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So I was changing out a leaky pinion seal in my 05 FX4 5.4L and after I pulled out the seal I pulled the cone bearing right behind it to see how it looked. I noticed a little pitting. Is this a part that can be swapped right out or is there more to it than that? If it is just an easy swap can anyone give me the part number? I have the 9.75 LS differential. Here is a picture of the bearing. What do you guys think?
That's pretty severe pitting. Not a simple replacement, but should be done. Know the procedure on other rear ends, not the 9.75
So what makes the replacement so hard? This is the outer bearing and I literally just pulled out the seal, the slinger, and then this bearing. It's not the bearing that is at the base of the pinion. Does it mess with the other components if it's not all replaced at the same time?
You have to reset the pinion gear depth, I believe. There's a whole procedure, involving removing the diff and setting backlash and verifying proper gear pattern. By the time you're done, you've essentially rebuilt the diff.
If you want to take a chance, and people will hate you for it, you could buy a new pinion shaft bearing but just use the bearings and inner race. Not the outer race. It might self-destruct quickly or it might take you back, almost, to the specs it had when first installed. I've done it with a front wheel bearing and it worked fine. But you have to trust the QA department of the bearing company you're buying from . Get the same brand as what's in your hand, and if the outer race is not too worn, it will not notice the new parts. Thank Deming if it works.
That's a lot of pitting though, so even what I suggested might be better than putting those worn out rollers back in. Hard to say for sure.
Last edited by BareBonesXL; 01-13-2018 at 11:29 PM.
You have to reset the pinion gear depth, I believe. There's a whole procedure, involving removing the diff and setting backlash and verifying proper gear pattern. By the time you're done, you've essentially rebuilt the diff.
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The issue is that if you set it too loose (not deep enough) you break teeth, and if you set it too deep, you burn out the gearset through friction. It's a fine line, measures in thousandths.
It's certainly important. Bearing wear takes you away from that perfection though.
If you've removed a diff that fell out in to your hands, then firmly tapped in the shims for the diff with new bearings, you might have wondered about just how wide that range is. Why didn't it fail when the bearings were loose?
The new bearings on an old race might be of more concern. Rapid bearing wear. I don't know, I was just throwing out a possibility. It's what I would probably do, then I'd get the parts together for a full job, while I waited for the bearing to fail. If you need to drive it, it seems better than putting the old pitted bearing back in. On the other hand, the old pitted bearing was working.
Thanks for the advice guys. I need to get it back together today so I'm going to put the old one back in to get it driving. I'll go ahead and purchase a kit so I can change it all out later.
The forward pinion bearing is always the first to fail. It's the furthest from the lube and the closest to the elements. How does the corresponding race (cup) look? Usually the bearing deteriorates faster than the race. I'd drop in a new bearing and set the pinion nut back to where it was. It won't affect the pinion depth.
Frankly, once it's done I'd just keep an ear peeled for a change in sound as time goes by. It may go 50K with no further issues. If the bearing does start to fail again, you're going to hear it coming.
01-13-2018, 08:24 PM
Pinion Bearing question
