Differential, or...?

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T.Hanson
Posts: 1696
Joined: Wed Jul 26, 2006 7:39 am

Differential, or...?

Post by T.Hanson »

I'm hoping for replies to diminish the odds of the worst case scenario. On the freeway, not so much as a squeak for a warning to ignore, a loud grinding noise came from the rear end. Whatever it is kept making the noise for the ten mile tour through neighborhoods, to get to the barn. (It was ten degrees, I picked making the field over waiting for the flatbed.)

A look at the differential revealed minor leaking around the area where the drive shaft connects. Also, a shiny circle on the shaft, perhaps polished by an exhaust clamp. The oil is topped up, not dry.

For detectives, the lowered suspension had previously allowed contact, noticeable, on a steep parking lot hill. Like one of those raised speed bumps. Not at speed, violent, but it made noise underneath.

Is it a toss up the differential innards have gone crunchy, universal joint, half shaft bearings, axles ? I.e., only jacking and listening (in the spring) will tell ?

Or from being able to limp home, ten miles, same noise,...maybe it's not the differential, to require replace, rebuild ?

I hope, I hope.
pappentl
Posts: 161
Joined: Tue Jan 06, 2009 7:11 pm

Differential, or...?

Post by pappentl »

Did the differential mount let go? Is the diff sitting lower than usual?

...tom



-----Original Message-----
From: T Hanson <trhanson@earthlink.net>
To: tech_forum <tech_forum@firstfives.org>
Sent: Mon, Jan 13, 2014 10:33 pm
Subject: Differential, or...?

#AOLMsgPart_1_00d02699-d9ff-4228-994e-f00123593a34 td{color: black;} I'm hoping for replies to diminish the odds of the worst case scenario. On the freeway, not so much as a squeak for a warning to ignore, a loud grinding noise came from the rear end. Whatever it is kept making the noise for the ten mile tour through neighborhoods, to get to the barn. (It was ten degrees, I picked making the field over waiting for the flatbed.)

A look at the differential revealed minor leaking around the area where the drive shaft connects. Also, a shiny circle on the shaft, perhaps polished by an exhaust clamp. The oil is topped up, not dry.

For detectives, the lowered suspension had previously allowed contact, noticeable, on a steep parking lot hill. Like one of those raised speed bumps. Not at speed, violent, but it made noise underneath.

Is it a toss up the differential innards have gone crunchy, universal joint, half shaft bearings, axles ? I.e., only jacking and listening (in the spring) will tell ?

Or from being able to limp home, ten miles, same noise,...maybe it's not the differential, to require replace, rebuild ?

I hope, I hope.









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...tom
and now an '80 528i, the 7th and last in the series
1981 528i, no. 6 in a series... only 270 k miles
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Blaise
Posts: 917
Joined: Wed Apr 21, 2010 4:01 pm

Post by Blaise »

Hard to say based on what you know so far.

Could be a wheel bearing (crazy high torque to replace). Could be a half shaft issue, but you would probably have a compromised boot before it failed.

Or it could be inside the differential. My jeep's differential started getting louder and louder, so I am rebuilding it now. I could not believe the damage that I found (previous owner neglect).

Spider gear:
Image

Carrier bearing:
Image

Hope I did not scare you with those carnage photos:)

I am setting up the new gears now.
1977 BMW 530i
1973 R75/5 BMW (motorcycle)
T.Hanson
Posts: 1696
Joined: Wed Jul 26, 2006 7:39 am

Post by T.Hanson »

Thank you, I think the mount is good, or not the source of the noise. I have a spare differential, which is what kept me from choosing to wait for a flatbed, one block at a time.

I guess having to service, replace a few large items every thirty five years isn't all that unexpected. Just strange there weren't any sneak preview leaks or sounds.
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Peter Florance
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Post by Peter Florance »

T.Hanson wrote:Thank you, I think the mount is good, or not the source of the noise. I have a spare differential, which is what kept me from choosing to wait for a flatbed, one block at a time.

I guess having to service, replace a few large items every thirty five years isn't all that unexpected. Just strange there weren't any sneak preview leaks or sounds.
Maybe change the fluid and check for metal bits. I find these diffs to be pretty strong.
Peter Florance
First Fives.Org - The E12 Registry
1981 E-Street Prepared Euro BMW 528i w/3.5L & Megasquirt Fuel Injection
http://www.firstfives.org
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Pierre
Posts: 263
Joined: Tue Jan 06, 2009 11:02 pm
Location: Camarillo, CA

Post by Pierre »

You can't make any educated guess withiout at least raising the rear wheels off the ground to, at least eliminate the possibility of a wheel bearing first because it's the most likely culprit.
It may even be the brakes.
10 degrees? Yikes. We hit 88 today. It's pretty disgusting for January. But 10??? I would park it and wait till spring too.
Pierre in Camarillo
76 530i (3.3), 69 2002 (M20), 74 tii, 75 2002, 79 323i, 84 733i, 84 323i (S52), 91 318is, 96 318ti (S52), 97 Z3, 01 540i, 02 330i, 02 1150RTP.
OO==00==OO
T.Hanson
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Joined: Wed Jul 26, 2006 7:39 am

Post by T.Hanson »

Great ! I'll take wheel bearing.

Even if it isn't, I can think it is, until I find out different in two months.

Anyone for loose muffler clamp ?
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