So after having my diff opened up for the third or fourth time in its 88k mile life and having the ring and pinion replaced (very bad pinion - major chunks) it's gone again after only about 900 miles. I had the ring and pinion replaced with Rick's 4.57's, gave them a nice gentle break-in for OVER 500 miles and eventually got to where I am now.

The shop drained the fluid and found nothing more than small metallic bits, fine shavings really - to be expected from new gear break-in. No chunks. And they admit that it sounds like a bearing has gone bad - it's more of a whine than anything - but that it's definitely coming from the diff and not a wheel/hub.

So, after a fresh rebuild on the diff with all new bearings but a catastrophic failure previously (due to mis-shimmed pinion gear - the caps are intact), could the case itself be a factor in a bearing failure? Not enough fluid? Improperly installed bearing?

Assuming the ring and pinion are intact, what could cause this odd failure so quickly? They're going to pull the diff and disassemble it later this week.

Thanks for any input!

 

isnt it normal for 4.57 gears to whine?

 

I thought with 4.56 or 4.57 the gears were supposed to whine.

 

and isnt it normal for them to have the fine metallic shavings just like you found from the break in?

I think you might be overreacting.

 

i think your going to have to expound upon what you mean by "gone."

 

Whine is normal with 4.57s, yes. It was especially noticeable around 60mph (indicated). This is NOT normal. I drove the car for 800 miles or so before this LOUD whine - at all speeds, but especially noticeable below 30mph or so, showed up. It's almost a grinding. If you've had a bearing go out on a rear hub you'll know what I mean.

And yes, the shavings - I wasn't overreacting, I think you just misread what I'd written. I was saying that it was normal and that the lack of large pieces was hopefully a good indicator (shavings "to be expected from new gear break-in").

By "gone" I mean failed.

I think the question is if a bearing has failed in such a short period of time with no harsh external input (being driven gently, no shock or accident, etc.), is it possible that the problem is not the bearing itself and rather the case, the pumpkin or some other damaged part that has no indication of damage. Or is it at all likely that a new bearing would be bad?

Basically "Has anyone seen anything like this before - what is a likely explanation?"

 

was the backlash check during install?

 

I've been told that the backlash was triple-checked by three different techs with the proper tools because they wanted to make sure it was perfect.

 

If everything was replaced and the backlash properly checked during install then I would like the most likely culprit would be a damaged pumkin or stretched caps.

 

Thanks. That's what I was looking to figure out.

The caps are visibly undamaged. Short of a magnaflux I don't think there's any way to tell if they're compromised.

The shop is telling me that they'd recommend just replacing the whole thing with a complete, unopened working stock diff unless I REALLY want the 4.57's

I'm just ready to sell the damned thing. It's cost me a LOT in broken parts these past couple of years and I'm not even tracking it. I think I should probably just put a stock pumpkin in, sell the gears and call it a day.