Rear Diff Pinion Seal Replaced...No more leaking
 

Well the pinion seal has been replaced. Decided to do it myself rather than pay $165 (parts & labor)…mainly because my brother was on hot standby 800 miles away and I could call him the moment a problem would arise. :-blahOnly had to call him a couple of times. The Pinion shaft nut took a 1 1/8” socket. I had to use a propane torch to heat up the four 12pt 12mm Driveshaft support bolts before I could back them out. I used the count the turns of the nut method after marking the pinion shaft and yoke and socket and …you get the ideal…The main headache I had was the Yoke companion flange…it did not want to come off easily:-banghead…so I had to employ a gear puller…still with the puller and tap as I went along, it took approx 45 minutes to finally get it off :-X09(my brother thought this was peculiar). Old seal came out; new seal went in (textbook). Put the Yoke back on and tightened her back with the same amount of turns that came off…plus a scoatch….torqued down the driveshaft bolts, topped off the pumpkin and scrubbed the under carriage to clean off the splattered gear lube. No leaks. :-X24 <!-- / message --><!-- BEGIN TEMPLATE: ad_showthread_firstpost_sig --><!-- END TEMPLATE: ad_showthread_firstpost_sig --><!-- sig -->

Thanks for the scoup on how this was done. I was wondering. If mine leaks I will do it at home now.

That is the way to do it...now just monitor.

iron1951...just as a sidenote...by scoatch I mean 1/16th of inch. Once you pick up the new seal...compare it with the old one still seated, so you know what parts come out and what stay. That way you know where to get a needle punch under the lip of the metal outer ring...once I got that bent out a little I grabbed it with visegrips and hammered the visegrips shaft to pull the seal out (this is right out of the manual). Putting the new one back in (after lightly greasing the outer metal race and inner rubber ring of the new seal) was accomplished by holding in place with the left hand using a block of 1"x2" wood and tapping in with the right hand...or reverse if you're a southpaw. Make sure it seats fully and you're good to go.

Nice write-up, my pinion seal is seeping a bit and I will be doing this SOON!! Thanks:-X04

be sure to mark your driveshaft location before remove. that is about the only thing I think he did not mention.

senix...thanks for pointing that out...I did use a paint pen and marked the driveshaft orientation to the yoke companion flange...I even went as far as individually marking each of the four 12mm/12pt bolts with paint dots 1,2,3, and 4 to ensure they went back in the exact bolt holes they came from. Kinda anal, but I didn't want any problems later on.

it good to be aware of driveshaft orientation, but the only time it is of concern is if you pull a slipjoint apart. the issue is when 2 adjacent ujoints are not in phase. what i mean is that if you take a driveshaft with 2 yokes they must both have the crosses the same.if the front cross is facing 12 and 6, the rear one must be the same. it is possible to be off by 180 degrees so its good to use a paint marker or punch to mark the join at the slip joint. 180 is not horrible but it throws out the balance job, sometimes it'll vibrate sometimes its ok

The slip joints in SuperDutys have one spline that's twice as wide as all the others, effectively "keying" the two pieces, and preventing you from mating them in any other way than how they're supposed to be.

You're only going to get it back together one way. The correct way.

Pop

i have changed the pinion seal in my f250 also,but am running into problems replacing the pinion flange. it will start a lil but thats all. i bought a new flange from ford and no luck.

jayford. Once I placed the yoke flange back on the pinion shaft splines I had to tap (not too hard) it until I had a couple of rows of exposed thread IOT get the pinion nut started. Once I got the nut started I just worked it around counting back the same amount of turns it took coming off....it will actually walk the yoke companion flange back onto the pinion shaft and tighten up like its supposed to. Good luck.

I have fixed hundreds of rear ends and counting the threads to get the nut back into place is a bad idea. You are not accounting for any wear of the pinion bearings and the possibility that the nut has backed off. Chances are the seal was bad in the first place because the pinion was loose. Thats like putting your boot laces back to the same tightness after going half way through a hike. Tighten the nut down until there is a slight drag on the yoke (like it is supposed to be). Go slow here so you don't have to back the nut off to attain the drag.:-X16 Not only have you not accomplished anything but now the nut is loose and prone to backing out. Use a seizing compound also.

EXv10...you're one of those rolling torque guys huh? So what you're saying (which differs from very many both on this forum and other sources) is that everyone should just go to the dealer to get the repair done....wrong answer. DIY....they do it EXACTLY as I described...I checked two local dealerships and 2 independent mechanics ....Why pay +$165, when the part cost $17. Jayford ...DIY, don't listen to EXv10...unless he's willing to share by breaking down his method for you in detail on this forum. lol

Who said anything about going to a dealer? Your post makes 0 sense to me?????????????What rolling torque????????? What part costs $17? Are you a mechanic?...........Your truck is pretty cool with that locking gas cap LOL

Easy guys !
i've done them both ways (rolling torgue or nut torque).
But in a pinch done his way also.
Being a retired ford tech ,you find ways to beat the slt times given by ford to make money.
Never had a comeback on either way.
A key thing to remember about pinon seals is if the seal runs dry an scores a groove in the seal surface ,it will leak again in a very short time.
If you reused the same pinon nut you had better chk on its tighness down the road .
They are not to be reused. they are like a nylock nut.one time only

If you need or want the written way for proper rolling torque or nut torque ,I will explain it .

Rich

14; The pinion bearings are supposed to run snug and when you just put the nut back where it was the pinion will be as loose as it was before and the nut will be loose also and could of back off. At least use a new nut if you use this inferior method.:-RTFM I didn't say anything about rolling torque but having a light drag on the pinion is 10 times better than the "counting the threads" method. I guess the guy that fixed hundred of rear ends never learned anything.:confused:

The shop manuals are full of facts, figures, and specs but the seasoned mechanic doesn't have his nose in the book half the day. I have seen many of used rear ends with no drag on the pinion that worked perfectly and some that worked perfectly with so much drag on the pinion still after thousands of miles that you could barely turn the pinion by hand. When I set up my first few pinions I checked the torque and never checked one with a wrench after that and never had a problem. :rolleyes: 14; don't listen to me? No, listen to the guy that never was a mechanic. It's uninformed people like you that spread bad info in here.

Listen...you started this with your ******* comment above. So yoiu say you're a mechanic, but again I submit that you offered no insight to how it should have been done by YOUR textbook or memory of having performed 100's of rearend jobs...you think you could at least offered the guy some assitance ...instead you down-play or degrade those on this forum who do at least offer advise and assistance...(and no i don't mean ..."Yeah going to the dealer is like going to the dentist"...get over yourself...please. Its guys like you who taint this forum with your constant bashing and no real answers...and by the way...I'm am currently attending college as an Automotive technician....so who knows maybe some day I could officialy call myself a mechanic...but I wouldn't brag on it unless I could feel I was truly helping someone. And the call sign is Moyockpowerstroke...not 14....whatever...:-missingt

Moyockpowerstroke step back a little.

Just because you think EXv10 didn't detail the way he does it, he DID bring up an important point. While I agree both methods CAN work, the best way to do it is to set the bearing to the proper preload. Setting it back to the same spot only ensures you are probably not worse off than you were to begin with. I believe these differences were discussed in another thread.

Many of us that have done this for a long time can do it by hand, or compare the before to the after. There are specs for bearing preload, but if you are not going to be removing the tires, brakes, axles, (on a full floating rear you only have to slide the axle shafts out) and differential carrier, they are worthless because they only account for the pinion bearings.

The important thing is to consider all input while learning to do something, and since this is your first seal replacement, you are in no position to make a determination on what way has worked best for you, least of all which method is best.

Good post, Chris.

Let cooler heads prevail at FTE.

Thanks.

Pop

Good example here of why I said in the other thread that I wouldn't attempt this in the driveway. Avoiding this discussion, and the second thoughts that it is sure to inspire, would be well worth the $165 to have it done by an expert.

Actually, I think both methods are flawed, without CHECKING THE PINION PRELOAD IN THE FIRST PLACE.

Pinion seals usually do not just start leaking on their own. There is usually a cause besides wear unless you have a huge amount of miles or the pinion seal surface rusted. Loose pinion bearings, or a clogged breather. I would definitely check the breather before it starts to leak again ;)

But seriously, without removing the differential from the case and checking the real pinion preload BEFORE pulling it apart, you're playing with fire.

Yes, most mechanics do "count the threads", but they usually don't get a report back in 30K miles when it starts leaking again because it's loose, or the pinion bearings overheat because it went back together too tight.

If I ever have to deal with this on my Superduty (after having dealt with it on plenty of other rear ends, and having rebuilt quite a few too), I'm getting a new crush collar, a new nut, and doing it by the book.

Actually, if I ever have to deal with it, I'm going to use it as an excuse to upgrade from 3.73s to 4.30s :-X14

This is also just good CYA procedure too. You do a pinion seal, and a few months down the road it's making noise, you were the last one to work on it. You could have set it back to accepted "used" bearing preload, or where it was before, but if there is an impending failure in the pinion bearings you wouldn't have known.

However, in practice this is rare IMO. Usually if something is going wrong, you will notice real looseness, noise or roughness beforehand and two, most people won't pay for that kind of tear down for a seal. I (want to) agree that any rotating seal shouldn't fail unless there is something else wrong, but it does happen. Could be dirt, water, manufacturing variance etc.

I think this is one of those cases where yes you are playing with fire, but you won't get burned, it will just explode. And the chance of exploding rarely happens. Kinda like airplanes are the safest form of travel, but when something goes wrong, it really goes wrong.

All great points...I admit I was a little hot headed...EXv10...I apologize...lets bury the hatchet...we all need each other from one time or another and I hope we get along and make ammends. Thanks for everyone's comment and continued help and assistance.

Actually, just making sure you have a slight drag on the pinion when everything is buttoned up is a very good way to go. I have done it many, many times and it works very well. It sure beats taking it all apart right down to the lightly lubricated pinion and the torque wrench. Using a new nut when you do this procedure is a good idea also.

BTW what is the torque on the 12mm driveshaft yolk bolts? The source I have shows 86 ft lbs, is that right? Also is there a torque the pinion nut SHOULD be at? I read a running torque of 8-14 in lbs and a breakaway torque of 20. Do these numbers sound right. I am just replacing the pinion seal.

I did torque the 12mm12pt shaft bolts @ 86lbft...the Pinion Nut (of much debate) was returned to where it started plus 1/16th". I understand that where it started may have been wrong in the first place, but that was my reference point and since the companion yoke wasn't coming off without effort, I assume the bolt was not backing off on its own. I will keep a close eye on where I landed it. Use blue locktite or thread locker.

Thanks, I'm going to be working on it tomorrow! I've got the new Aluminum diff cover going on too :-D. MAN the 75W140 is SPENDY!!:-X09
I got Mobil 1 75W140 LS I'm going to put it in and see IF I need the friction additive on top of that. I picked up 8 oz of it but it looks like the Mobil 1 has some in it already?? I will take some slow corners on pavement or concrete and listen for the tires to scrub or not.

Yep, just ordered my '08 rear diff cover...should be here before the weekend. I will also be adding Mobil1...heard it already has the LS additive package already in the mix. Did you order the bolt set as well, heard longer bolts were needed with new cover?

I too heard they needed to be longer so I just went to my local NAPA and picked up twelve 1 1/4" long 5/16 18 pitch (coarse) grade 5 bolts. They were like .40 each!!

Pinion bearing preload
 

Just to elaborate on the "putting the pinion nut back where it was" idea; it's a bad idea. If you replace the pinion seal and don't know how tight the nut should be, consider the fact that the bearings have probably worn and the nut may have backed so. The pinion bearings like to run snug and using a torque wrench the check "rolling torque" when there are no torque specs for a pinion in a vehicle full of grease the best method (vs counting the threads) is to preferably get a new nut and run it down until there is a noticable drag on the pinion. The crush sleeve will spring back a few thousandths after being relieved of the original crush and the slack hasn't been taken up by the worn bearings so in effect you already have a new crush sleeve in there. This in conjunction with the new nut will assure a secure unit and a proper preload on the bearings. I have seen pinions with so much drag on them they were hard to turn by hand (after thousands of miles) and they worked perfectly so the torque is not that critical but you do need some drag on the bearings.

GREAT information, thanks Greg! What is the rational used in the recommendation for using a NEW pinion nut? I can see IF it is a nylon insert style nut. I was an aircraft mechanic in the AF and had MANY nuts that were 1 time use, mostly all had the nylon insert tyhat would loose it's grip ( so to speak) if you were to reuse it. But we were working on critical aircraft components.

Many pinion nuts are the self locking type. Just added insurance, you probably wouldn't need it.

Counting to ten......