changing leaky front diff seals..

[jasonb]

my front diff is leaking at every seal basically. it leaks at both ends of the axle tube as well as at the driveshaft. i'm assuming its just that all the seals are bad. i will be putting a front locker in soon and would like to change these seals while its out. is there much to it? sounds like i may need a special tool to seat new seals. any tips or info is appreciated. i'm looking to do this toward the beginning of november.

 

[twomedicine]

seals

JB,

You'll get a better reply to your question than mine, but just to let you know my '99 leaked at all 3 shaft seals too @ 70K when I got it (did not know 'til later). I had Cottman do the entire job on mine, including some new internal parts and some work on the trans case.

If you look at your manual it looks like the replacing stub shaft seals are the easiest part of the job. It's getting to them that had me take it to the shop; you'll need a friend to help and a floor jack to hold up the assy while separating the hub.....

The one thing you might want to know is that after I replaced the pinion shaft seal myself, it still leaked. The reason was that both the yolk and the pinion bearing and related crush collar/washer were shot. So you might want to get those parts as well when you are doing the job.

 

[jasonb]

thanks man.. it doesn't like an easy job! i'll have a friend with me when i pull the diff so hopefully we can get it done. its not really leaking much, but i figure this is a great time to replace the stuff. anyone else got any info?

 

[utmustang88]

im doing the front pinion seal right now....im waiting for the front yoke to come in from ford(37$ + 10$ for new seal should be here today).....on the old yoke the pinion seal wore a groove on three places. my dad and i thought it would be a good idea to get a new yoke so there would be no grooves on the machined surface; possibly causing the leak?
THAT DARN 1 3/8" nut holding the seal/gear/yoke in place was a PITA! We didnt have a impact socket big enough for it....so my dad and I got a screwdriver to jam in the 4-prong thing so it would stop spinning and then we had to apply somewhere in the mist of 100ft-lbs with a very long wrench to get the darn nut off! maybe it was rusted or something, but i thought the car was going to come off the jacks! ill update when i complete project.

 

[JDraper]

Changing the axle end seals is pretty easy while you're in there to put a locker in. To take them out, you pry them out with a screwdriver, being careful not to scratch up the area where the seal seats in the axle. To put them in, you can improvise with a large socket and a hammer. find a socket that is juuussst smaller than the ID of the axle, and drive the seal in by placing the socket against the seal and hitting the back of the socket with a hammer. Take your time and drive it in straight.

The pinion seal is more of a PITA because you have to loosen the pinion bolt. When you do this, I'd recommend replacing the crush washer too. To do it, you need to have an in-lb torque wrench, and the spec's for rotational drag on the pinion. Check out Randy's Ring and Pinion. Look in their Tech library for the specs on torque for your axle. Be very careful to make sure you get all the shims back in the same way so you don't mess up your backlash. Air wrenches are a big help because you need up to 400 ft lbs of torque to properly seat a new crush washer. I did the gears in ExplorerEB96's truck in my garage and they came out fine.

 

[jasonb]

thanks guys.. i'm thinking i will change a lot of stuff at the time. maybe even balljoints. mine are stock and i don't PLAN to take the front end apart again anytime soon...

 

[utmustang88]

things didnt go as planned....ordered the yoke from ford on friday, they said it would be in on saturday....it never showed up...boy did i ream that guy a new a#$ hole. explorer is still sitting on ramps until i come home from school..piss on ford's service department. had to borrow dad's jeep rubicon!

all im replacing is the yoke and seal....not the bearing, sleeves or anything(dont really want to mess with the beaing). hey i got some valvoline 90-140 gear oil, that should be fine for the front diff right? and i am correct to say there is no locker in the front, so no friction modifer has to be added. also how many qts have to be added to the diff. thanks

 

[JDraper]

To replace the yolk, you still should replace the crush washer because it sets the pre-load on the pinion bearing. You can't just put the nut back on an crank it. I really suggest you go to the Randy's ring and pinion site I linked to above and read up on it. If you don't set your front pinion bearing pre-load correctly, you can burn out the bearing quickly.

 

[twomedicine]

Crush washer

That's correct about replacing the crush washer. And your bearing probably has too much lateral end play making a good seal impossible.

You could try your way, but chances are it'll leak still and you may do more damage in the long haul.

 

[utmustang88]

ok finally got the new pinion seal in and the new yoke installed. oil'ed up everything good and i have been driving around for the last week. things seem to be good to go, no leaking anywhere around the pinion seal.

the one thing i want to B$%# about is changing the oil in the diff. i went to auto zone and got that pump...well the darn plastic tube it came with didnt even fit past the gears once inside the hole......worthless. i found a smaller diameter hose and put it on the pump and went from there... i didnt get all the old fluid out b/c i didnt know how much was in there until i put the new stuff in. oh well the job is done and so far so good!

 

[twomedicine]

Gear lube change

Can't you take the cover plate off and drain it out thoroughly? Get a new gasket and do it that way/

I know the cover plate bolts are had to get to but it's do-able

 

[JDraper]

You might be able to the bolts, and you might be able to get the cover cracked loose, but how are you going to properly clean the mating surfaces and seal it properly?? You can't remove the cover because it will catch on the ring gear. There isn't enough clearance to remove it. The Gen II Explorer's front cross member gets in the way.

 

[twomedicine]

Bad idea, good thing you caught me

I never thought of that ring gear getting in the way of the front diff. plate while removing. Yeah, it's very tight in between that crossmember and the front pumpkin. And they used ATV sealant from the factory instead of a gasket, so even if you broke it loose for draining, chances are the seal would be messed up, and in case you had to retreat without putting a new gasket on the surfaces you'd be up the creek.

Bad idea. Poor design for service. They should have put a drain plug in that front one, but it does seem a lot of this vehicle was built without service/maint. in mind.

When Cottman did mine it must have been re gasket'd while the whole housing was pulled and on the bench and while other repairs were in process.

 

[jasonb]

hey jeff.. do remember the spec for the crush washer? i looked at randy's tech library and didn't see it. maybe i'm blind!

i've got my diff out and just ordered the pars so i have a day or so to figure this out. i hope my air wrech will push that much!

 

[JDraper]

Oh jeez, my memory ain't that good!! However, the torque you measure is the rotational torque of the pinion shaft, not how much torque you put into the bolt. What you are actually measuring is the pre-load on the bearing. There are two different torque values, one for new bearings and one for old bearings. Both are in the inch-pound range. If I remember correctly, you can use the values for the Dana 30, which are 12-15 in-lbs of torque for new bearings and 6-8 in-lbs of torque for used bearings. If you look at the "Set Up Specifications" in the Ring and Pinion section of Randy's tech library, all the Dana axles below a D-50 use roughly the same setup.

My air wrench worked fine for doing it. I'm on a 20 gallon tank with 1/2" hose and a 400 ft-lb gun. I ran the gun at 110 psi, which is a little higher than recommended, but it gave me the torque I needed.

Have fun! and take your time....

 

[jasonb]

so basically, if i get a new crush washer, i just tighten it enough to "crush" it and that is good? is the washer set to give the right preload? this is gotta be simple but its confusin the hell out of me! i don't understand what the preload is and how you measure what you've got setup.

and how much trouble am i going to have, if any, with getting everything back perfect. sorry for all the questions, but i only want to do this once.

 

[JDraper]

No, that's not how the crush washer works. What you do is start to tighten down the pinion nut, remove your gun, put an in-lb torque wrench on the nut and read how much force it takes to turn it. If it's below spec, hit it with the air gun again. Repeat this until you are within the torque specs. WARNING The torque level will jump quickly as you get near the proper crush in the washer, so use the air gun in short bursts. Couple of hits, measure the torque, couple of hits, measure the torque, etc.

How much force it takes to rotate the pinion is how you measure preload. Preload is how hard the bearing is seated into the bearing race. As you torque down on the pinion nut, it forces the bearing harder against the race. This creates friction between the bearing and the race, and that's what you are measuring with the torque wrench on the pinion nut. The crush washer is designed to give at a certain pressure, but you can crush it too far. If you do that, then you have to go out and buy a new crush washer and start over.

 

[jasonb]

gotcha! that all makes sense now! thanks jeff.

 

[Hoppy]

That Randy's website has nothing that I could find on the front bearing crush sleeve preload. Anyone know what the preload is?

Hoppy

 

[JDraper]

That Randy's website has nothing that I could find on the front bearing crush sleeve preload. Anyone know what the preload is?

Hoppy

Look 4 posts above yours....