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diagnosing front hub seal failure

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syncro_G
Posts: 824

diagnosing front hub seal failure

Post#1 » Sun Feb 22, 2015 11:47 am

about 2-3 months ago, I had my right front hub overhauled. new bearings, seals, wipers, hub.

Last week I discovered that hub was making noise on turns while on a multi-day road trip.
By the time I got home, the bearings were toast.

So the other day, Chris B helped rebuild the hub with fresh bearings and seals. the CV and hub were still in new shape.
within about 30 miles of driving after that, the outer seal failed. I had about 80 miles of driving left before I could park the truck.

At the moment, I can't feel any play in the hub. Perhaps its a little too tight but definitely not loose.

Any ideas on what would make the outer seal fail?

Edit...

I was on my way to visit Vadim - he was kind enough to send me off with a spare housing and hub but I'm hoping I don't need to use them

VolvoC303
Posts: 1512

Re: diagnosing front hub seal failure

Post#2 » Sun Feb 22, 2015 11:58 am

Has to be a bad race in some way.

User avatar
Gelande
Posts: 5327

Re: diagnosing front hub seal failure

Post#3 » Sun Feb 22, 2015 8:16 pm

Bring your parts over tomorrow and I will look at them and tell you what happened

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stevegsmith
Posts: 2666

Re: diagnosing front hub seal failure

Post#4 » Sun Feb 22, 2015 9:59 pm

mserpe wrote:Bring your parts over tomorrow and I will look at them and tell you what happened


Ooooh! Listen to mr. crystal balls genie-pants! 8-)

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inkblotz
Posts: 8202

Re: diagnosing front hub seal failure

Post#5 » Mon Feb 23, 2015 3:33 am

stevegsmith wrote:
mserpe wrote:Bring your parts over tomorrow and I will look at them and tell you what happened


Ooooh! Listen to mr. crystal balls genie-pants! 8-)


:D

User avatar
Gelande
Posts: 5327

Re: diagnosing front hub seal failure

Post#6 » Tue Feb 24, 2015 8:17 pm

taste what?

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syncro_G
Posts: 824

Re: diagnosing front hub seal failure

Post#7 » Thu Feb 26, 2015 3:50 pm

Ok, finally got time to pull the hub apart. whew. Though not as complicated as tearing into a gearbox, it was a bit of a struggle since I don't have any specialized tools for this sort of job.

1. after removing brakes and rotor, I tested play on the hub. WIS says you should see .02mm of axial play. This hub is very tight. no play at all...
dial indicator.jpg
test play with a dial indicator


2. On disassembly, I couldn't get the hub off of the CV spindle. My claw pullers weren't up for the task. I thought the hub was supposed to slide right out. So instead, I pulled the knuckle housing out along with half shaft.

3. Once off the truck, it wasn't too hard to beat the shaft out of the hub with a rubber mallet.

4. Hub was still not coming free from the knuckle housing! I set the housing up on wood blocks with the hub flange face down. then used a matching socket and rubber mallet to beat the hub out of the bearings. That took a little while. The inner bearing's inner race had a very tight grip on the hub!

5. outer seal had obvious signs that grease ran out. However, the seal looks pretty good (it's only a week old!) It's not exactly seated level. one side is maybe half a millimeter higher than the other. could that be the cause?

6. cleaned everything up. an old plastic spatula works great for wiping out the old grease.

7. Here are the parts after cleanup. no signs of heat or wear really.
hub spindle.JPG
hub spindle

housing.JPG
knuckle housing

cvjoint.jpg
cv joint


the CV joint is in great shape and all parts except the knuckle housing are fairly new. hub is a few months old (under 7,000 miles), seals and bearings just a week old with less than 200 miles on them.

User avatar
syncro_G
Posts: 824

Re: diagnosing front hub seal failure

Post#8 » Fri Feb 27, 2015 9:38 am

Just did some comparing between my hub and a known good one.

it turns out the inner bearing was not to spec. The previous one was made in Germany. the current one that is too tight is made in Brazil. Both are the same manufacturer and part number.

Also the latest seals used were not to spec. they had a single lip instead of the double lip of OEM.

So now, I need to track down the appropriate replacements!

Also some quick questions:
1. the big yellow/white swipe seal on the bell housing has a chamfered inner surface. which way is it supposed to go? The WIS doesn't show this part in enough detail to figure out. is the acute edge supposed to press against the ball or is the beveled face supposed to press against the ball?

2. I don't see the foam dust seal that fits between the hub flange and the outer hub seal. is this something I need to find and install?

User avatar
Winston
Posts: 3110

Re: diagnosing front hub seal failure

Post#9 » Fri Feb 27, 2015 10:46 am

I think the chamfered edge on the swipe seal faces the wheel but I can't exactly remember. Sorry

Where did you get your Brazilian parts?

Edit:
Tech article says chamfer out: http://www.clubgwagen.com/gtech.php?pageTitle=G-Tech%20Article&sid=item&tid=29

User avatar
Gelande
Posts: 5327

Re: diagnosing front hub seal failure

Post#10 » Fri Feb 27, 2015 10:52 am

Foam seal, should sit on the inside of the hub, so if you don't have one, get one
They are about $35 at mercedes dealer
use part number 460 334 02 59

This seal is ONLY for keeping out the dust, not grease in

There are no special tools required for this job other than the toothed socket and torque wrench that goes up to 220

This is the only seal on the G that I have not found a suitable aftermarket replacement for, having to always depend on MB for it at high price, but not that big of a deal really. They are a week out usually from the dealers MBUSA.

Seals from Petaluma will not have 2nd lip. Corteco does make 2nd lip type aftermarket seal, but Petaluma could never seem to order that one for me.... you can get thru other Corteco suppliers, otherwise, just get the blue MB seal, its not that much difference in price and any MB dealer should have it in a day out of LA MBUSA warehouse or 2 days out of NJ

The second lip is for dust anyways (like brake dust) and H2O to not get in.... not meant to stop stuff from getting out from what I recall.... aren't those lips facing different directions...one inward, one outward??

Please note that upon installation of the seals, you should coat the outer circumference of metal (not rubber) with sealing compound #2
part number is 387 589 04 15 00 or use aftermarket

When you drive in the seal ring you should be flush or max 0.3mm lower

Seal rings with external rubber coating do not require use of sealing compound

on the issue of hub tightness:
Sounds like claw tooth hub nut was possibly too tight and if seal was not straight then it is likely not because of 1 lip or 2 lips, rather that seal was not straight in the seat it sits in.....but maybe seal is not made right....try a new one either way...don't reuse.

When you drive your bearing or race onto the components, use lube on it first

When you put on your slotted nuts and washer, use only new nuts and washer.

Grease inner slotted nut at contact surface and tighten it to 200nm while turning the whole joint housing which will provide for settling and aligning the bearing rollers.

At this point you will likely have no bearing clearance, so then next step is to Release inner slotted nut until you have bearing clearance of 0.1mm with dial gauge, then insert lock tab. Anything more than 0,3mm on new bearings is too much...range should be .1 to .3

IMPORTANT STEP OFTEN MISSED: While you release the inner slotted nut tension, be sure to turn the hub several times and with several poly hammer blows on the hub, seat and align the tapered rollers, then retighten nut to 200nm.

Next sand your slotted outer nut on the contact surface to the lock tab washer. Follow up with grease and then tighten it to 170nm first, and then to 190nm. IMPORTANT: The chamfers of the nuts must point to the clock tab side

Now check your overall bearing clearance again with dial gauge, should due 0.03mm

Above all, before reassembly make sure with a lupe or magnifier that you have perfectly clean surfaces on the knuckle housing and hub where all seals and races and bearings go.

Note that if you repack your old bearings then they will need clearance of 0,03mm not 0,01 or 0,02
Manual states range for new bearings is between 0,01 and 0,03 but must be right at 0,03 for used repacked bearings

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