Rear Coilover 4-Link Suspension

The rear ride height of my Mustang was a little high for the look that I like. I thought about installing some lowering blocks but wanted something more modern with a little better performance.  After researching a few rear suspension options, I decided to update to a coil-over suspension and install a suspension kit. Combined with the front coilover suspension, the end result will be a classic street machine that handles more like a modern sports car. 

I decided to go with a bolt-on kit from TCI.  Considering that many vintage race cars run factory style leaf springs and lots of people race with that kind of set up and have few failures, I didnt see the need for a full on competition suspension kit.  Bolt-on works well in a factory leaf spring style setup so a beefed up bolt-on 4-link system should work well too - albeit less sexy than a pre-welded Fab-9 or Moser setup.

Weld-on brackets

Once the old setup was out I could begin mounting the new control arm brackets.


The upper control arm brackets are welded to the axle tubes at specific locations, centered between the axle flanges.  A jig is provided for exact placement. A heavy duty welder is needed as the brackets and tubes are pretty thick metal. 

 The lower control arms bolt to brackets that get bolted to the existing spring perches.  If you have Ford 9 inch with 3" tubes then you can cut off the stock perches and weld on brackets like most of the beefed up kits use.  My housing has tubes that taper to 2 13/16 (2.8125) inch diameter so there would be a lot of slop to fill in the 3 inch holes. I went with the bolt-on brackets and did a couple welds for extra insurance.  


Powder Coat
Once everything was welded and ground, I dropped the housing and kit pieces off at the powder coat shop.  At the powder coater, they cleaned and media blasted everything and applied a custom metallic gunmetal on the housing and metallic silver on the control arms, sway bar, and crossmember.  The frame brackets were powder coated in chassis black to match the existing metal.

Install
After drilling holes in the frame rails and floor at the prescribed locations, the chassis brackets are bolted on.  The kit also provides thick reinforcement plates that bolt to the opposite side of the brackets.

With the brackets in place, it was just a matter of positioning the housing and bolting in the control arms.  This was followed by installation of the center section, the axles, and the drive shaft.

Heater Box

I found a few minutes to get some work
done so I thought I'd do a quick write up on the old heater box.  This was a pretty simple rebuild.  

The heater box is fiberglass shell held together with small metal spring clips.  You have to be really careful prying these clips off since the fiberglass is dried out and brittle. 

Once the shell is open, you can remove the heater core and spacer bracket. Mine was already open and the heater core was gone.  Just a few crumbs and black dust were the only the evidence of the seals that were once there. 

First step was to clean out the shells and remove and remaining seals.  There are two screws on the outside of the that hold the heat diverter box. 

Once they are removed, you can remove the diverter and clean it.  It helps to take a few pictures if you need help getting it back together later. 

The metal parts were pretty rusty so I wire brushed and sanded them (a media blaster would be nice right about now).  

After a little primer and paint it was ready to go.

Next is reassembly.  I picked up a can of general purpose spray adhesive from the auto parts store.  It looks like rubber cement and seems to hold pretty well.

I found that the best way to stick the new foam on was to first dry fit the pieces and know where each one goes before spraying.  The triangles that go on top and bottom of the diverter had to be punched out first to make clearance for the crank arm.  

Then I sprayed the foam pieces one at a time, letting the adhesive tack up for a minute before pressing into place. I just hope this glue holds well with all the heat that blows through there.

There are pre-cut foam squares and strips for the all the doors and the diverter box.  The instructions that came with the CJ Pony Parts heater rebuild kit had diagrams that were a little small but usable.

The pieces that go inside the diverter box can be tricky to line up when covered with adhesive so it helps to figure out how it lines up before spraying.

To aid in lining up the strip that the diverter screws go through I ran the screws into the pre-drilled holes in the foam and sprayed the foam. Then used the screws align to the holes in the case. Once the glue was holding, it removed the screws.

Then I laid in the diverter box.  This requires that you spread the case open a little as you press it into place. Its a little scary to do as it sounds like the case is about to split.  Fasten the diverter back in with the two little screws.

Next, I sprayed glue on one of the heater core seals and stuck it to the case - have to line this up carefully so that it seals against the core. Then carefully laid the core over the seal and making sure the tubes are centered in the holes.

The last thing was to close up the case, carefully lining up the edges. On mine, this was a little tough as the new seals made it hard to squeeze the halves together. I tried slowly clamping using vise grips an a couple edges bit one of the lips cracked. Be really careful, the outer lips can snap right off.  I found that I could use a larger clamp on one of the larger surfaces to bring edges close enough and was able to get clips on. There really needs to be a special tool to stretch the clips because there is not good edge to push against.

Headlight Install and Wiring Relays

Next job is to install the parking lights, headlight bowls and headlights.  After that, wire in the headlight relays.

Assembling the headlights

I would recommend mounting the parking lights in the valance before bolting on the valance itself.  The mounting nuts are easier to get to if the valance is off the car.    Once the parking lights are in, feed the wires up through the hole in the bottom of the headlight recess and plug into the harness. 
This is a good time to inspect headlight plugs and wiring before moving on.  Make sure the wires are not melted or frayed and about to break off.  The replacement headlight pigtails are easy to get if needed.  Luckily, I didn't need to replace mine.
Next, I installed the new headlight adjusters, springs and bowls.  Here is an easy way I found to install the bowl and springs. 

• First snap in the adjusters and remove the two adjuster screws from the plastic mounts. 
• Then, with the spring hooked in the back of the slot and holding it in place with one hand, I turned the bowl around so the front is facing back and hooked the spring into its hole in the headlight bowl. 
• Next, carefully turn the bowl around with the spring still hooked and line up the tabs with the adjuster holes. While still holding the bowl in place, start one of the adjuster screws, making sure that the slot in the screw is engaged correctly with the slot in the tab.  
• Start the other adjuster screw and run in both screws until the bowl is pointing basically straight ahead.  

From here its pretty simple.  Plug in the headlamps and mount with the stainless retainer rings.   After a quick test I found that my headlight ground wires were not attached. Oops.

Headlight relay modification

Once I knew the headlights were working right, I started the upgrade of the wiring.  
Its a pretty simple concept.  Control a high amperage circuit with low amperage circuit. A simple way to do this is with relays and I found a couple 12 volt ones that can easily handle the load.   The circuit diagram is pretty simple.  You just cut the low beam and high beam wires and use them to energize the relays.  Then run 12 volts to the common terminal and the other end of the cut wires to the Normally Open contact.

The idea of adding the relays is to reduce the current flowing through the headlight switch and thin wiring and should eliminate burned out switch and melted wires.
On my Mustang, I placed the relays up front on the apron close to the radiator support.  This way, the wires to the headlamps are short.  
Make sure that the lights already work properly or you will be troubleshooting old problems. Also, remember to disconnect the battery.  The relays I used came from Summit Racing http://www.summitracing.com/parts/via-80238.
They are not very weather proof but they should be fine for my application. 

Note:   Modifying wiring incorrectly (especially without a fuse) can be a fire hazard and should be performed by an experienced technician. Author is not responsible for damages caused by incorrect wiring. Use of these directions is at your own risk.

• I started by unwrapping the headlight harness at the junction where the wires split off to the right side.  Next locate the thin red-black and green-black wires.  These are the wires that come from the dimmer switch to power the high beams and low beams. I chose a spot about 6" back from the split and cut just the red-black and green-black wires.  

• For my car, I chose to solder the wires for solid connections and use shrink tube to insulate.  
• Solder the red-black wire coming from the firewall to one of the relays coil wires (labeled '85') and the green-black coming from the firewall to the other relays coil (85). Next, locate each wire that comes out of the relay coils (86) and solder both together to the same black wire and crimp a ring terminal to the other end of the black wire. Ground this wire together with the original headlight ground wire to the body. (This is a good time to check the old headlight ground wire terminals. If the end looks frayed you will have problems. Best to cut it and replace the crimp terminal.)

• Next, you need a hot lead to power the headlights. Find a 12v lug to connect the hot lead. On my Mustang, I have a 12V lug in the area where the battery used to sit. You could also use the hot side of the starter relay.  I chose to use a 20A circuit breaker instead of a fuse.  Do not wire this up without a fuse or breaker! Connect a 14 gauge wire from the hot lug to the breaker/fuse then from the breaker/fuse, routed to the headlight relay area.  

• Locate the 'common' terminal wire (labeled '30') on both relays and solder both of them together to the 14 gauge hot wire.  On the relay with the red-black wire soldered to the coil terminal (85), locate the the N.O. terminal on one relay (labeled '87') and solder that wire to the loose red-black that goes to the headlight. Repeat for the green-black wire, solder to the other N.O. wire (87)
• Connect the battery and test the headlights. Try hi beam and low beam. Re-wrap the harness and make sure the new hot lead is secured. Mount the relays.

Originally the current flowing through the headlight switch and wire for my 55 watt head lamps was 5 amps. Now its only 0.14 amps. Now you can run those high watt headlights and not burn out your 47 year old switch and wires.

Troubleshooting

If your headlights glow really dim, its likely that one headlight ground is disconnected and the power is back-feeding through the other filaments to the good ground.