80 grit on a flapper wheel
So this is where we left it after two days of lots of interruptions which included attending two BBq's
