This stuff was all written before the project ever started. Every one of these issues has since been resolved and checked off the list. I'll have to come through and revise everything when I have time. For now, click on the navigation bar on the left to take you to your area of interest. Just about everything I did is explained there anyway.

-Quint

Engine
The engine/transmission from a 2004 was never intended to fit in a 1978 bronco. However I’m betting that the large engine compartment of the ’78 will at least contain the new 5.4L. I’ll take advantage of the hydraulic engine mounts from the ’04 by reattaching them to the engine then welding them to the bronco frame once the engine and transmission are positioned. That way I should get a perfect fit.

Transmission/transfer case
The transmission and transfer case from the ’04 are electronically controlled, meaning the mechanical linkages in the bronco will be replaced with shift lever position sensors and 4wd selector switches on the dash. The mounting points will also likely be different so I’ll try the same position and weld technique used to mount the engine.

Suspension
The suspension on the ’04 was severely damaged in the crash so I probably won’t bother trying to adapt it to the bronco. The limited slip rear end would be nice, but the 3.55 gears wouldn’t function well with a 3.50 front end in 4wd. The axle housing looks like a noodle on the left side from the wreck so the decision is made for me anyway. To give you an idea of the severity of the wreck, the left leaf spring was actually broken off at both ends!

Vehicle Speed Sensor (VSS)
One additional reason to use the rear axle from the ’04 is the vehicle speed sensor mounted on it. Without that input the engine computer won’t know how fast the vehicle is going which will lead to poor shifts and non-functional speedometer, cruise control, and rear ABS. The ’04 axle ring gear has a plate mounted to it with several (108?) teeth on its circumference that pass in front of the VSS as the ring gear turns. The Ford 9 inch rear end was discontinued long before vehicle speed sensors and as such has no allowances for them. How will I get a VSS input? One option is this.

These guys mounted their own set of teeth on the output shaft of the transfer case then mounted the sensor above off the case housing. This would be a problem for me since the slip joint on the ’04 is inside the transfer case. Whenever I went over a bump the slip action of the driveline could move the teeth out of alignment with the VSS making the computer think I’d locked up the brakes or come to an instant stop. The simple solution to that would be mounting the same toothed setup on the input shaft of the rear axle. This is the theory I’m going on right now, but I’m a little concerned about durability with all the branches and rocks and crap that are likely to impact that area during off road driving.

Anti-lock brakes (ABS)
The ABS system takes inputs from the vehicle speed sensor on the rear axle and individual sensors on each of the front wheels. It looks for a sudden reduction in wheel speed that would be unrealistic for the vehicle in question. This is exactly what happens when your wheels lock up. The vehicle is moving along and suddenly the wheel speed drops almost instantaneously. Under those conditions the ABS computer recognizes a skid and rapidly bleeds of the pressure to the brakes to allow the wheel to regain contact with the road. It’s able to engage and disengage the brakes very rapidly while you simply hold the brake pedal trying to stop. Would I like to have ABS? You bet. However I’d need to integrate the front wheel sensors into my hubs which looks nearly impossible at this point. Can I simply disregard the front wheel sensors? No. The ABS computer will generate a trouble code if it sees a steady difference between the front wheel speed and the rear wheel speed. Can I just fool the computer by using the rear speed sensor for the front wheels too? (tie them together?) No. The rear sensor is reading a toothed wheel with many more teeth than the front sensors and as such inputs a higher frequency. My thought is to use a use a simple counter/divider circuit that can divide the VSS input by a set number thereby outputting a slower frequency. Basically it will count the input pulses from the VSS up to whatever number you choose then send a single output pulse to the ABS computer as a substitute for the slower front sensor signal. Sound complicated? It’s not. I just hope my circuit is sensitive enough to read the sine wave input (analog) of the VSS and translate it to a nice square wave signal (digital).

Update 10/23/04
I believe I've found a way to integrate the front wheel sensors into the bronco hub. I'm either going to drill holes in the brake rotor to replicate the teeth of a signal wheel, or press fit a toothed ring in the back of the rotor. This will allow me to have functional ABS on my bronco.

I've also determined from examining the caliper/rotor geometry between the two vehicles that using the booster and master cylinder from the '04 with the stock bronco calipers should give me 95% of the '04 braking power. This should be a significant improvement over the stock bronco brakes.

Airbags
These are a nice safety feature on vehicles manufactured in the last decade. The ’04 has driver and passenger side airbags that somehow remained intact. That means I could and should put airbags in my ’78 bronco! WRONG! The ’04 has crash severity sensors in the nose (plus a driver seat position sensor) that tell the airbags when and how hard to inflate. It also has front crumple zones that help reduce the felt G-forces in a crash situation. My bronco has no such crumple zones and will either destroy (my preference) or bounce off of (much higher G-forces, ouch) an object it runs into. Let’s say I leave the airbag systems active and get into a head-on collision. If the airbag deploys too soon I’ll slam into a deflating bag and hit the steering wheel like I normally would. If it deploys late I could have already impacted the steering wheel only to then be slammed backward by the delayed explosive inflation of the bag. No thank you. I’ll stick with my seatbelts.

Dash
The original dash in the bronco has a classic look, but if you’ve ever owned a late 70’s Ford truck you know the plastic molding is a pain to work with. It’s made from a brittle plastic that’s easy to crack just by tightening a screw too much, and it’s impossible to find one that hasn’t been scarred up or broken. Unmodified the '04 dash would sit almost three inches closer to the seats in the bronco than it does in the ’04 truck which would just contact my knees. Also the curvature of the dash is sharper than in the bronco. I may have to cut the front of the '04 dash just to make it fit in the bronco. Some benefits of the new dash will be the factory cd player and the ventilation system. Ford deserves some credit for this one because they finally put a fan in the dash that blows more air than you’ll ever want, which is just right.

Steering
The only good thing about the bronco steering is the tight turning radius. The column doesn’t tilt and the thing has so much play you have to be an expert to keep it on the road. With my hand at the top of the wheel I can almost hit 45 degrees to either side before it affects the path of the vehicle. I had my heart set on using the rack and pinion steering out of the ’04 until a friend told me it would give the bronco a wicked case of “bump steer”. This is due to the differences in front suspension geometry between the two trucks. The bronco has a solid front axle with radius arms coming straight back to the frame allowing the axle to move up and down with the bumps in the road. There’s also a bar that goes from the passenger side of the axle to the frame on the driver’s side. This keeps the axle lined up with the frame left to right. As you can imagine this means when the axle goes up and down it will be forced in a slight arc relative to the frame. If I had a rack and pinion steering box in the bronco as the axle moved to the right on a bump the steering linkage mounted to the frame would hold the steering knuckle in the same position effectively turning the wheels to the left. I’ll see if I have time to post a diagram in the future. The stock bronco steering works because it has a single arm coming off the pitman arm that parallels the bar positioning the axle.

I won’t be able to use the new steering box, but I will use the pump and column. The new column will give me cruise control buttons on the steering wheel and tilt function. It also has an airbag in it but I’ve already discussed why I won’t be enabling that feature.

Passive Anti-theft System (PATS)
When I first got the donor truck from the wrecking yard it had a key they had cut for me that would allow me to turn on the stereo and air but wouldn’t even crank the starter. This is because it was only a standard key blank cut to fit the lock tumbler. It was not a “pass” key which has a tiny RF transponder chip in a black plastic housing. To get one of those you have to tow the vehicle to the dealership and pay them to connect a computer to your vehicle and program a new key. Well I’m an electronics nut so I can beat this thing right? Wrong again. There are two send/recieve wires connecting the anti-theft module in the steering column to the engine ECU. Without the proper multiplexed signal down those wires the ECU won’t enable the starter, injectors, or ignition. That throws all my stone age tricks out the window. The ECU supposedly queries the anti-theft module which sends a signal to the key via an antenna wrapped around the ignition lock. The signal energizes the key which responds with its own signal that’s picked up by the same antenna and sent back to the ECU. The ECU checks the signal against the known programmed keys and if it’s a match the car will start. The best I could do is datalog the signals off an existing key then try to replicate those signals to the ECU using my laptop or some other gadget. Except if I had a key I wouldn’t need to do all that! Luckily there was enough personal info hidden away in the vehicle that I was able to track down the original owner of the truck the night before a scheduled appointment at a dealership for a key. Once I got the key and reset the inertial cutoff switch the engine roared to life.

Fuel system
The fuel systems on the two vehicles couldn’t be more different. The bronco has a vented tank with a mechanical pump on the engine that pumps continuously against a needle valve in the carburetor controlled by a float. The ’04 has the latest “returnless” fuel system with an in-tank electric pump. A special driver module “modulates” the 12 volts to the pump to make it run slower or faster depending on what the engine needs at the time. The older fuel injection systems simply ran the pump wide open continuously with an overflow line to send whatever the engine didn’t use back to the tank. All that fuel flowing around created excess vapors in the tank which had to be collected in a canister then sucked into the engine. The new system still has a canister, but it has far less vapors to deal with. Just like anything else on this truck, the computer monitors the fuel pump to make sure it’s working properly. Did I mention the new tank has a sealed gas cap and a pressure sensor on the tank? I’d like to take the ’04 tank and just mount it right under the bronco, but the tank is six feet long and won’t fit. Also the new tank is plastic so I can’t just weld portions of them together. My current plan is to cut the plastic tank around the new pump and seal it to a slightly smaller hole in the top of the old tank. That way I’ll keep the factory fuel level sensor and everything should work fine.

Mirrors
Both ’04 mirrors were damaged extensively in the wreck. I’d like to have power mirrors in the bronco but they wouldn’t look right from the outside. I’d like to keep the exterior of the vehicle looking as original as possible. One thought I had was to mount the mirror motors on the headlights of the bronco. I could tune them on the fly for whatever road conditions I had. This is likely to be the last thing I would attempt on this project.

Power windows
The bronco had manual windows but I’m betting I’ll be able to retrofit the ’04 window motors somehow. The windows that still have glass make an attempt to roll down until something binds up inside the door.

Power Locks
The bronco had manual locks and I'm hoping the solenoids in the '04 will have enough force to actuate the stock locking mechanisms. I'm really looking forward to walking up to my old bronco and remotely unlocking the doors.

Seats
When I did all the bodywork on the bronco I also installed bucket seats from a ’93 extended cab. In my opinion they’re way more comfortable than the ’04 seats, but the new seats look really really good. I’d much rather sit in the ’93 seats on a long road trip but I’ll probably end up using the new ones for the effect. One problem is the ’04 is an extended cab so the seats don’t slide forward far enough for someone to access the back seat in the bronco. I’ll have to try and make them work on the ’93 seat frames. Possible? I hope so. There’s also a seat position sensor on the ’04 that ties into the airbag computer which I’ll have to fool somehow.