Differential or pinion and ring gear

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Lenny D.
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Differential or pinion and ring gear

Post by Lenny D. » Wed Jul 17, 2019 1:37 pm

Hi all,

Long time no post.. :oops:

A slow input shaft seal leak has manifested itself into a whining 25-30 mph noise under light acceleration or maintaining speed.

Seal has been replaced and low hypoid fluid changed with an additive MGC 325 from BG but the whining continues, higher in pitch than bearing noise and only (for now) at this speed, so - likely ring and pinion. 303k on the diff.

Anyone here on this board with a good, low mileage, quiet diff? Or ring and pinion set with little wear? Mike?

Thanks
HTH

'80 528i

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Mike W.
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Re: Differential or pinion and ring gear

Post by Mike W. » Thu Jul 18, 2019 12:52 am

No spare diff's here. Never been into one but I've heard it's usually the bearings, not the R and P that's the problem, so I'd consider new bearings instead of the typical 300K replacement. Again, I've heard, not done, but I've heard it's possible to mark the nut and shaft, then tighten just to that mark rather than trying to measure the rotational friction with a new crush sleeve. However new crush sleeves still appear to be available contrary to what I'd heard a while ago.

Sorry about lots of I've heards, but the last diff I was into was on a aircooled VW transaxle. :shock: And that was a long time ago.
Mike W.



1980 528i, 3.5 euro, 5 speed conversion
1981 528i, 3.6, Recaros and more. Project
1998 328is, quick and efficient, but not satisfying
2000 528iit, Vacation mobile/wife's grocery getter

waltb
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Re: Differential or pinion and ring gear

Post by waltb » Fri Jul 19, 2019 5:16 pm

Years ago I had a differential go bad but it took years before it finally went. It was whining lightly for quite a while (many years) and suddenly the whine got very loud like a siren. In my case It was the pinion bearings going bad. Of course the final failure started occurring far from home. Eventually one of the bearings pretty much locked up, trashed the pinion shaft, and got the nose of the differential case so hot it turned blue. In my case because of the carnage I just got a used differential to replace the original. One side note, I had put Red Line oil in it about a year before. Even with all the heat and metal flakes, the oil did not burn or sludge up. It looked pretty much the same color as it went in. I think the synthetic gear oil probably helped me to finish my trip and get the car back home.

So the moral of the story is they can whine a long time and work fine. My experience is once they start going bad you will know.

waltb

80 528i

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Mike W.
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Re: Differential or pinion and ring gear

Post by Mike W. » Sat Jul 20, 2019 12:21 am

I had another thought. I think diff's have magnetic drain plugs. I know trannys do, but I'm not sure about diffs. But pull the drain plug. If it's magnetic, it will have metal particles attached to it, even if it's perfect. But if it's a bearing, there won't be a whole lot. If it's the R and P I suspect there will be shavings an inch long.
Mike W.



1980 528i, 3.5 euro, 5 speed conversion
1981 528i, 3.6, Recaros and more. Project
1998 328is, quick and efficient, but not satisfying
2000 528iit, Vacation mobile/wife's grocery getter

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Lenny D.
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Re: Differential or pinion and ring gear

Post by Lenny D. » Sat Jul 20, 2019 1:02 am

Thanks, guys, I'm going let my indie BMW tech replace the bearings..stories seem to point there first so I should try..he also wants to do the output bearings as well at 300k..and do pinion preload with a new crush gasket ..he used to work at the dealer, owns his own place.
At least I'll find out what's going on in there.

Walt, when and what was your mileage when that happened?

Mike, thanks for the PM.
HTH

'80 528i

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Lock
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Re: Differential or pinion and ring gear

Post by Lock » Sat Jul 20, 2019 4:12 pm

Agree with this, if you're opening it up, replace all the bearings, seals and maybe crush sleeve. My e12 diff is almost silent but I recently put a LSD center into my daily driver Nissan and the front pinion bearing whines at cruise around 65. It's annoying but it will last for a while and I'll take it out and get everything replaced. I take diffs to a trusted local shop because for $150 they'll swap gears and bearings and set everything up right. I don't have the tools or inclination to do that work as well as the shop can.

At some point I plan to upgrade to an e28 subframe, at which point I'll be putting my e12 diff and subframe up for sale here.
1979 528i 5-speed conversion G260/6
1980 Honda CX-500

waltb
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Re: Differential or pinion and ring gear

Post by waltb » Sat Jul 20, 2019 8:47 pm

My differential went bad when the car was about 25 years old. However I only had about 130000mi on it. I have been storing the car in the winter for years. I always wondered if the winter storage had some detrimental effect on the bearings. The replacement differential actually had about 180000 miles on it (I knew the history of the car that I got it from) but its been great for the last 14 years and I am still storing the car in the winter so maybe the original differential pinion bearing just decided to randomly go bad.

waltb
'80 528i

waltb
Posts: 29
Joined: Tue Jan 13, 2009 9:20 pm
Location: South Western, PA

Re: Differential or pinion and ring gear

Post by waltb » Sat Jul 20, 2019 8:48 pm

My differential went bad when the car was about 25 years old. However I only had about 130000mi on it. I have been storing the car in the winter for years. I always wondered if the winter storage had some detrimental effect on the bearings. The replacement differential actually had about 180000 miles on it (I knew the history of the car that I got it from) but its been great for the last 14 years and I am still storing the car in the winter so maybe the original differential pinion bearing just decided to randomly go bad.

waltb
'80 528i

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Lock
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Re: Differential or pinion and ring gear

Post by Lock » Sun Jul 21, 2019 1:29 pm

Maybe some moisture condensed inside and caused some surface rust on the bearings, which led to accelerated wear? Most diffs have a vent which should be one-way (out only) but maybe that's failed or ours is just a hole. Daily/weekly driven cars will boil off moisture inside engines, gearboxes and diffs. If it's not sealed up in winter maybe on a couple of cold dry days you could take it out and warm it up?
1979 528i 5-speed conversion G260/6
1980 Honda CX-500

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