pinion seal replace

[dagenham]

Do I just have to remove the nut and the yoke to replace the pinion seal, or is there more to it than that???

[MikeFleming]

Yes, but ...

There's this crush sleeve between the two tapered bearings and how tight the pinion nut is set determines how much that sleeve crushes, which determine the shaft endplay, and rotation force. So it's critical to set that nut load properly.

Most folks I know that do ring/pinion gear setups set the pinion depth using shims (that won;t change when doing the front seal) then tighten up the pinion nut assembly in steps until the shaft rotation force reaches spec. Then the nut can come off and as long as the installed pieces stay the same, the nut gets tightened to spec and all is well. If the nut is too loose, then endplay may be excessive while if it's set too tight the crush sleeve will get crushed more than desired and preload will be too high.

My advice would be to have a shop experienced with the Ford 7.5/8.8 do the seal change. Besides if the seal is leaking that probably means there's some wear on the unit and it may need new bearings, which gets more complicated.

[SVOfish]

The proper procedure is as follows; this is how I was taught Via Ford.

1. Remove the rear brake calipers and hang them up using wire/bungee cords etc.Mark the relation of the driveshaft/pinion flange and remove the driveshaft bolts (12mm 12pt)


2. Using a beam style inch/lb torque wrench measure the amount of torque require to rotate the pinion nut. Measure several times to assure a consistent reading.

3. Using a pinion flange holding tool, remove the pinion nut. ( I just use a 1/2 impact at the dealership to remove the nut) you can make/ buy a holding tool if needed.

4. Using a 3 jaw puller, remove the pinion flange.

5. Using a seal puller, pull the pinion seal out. Clean the surface, lube new seal with gear oil, tap new seal in flush.

6. Install pinion flange assuring the splines are lined up, tap gently! With a soft face hammer to start seating the flange, you won't get far with seating it, you just want to give it a couple of taps.

7. Using the flange holding tool, install pinion nut, and torque to min. Specs ( I believe its around 8-15 inch lbs) continue tightening the pinion nut, while taking frequent rotational torque measurements in between tightening, until the recorded rotational torque is achieve from step 2.

8. Line up your driveshaft/ flange marks, install locktite on the driveshaft bolts, and torque them to spec.

9. Top off diff. With gear oil, would be a great time just to drain and fill with new fluid anyway.

10. Install your calipers/ wheels etc. Go for a ride.

[SVOfish]

Many times when I am doing pinion seals I find that the vent tubes are clogged causing pressure in the housing and most likely causing fluid to get past the seal and leak. Being a Ford tech 9/10 times the vent is clogged. You can also tell if you take the fill plug out and a whoosh of pressured air is heard.

[dagenham]

Thanks guys, I knew there was actually more to it than what I wrote. I just asked the basic questions.