i'm making plans to replace the leaking pinion seal in my '86 8.5" rear axle that came from 442. i haven't disassembled the axle yet, i wanted to purchase the required parts so i would be ready. on the napa web site, it lists an inner and outer pinion seal. i thought they may have gotten this wrong so i checked on the rock auto site, they only list one pinion seal for a '86 442 rear axle, but when i look up for a grand national rear axle, they too list an inner and outer pinion seal just like the napa site.this is a head scratcher. so i consult my '85 olds service manual, they only show one pinion seal. so I'm turning to my brain trust on here for help. how many pinion seals are in an 8.5" rear axle?
how many pinion seals in an 8.5" rear axle??
- Thread starter oldsmobile joe
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Im not sure what an inner or outer pinion seal would be. All I have ever known them to have is the basic shaft seal right behind the yoke.
I read through all the data by clicking on the various the 'info' buttons. I think someone at RockAuto made a mistake entering the data. The 7.5 uses a 1.5" yoke seal, and the 8.5 uses a 1.93" yoke seal. The 'Inner' one reports a 1.5" diameter. Does that help? If you look up R&P kits on Summit, they only show one seal all the pictures. The only exception is the Super kits that also show two axle end seals...
There is only one seal. Have you ever done this job? Do you know about pre-load? In case you don't and for the benefit of others- here ya go. The bearings are pre-loaded to a certain spec to keep them in position under the strain of drivetrain torque. You must not change the pre-load. The best way is to remove the drive shaft and wheels and then take a torque wrench and measure the pinion nut for pre-load and return it to that same exact spec. Or, second best, which we all do, is this- Begin by taking a cold chisel and marking the pinion nut and the end of the pinion gear shaft. Make it so you can return the nut back to that exact position. Then count the visible threads and WRITE IT DOWN. Now you can remove the pinion nut, washer, companion flange, and oil seal. Change the seal. Use a good sealer around the rim. When you install the companion flange smear oil on the lips of the seal and the flange surface. Also use a good sealer on the splines and under the washer or else oil will migrate down the splines. When you screw the nut back down feel as the slack is taken out and come up on the pre-load slowly. Return the nut to the EXACT same position with the same number of visible threads and the mark you made. If you under or over tighten the nut you will change the pre-load and cause expensive problems with the gears. Done. If you are really clever you will use a torque wrench and measure the pre-load first, do the above, and check it again when you are done. While you are down there, check the rear end oil level.
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thanks for the help. i have found too much conflicting info on the web. I'm just going to bite the bullet and tear it down. i'll post and take photos if it is out of the ordinary.
"I have found too much conflicting info on the web" -exactly. Find a factory manual and read the section on rear end gears, as many times as it takes. I guarantee you will get the headache of a lifetime. It took me many years and broken parts to finally understand the concept. Just don't do what my professional mechanic friend did. He had to change the pinion seal on his Chevy truck 8.5" rear and his boss told him to "just slap em' in there". He used an impact wrench to bang the pinion nut tight. So tight that on the way home the rear started howling. Within a week, three teeth broke off the ring gear.
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