Pinion seal 8 3/4 489

[Mopar5]

Hi Everyone looking for some advice i am going to replace the pinion seal on this diff . I am going to use a new crush sleeve or maybe a sleeve eliminator. What rotating torque should I be looking for in a well used diff with the old bearings I know its different  for new bearings vs old bearings . Im not changing or adjusting anything other than pinion seal. Thanks Mike

[fc7cuda]

I did a 489 recently and seem to recall it was 12-15 inch/lbs, although I don't have the manual in front of me at the moment.   

[73_Cuda_4_Me]

10 inch/lbs for used bearings... that is with a crush sleeve torqued to a minimum of 125 ft/lbs (found on moparchat)...

That is pinion only preload...

Total preload (spinning ring gear/pinion without axles installed) should be around 25-30 inch/lbs with used bearings... (ref. Hotrod 8-3/4 axle assembly article)

[1 Wild R/T]

How do you plan to replace the crush sleeve? The pinion needs to come out in order to replace it which means complete disassembly... If your doing that you might as well consider bearings...

Or just replace the seal & just make sure the pinion nut goes back exactly where it was.... 

Mark the nut & the end of the pinion before disassembly, break it loose & count the turns... As long as you reuse the nut (With Red Loctite) & the same yoke the setup shouldn't be effected... I've done exactly that many times... Though I do one little trick to make sure there is tension on the crush sleeve... If you can get the front bearing out without damaging it I add a .010 shim between the crush sleeve & the front bearing, that way the crush sleeve winds up crushed an additional .010 when the marks on the nut & pinion line up...

[Mopar5]

I still have questions on this so I am going to go look at it again and I'll be back.

[1 Wild R/T]

Looks like 3:55's with a non-sure grip.... I would at least pull the cross pin & spiders to check for wear....

[Mopar5]

Yes I was surprised to see this is an open diff.The front pinion bearing has some slight discoloring on the rollers and you can just catch a fingernail on the grooves.So so much for just a pinion seal It will need to come apart. The question now is do I keep the same gears and open carrier using the original pinion shim and just replace all carrier and pinion bearings and races. My thought is by leaving everything but bearings pinion depth should remain the same if using the same pinion shim on original pinionThen the only adjustment will be backlash for the setup as well as pinion preload?

[Mopar5]

Here's a photo of the small pinion bearing and there is a very light shim probably less than .010" between the bearing and yoke

[1 Wild R/T]

Measure back lash before you loosen anything, write it down cause you should set it the same going back together...

Mark everything so the caps go back in their original locations, adjusters go back.. Etc....   If you mark the adjusters to the caps count the turns & put it back exactly the same with new bearings it should be good or at least very close...

Using the same case & gears the pinion depth won't change, bearings are made to the exact spec & there shouldn't be any change...

I would put in the crush sleeve eliminator...

If you decide to change out the open center for a sure grip or other carrier then the backlash adjustment is gonna change from the count the turns method.. Which isn't a big deal you need to check it either way anyway...

Mopar suggests setting carrier bearing preload to zero, then by loosening the cap side adjuster & tightening the gear side adjuster equally you bring the gears together till you achieve zero backlash, the you tighten the cap side adjuster to obtain your backlash which I seem to recall should be .008-.012  But what you really need to shoot for is exactly what it was before...

If the gears were quiet before even if the pattern looks bad put it right back cause it was quiet & ran fine.... If you change the setup on used gears even if you set-up a beautiful pattern they will make noise...

If the old gears were noisy, throw them away..

[Mopar5]

I personally have never seen shim between the yoke and front pinion bearing

[1 Wild R/T]

Well now you have, and it's not really a shim, it's supposed to be an oil slinger...   Ok correction it's just called a washer.... On a Dana they call it an oil slinger..

[Mopar5]

Thanks for the info just wondering how that little shim is supposed to sling oil seeing that everything else along with it is rotating as well

[Mopar5]

Thanks for the view I see what your saying

[Mopar5]

Looks like on Dana they also have an additional seal after the slinger and before the pinion seal

[1 Wild R/T]

They also show a drain plug on the Dana but that went away in 68... I suspect the gasket went away too cause I've owned a few Danas & never saw that gasket..