The purpose of this article is to explain and cover some basic info about do it yourself C-4 Valve body service. The actual valve body is from a 1974 Bronco, therefore the illustrations may differ slightly from what you may be working on.  If you are inexperienced as a mechanic, perhaps you should get help when performing the steps shown below. It is recommended that you read the entire article first so you may prepare all the tools and materials as well as a clean work environment. After reading through the article first, you can then make notes on where your valve body may need attention. Some steps that are performed later may be mentioned early in the article in order to save time and computer space. VB is referring to Valve Body.

VB disassembly starts with the removal of these 2 bolts shown circled in green below.

Note: The 2 dots show where the Kick-down lever and the pin on the rooster comb must go to be properly indexed while installing the VB back into the Trans.

Next, remove the long main filter bolts and the 9 shorter VB bolts. Notice the correct location of the ID tag. This picture shows the throttle pressure limit valve and spring have not yet been removed. You should remove them at this time before taking the VB halves apart.

When the VB halves were first split apart the hockey puck was stuck to the separator plate indicated by the arrow. The circles show the proper locations of the viton shuttle ball and puck. Discarding the puck from the assembly will aid in firming up the shifts and will not hurt the transmission.

Next, remove the bolt holding the separator plate and gasket to the channel plate. Note proper locations of the 2 remaining Viton Check Balls. The one in the bathtub is mandatory; the other one can be removed for a firmer 3^rd gear shift. The channel plate is where a lot of sediment can collect and it is very important to clean it thoroughly. After cleaning with a suitable solvent, these components should be dried with compressed air in order to keep foreign particles like dirt and rag lint to a minimum. We refer to these channels that the hydraulic pressure travels through as “Worm Tracks”.

Drill separator in 2 locations as shown. Remember, these modifications are non reversible unless you have a spare unmodified separator plate. If you are unsure about having a firm shift, you can use the next two smaller drill bits 7/64” and 3/32” accordingly for a less aggressive modification that is near stock but slightly firmer. Caution: Do not drill any holes larger than 1/8” This is unnecessary and can cause valve body cross leakage and gasket damage.  Drilling these holes larger than 1/8” is also rough on the rest of the Bronco drivetrain, Axles, U-Joints, Splines, Differentials, Transfer Cases, and Motor Mounts, etc. A high speed steel counter sink bit works very well for taking burrs off of holes that have been enlarged. (See last photo # 23)

This picture shows a 2 oz. ball peen hammer and a 3/8” steel ball bearing being used to knock down the sharp edges around the 2 holes on the separator plate where the shuttle balls need to travel. By doing this you will add longer life to the Viton Checkball. Do this to the plate in each of the 2 bathtub locations on the side of the plate that actually makes contact with the shuttle ball (Viton Checkball). Also prepare the 3^rd check ball location, it’s the larger hole that covers the single well used by the direct clutch feed passage. You don’t need to tap it very hard because all you are doing is dulling the sharp edge left by the factory hole punch and making a tapered seat for the ball to seal against.  I’m using a machined flat piece of steel as a backing plate during this modification.

The next picture shows the valve components from left to right and top to bottom in that order. After cleaning, all valves must move freely in their perspective bores.

1. Shift valve retaining plate.

2. 1-2 Shift valve.

3. Manual 2^nd valve.

4. 1-2 Shift valve spring.

5. 2-3 Shift valve.

6. 2-3 Shift valve spring.

7. Throttle Modulator Valve.

8. Retaining plate for Transition and Cutback valves.

9. Transition valve spring, (outlined in red) which should be removed and discarded for Heavy Duty use

10. Transition valve.

11. 2-3 Back-out valve.

12. 2-3 Back-out valve spring

13. Cut-back valve, which uses no spring. For Heavy Duty and street versions, this valve can be blocked by inserting a spare viton checkball in the bore before inserting the valve and retaining plate, noted by the red dot.

This picture shows the shift valves installed after cleaning. They have been lubricated with a 50/50 mixture of Slick50 and Type-F transmission fluid. Note the spring tension is pushing the valves partially out of their bores. Install all valves and their retaining plates but when tightening the retaining plate bolts make sure the retaining plate will have plenty of clearance with the separator plate when the valve body halves are bolted together.

This picture shows the proper order of the servo accumulator valve.

By reversing the order of the spring to the outboard area of the valve will cause a firmer 2^nd gear shift. You may not want to perform this modification at first. Experimenting with the other milder mods first, may give you the desired results.

The main pressure regulator valve, and the Booster valve with its sleeve is shown removed for cleaning purposes. Note the spring retainer slips over the tail of the valve. And the smaller Booster spring rests inside the larger pressure regulator spring. Use a dab of Vaseline to hold the booster valve in its sleeve for easier assembly of the pressure regulator valve and springs. Vaseline has a low melting point and is perfectly compatible with all transmission fluids. The booster sleeve is retained by a small spring-clip, some models will use an (L)-pin in this location.

Pressure regulator components are shown from left to right in this order.

1. Retainer clip and booster valve sleeve.

2. Booster valve

3. Main pressure regulator spring.

4. Booster valve spring

5. Spring retainer

6. Main pressure regulator valve.

Check the operation of the kick-down valve by pushing the plunger shown in the first picture, make sure it moves freely and returns fully after the valve casting half has been cleaned with solvent and dried with compressed air. You may also move the other remaining valves with a pick/scribe to assure that they slide freely in their bores. If any of these valves are sticking or frozen, It is recommended that they be removed from their bores and the valve casting be cleaned carefully.

The picture shows a pick being used to move the valves against spring tension to see if they return to the home position.

After cleaning and assembling the valves, and cleaning and removing all traces of dirt and old gasket material, you will be ready to assemble the VB halves together. Start by selecting the proper gasket and with a few drops of trans oil, position the new gasket on the plate. Make sure the gasket is on the correct side between the separator plate and the lower VB channel plate. Position the gasket so all the holes are centered as much as possible. Some commercial Valve body modification service packages may ask you to delete this gasket. If your VB shows signs of having commercial aftermarket VB modifications installed, it may already have this gasket missing. If so, do not re-install a new gasket.

The next step is to turn the plate over and make sure no holes are blocked by a mis-aligned or wrong gasket.

The plate can then be placed over the channel plate. Make sure the necessary shuttle ball is in place and if desired, replace the 3^rd gear Kick-down check ball.

Here again shows the channel plate and check balls before the separator plate is placed into position.

Secure the separator plate with gasket to the channel plate with 1 of the short 10-24 bolts finger tight to make up the channel plate sub-assembly and set aside.

This picture shows the valve casting assembled, with the check ball and hockey puck already installed; ready for attachment to the channel plate and separator plate sub-assembly.  Refer back to illustration No. 3 to see the proper location of the hockey puck and shuttle ball.

This picture shows the channel plate assembly with the valve body in position. Note the 2 quarter 20 bolts installed only finger tight at this point. A pair of tapered awls used in 2 specific locations for aligning the separator plate with the channel plate. At the time these awls were purchased I thought that MAC TOOLS made the best tools for this particular job. Tapered punches or dowels can also be used for this.  These are the only 2 holes that should be used to align the plates before tightening the bolts.

• 120 inch pounds on the ¼-20 bolts.
• 46 inch pounds on the 10-24 bolts.

The following picture shows a well proven tightening sequence for these particular fasteners. The last bolt shown by the arrow, is installed loosely for alignment purposes during the assembly of the valve body. It will be removed and re-installed again after the valve body has been bolted-up to the transmission case. If you use a torque wrench, and have the ability to work in a clean environment, you are well on your way to putting together a quality piece of craftsmanship.

You should always try to include a filter gasket when doing work on the Bronco C-4 filter, even a used metal gasket is better than none at all. Be sure to install the throttle pressure limit valve and spring before installing the filter screen. NOTE; The Bronco specific sump pick-up pipe is missing from the filter in this illustration. It will be installed into the filter before the transmission pan is installed.

This picture shows the 2-3 shift valve and spring, and the throttle pressure limit valve and spring for size comparison. Notice the shift valve spring is slightly longer. The springs are very similar, don’t get them mixed-up.

This picture shows the filter being positioned, again using a tapered awl for alignment of the filter, and filter gasket with the bolt hole before tightening the filter bolts. Refer back to the tightening sequence to complete the filter installation. Don’t forget the 3 bolts on the other side need tightening, and it doesn’t hurt to double check the valve retaining plate bolts, if you leave them loose, you will get no upshift. With all the bolts properly torqued, this VB is ready for installation.

A little something regarding screens and filters:

With the C-4, always use them whenever possible, they will save you a lot of time and headaches. Ford engineers put them there for a good reason, clean and re-use them don’t leave them out!  The C-5 uses the same screens and they are no longer available new. So if you need them try to get them from a used transmission where the last technician had enough sense to put them back where they belong.

On the left is the Governor screen, it is installed in the governor support distributor housing feed passage before installing the governor valve assembly. Service to the governor will not be included in this tech article, but I thought it was important enough to mention the need for this screen that is commonly deleted from the assembly during service. On the right is pictured the larger pump pressure port screen, which is installed in the case passage before the valve body is installed. There are 2 ports that are often confused that this screen will fit in. Correct installation is in the port closer to the shift lever.  Both of these screens can help to save you from having sticky valves and damage due to particle contamination in the valve housings.

Here is a picture of my countersink drill bit I use it in the drill chuck with very light pressure to remove rough edges after drilling/enlarging holes in the separator plate.

I hope you enjoy reviewing this info as much as I enjoyed sharing it with you.

I also wish you success with your VB repairs and hope this article is helpful for those of you who want to improve the performance of your C-4 or just make the VB function correctly.

Tech article by BwoncoHowie

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Since I’ve owned my 1966 Bronco it never got past 3rd gear for years and I drive the freeways in Los Angeles all the time.

Finally I collected the parts to install my new NV3550 and a twin-stick shifter I purchased made for an early Bronco.

The problem simply was the twin-stick shifter wasn’t designed with the offset of a NV3550 in mind. With the mounting bracket of the twin-sticks, the bracket supplied by Advanced Adapters, and the height of the shifters I could see it wouldn’t work.

I wanted to have a clean twin shifter that would not be killing my right knee all the time and cleared the shifter from the NV3550. Additionally I wanted to close the whole in my floor where the 3speed shifter was previously installed. So I decided to design and fabricate my own shifters and a sheet metal floor patch or access panel which would allow me to install a stock carpet kit one day. After all these are just two levers on a common pivot point, right?

Parts and Supplies Needed:

.

.

I didn’t like the way prefab tubing fit; it had too much play. Instead I took solid metal rods and drilled them to make snug fitting tubes for my pivot points.

Including machine shop expenses and materials my total spent was just under $80 not including tax or shipping.

Fabricating The Floor Patch.

1. Measure the whole in your floor that needs to be covered.

2. Cut out a large piece of paper from a grocery bag. Making sure your lines are square, draw the outline of the patch to make your template. I added a 3/4 inch tab on the edges to allow for the tabs to make a physical connection over the existing floor. I also labeled the template to show front and top.

3. Double check your measurements, measure twice, cut once. With that said, cut out your paper template and fold it to match the different angles of the floor. When you are satisfied with your paper template carefully trace it onto your sheet metal. For my patch, I used a scrap piece from an old hard top.

4. After double checking your measurements, cut out your sheet metal patch. You can use a cut off wheel on a grinder or sheet metal sheers. I prefer to use my electric sheet metal sheers from Harbour Freight.

5. To make my bends I have several pieces of extra metal bar around the garage I use to bend my sheet metal patches. Here I clamp the first bar under the patch with two vice grips at each end. Next I clamp the other bar on the top side of the tab which I am going to bend down. I couldn’t find my extra vice grips so I just used a channel lock instead and slowly bent my first tab.

6. Check your bends often during this process. Bend the patch carefully and make sure you apply even force to keep your bends straight. This takes a bit of back and forth work to check each bend as you go.

7. With the bends completed, try a test fit. At this point the big whole in my tunnel was completely covered.

8. Sand, paint or coat the patch to match your floor. I Herculined my floors so I did the same to the patch and let it dry. Later on you will be removing a portion of your new patch for the shifters to come through the floor so you may want to wait to paint the patch until the end of this project.

Fabricating the Twin-Stick Shifters

Their Shifter

Our Shifter

1. The first thing to establish here is what transmission you are using and does it come with a mounting bracket for the 4×4 shifter. In my case Advanced Adapters provided this backing bracket with the NV3550 kit. All I needed to do was drill a 7/16 diameter hole in the center for the pivot point of my shifters. For you, you may want to fabricate a bracket of your own depending on your transmission. A simple solution is a flat metal bar with 3 holes drilled into it. [The correct length will vary depending on your application.] Your mounting bracket will require two outer holes to be drilled for mounting the shifter to the transmission and one hole drilled in the center to mount the pivot point for your shifters. With my setup I drilled a 7/16 hole into the center of the bracket supplied by Advanced Adapters. I then welded the 7/16 course thread 4 ¼ inch grade 5 bolt used for the pivot point. Later this 7/16 bolt was trimmed to the exact length required.

2. With my high quality napkin and tin foil I made 2 bendable templates for the upper rods of the shifter. I started by rolling the foil with the napkin in the center and then cutting the foil rods into two 12 inch length.

My goal here was to first shape the rear axle shifter then the front axle shifter. I wanted to have the end result to allow clearance for the two shifters to be able to move freely with out binding up when the shifter knobs were installed. Also I wanted them to be low enough to allow for full shifting of my NV3550 shifter in all gears and for clearance to my left knee to not hit at all. Last but not least the ending product had to be able to fit under my sheet metal patch for the floor. Easier said than done.

3. With the mounting bracket installed onto the transmission I next installed two 1 ½ inch long pieces of drilled metal rod onto the pivot bolt. The shifters and lower arms will later be welded to these with washers and a lock nut.

4. I designed the rear axle shifter to be in 2 wheel high when the shifter was in a low position on the floor with the shifter knobs both being at an equal height when in all positions. Forming the foil rod here took some practice, imagination for future clearance, and some trimming. At this step I marked on the inner tube with a Sharpie the position of the foil rod and drew two alignment lines from the foil rod to the tube.

5. I repeated this step for the front axle shifter. To make sure I was going to have the desired end result I had a flat piece of card board I used to cover the large tunnel hole to represent the sheet metal floor patch. I trimmed a small hole in the card board allowing for the foil rods to poke up through the floor.

I used a small amount of blue masking tape to hold the shifters in place at times while I shifted the foil rods through all positions.

6. To bend the metal rods I strongly recommend you cover the threaded end of the rod with a lot of making tape. Don’t screw up the threaded ends of the rods. Start from the top of the rod and make your way down. This helps to protect the threaded end from accidentally being crushed when using the long pipe/breaker bar to bend the rod.

7. Starting with the first bend, compare the foil rod to the metal rod marking on the metal rod a line where the first bend is to be done. Carefully place your metal rod in one side of your vice, the foil rod in the middle, and a small 1 inch piece of scrap metal rod on the left side in the vise. Line up the mark on the metal rod with the edge of your vice, place your long pipe/breaker bar over the metal rod and slowly bend.

This was tricky and very time consuming. You will do step 7 over and over before achieving the correct shape of your metal rods.

8. You may want to cut the non-threaded ends of the shifters to the correct length for your application. This will very depending on your body lift height. Try to contour the end of the rod with the grinder so it will fit over the pivot point metal tubes.

9. Tack the rods into place but do not weld them completely just incase you need to reposition them later.

10. With the rods tacked in place, remove the protective tape from the threads and mount your shifter knobs. Try moving them freely, imagining where you want the final location of 2 wheel high and 2 wheel low to end up.

11. At this point I found the metal tubes could be trimmed allowing the shifters to be installed closer together. I trimmed them just a little at a time, installed the 7/16 washers, and the lock nut loosely.

12. Cut two pieces of the 1 metal bar, a 3 inch, and a 4 inch piece. Cut out a shape with two long outer finger which fit over the metal tubes at the bottom of the pivot(See the parts photo). The rear axle arm will be somewhat shorter than the front axle arm. Grind out a slight angle on the inside of the bar between the fingers.

13. Drill a ¼ inch hole about ½ an inch away from the end of the two bars. Take some time to view the movement of the arms under the metal tubes. When I got the angles right here I tack welded them into place.

14. Cut two pieces of ½ inch wide card board strips. These will connect the bottom of your shifter arm to the transfer case rails. At this point the length will vary. The rear shifter connection bar was about 3 inches and the front shifter connecting bar was almost 5 inches long. Your exact length will vary. (The pair in the photo were too short, I made another set) Double check the movement with the card board connecting bars first. Next cut to length your metal bars and before you start to do any bending, drill 2 ¼ inch holes at the ends of each.

15. To bend the lower arms of the shifter I placed it in the vice and used a large adjustable crescent wrench to make my final adjustments. Keep the bends in the middle of the bars not at the ends. The ends will require flat surfaces for the connections at the clevis pins to move freely. Also some twist will be needed to make the connection rods move freely. Try assembling the shifter and moving it check to make sure it doesn’t bind up.

16. Cut the clevis pins to length and welded them into place on the lower arms of the shifter. At this point I did my final welding making it very solid.

17. Paint. I filed the metal tooth marks from my vise off, cleaned the metal with acetone, masked off the threaded ends and gave the shifters 2 coats of semi-gloss black paint. I also prepped and painted the sheet metal screws too.

18. Finally I installed the twin-stick shifters, trimmed the sheet metal floor patch, and installed the patch, and shifter boot. The trim ring did also need some adjusting to make it fit flat on the floor.

After all said and done I am very happy with my ending result. If anyone has questions please feel free to contact me.
Chris taipeichris13@yahoo.com

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To make things much easier first go the website of the Lonestar Early Bronco Club. Go to TECH, INFORMATION, KOENIG WINCH INFO. Print off a copy of the PTO EXPLODED VIEW. I will refer to and give you a cross reference of some of the numbers on this exploded view of the pto.

Before beginning disassembly have a notepad and camera available to make notes and take pics of the entire process.

My PTO I have photos of is different than the page you printed off of the Lonestar site. The photos are of a PTO with a front and rear output shaft. The only difference is that the out put shaft is longer, and in place of the rear bearing cap #65-8, mine uses a bearing cap with a seal in it just like the front output shaft has,#65-10 with seal # 65-18.

New parts needed are:

• bearings (cones & cups) 2 each Timken #LM67048 & #LM67010 (replaces Koenig #65-17).
• Needle bearings ( qty.2) Timken #B1416 (replaces #65-16).
• Oil seal (qty.1) CR #6315 (replaces #R35)
• Oil seal (qty.1) CR #12336 (replaces #65-18)
• O-ring (qty. 2) Motion Ind. #00619831 (replaces #65-19)
• New parts were purchased at Motion Industries.

Begin by removing the old gasket that was between the pto and transfer case. Remove allen set screw #65-26. With a brass drift punch tap input shaft out of case. The two washers may fall into the case, these can be retrieved later. Set aside all the parts that were on the shaft. Remove detent plug, spring and ball. Remove shifter yoke from shifter shaft and take shaft out of case. Take bearing caps off of output shaft. Remove bearings from case then remove the split lock ring from the shaft. Tap output shaft shaft through gear and out of case. Remove any parts from case that may have fallen in.

Degrease and clean all parts, let dry and wipe with clean cloth.

At this point you may want to paint or coat the case. I used the POR 15 system. Marine clean ,metal ready and their Silver paint. Clean machined surfaces of paint at seal openings, bearing bores and input shaft bore. Remove needle bearings from input tube. I used a deep well socket that was slightly smaller OD than the new needle bearings and pressed the old bearings out of the tube.
Note: Put a light coat of oil on all bearings before pressing into place.

To begin assembly:
1) install new seals into bores at shifter shaft and bearing cap.

2) Press bearing cup in case at front output shaft bore.

3) Seat bearing cup to correct depth by installing bearing cap, tighten bolts sequentially.

4) Remove the bearing cap and bolts.
5) Place bearing cone into case and into bearing cup.
6) Carefully set output gear into case.
7) Install two piece lock ring onto output shaft.
8.) If large woodruff key came out of shaft replace it now.
9) From back side of case install output shaft through opening with 7/8″ diameter end of shaft into case and through gear lining up key and keyway and centering through bearing on front side of case.

10) With case on its front side and supported around bearing opening center shaft in bearing and tap in place with hard rubber hammer.

11) Slide spacer onto output shaft.
12) Place rear bearing onto shaft, install cup on bearing, tap in place.
13) Seat rear bearing in place as in step #3.
14) Lightly coat the bore of the shifter shaft oil seal and carefully slide in shifter shaft approx. 2″.
15) Place shifter yoke in case and slide shifter shaft through yoke.

16) Rotate shifter shaft so that the small groove will be in line with the detent plug ,spring and ball.
17) Place bolt with lockwasher through shifter yoke and tighten into tapped hole in shaft.

18) Insert spring into detent plug, place ball on top of spring, hold the case so you can thread the detent plug assembly into the case.

19) Test shifter shaft operation, you should be able to feel positive stops at the engaged and disengaged positions.
20) Press both needle bearings into input tube.
21) Place input tube into sliding gear with key and keyway lined up.

22) Set sliding gear and tube onto shifter yoke.
23) Place an o-ring on the front end of the input shaft.(rear of the input shaft has the groove for the setscrew to index into, inboard of the o-ring groove).

24) Start rear of input shaft into bore, just before end of shaft enters case cavity place one washer inside case lined up with bore, push shaft through washer and into input tube.
25) Place the other washer at the rear of the input tube, between input tube and case, continue to push shaft through washer and into rear bore. Shaft will stop when o-ring touches front bore.

26) Tap front of shaft through bore just enough to expose o-ring groove on rear of shaft.
27) Place o-ring into rear groove and tap shaft back into bore. Center shaft in front and rear bores. Install setscrew into case to lock input shaft in place.

28) Using PERMATEX ULTRA-BLACK RTV SILICONE GASKET MAKER use on bearing caps instead of gaskets. Follow directions on package.

29) Install bearing caps.

30) PTO is ready to be installed on transfer case.

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This write-up summarizes how I put on-board air into my 1971 Bronco. I have a 3.5” suspension lift, a 2” body lift, and enjoy wheeling. Having on-board air is not only a nice benefit to airing up and down tires but could also come in handy for a variety of other uses (i.e. any air tools, nail guns etc.) Deciding on the proper system for your application is always the hardest part. I searched the internet and found all kinds of articles on how to do it – except for the installation on an early Bronco.

Having the CO2 tank route strapped into my bed or onto the roll bar was out of the question since room is at a premium. Continuing on my checklist, a 12-volt system was just too darn expensive for me. I decided to go with a York belt-driven compressor; they have high output and are also cheap. I found one in a local junkyard from a Volvo and bought it with the bracket for $35.00. I figured that the bracket would make a nice starting point for making my own mount for the compressor.

Having the main parts to my system, I next needed to figure out where to place my compressor and how to build a bracket. As the picture illustrates, I placed the compressor next to the battery and over the top of the alternator. As luck would have it, I happened to have a dual pulley, so I figured that running a belt around the alternator and the compressor would be just fine. I manufactured a bracket that utilizes the alternator spacer and a block bolt hole to allow the bracket to support the compressor. After fabricating the parts I used some high-temp Ford Blue spray paint to give it a factory look. I know if you try this modification that you may have a different scenario under the hood; just be patient and think it all through.

With the bracket mounted and the compressor in place, I ran into another problem. The fittings on top of the compressor are not national pipe thread (NPT). You can go to kilby.com to order the NPT fittings for your system, but they were too expensive for me. I went to the hardware store and bought a brass cap for both sides and a 1/8” thread – 3/8” hose barb. When I got home, I drilled the cap’s center out with the proper drill bit and pushed the hose barb threaded end through. I then soldered the hose barb to the cap, thus creating an adapter that works great for this application, not to mention constructing it for less than $50.00.

Note that the compressor itself puts out 4 CFM or more depending on engine speed. This is more than capable of inflating tires, but if you want more out of your system, then you will want to install a tank as described in the next section.

This step is the most costly if you want to use your new compressor as a true compressor. Some compressors, but not all, spit oil out of the discharge side; there are all kinds of articles relating to this problem. My compressor does not seem to spit oil out thus far. All of the following are needed in order to have the compressor work properly and safely: a pressure switch, safety valve, coalescing filter, air tank, check valve, and miscellaneous parts that you may want. The price tag for these components can go way up and varies by location. I suggest shopping around and using ingenuity when it comes to designing your system. I drew a picture on a piece of paper to keep me focused and to prevent the project from getting out of control.

After designing and hooking up my manifold, I needed a tank system to store air. I used two old nitrogen fire extinguisher bottles and mounted them up underneath the rear of the Bronco. I ran a ½” hard line black gas pipe down the frame rail and braced it in place. I used flex line at any movable location. With all of my fittings, I set out to plumb my system with an array of quick couplers so I can get around the Bronco with one hose.

I wired my compressor though my Painless fuse block and installed a rocker switch. Testing to see if things work is easy: just flip the switch with the key on and listen for the clutch to engage on the compressor. With all of this out of the way, I started up the Bronco and flipped the switch. I let the compressor switch cycle to its factory set pressure and plugged in a pressure gauge to see where it was. I adjusted the switch to give me 125 psi for now. I then walked around and checked everything for leaks and tightened hose clamps as necessary.

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While gathering parts for my 5.0 EFI install I happened across a two speed electric fan from a 2004 Jeep Liberty, part number 55037669AE. This Liberty did not have the towing package. With the towing package the Liberty will have a different electric and a mechanical fan. The shape looked simple enough to make fitment easy and the depth was only about 4 ½” which was as short as I have seen any others.

After comparing it to my Ron Davis radiator I found that only minor trimming would be required to seal it to the radiator. Other Bronco radiators would probably have a similar fit.

Here’s a little more detailed view. Some minor trimming was also required at the upper radiator mount areas.

As you can see the fan shroud completely covers the radiator core with about ¼” to ½” extra over the tanks. This will prevent the fan from rubbing holes into the core tubes.
To mount the fan I used the radiator’s shroud mounting flanges at the top and bottom along with some ½” x ½” aluminum angle and some ¼”-20 bolts and locknuts . These photos show the bottom mounting.

The top is similar but the angle is reversed. I found it necessary to use captive speed nuts on the top four bolt holes. Can’t get to the inside once the fan is on the radiator.

I didn’t have the mating plug for the fan connector so I replaced it with a 3-pin Weatherpack connector. If you get the fan from a wrecking yard be sure to grab the other side of the connector also. The fan side of the connector is at the top. The black wire gets connected to ground and 12 volts on either of the blue wires will provide low speed. 12 volts on both blue wires will give you high speed.

I mounted two relays and a terminal strip on the inner fender just behind the battery to power the fan. The 12V control wires for the relays both run inside to a control panel.

I made a control panel for the fan and mounted it in the speaker opening of the dash. The amber LED will light if the fan is off (disabled). The green LED lights when the fan is actually running. No lights are on when the fan is enabled in automatic mode but not running. The LEDs are from Radio Shack, part numbers 276-272 and 276-271, $1.99 each I’ve wired it so automatic mode will only operate with the key on, manual mode will operate at any time.

Wiring for the switch panel is shown here. You’ll need two DPDT ON-ON miniature switches and one SPDT ON-ON miniature switch. I used some switches that I’ve been holding on to for years but Newark has part number 98K4949 for $1.46 each and 98K4963 at $1.10 each.

In order to have an automatic mode I needed to install a temperature controlled switch. I used an adjustable thermostat (upper thermostat) from an electric water heater. I found it at Lowes for about $14, item #: 26358. I removed the unneeded upper portion of the thermostat and used an ohmmeter to determine which contacts to use. You want the normally open contacts that close as temperature exceeds the set point. I mounted the thermostat on the lower radiator hose close to the radiator.

The thermostat works surprisingly well during most driving conditions and is easily adjustable for turn-on temperature. It does have some time delay between when the upper engine reaches temperatures above normal and when the switch closes. This will cause my engine temp to swing between 190 degrees (195 degree thermostat) and 215 degrees during very steep uphill climbs or prolonged idling. During these conditions I can select the manual fan mode and the fan will run continuously, keeping the temperature at a steady 190 degrees. Eventually I will go to a top mounted fan switch to prevent this hysteresis. This will only involve installation of the new switch and re-routing of the existing thermo-switch wiring. I have not found it necessary to use the high speed setting yet even during strenuous off-roading sessions on hot days. On the flat, open road the fan does not switch on at speeds over 35 mph. Also the fan is so quiet that I can’t hear it with the engine running from inside. I should also add that in automatic mode the fan speed is determined by the position of the Hi-Lo switch.
Installed, I have 3/16” clearance between the fan and the explorer serpentine water pump snout. It is possible to trim the plastic back of the fan housing a small amount to provide another ¼” of clearance if needed. I haven’t done this and don’t see that it’s necessary for my application.

The top, bottom and sides fit very nicely to the radiator tanks and overall it looks like factory fit. After a month of testing this fan and control circuitry I am very pleased with the operation of it. I’ve taken it on some very steep 4-low crawling hill climbs and it has performed flawlessly.

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Many modern vehicles with trailer towing capability have dealer or aftermarket support for trailer harnesses that simply plug in to the vehicle’s factory wiring harness. Early Broncos do not. However the factory Bronco harness has the advantage of simplicity of design. After examining the taillight harness it became clear that a plug-in trailer harness would be a piece of cake to build.

The stock Bronco taillight harness runs down the driver’s side frame rail toward the rear bumper. Just above the rear spring hanger is a harness connector that supplies running lights, brake/turn lights, and backup lights to the rear. This is a 4-pin flat connector just like those used for light duty trailer applications. There is also a taillight grounding bolt within 6” of the connector. Everything needed for a simple trailer hookup (running/turn/brake lights, and ground) is located right there and the factory harness already uses the most common trailer connector.

Parts List:

I picked up the pigtail and extension at my local Checker Auto parts.

Basically what you’re going to do is plug the 4-pin extension in between the factory connectors with the pigtail attached to the extension. Pretty simple right? Well almost. The only part that requires thought is the color code of the wires and their attachment to the extension. Ford used its own color code in the Bronco harness and standard 4-pin trailer connectors use almost the exact color code.

So far so good. Now for a couple problems. The standard 4-pin has a particular pin order in the connectors and the Bronco harness uses a different pin order. The 4-pin has a ground wire in the connector and the Bronco harness doesn’t, it has the backup wire instead. These problems are easily remedied when the pigtail is connected to the extension. When connecting the pigtail you need to match its wire colors/functions with the Bronco colors/functions, not the extension’s. In other words disregard the extension’s wire colors because they’re not in the same order as the Bronco harness order. For the ground wire in the pigtail you will just attach it directly to the Bronco ground point.

On the extension separate the wires.

Label the wires with the Bronco wire order.

Near the mid point cut the white, brown, and yellow extension wires. Leave the green wire intact.

Split the pigtail wires approximately 11” down. Cut the yellow, green, and brown wires so as to leave the white wire about 10” longer than the other 3. Strip the ends of all wires.

Now attach the pigtail colors to the colors you marked on the cut extension wires. You will be joining 3 wires together at each point, both pieces of the cut extension wire and the corresponding pigtail wire. Don’t forget the heat shrink tubing before you solder.

Slide the heat shrink tubing over the joints and heat. Attach a lug terminal to the white wire on the extension.

If you want a professional look add some wire loom.

Unplug the factory connectors and plug the extension in. Attach the ground lug to the ground point and route the pigtail out the back.

That’s all, you’re done. Now you have a trailer harness that requires no modification of the original Bronco harness and you can add or remove it with just one bolt.

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Product Review by Jon Hanna (Admin)

AUSSIE LOCKER Following are my notes from installing an Aussie Locker from Torq Masters into my Dana 44 front end. The unit itself is well made and very stout. The instructions are detailed and well thought out. They don’t leave you scratching your head trying to figure them out like many product sheets. The install went very smoothly and would probably have taken half a day if I hadn’t also been taking photos and setting up new gears. I ran into only one issue and that was with my existing parts, not the locker. Hopefully my experience will help you avoid the same problem. In addition the tech support (Bill Cole in particular) was very responsive in helping me track down and solve the problem. Trail Review: A couple of weeks after writing this article I was finally able to get out on the trail and really see what it could do. My test trail was Lower Terminator because it’s fairly technical (rated 3-4 depending on conditions) and I’ve been on it several times before. I was familiar with the obstacles that had given me problems in the past and was curious to see how my new Aussie Locker would handle them.I can tell you right now that I’m not going back to an unlocked rig. I upgraded from a factory limited slip to the Aussie Locker and the difference was amazing. I imagine going from an open differential would be that much more impressive. The extra traction meant I was able to use much less throttle and much more finess. Obstacles that took me several attempts in the past were conquered in a single try. And all of this is still with my rear end unlocked. One item of note is the affect on steering. It’s minimal, but there (at least on my install). I can definitely tell the difference now between driving down a dirt road in 2 and 4 wheel drive. Also, in the rocks the wheel tends to fight you a little more. I don’t consider the affect severe enough to be a negative, but rather just something to get used to and keep in mind. Overall I’m very happy with the Aussie Locker. It’s easy to install, performs great and for about $230 it’s an excellent value.
A few notes before you begin. The Aussie Locker is designed to be installed in an open carrier. If you have a limited slip differential (ie. the factory installed Trac-Lock) you’ll need to switch to an open carrier. See the end of this article for more info. This article assumes you will be reusing your old carrier, ring & pinion gears and bearings. That way everything can go back in the way it came out and you won’t need to setup new gears, which is a much more involved process. Look for a separate tech article in the near future on new gear setup. Because of the length of this article I’ve split it up into a few sections: Differential Disassembly – The basics on pulling your axle shafts and carrier so you can install the Aussie Locker. Examination of the Parts – Checking your existing parts to be sure they’re still in good shape. Checking Case Tolerances – A partial install of the locker in the carrier so you can double check the tolerances. Preparing the Remainder of the Parts – Installing the rest of the locker and getting the carrier assembly ready to go back in. Reassembly – Putting the carrier/locker back in your front end and testing it out.
Parts Overview:
	When you open the box you’ll find (2) cam gears, (2) axle gears, (2) spacers, (4) pins and (4) springs. Also included is the installation manual and Operator’s Guide.
Differential Disassembly:
Here’s what a few deep water crossings will give you. Hopefully your gear oil looks a little clearer than this.	Park on a level surface. Put the transmission in gear (or park) and chock the rear tires. Raise the front axle with a floor jack and secure jack stands under each end. Place a drain pan under the differential and remove the cover bolts, which should start the flud draining. Let it drain while you work on taking out the axle shafts.First remove both tires and then disassemble the locking hubs. If you have disc brakes remove the calipers, hub/rotors, sprindles and backing plates. If you have drum brakes remove the drums, shoes and backing plates. You should now be down to the bare knuckles on both sides and can pull out each axle shaft.
	By now the differential should be completely drained. Finish removing the cover if you haven’t already. Inspect the gear and inside of the housing for any metal shavings or damage.
	Now take a look at the pinion shaft (cross shaft) in relationship to the ring gear. If the ring gear is thin enough you may be able to slide the shaft out past the teeth, which means you don’t have to take the carrier out of the housing. But typically with a Dana 44 the ring gear is too thick and so the carrier has to come out and the ring gear removed. (See photo)
	Before you remove the carrier side bearing caps you need to mark them. They need to be reinstalled in exactly the same way they came out. You can’t turn them over or switch sides. If they haven’t been marked by the factory or a previous owner (see photo for example) then you’ll need to mark them with a punch or dremel.Next loosen the cap bolts, but leave them just a few turns from coming all the way out. Now pry and wiggle the bearing caps away from the carrier, being careful not to damage the races. Leaving the caps loosely attached will allow you to pry the carrier most of the way out, but also keep it from suddenly falling out and dropping on the floor (or your toes).
	Now it’s time to remove the actual carrier. This can seem like the most difficult part of the whole process. Most carriers take a lot of determination and some really choice words to get out. Start by using a large prybar, but be careful not to pry against the ring gear teeth or inner spider gears. You might try a chain or strap wrapped around the carrier. Then you can slip the prybar through the strap and leverage against the axle housing instead of the carrier or gears. One trick is to wedge a rag below the ring gear and then turn the gear (or pinion). This forces the rag to get sucked in where the ring gear and pinion gear teeth mesh and should help leverage the carrier out a little. Then follow up with the prybar.
	Once the carrier is loose finish pulling the side bearing caps and lift the carrier completely out of the housing. Be sure to keep each side carrier bearing race with it’s respective bearing since they’re matched.Move the carrier to a clean work surface. If you plan to re-install your old ring gear then mark it’s position on the carrier. It needs to be reinstalled the same way it came off. Once it’s marked unbolt the ring gear and set it aside.
	Now use a punch to tap out the roll pin holding in the pinion shaft (cross shaft). If you don’t have the right size punch an old drill bit makes a good substitute. Just be sure to use a brass or plastic dead blow hammer and definitely wear eye protection. Drill bits are hardened and a normal steel hammer can shatter them. (Photo shows roll pin already removed)
	Tap the pinion shaft (cross shaft) out of the carrier and the spider gears should fall right out. You can toss all 4 spider gears, but you need to re-use (or buy new) the thrust washers. These are the larger washers behind each side spider gear. (2 total)Now you’re left with the pinion shaft, thrust washers, and the carrier itself.
Examination of the parts:
	These are the parts you’ll use from your existing open carrier; pinion shaft, thrust washers, and the carrier itself. You should also buy a new roll pin to secure the pinion shaft in the carrier.The spider gears (side gears) inside the carrier will be discarded since the Aussie Locker replaces them.
	Check that the pinion shaft isn’t worn. Using a micrometer compare the diameter at the end of the shaft with a spot where the side gears ride. There should be no more than .002″ difference.
	Double check the hardness of the shaft by scratching it with a small file near the center. The file should slip off the surface, not leave a groove. If it leaves a groove then the shaft should be replaced.
	Examine your carrier for chips, cracks or other damage. If you find any you’ll need to get a new carrier. Here you can see one of the four cracks that I found when I removed my carrier. This was a disaster waiting to happen! Luckily I wasn’t going to reuse the carrier anyway since it’s a limited slip carrier and the Aussie Locker requires an open carrier.
	Check your thrust washers for wear and warping. When I first insalled the locker I couldn’t get the tolerances to meet specs (see next section). It turns out my original washers were warped. A quick trip to the Ford dealer got me two new ones. See the photo to the left comparing the new (left) and the old (right).
Checking Case Tolerances:
	In this step you’ll need to partially assemble the locker in the carrier/case to be sure the tolerances are within spec.First, place your carrier in a bench vice. Be sure to use plastic or rubber vice jaw inserts so you don’t damage the carrier. Open the Aussie Locker box and take out the Axle Gears and the Spacers.
	Coat the Axle Gear teeth, center opening and back with medium to heavy axle grease. This will help hold the parts together during assembly.
	Take your existing thrust washers and install one on the back side of each of the two Axle Gears.
	Install one Axle Gear with thrust washer into the carrier.
	Now the other side.
	Put a little grease on the back lip of the spacers and install one on each Axle Gear. The open end of the spacer goes toward the Axle Gear.
	Now carefully install the pinion shaft (cross shaft). Always use a plastic or brass hammer to avoid damaging the shaft. As the shaft starts to engage the spacers be sure they are completely pushed to each side so the shaft can pass between them.
	Tap the shaft completely into position. The ends of the shaft should be flush with the outside surface of the carrier.DO NOT install the roll pin at this time. The pinion shaft is coming back out for the next step.
	Using a screw driver pry one of the spacers away from the pinion shaft. Measure the gap (at the tightest spot) using a feeler guage. Repeat for the other side. The gap should be .006-.020″. This is a critical measurement and will affect how the locker functions. If it’s not within range you need to figure out why and correct it before proceeding.If the gaps are within range you can go on to the next step. Slide the pinion shaft back out using a brass punch. Also remove the Spacers, but leave the Axle Gears and thrust washers in the carrier.

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This is the second article in a two part series on popular transmission swaps into your early Bronco. The first article focused on several manual choices for those who like to row their own gears. This second article is for you folks who prefer the ease and drivability of an automatic.The 3 speed manual or C4 automatic that came stock in the Bronco serve their purpose, but they’re not the best to be had. Some people want a stronger, more reliable transmission with ultra low gearing for those tough trails. For others, street performance is more important and a highway friendly overdrive becomes essential for those long commutes. And then there are some (all?) of us that want both!

This article is meant to give you some basic information to help you decide which transmission is best for your needs. There are several fine points to each conversion that aren’t covered here, such as TV cables, shifters, wiring, etc. Once you pick a tranny to go with you should research it thoroughly with the company providing the adapter.

Automatic transmissions are complicated and can be very daunting to the novice mechanic. It’s recommended that you have a competent shop do a rebuild since many of these units have weak points that a qualified rebuilder should be able to correct. Typically a new torque converter should also be installed, and you should research your choices here as well. The torque converter can have a significant impact on how your Bronco drives. As with most transmission swaps, headers can cause all sorts of grief. If you have headers, or plan on installing them, you should measure thoroughly so you aren’t surprised when you try to shoehorn that new tranny in.

This article assumes a small block Ford V8 engine is being used and the Dana 20 transfer case retained. The pricing shown is very approximate and conservative. Your prices may vary depending on your location and how friendly you are with you local salvage yards.

Use the following links for individual transmission pages:

Intro to Manual Transmissions

• NP435
• T18
• Toploader
• ZF
• NV4500
• NV3550

Intro to Automatic Transmissions

• C4
• C6
• AOD
• AODE & 4R70W
• 700R4

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