I replaced my axle seals last weekend, afterwhich I found that my pinion seal is leaking as well (I guess 200,000 miles of hard driving has taken a toll on my rear end). My questions is, how hard of a job is it to change a pinion seal (let's say in comparison to doing the axle seals)? Will it require any special tools? What are the pitfalls that one needs to pay attention to when doing the job. Also, my local garage said that they would do the job for $140. Is this the sort of job that can be easily messed up by the fairly competent DIYer? If so it might be worth it to let the local garage do it at that price. What are your thoughts?

 

The pinion seal requires special tools like a long breaker bar and a pinion holder. You have to be careful to mark the pinion nut, then count the number of turns to get it off. After you replace the seal, the nut has to go back on the same number of turns until the marks you made line up. Failure to put the pinion nut back in the exact same spot will cause the rear end to start making gear (whine) noises.

If you do it right it's a fairly easy repair that will take about an hour.

 

Oh and you have to be fairly strong to do this repair cause the nut get torqued down to something like 160 ft. lbs.

 

Good info, allpro.

I will take a look at it tonight to see if I feel comfortable taking on the project.

 

For $140, I might pay somebody to do that one. It isn't a difficult repair, but if you have to lay on the ground and do it, getting the piion nut off and on with hand tools is difficult as the others have mentioned. If you have air tools, then I would take it on myself. I changed gears on an old Nova a few years back. Turned out great but the pinion was a struggle to be sure.

 

After looking under my Exp and reading the Haynes manual, I think I will take it on this upcoming weekend. I do have air tools but can't really see how they would help all that much (this of course is coming from a guy that hasn't ever done the procedure so I'm sure I am way off base). It seems that the only time that air tools would come in handy would be get the pinion nut off. I had not planned on putting a new crush sleve in so I had not anticipated needing a lot of force to put the nut back on, am I missing something or thinking of something incorrectly here? From what I have read, the job includes the following steps:


1) Mark the orientation of the pinion, flange, driveshaft and differential housing with paint (I thought I would use liquid paper for this)
2) Disconnect the driveshaft
3) Count the number of threads showing on the pinion bolt
4) Use a torque wrench to determine how many inch pounds of force it takes to rotate the pinion (I had planned on doing this with the tires off the ground, but with the tires still on the hubs, can I do it this way or do I have to remove the tires?)
5) Remove the flange (I think that is what it is called, its the part the driveshaft bolts to and mates with the pinion). I might need a puller to get this off
6) Remove the old pinion seal (I'm sure this part will be more difficult than it should be if my history holds true)
7) Clean up the surface where new seal will go
8) Install new seal
9) Put flange back on making sure allignment marks I painted on prior to disasemble all line up
10) Put the pinion nut back on with thread lock and tighten it back down until the I have the same number of threads showing that were showing prior to disasembly and make sure that the allignment mark on the nut ligns up with the other alligmenment marks
11) Test preload with torque wrench to ensure it takes 2 to 5 more inch pounds to rotate the pinion than before (should take more force to rotate it now due to the drag from the new pinion seal)
12) put a little silicone on the end of the splines coming out of the pinion nut to ensure fluid can't work its way out of the splines.
13) Reinstall the driveshaft.


Am I missing anything here, or is this pretty much it?

 

That's it, except you don't really need to do the rotate with a torque wrench steps. That step is totally inaccurate unless you pull the axle shafts out of the carrier, because you will not get the same reading twice. As long as you put the nut back in the exact same spot, it will be like you never took it apart.

Oh and as far as air tools go, I don't recommend them to take the pinion nut off or to run it back on. For one, you cannot count the number of turns to remove the nut, and two, the high impact force needed from the gun can chip gear teeth or damage bearings.

 

OK, I ran into a problem that I was not ready to address. I marked the locations of the pinion nut, pinion shaft, driveshaft and yoke, I counted the threads protruding on the pinion shaft (6 threads) , I counted the number of turns it took to remove the pinion nut (16.5 turns), but what I did not plan on was the pinion nut being backed off prior to me removing it.

After counting the exposed threads I put my breaker bar on the pinion nut expecting it to be difficult to move, but to my surprise I was able to start it moving by using only one arm, and not even really pulling all that hard with that one arm (maybe using 75% of the strength in that one arm). I believe that my pinion seal had been leaking because the pinion nut had backed off. At that point I know all of my prep work to ensure the pinion nut went back on correctly was out the window. I was then in the land of "OH CRAP, WHAT THE HECK DO I DO NOW".

When I put the pinion nut back on and turned it to the 16.5 rotations that I had had to turn it to get it off, and aligning the marks on the nut with those I put on the pinion bolt, I could move the pinion in and out at least half an inch. I searched the web looking for info on alternate ways to set the preload correctly and ultimately landed on tightening the pinion nut to the point that the play in the pinion bolt went away plus 1/4th of a turn more. Ultimately I ended up torquing the pinion nut to about 155 ft/lbs. I have driven the Exp about 120 miles since then with no rear end noise and no signs of problems or fluid leakage.

My questions are

1) If I didn't not get the bearings preloaded correctly, would I have already had a rear end failure with 120 miles driven?

2) Is 155 ft/lbs of torque about right for the pinion nut assuming that I did not install a new crush sleeve?

3) What signs should I be looking for if I did not get it preloaded correctly?

Any info will be greatly appreciated.

 

How's that saying go? If it weren't for bad luck, I'd have no luck at all.

1) The rear end will not flat out fail, it will start making a whirring noise first. Even then, you can go for 10s of thousands of miles.

2) I believe 160 ft. lbs. is the initial torque before fine tuning it with an inch pound torque wrench, so even if you're not perfect, you're in the ball park.

3) A whirring noise and/or fluid leaking from the pinion seal.

 

Thanks for the feedback Alloro.

It's comforting to know that although I mght not be exactly right on with my preload, I'm likely really close to being there.

What I wonder is what would my local garage have done to get the preload right. My guess is that they would have started off using the same process I did (counting the threads, counting the turns of the pinion nut, marking the nut and pinion bolt....). For the $140 they were going to charge me to do the job there is no way they were going to go the route of checking the preload with an inch/pound wrench because to do that you have to open the differential and remove the axles. They were not going to do that $140. The fluid alone to do that would have been $60. So ultimately I think they would have been in the same boat that I was.

 

"2) Is 155 ft/lbs of torque about right for the pinion nut assuming that I did not install a new crush sleeve?"
My understanding is 12-15 Inch-pound of torque for the pinion nut with new crush sleeve and 15-19 Inch-pound with the old crush sleeve per Ford Service manual to preload the pinion bearing. It's also recommended to throw away the old pinion nut and to buy a new pinion nut from a Ford dealer because it comes with new sealant on the thread area.

 

Those values are the amount of torque it takes to rotate the pinion shaft/differential with the axels removed. To go that route you have go through the whole removal of the axles process that I listed above. The values you reference are an indicator of how much force it should take to rotate the differential when unloaded, rather than an indication of how tight the pinion nut is. I believe the intent is that with around 160 ft/lbs of torque on the pinion nut there should be about 15 or so inch/lbs or rotational resistance on the differential

Good info though.

 

Great summary, wish I had seen this before I started my project. I am sure that I have overtighten the pinion nut as after about 2000mi I am hearing a slight whine and now I have evidence of the seal leaking again. Now what? Buy another seal, new pinion nut and reinstall? I am not sure of the condition of the crush sleeve and how can I load the bearing to the correct position since the current location is clearly too far? Is it an axle removal and verify torques from the pinion assembly first.

Any help would be appreciated.

 

I would be more inclined to think you under-tightened the pinion nut if the seal is leaking again. For a new seal to leak, it is not due to wear but rather side to side play. You would only get the side to side play if there was insufficient bearing load (loose pinion nut.)

The first thing to try is to torque the pinion nut to 160-170 ft. lbs. to see if the nut turns. If it turned then likely you're all set. If it doesn't turn, then it likely you're going to have to replace the seal and crush sleeve.

 

what size socket is used to remove the pinion nut? I can't find that info anywhere.