How To Disassemble and Rebuild the Rear Differential including Seals, Bearings, and Brakes on a Ford 4000 Tractor Pt. 2

At this point we are almost ready to begin re-assembling all of our major parts, but first, we need to rebuild our axle assemblies.

Start by installing the wheel bearing races and wheel hub seals in both wheel hubs.  MAKE sure to install the wheel hub seals with the lip facing inward.












Next, slide the wheel hubs onto the brake backing plates.  Then, place a little wheel bearing grease on the inner part of the wheel hub seal and then slide the axle through the wheel hub assembly.  Now, fill the race with grease and pack the wheel bearing with grease as this wheel bearing does not receive gear oil during operation.  Once completed, slide the wheel bearing down the axle until it stops.  Taking at least a 30″ pipe with a 2-1/4″ I.D. drive the bearing down until it stops.  Next, drive the locking collar down as far as it can go behind the wheel bearing.  A word of WARNING, this procedure is supposed to have the locking collar heated up to exactly 800 degrees F before driving the collar on using a temperature crayon to verify temperature as overheating can cause distortion in the collar and possible need for replacement.  I chose to drive them on cold as the length of the axle made it unable to fit in the hydraulic press.


















It is now a VERY good idea to re-install your shims on each side.





Next, remove the old pinion bearing races from the steel housing and press in the new ones.  Now, re-assemble the pinion shaft into the steel housing, using a bit of gear oil on the new pinion cone bearings.  I set up the assembly in a vice which allowed me to torque the assembly with relative ease.  However, I had to get creative using aluminum foil as I did not have the factory torque strap tool nor a socket that would fit perfectly onto the pinion splines.  So, below you can see how I tightly wrapped the pinion splines with the aluminum foil and then “pressed” on the socket in order to check for proper torque as I adjusted the two pinion nuts for preload.  The torque spec is 12-16 in. lbs.  Once torqued, bend the lock washer tabs over both nuts to hold in place, replace the pinion steel housing square o-ring seal that seals against the rear case housing, and then slide the pinion assembly into the rear case housing.

















Then, install the pinion assembly in the rear case housing making sure to slide on the rear barrel pinion bearing onto the rear of the pinion shaft bushing first, and put a little gear oil inside the rear casing where the barrel pinion bearing will slide into it.




Once the pinion assembly is fully seated inside the rear case housing, align the steel cone pinion housing cover over the pinion assembly and torque the bolts which hold all of it to the rear case housing.  If yours is like mine, it was time to install a new seal before placing it in position – remember to add a little gear oil around the lip before sliding it over the pinion shaft.









Then, install the bearing retainer plate.   Mine was distorted so I had a new one made at a local machine shop for about $25 but I had them make it out of slightly thicker gauge steel.  Instead of using rivets, I chose to use grade 5 bolts, with flat and lock washers, and nuts – its a good idea to use thread locker as well.








Before installing the rear housing, it is a GOOD idea to replace the gasket and O-ring on the hydraulic lift sump cover located on the bottom of the rear housing along with placing a little bearing grease on the brake actuating rod that pivots on the bottom of the rear housing.  Then, install the freshly painted rear housing case making sure to install a new gasket and new o-ring seals between it and the transmission housing; which seal the hydraulic passages.  And, REMEMBER to install the shaft that slides on the front of the pinion shaft before mating up the surfaces.













I like to use gasket sealer (marine grade) for mating surfaces, and holding O-rings/gaskets  in place.  Make sure the o-rings on the pressure and return ports stay in place, along with the main gasket.








Time to start assembling the rear differential.  Start by adding a little wheel bearing grease to each outer axle tube seal before bolting it to the side of the rear housing.  REMEMBER to install a new seal between the rear housing and each axle tube (this one uses a large squared O-ring but some use a flat gasket).  Install the right side axle tube first.









Next, place Vaseline on the right axle splines (make sure your shims are still on) and then slide the right axle assembly into the right axle tube being careful not to damage the outer axle seal.  Make SURE to slide into place the brake rod actuator at the same time.  Also, notice the pic of the brake rod actuator cavity on both sides of the rear housing.  I filled both with wheel bearing grease to keep water out, and for easier rotation.  Once aligned and flush against the rear housing, install and tighten the axle hub nuts.











Now “slide” the third member into position making sure the right axle splines align allowing the third member ring gear to fully engage the pinion gear.  Its optional to pour a little gear oil onto the carrier bearings before sliding the third member into place.





I like to put the tractor in neutral, apply pressure to the left side carrier bearing, and have someone rotate the right axle just to make sure nothing is binding.  Once you know that’s good, install the left axle tube, brake rod actuator, and axle assembly in the same order you did the right side.







A couple pictures of the inside once the axles are installed.





Next its on to assembling the brakes on both sides.  I like to put synthetic grease on the medal contact points, and remember to grease the inside of the brake shoe adjuster on each side.   Once assembled, slide on the brake drum and rotate while adjusting the brake shoe adjuster until you feel a solid drag – my experience, this needs to be a little tighter than automotive brake shoes.  To loosen:  left side rotate the adjuster from back to front / right side rotate the adjuster from front to back.  Obviously, to tighten, do the reverse for each.












Then, put a little Vaseline on the splines of the PTO shaft along with a new gasket to seal against the rear of the housing and bolt it in place.  At this time you can also bolt up the extension bracket used for a hitch and drawbar.









Next, install the PTO lever using a new gasket.





Then, make sure the top of the housing opening is clean of all debris, install a new gasket making sure to set the O-rings in place to seal the hydraulic pump lines, and then set the lift cover in place while bolting together.  If you haven’t already done so, it is a good IDEA to tap each hole just to make sure no rust/debris is in any of the holes before setting the lift cover.  I used a chain and engine hoist to set it in place.








Once in place, I began bolting up the wheel fenders and attaching the lift arms making sure to add a little bearing grease at any medal to medal contact points.  Also, I put anti-seize on the bolt threads since they are prone to have water/dirt on them over time.








Then, place the rear wheels over the axle studs and install the lug nuts.  Next, install the rear wheel weight bracket and nuts that hold them to the lug nuts.  Once all that is torqued, begin installing each rear wheel weight and bolting them to the rear wheel weight bracket.  A GOOD word of advice, tap each rear wheel weight bracket hole before installing, use new grade 8 bolts, flat washers, and lock washers, and use anti-seize on the threads of all the studs/nuts.








Fill the rear housing (both compartments) and transmissions with new, clean fluid and bleed the hydraulic pump bolted up along the right side of the engine block.  Then, take it for a test drive making sure to check for any leaks.

Congratulations!!! You just finished a BIG job and saved yourself thousands of dollars.  Good work!