8 3/4 pinion seal

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andysauto1

andysauto1

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what is the procedure for changing out front pinion seal on 8 3/4 rear end, also how do you identify which case you have?
 
Last three digits of the large number on the driver side nose of the differential. ex... 741 742 489 You have to pull the yolk to replace the seal
 
P.S. The 741 and 489 take the same seal. The 742 is different.
 
andysauto1, Just so you know, if you've never done this before, the pinion nut will be very tight when removing. A strong impact gun is recommended, the pinion yoke itself most likely will NOT slip right off, it is also a very tight fit & probably need a puller to remove it & last but not least, mark the pinion gear nose (Where the nut threads onto) with the nut itself before removing it so you can tighten the nut back up to where it was before removing it, to lessen the chance of disturbing the crush sleeve, otherwise the rear may be noisy when done. Not a simple job, in most cases IMHO.
 
Thanks, great information, I'm just a body man not a mechanic
 
niceolddart said:
andysauto1, Just so you know, if you've never done this before, the pinion nut will be very tight when removing. A strong impact gun is recommended, the pinion yoke itself most likely will NOT slip right off, it is also a very tight fit & probably need a puller to remove it & last but not least, mark the pinion gear nose (Where the nut threads onto) with the nut itself before removing it so you can tighten the nut back up to where it was before removing it, to lessen the chance of disturbing the crush sleeve, otherwise the rear may be noisy when done. Not a simple job, in most cases IMHO.
Click to expand...
IIRC, the 489 case is the only unit that uses a crush sleeve. The 741 and 742 use shims to adjust depth and pre-load.

As an aside..............They make a kit with various shims to do away with the crush sleeve in 489 cases.......Lots of trial and error to get the right combo.
 
..............
www.doctordiff.com

Pinion Comparison - Quality Body Shop Drivetrain

All Chrysler 8 3/4″ rearends are good all-around designs, with none having a significant design advantage over the others. The 741 case 8 3/4″ has unjustly earned the reputation as a “weak” rearend, which these pictures will dispell. 8 3/4″ pinion shaft designs: Notice, all pinion shafts neck...
www.doctordiff.com

Drivetrain :: Mopar 8 3/4"

www.doctordiff.com www.doctordiff.com
 
I've done this several times using the method that @niceolddart recommended above and have never had a problem afterwards. Done it to Dana 60's and 8 3/4's. I use a chisel to mark the nut and end of pinion. Be prepared for some leakage and you will probably need to clean the pinion where the old seal rode. I set the parking brake as tight as it will go and chock opposite corner tires to keep the vehicle from moving if it's sitting on the ground or a 4 post lift. Good luck with it!

:thumbsup:
 
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