I need some advice, the differential is leaking. I am not sure from where yet, I do think it is one or more of the seals.
I have the front of the car up on stands now and I am almost done there and will be putting the back up next, then
I can see exactly what the problem is. My question is if I remove the half shafts am I going to be able to get the
half shaft yokes off the rear ?? Would it be eaiser to remove the whole rear and take it to a machine shop and have them
replace all the seals ? What do you guys think, anyone done either method before ?
Thanks.

 

There is 4 places the rear diff can leak. The pinion seal (front yoke at driveshaft), the two side yokes (at halfshafts) and the mating surface between the cover and the diff itself.

Unfortunately you cannot fix the side yokes or cover surface with the diff in the car. The side yokes are held in by a snap-ring on the inner end of the yoke. To remove the cover, you must at least drop the diff.

The pinion seal should be replaceable without removing the diff, but you risk misadjusting the gear lash, if you do not do it properly.

Tom Melton
82 CE
86 Z51 Coupe

 

Mine leaks a little too. It has for about a year now. Not bad enough to even drip, just enough to see. I will run it like that till it gets *bad* then do the necessary work. It looks like a real PITA to get it out. By by the time it finally goes with the new setup I will just go with a new Dana 44. If you find a way to do it in the car let me know.

 

The ring gear back lash is determined by shims behind the side bearings that are pressed on to the diff case (in side the rear end). The pinion depth is controlled by shims behind the pinion inner bearing cup where it presses into the differential housing (in side the rear end). The pinion bearing preload is established by a shim pack between the two pinion bearing cones. The only shims that can be accessed by removing the yoke, are the shims between the pinion bearing cones. The bearing thrust washer and the pinion outer bearing cone would have to be removed to get to these shims. This is not something you would do, either on purpose or by mistake in changing the pinion seal. The pinion nut torque spec is 200-220 ft lbs. As long as the nut is tight, the preload will be retained, and none of the other adjustments of the gear set CAN be affected by changing the pinion seal. Don't let the fear of altering gear adjustment deter you from changing a pinion seal. Good luck.

 

CFI-EFI, glad to hear that. I guess that my reasoning was based on history with the earlier (C3) diffs, as there was a crush sleeve, and remember the service manual stating something about not overtightening, and having to use a inch/pound torque wrench to get the drag right, etc.

-Tom

 

Thanks guys, I didn't get a chance to check the forum over the weekend. Mine is leaking pretty good so I am going
to have to fix it, and with my luck the chances of it being the seal I can replace with it still installed is slim. Can you
remove just the differential without taking the carrier off or the wheel ends apart ? What else should I change while
I have it apart ?
Thanks.

 

Hey Jeepie,
While it seems lke alot of work,its not that bad to do,rear end removal that is.Its much easier to drop the rear/carrier as a unit then try and take it apart under the car.

I removed the rear and re sealed the carrier/rear seal myself and it wasnt bad at all.

With the car on jack stands,drop the exhaust down and remove rear exhaust,support the rear/carrier with a floor jack and remove the support beam,(support the trans. when doing this)loosen rear drive shaft straps off and slide drive shaft to the side,remove/lower strut rods,loosen halfshafts at rear and move out of way, and carrier bolts (2),remove rear spring,etc and it will drop down with the floor jack.(always follow the manual for correct steps/procedure and also info to preserve alignment etc)

Once the rear end/carrier is out,its easy to have it serviced if you need new side seals or so.Also easier to drain the old gear oil out as well.Its not even that heavy.My GF and I lifted the rear/carrier into the trunk of my other car to get other professional work done.

If you can do alot of removal at home, its not a bad job at all, just takes some time to remove things and etc.Its far cheaper then payng alot of labor money to a shop.Btw,if you dont feel confident you can do it,let a pro do it and pay them.I had fun doing it and saved a ton of money doing the removal at home.
:)

 

You are correctamungo, Tom, The majority of car and light trucks using non Dana axles have a crush sleeve to establish the pinion bearing preload. The pinion nut is tightened gradually, until the sleeve crushes sufficently to establish the desired preload. The preload is measured by rotating the pinion with an inch pound wrench to check the amount of force required to rotate the pinion. The ring gear cannot be installed to take a measurement. With a crush sleeve type axle, if you go too far, you get a new crush sleeve and start over. All the Danas I'm familiar with use shims between the pinion bearing cones to establish the preload. The preload is checked in the same manner, but a little over tightening of the pinion nut won't change it, as it can in a crush sleeve axle. Is this as clear as mud?

 

The D44 in our cars does indeed have a crush sleve, the D36 does not so it depends on what you have.You can get away with reuseing the crush sleve just to chang the seal if you are real careful,but I would just get a new one. :cheers:

 

Ok, I have an update.. I now have the rear of my car up on ramps and I did take a quick look under there. All three seals appear to
be dry, and it looks like it is leaking from the cover. I checked the bottom bolts and the one on the driver side was loose, it took about two
turns to get it snug. My next question is can the gear oil leak from the bolt hole if it was loose ???
Thanks.

 

I believe that if it was the bottom center bolt, the answer is yes. The 92 shop manual shows that by removing this bolt you can drain the unit. I didn't read the manual and used a suction pump. Alot harder and apparently unnecessary. We all learn at our pace. :smash: