Differential Noise? - Page 4 - PeachParts Mercedes-Benz Forum

vstech · #46 12-15-2010, 11:25 AM

likely for you, the spiders are not the issue as much as actual pinion bearings or ring/pinon teeth wear.

GGR · #47 12-15-2010, 11:51 AM

This is a rear axle that I have "rebuilt". It is originally a 3.27 out of a 4.5 with open diff. I Have replaced the carrier with an LSD out of a 4.08 one.

Pinion bearings are new. Carrier bearing with races were not replaced as they looked and sounded good. Backlash and pre-load were adjusted as per manual. I put grease on the ring and pinion and studied the traces left on them after assembly and they also looked as per the manual. But this is my first "rebuild" furthermore using parts from different axles so obviously there is a lot of room for something to have gone wrong.

At first I had a lot of whine at any speed both at acceleration and desceleration but it has diminished a lot and after 5000 miles I'm just left with a slight whine between 40 and 60 mph, under acceleration only. Whine is decreasing with mileage.

I made two oil changes. The first one was 500 miles after rebuild and oil was grey, I guess from all the grease I had left in there. Second oil change was 500 miles ago and oil was clean.

I'm trying to diagnose the cause of this this rumble (different from the whine that seems to cure itself over time) as I don't want to disassemble all again, try a fix and get the noise again. It's obviously inside the differential as replacing it cured the problem for BHutch. I'm trying to determine if it's a backlash problem, a pre-load problem, a worn bearing problem or an issue inside the spider.

Thanks in advance for the help!

vstech · #48 12-15-2010, 11:54 AM

it could also be from the axleshafts...

GGR · #49 12-15-2010, 11:57 AM

Hum.... I had the axle shafts measured by a machine shop and they did not look too far from specs. How could they cause that rumbling noise when easing on the gas pedal?

thayer · #50 12-15-2010, 12:12 PM

I know the sound the OP is talking about...my SD does it too. Only makes it under slight load at highway speed. I described it as "crinkling" like foil. IF a Diff swap fixed it then thats yet another excuse to get a taller gear for the old girl.

vstech · #51 12-15-2010, 12:13 PM

the same way a diff can make noise, it's a shaft rotating in a bearing set. if you have a bad ball, or groove, it'll make noise.
"not too far from specs" does not sound like a good axle to me.
I sell rebooted original axles by the way...

vstech · #52 12-15-2010, 12:14 PM

Quote:

Originally Posted by thayer

I know the sound the OP is talking about...my SD does it too. Only makes it under slight load at highway speed. I described it as "crinkling" like foil. IF a Diff swap fixed it then thats yet another excuse to get a taller gear for the old girl.

heh, I've got a 2.47 sitting in a box in my shop...

GGR · #53 12-16-2010, 08:32 AM

Quote:

Originally Posted by vstech

the same way a diff can make noise, it's a shaft rotating in a bearing set. if you have a bad ball, or groove, it'll make noise.

On the W108 rear ends the wheel shafts are in between the wheel bearing at one end and the spider on the left and the universal joint on the right. Could any of these cause the ligh rumbling when I ease on the gas pedal? The noise only appears above 70mph.

thayer · #54 12-16-2010, 11:21 AM

Quote:

Originally Posted by vstech

heh, I've got a 2.47 sitting in a box in my shop...

And I've got a working speedo out of a gasser 420sel.

BHutch · #55 12-16-2010, 01:48 PM

Well, the "new" differential that I had swapped in last summer has been holding up just fine. No hint of the noise returning and only the slightest hint of a wine at very low speeds and no throttle. I'm going to hold on to the original diff, though, if I can ever figure out if it is fixable, since the '85 with ABS seems to be like hens teeth. I still haven't come across a "Driveshaft Specialist" of differentials. If anyone has any success in this area I would be interested in knowing about it.