Pinion Bearing Squeal

History: Ford 8.8 rear axle; set up with 4.88s/Detriot and a Yukon master install kit several years ago. Probably 5-8k on it. Pinion seal leak repaired August 08. Noticed "angry sparrows" consistent with ujoints around October. Changed all ujoints and centering yoke in d/shaft, still noisy. Traced it to the outer pinion bearing, changed last week. Old bearing slid right off the pinion and had wear marks inside. New bearing tapped on with piece of tubing and a hammer. Reassembled, drove for a few days.

The squeal is now back and is coming from the same place. Under 20 MPH - nothing. 20+ it squeals. It is worse under load, but still makes noise while coasting. I have verified the diff is full of fluid to the fill plug (Solid cover), so I know it is getting lubricated. When we reassembled the pinion, the nut was tightened until there was no in/out play, and it spun with just a bit of drag. Can't remember torque offhand.

Any ideas on why the bearing would be making noise after only ~20 road miles? Preload or torque incorrect? When the seal and bearing were replaced, both times only the pinion was touched, the diff cover wasn't even opened.

did you change the race also or just the bearing?? if the pinion is pointed up it may not be getting enough oil to the bearing that keeps failing

Just the bearing. The pinion is pointed up, and the oil level is just below the bearing when sitting still. It should be getting slung back when rotating.

Did you happen to check the condition of the inner pinion bearing?

No, I didn't, but with the Jeep up on the lift and in drive, it was pretty easy to pinpoint the noise to the outer bearing.

I have the same problem on my 8.8 with ARB and a Solid(Rockcrusher) cover. I haven't changed the bearing yet, but I have changed to a thinner synthetic lube and it now only squeeks on long, steep hill climbs.

I also had problems with lube blowing out of the breather, I had thought my ARB was leaking but it's working fine. I have been experimenting by filling the axle with less lube. The Rockcrusher fill hole is higher than stock but I don't think adding any extra lube is doing any good as it just gets blown out.

Now that you mention it, this all started not long after I added the Solid cover. What weight gear oil are you using? IIRC I put in good ol' 80w90 dino last time I changed fluid.

Mine also leaks/blows out my breather. It would probably blow out the vent tube but the threads don't seal 100% so it leaks out. :doh:

I don't think its getting enough oil. Sure there is some slinging around, but when going down the road I bet the oil level gets alot lower as the thick oil will hang on the ring gear and bring the level down. Just my .02 as I fill my 8.8 with the factory fill plug since its on the front of the housing it basicly corrects the fluid level for your pinion angle.

one thing you might want to check is both of your cv's (if you have one on your rear driveline), i had a nasty squealing just like you discribed and after trying to chase it down forever it ended up being the cv ball in my front driveline all dried up, took apart the cv and re-greased it and ended the squealing noise. wouldnt hurt to check.

dan302492 said:

one thing you might want to check is both of your cv's (if you have one on your rear driveline), i had a nasty squealing just like you discribed and after trying to chase it down forever it ended up being the cv ball in my front driveline all dried up, took apart the cv and re-greased it and ended the squealing noise. wouldnt hurt to check.

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Changed all ujoints and centering yoke in d/shaft, greased the heck out of it. When up on the lift, it is pretty easy to pinpoint the source. I'm thinking a lubrication issue, I'm going to check preload and see about adding more fluid at work Monday.

IllianaXJ said:

What weight gear oil are you using?

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I can't remember exactly, but I think it was a synthetic 75w-90. I still have the old bottles in the garage. I will have a look in the morning and let you know.