differential bearing and seal

who has replaced these and can it be done quickly with axle intact? my seal is leaking and figure if bearing is easy might as well do it.

Do you mean the differential cover and gasket? Yeah its pretty easy to do with it still in the car.

no i know that one is easy the pinion one

mega wrote:

no i know that one is easy the pinion one

You will have an easier time of it if you grasp the idea of two separate preload issues on pinion installation.

Otherwise, if you have never done it before, doing this job can give you unreliable results.

1st, you must achieve the proper amount of tapered roller bearing preload, on used bearings 15-18 lbs/inch, with no ring gear turning against it or seal installed dragging on the yoke.

2nd, you must apply the crush collar preload, that presses (locks) the two timken inner cones securely. This can take 200 300 lbs/feet to get done on a new crush collar, and you shouldn't reuse the old crush collar.

One of the most important functions of the crush collar is to maintain a constant preload against the yoke and nut to keep the bearing preload from loosening up, due to a rotating nut.

In order to get a satisfactory result, you must avoid some of the possible pitfalls.

The factory service manual will give you a reasonable set of guidelines in order to get it done properly.

MANY mechanics just swap out the seal, and put everything right back in and send you down the road.

I don't doubt their claims that they never have any comebacks, but these guys do this so regularly that they have developed a method that works for them.

They will admit that they take shortcuts, but they also save you a bunch of money, because they are not following the FSM procedures that require nearly complete rear end disassembly.

After having done this job countless times, I can usually grab a pinion that is installed in a completely assembled rear, and feel if the pinion preload is dead balls accurate.

This is what makes those experienced mechanics who take the shortcuts able to get away with it.

so in other word if the bearing is ok just leave it alone and do the seal. i watched a video on it seems kinda easy just gotta remember to count threads and mark everything.

mega wrote:

so in other word if the bearing is ok just leave it alone and do the seal. i watched a video on it seems kinda easy just gotta remember to count threads and mark everything.

If ya don't mind, post the video link here, as I'd like to see what method they recommend for re-setting the pinion pre-loads.
I want to make sure that you know what your looking at, in case the seal when bad due to some other cause, such as a loose bearing preload.
That method will only work if all other parts and preloads are already very good before you even take it apart.
Remember, you will not have the same preload on the crush collar if you re-use the old one, but you will likely have the duplicate bearing pre-load though.
You should also sand, scotch-bright, polish, wash and lube the seal surface on the yoke to prevent another early seal failure.
If the seal surface is too badly trashed, you can install a seal repair sleeve or just buy a good used or new replacement yoke.
If ANY of the following parts are changed (nut-washer-yoke-bearings-races or pinion gear) then the thread count and nut clocking method will NOT work for you.
There is also another pathway for oil to escape out past the pinion nut, so you should put some silicone sealer on the splines to yoke interface.
I am not trying to discourage you, I simply want you to have a good result for a low cost outlay.

ill find it again but it only covered the sealhttps://www.youtube.com/watch?v=15zHpz6Zx8c

Well done by that mechanic, thats how its done properly in a repair shop to get you back on the road fast and fair.

The only things I would have added was that:

1) You might as well drain and replace the gear oil, since there was so little in there to start with.

- - - It is possible that there were contaminants (abrasives) in the old oil that accelerated the seal failure in the first place.

2) He also could have mentioned that as he was tightening up the nut, there still was some leftover preload in the old crush collar. His good fortune!

- - - Had there not been enough, the nut would have been easy to bring up to the same clocking point, and then it would not deliver sufficient crush collar preload. And remember, that is what keeps the whole thing tight.

- - - In that case, he would have had to pull out the front bearing and replace the collar, and THEY can be a bear to collapse to the correct preload . . . (first timers).

3) As you see, he did put grey sealant (I use Ultra-Grey) on the splines, but when NOT replacing the crush collar, it would be prudent to apply some red Lock-Tite to the pinion nut threads, as insurance.

Gotta love that big ALCOA drive shaft!