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Floobydust
Veteran
Date registered: Mar 2014
Location: Massachusetts, USA
Vehicle(s): 1995 E320 Cabrio, 2003 G500, 2000 SL500, 1980 TR8
Posts: 284
| Front Differential Bearing Replacement
It is clear that there is an issue with the bearings in the front differential on my G and I have been unable to source a good used front axle, so I have ordered the bearings and other parts required with their replacement. My local Indie is familiar with both 4x4 and German differentials, however, he does not want to do the R&R on the swivel housings and axles because that would keep a spot in shop occupied for too long. His concern is that if additional parts are needed, he doesn't want an unmovable truck in one of his lift/work spaces for what could be some time. That being said, it has been his experience that merely replacing the bearings will require not usually a re-setup of the differential (although is will still check the contact pattern) because modern bearing production tolerances are so good that the error from new bearings is typically less than the shim step sizes. A new set-up is usually only needed when the ring & pinion, the differential carrier, or the axle housing itself have been replaced or there has been some other damage.
So I am going to remove these items and then remove the axle housing and take it to him for the work on the differential. When it is done, I will but everything back and hope that the final gremlin has been banished.
As a side note, I have been reviewing the WIS procedure on the front differential, and in fact, it appears that the special tools are only necessary if one wants to set up the differential from scratch correctly on the first try. All the critical specifications (pre-load, backlash, pinion rotational torque) are given and so could be accomplished, albeit with the trial and error, the old fashioned way using a dial gauge and machinist's dye. In fact, the WIS instructions say, that the special tool method should produce the proper setup, but check the tooth contact anyway. The WIS then goes on to describe the good old fashioned way of changing the relative positions of the R&P while maintaining the correct backlash. What do people think about this? Am I overlooking something?
Thanks,
- FD
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chris505
Date registered: May 2007
Location: San Francisco
Vehicle(s): '79 280E/'80 280GE/'00 G500
| RE: Front Differential Bearing Replacement
I wonder if I am the only person in this country with all the special G axle setup tools (thanks to my Father who was Europa Intl. first G mechanic back in the early eighties)?
He was adamant that you should never trust bearings to be exactly the same when it comes to G axles and transfer cases, and insisted on verifying everything with the special tools.
Now that I have been rebuilding G axles for over 15 years Id have to agree with him, but don't just take my word for it, you could ask Europa Intl's last G mechanic Marc Bayer @ OCD customs in Santa Fe what he thinks: http://www.ocdcustomcycles.com/about.html
So, are we to assume that your noise/vibes were not cured by the transmission output bearing replacement?
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Floobydust
Veteran
Date registered: Mar 2014
Location: Massachusetts, USA
Vehicle(s): 1995 E320 Cabrio, 2003 G500, 2000 SL500, 1980 TR8
Posts: 284
| RE: Front Differential Bearing Replacement
Chris - Thank you! I wish I still lived in the Bay Area so I could ply you with whatever it takes to rebuilt my front axle!
And no, the output bearing is not at fault. I spoke with Marc and Sunvalley (who is great to talk to) and he said that what I was observing at the tail shaft of the transmission was normal. I have since been able to run the G on the lift several times and the front diff is definitely making some bad noises.
I agree about verifying the operational dimensions (pre-load, backlash, and contact pattern) of the differential after a bearing replacement, but it still seems to me like it is possible to verify these with traditional measurement methods. The special tools provide the setup, but the check measurements don't seem to require them. If the values are too far off after the bearing replacement, I could be in trouble, but if not, it should be possible to titrate per the WIS. In any case, I don't seem to have a lot of choice as all of the G expertise appears to be on the west coast. And so it seems I am going to have to "just do it", to pinch a quote from Nike.
Thanks again,
- FD
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chris505
Date registered: May 2007
Location: San Francisco
Vehicle(s): '79 280E/'80 280GE/'00 G500
| RE: Front Differential Bearing Replacement
Just doing it is usually the only way forward.
I'm betting your front difflock was used inappropriately and chunks of the difflock teeth were sucked into the left side carrier bearing and beyond, once you pop the front diff out of the housing you'll be able to inspect the ring/pinion faces and also spin pinion bearings to see if they rumble. |
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Floobydust
Veteran
Date registered: Mar 2014
Location: Massachusetts, USA
Vehicle(s): 1995 E320 Cabrio, 2003 G500, 2000 SL500, 1980 TR8
Posts: 284
| RE: Front Differential Bearing Replacement
chris505 - 4/28/2015 2:01 PM I'm betting your front diff lock was used inappropriately and chunks of the difflock teeth were sucked into the left side carrier bearing and beyond, once you pop the front diff out of the housing you'll be able to inspect the ring/pinion faces and also spin pinion bearings to see if they rumble.
I would tend to agree - I have seen several posts about this kind of damage.
I took the diff cover off and found no metal fragments in the bottom and the oil was clean. I also did not see any visible damage to the ring gear. I took also each of the bearing caps off to get a better look at the bearings (which was not still not that great) and could not see anything there either. But, a bearing rumble is consistent with the vibration/noise I am experiencing. I have also noticed that the front diff lock is very hard to engage/disengage which may point to damage on the cogs. Lastly, when I re-did the right CV joint I found a small piece of metal consistent with metal from the corner of a cog lodged into the machining center at the end of the axle. The two axle ends face each other when installed and it is this space where a chip of a cog would likely end up, at least to start with. All it would take is one small piece from the corner of a cog to damage the bearing surface while not causing much other visible damage. |
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fernweh
Date registered: Apr 2006
Location: Calabasas, CA - Centenario, BCS - Luebeck, Germany
Vehicle(s): Few Mercedes-Benz, a Toyota Amphibious and a Vespa
| RE: Front Differential Bearing Replacement
Did you look for any discoloration on the outer carrier bearing race?
I found that to be a tell-tale, when I replace my damaged rear axle with another (used) one. I ended up overhauling the replacement axle before installing.
BTW I do have a complete front axle differential (carrier, ring & pinon gear) for sale....if needed.
First picture: carrier damage after driving (limping) with the destroyed carrier bearing, the truck back into civilization.
Second picture: the discoloration of the left carrier bearing outer race....in the "good" replacement axle
 (IMG_2500.JPG)
 (Left bearing discoloration.JPG)
Attachments
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 IMG_2500.JPG (209KB - 0 downloads)
Left bearing discoloration.JPG (87KB - 0 downloads)
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Floobydust
Veteran
Date registered: Mar 2014
Location: Massachusetts, USA
Vehicle(s): 1995 E320 Cabrio, 2003 G500, 2000 SL500, 1980 TR8
Posts: 284
| RE: Front Differential Bearing Replacement
fernweh - 4/29/2015 2:30 PM
Did you look for any discoloration on the outer carrier bearing race? . . . BTW I do have a complete front axle differential (carrier, ring & pinon gear) for sale....if needed. . . .
I did look for discoloration on the bearings and didn't see any at the time. Things may have changed with several thousand more miles on it since I last looked, so I will check again when I crack things open. It's good to know that you have the parts available, although I really hope I don't need them.
A question for future reference - how "perfect" do the diff lock cogs have to be? It seems that a small chip on the end of the teeth might be acceptable as long as the bearing race area is perfect, but I'm not sure.
Thanks,
- FD
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Floobydust
Veteran
Date registered: Mar 2014
Location: Massachusetts, USA
Vehicle(s): 1995 E320 Cabrio, 2003 G500, 2000 SL500, 1980 TR8
Posts: 284
| RE: Front Differential Bearing Replacement (Differ spreeader)
Does anyone have any suggestions as to the best tool for spreading the differential housing? The MB tool is NLA and most commercial tools actually spread the diff at the side whereas the MB tool compresses the top to cause sides to bow outward. The best solution I have come up with is to roll my own, but a well engineered tool is almost always better. Thanks! |
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chris505
Date registered: May 2007
Location: San Francisco
Vehicle(s): '79 280E/'80 280GE/'00 G500
| RE: Front Differential Bearing Replacement (Differ spreeader)
I have never needed that tool. |
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Johnny Christensen
Veteran
Date registered: Sep 2010
Location: Denmark
Vehicle(s): GD290 W461
Posts: 202
| RE: Front Differential Bearing Replacement (Differ spreeader)
I have used hydraulic press to do that. It does not take much force to spread the housing, so go slow |
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MiN
Extreme Veteran
Date registered: May 2006
Location: Alpujarras, Spain
Vehicle(s): No cars, at all.
Posts: 555
| Re: Front Differential Bearing Replacement
Same here, never needed that tool to spread the casing when extracting the diff. |
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fernweh
Date registered: Apr 2006
Location: Calabasas, CA - Centenario, BCS - Luebeck, Germany
Vehicle(s): Few Mercedes-Benz, a Toyota Amphibious and a Vespa
| RE: Front Differential Bearing Replacement
Floobydust - 5/3/2015 5:45 AM
A question for future reference - how "perfect" do the diff lock cogs have to be? It seems that a small chip on the end of the teeth might be acceptable as long as the bearing race area is perfect, but I'm not sure.
Thanks,
- FD
When had to overhaul the "replacement" axle, I noticed the worn locker gear teeth, and the resulting damage to the carrier bearing cage plus the groove cut into the axle housing.
The location of the groove, is in the contact surface of the thick shim (pre-tension) next to the carrier bearing. Please have a look at the pictures below.
Question: How can you position the diff carrier correctly for the backlash and pre-tension, with spreading the diff housing nicely?
BTW If you get permission from 4x4abc (Harald), I can send you the correct MB tool as a loaner. You obviously have to pay the shipping both ways for this heavy tool.
 (Diff lock at carrier.JPG)
 (Dog lock teeth.JPG)
 (Left carrier bearing race.JPG)
 (worn in groove.JPG)
 (spreader1.jpg)
Attachments
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Diff lock at carrier.JPG (88KB - 0 downloads)
Dog lock teeth.JPG (86KB - 0 downloads)
Left carrier bearing race.JPG (85KB - 0 downloads)
worn in groove.JPG (85KB - 0 downloads)
spreader1.jpg (308KB - 2 downloads)
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Floobydust
Veteran
Date registered: Mar 2014
Location: Massachusetts, USA
Vehicle(s): 1995 E320 Cabrio, 2003 G500, 2000 SL500, 1980 TR8
Posts: 284
| RE: Front Differential Bearing Replacement
fernweh - 5/3/2015 11:35 PM BTW If you get permission from 4x4abc (Harald), I can send you the correct MB tool as a loaner. You obviously have to pay the shipping both ways for this heavy tool.
Thank you for the offer - I will try to contact Harold to see if he is okay with that. I have seen posts of people using a press to "squeeze" the pumpkin and withdraw the diff carrier and I have also read (and my Indie says) that with some careful "convincing" it is possible to R&R the diff carrier without a spreader. I believe in being safe rather than sorry, so it would be worth the shipping just to be sure there are no issues. Of course, I would pay for all shipping costs.
BTW, my bearings arrived today. I got genuine MB, but I looked up the price difference for the "plain" non-MB bearings and it was a bit scary. But then again, I only want to do this job once. The bearing cross references I found on the MB bearings were:
002 980 11 02 SKF M86610/2/QCl7C (large pinion bearing)
001 980 69 02 Koyo/Timken HM803146-N (small pinion bearing)
000 980 19 02 Timken LM806649 (carrier bearings, 2 per diff)
- Scott
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4x4abc
Date registered: Apr 2006
Location: La Paz, Baja California, Mexico
Vehicle(s): 02 G500
| RE: Front Differential Bearing Replacement
don't do the work without the spreader if the new bearings do not get the correct preload, they might not last long
you are welcome to use my spreader (always wondered where the damn thing was, as I could not find it in the garage)
I have some other specialty tools for the G as well - they are all floating around in the G community |
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Floobydust
Veteran
Date registered: Mar 2014
Location: Massachusetts, USA
Vehicle(s): 1995 E320 Cabrio, 2003 G500, 2000 SL500, 1980 TR8
Posts: 284
| RE: Front Differential Bearing Replacement
Harold - Thank you, thank you!! I really appreciate it!
Karl - Thank you too! I am going to be on vacation starting next week, but I after get back I will PM/email you to coordinate the shipping costs, etc.
- Scott |
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fernweh
Date registered: Apr 2006
Location: Calabasas, CA - Centenario, BCS - Luebeck, Germany
Vehicle(s): Few Mercedes-Benz, a Toyota Amphibious and a Vespa
| RE: Front Differential Bearing Replacement
Floobydust - 5/5/2015 9:00 AM
Harold - Thank you, thank you!! I really appreciate it!
Karl - Thank you too! I am going to be on vacation starting next week, but I after get back I will PM/email you to coordinate the shipping costs, etc.
- Scott
I'll be driving to Vance, AL and Atlanta, GA next week.....could pack that heavy tool as an anchor, for the "off-roading" in the woods there. |
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atg
Veteran
Date registered: Nov 2014
Location: Los Angeles
Vehicle(s): 2005 G55, 1985 300tdt
Posts: 129
| Re: Front Differential Bearing Replacement
There's another Karl on here? |
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shochu
Extreme Veteran
Date registered: Jul 2006
Location: Jakarta, Indonesia
Vehicle(s): indonesian-assembled '97 G300
Posts: 452
| Re: Front Differential Bearing Replacement
my apology for hijacking the thread a bit
i, too, have been somewhat 'chasing' after a noise which i now kind of suspect coming from the front axle. it comes and goes, more prevalent on certain speeds, definitely when there's load, and also when slowing down coming to a stop. without load, my mechanic reported that there's no noise coming from the axle (they put the vehicle on 4 jackstands and run it)
on a 463, would it be advisable to remove the front prop shaft, and lock the middle diff, to kind of test out the front axle? i figured without load to the front axle, if the noise is still there it must means that it's coming from somewhere else. if the noise is gone, there's good chance it's coming from the front axle. and i'll look into the rebuilding process.
i've heard this done on 460s quite a bit, but never on a full-time 4x4 w463, but have never really understood why. i'm not mechanically inclined, nor do i understand much about engineering, so any thought will be much appreciated.
thanks |
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AlanMcR
Expert
Date registered: Apr 2006
Location: US, CA, Los Altos
Vehicle(s): G300DT E300DT 230SL
Posts: 3500
| RE: Front Differential Bearing Replacement
Sure, if you lock the center diff, you can remove either the front or rear driveshaft. Take it easy on the acceleration though - no drag racing.
Edited by AlanMcR 5/6/2015 12:54 AM
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DUTCH
Administrator Doppelgänger
Date registered: Apr 2006
Location: US, GA, Atlanta
Vehicle(s): 2015 Audi Q7 3.0 TDI,2018 Sprinter
Posts: 9963
| Re: Front Differential Bearing Replacement
atg - 5/5/2015 8:33 PM
There's another Karl on here?
Yup. He's been a helpful member of the forum since 2006. |
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