Hi, I'm new to working on the rear end and looking for answers
Its a 1970 Cuda with a 8-3/4 sure grip 3.55 that I want to service.
1)if I un-bolt and remove the center section from the axle housing to chg the leaking gasket and other seals will I have to mess with the backlash or other adjustments?
2)I also would like to chg the pinion seal... Can I just count the number of turns of the pinion nut when removing. and re-tighten same number of turns? Would rather not mess with a new crush sleeve and the torque to crush.

thx for any help

(1) no need to mess with the adjustments with a ring gear gasket change. (2) 489 case I'm assuming. Yes when you pull the yoke you will need a new crush sleeve & torque to specs or the solid crush sleeve replacement & not sure what you have to do or not do when going with the solid sleeve but it is recommended to go with it I believe. EDIT only pull the axles out far enough so the pumpkin can come out. if you do need to remove the axles if the end seals need replacement holler

While yer in there, IF it's OEM(with the threaded collar for end-play adjustment)I'd take a look at the axle-shaft bearings...

Although this is not a complicated job, the chances for mistakes the first time with no oversight, is high.

When you pull the axles out, try to hold them up off of the axle seals so as not to tear them. And either only pull them out a few inches to clear the center section or fully remove them and then change the axle seals. If you change the seals, it is best to use a certain seal driver to keep from damaging the seals. It can be home made.

You can change the pumpkin gasket with no other changes or adjustments.

If you change the pinion seal on a 489 gear case (check your last 3 numbers on the part number cast in the driver's side of the pumpkin) the yoke crushes the crush sleeve. So you can try replacing the yoke back where it began. (you are not supposed to do that, but it works okay occasionally).

Or you can replace the crush sleeve and reset the pre-load per the service manual.

If you decide to replace the crush sleeve with the solid tube, then you must set the bearing pre-load with shims.

Overall, it may be best to get some help on the first time you tackle this. It might just save time and money in the long run.

IHTH

agree with above. nothing hard, but there's a couple of mine's along the way to beware of.

If you're running stock type, non-sealed axle bearings; When you re-assemble, don't forget to reset the axle end-play. A bad end-play setting can cost you a rear end.

Thanks Guy's
I will probably hold off on the pinion seal chg for a little while, and just chg the ring gear gasket. it looks like thats were its leaking from anyway.

Can I assume the F.S.M is the way to go for adjusting the axle end play?
And if I am careful with pulling the axles out to check the bearings will the inner seals still be good or would you guys just replace the inner and outer seals/gaskets while checking the condition of the bearings?

Sorry for all the questions.

Verify which third member you have, if it is a 741 case you can change the pinion front seal with no problems on pinion bearing preload, make sure and torque(140+Ft Lbs.) the pinion nut properly As far as the inner and outer wheel bearing seals, if yours are not leaking now don't fix what ain't broke You might(should) want to buy four of the gaskets that go between the brake backing plates and the rear end housing and between the axle retaining plate and the front side of the brake backing plates Last thing is to make sure IF your posi unit is a early clutch type posi wth the buttons in the center to help set axle end play is to make sure both of them are in there when you put the third member back in

If you have the axles part way out anyway take them out and clean and inspect and repack the bearings with a good wheel bearing compatible grease. This is the only lubrication that they get. They are not lubricated from the rear axle lubricant as many believe. I would recommend installing new inner rear axle seals at this time too. http://www.moparts.org/Tech/Archive/axle/12.html

This might not be what everyone recommends but it worked for me: took out the axles when I removed the pumpkin but I didn't change any axle seals. They didn't leak before and didn't leak after I reinstalled the axles.
The axle diameter where the splines are is smaller than where the axle seal sits so it is easy to take out the axles without hurting the seal. I inspected the seal and there were no cuts/rips so for me there was no reason to replace them. You can also slide a sheet of thick paper over the splines when you take out the axles to make sure you don't cut the seals. In my case that wasn't really necessary as the splines were not that sharp.

Right-on..
I really appriaiate all the tips... FYI it is a 489 case...

Even if you don't replace the seals I highly recommend cleaning and inspecting the bearings and repacking with good grease.

Just a couple of things i would add I have changed hundreds of pinion seals on rear axles that have crush sleeve .
If you ever worked in a Jeep/Chrysler Dealer you would not make much time changing crush sleeves for a simple pinion seal replacement .
This is how we did it .
1.check the yoke for the backlash before you take it apart
you can get a good feel for it by rotating back and forth softly .
kind like rocking it.
IF back lash is tight then proceed to next step if loose like more than tight wiggle .
than the rear needs inspection.
2. with a bright light and a pick or finger nail count the threads protruding the pinion nut 3.record that thread count .
4. zip the nut off with impact gun while holding yoke with your free hand .
5. change seal .
6. clean rust off the threads and put 1-2 drops of red lock tight on the nut threads .
tighten to 175 foot pounds no more ,no less while holding the yoke solid with a pinion holding tool you can make one out of long piece of flat stock so it locks against the frame or ground while you toque the nut.
7. Count the threads if same leave it alone.
less tighten 1/8 turn until same threads show the key is to not over tighten.
If any one who has rebuilt axles knows it takes over 200 ftlbs to start to crush the collar.
IF this is done right no problems will come of it.
PS stock cone bearings on the axles need to be greased .