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Dwip,Dwip


GregsARed

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So I’d been riding all week (pre Mem. Day), it’s hot and my arse is a little sore. Near the end of the last day I notice a mess all around my rear rim. Darn It, my rear end is dripping right onto the rim and tire [honestly this has never happened before].

 

I’m not ashamed to admit this, my backend has gotten a lot of use, not abused though. I’ve always used sterile and quality lubricants. I even inspect it’s (normal) discharge.

 

I’m worried that it might be the big ‘C’. Many others here, I’m sure have experienced this, can anybody help me out? Maybe advice on treatments or maybe lead me to some support groups? [if you’re too embarrassed to come forth here you can PM me].

 

So how am I dealing with this, how did I react?

I realize it’s the Final Drive fluid and it’s source is somewhere above the drain plug. I remove the filler cap and the level seems almost normal so I continue the last 200 miles home. There I again check the level and find it down just a little. I remove the wheel and rotor and trace the leak to the shaft seal.

 

This Final Drive has 284K miles; I’m hoping it’s only a worn seal, not the big ‘C’, the Crown Gear. The wheel still spins fine, probably no gear damage but possibly a worn shaft bearing

 

So let’s think positive and say it’s only a worn seal. Can I pry this old one off and push a new one on? That sounds simple enough.

OR My reality, a worn shaft bearing and shims leading to this leakage. I understand this fix is a pretty delicate operation, requiring skilled hands . Do you folks have any suggestions on a support group, i.e. someone skilled, not necessarily representing BMW but experienced in this operation.

 

I’ve done the rear wheel wiggle, detecting a little play, but I haven’t done it often enough to know how much is normal, so I better check with a BMW tech.

 

Checking the oil I still find nothing unusual, so I’m off to get that professional opinion. However I don’t get very far before I’m disabled, not by my Final Drive but from a broken clutch cable.

 

“Whatever?”

Thanks

 

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Afternoon GregsARed

 

Could be anything from a simple leaking seal, to plugged vent, to worn bearing, to ????. Could even be a leak in the hub where it is pressed together (hope not).

 

If you have a magnetic drain plug in the final drive you need to remove that (drop the gear oil into a CLEAN container then strain it through a coffee filter or paper towel). Then take the filter out in the sun & look for sharp sparklies.

 

Check the magnet for anything sharp or gritty feeling. If the gunk is smooth between your finger & thumb then probably not a crown bearing problem (yet). If sharp things are found then you need to look at the bearing(s) inside.

 

If you don't have a magnetic drain plug then get one. In any case still change the gear oil & strain it then check for metal in the oil.

 

On the seal? Yes, you can remove it then just drive in another (don't damage the original seal so you can turn it over & use as a driver for the new seal. I have seen that seal pried out but that is risky & doesn't remove the seal without damage. I like to drill a couple of very small holes in the seal (mid center 180° apart & ONLY deep enough to break through the seal metal). Use a drill stop or something on the drill bit to limit drilling depth about 1/8".

 

Then screw a sheet metal screw into those drilled holes & use some vise grips on the screws to remove the seal.

 

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Thanks D.R.,

Your input is highly valued, thanks for responding.

 

The oil was fresh before this trip, I do have the magnetic plug (I wish the mag was larger because it never seems to pick much up, I guess it could be that there isn't anything to pick up). I did drain the oil into a clear container looking for frag and sparkles, no frag just a little fuzz around the edges of the mag. I still have the oil, I'll try the coffee filter technique.

 

Thanks for the seal removal procedure.

 

I'll be picking up the clutch cable and seal on Mon, hopefully on Tue I can have get their opinion/evaluation on any wiggle. Thinking about sending in the oil for analysis also.

 

 

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Michaelr11
I realize it’s the Final Drive fluid and it’s source is somewhere above the drain plug. I remove the filler cap and the level seems almost normal so I continue the last 200 miles home. There I again check the level and find it down just a little. I remove the wheel and rotor and trace the leak to the shaft seal. This Final Drive has 284K miles; I’m hoping it’s only a worn seal, not the big ‘C’, the Crown Gear. The wheel still spins fine, probably no gear damage but possibly a worn shaft bearing

 

So let’s think positive and say it’s only a worn seal. Can I pry this old one off and push a new one on? That sounds simple enough.

OR My reality, a worn shaft bearing and shims leading to this leakage. I understand this fix is a pretty delicate operation, requiring skilled hands . Do you folks have any suggestions on a support group, i.e. someone skilled, not necessarily representing BMW but experienced in this operation.

 

I’ve done the rear wheel wiggle, detecting a little play, but I haven’t done it often enough to know how much is normal, so I better check with a BMW tech.

 

This is not a major disaster. You got nearly 300K on the original Final Drive! I just completed this job at home, well in the garage. It is very possible to just R&R the shaft seal. But at this mileage and since you say there is a little play (there should be no play) at the rear wheel, why not R&R the big bearing at this time. If the bearing has not self-destructed (sounds like you are okay) then it is unlikely that the crown gear is damaged. The shim really doesn't wear either, and if all you are doing is replacing the big bearing, then the shimming should not change and you can just replace the bearing and reassemble.

 

This should take you to an MOA discussion thread where Paul Glaves provides a step by step for doing the big bearing R&R with the final drive case left on the bike.

http://www.bmwmoa.org/forum/showthread.php?t=17974

By doing it this way you avoid having to R&R the swingarm pinion bearings. If yours are still tight then don't disturb them. It's just a little more work since you won't have the case on a workbench in front of you - instead you'll be doing some of the work with it on the bike.

 

The only problem I had was inexperience with heating the new bearing so it would expand enough to drop onto the crown gear shaft. I screwed it up and ruined one bearing, had my dealer put the new bearing on after that. Everything else went together easily without much swearing.

 

The parts you will need are; the deep grooved bearing, shaft seal, O-Ring for case cover and new screws for the brake rotor. You'll need a heat gun or torch to heat parts on several steps.

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[quote=Michaelr11---- The shim really doesn't wear either, and if all you are doing is replacing the big bearing, then the shimming should not change and you can just replace the bearing and reassemble.

 

----

 

A person really needs to at least check the crown bearing preload shimming when installing ANY new crown bearing.

The bearings are not that precise that they can just be installed without checking.

 

Sometimes the preload is the same & sometimes not. Also a lot of times it wasn't right to begin with.

 

This isn't to criticize how you personally did yours it is for future readers to understand they need to do a proper shimming check when ever a new bearing is installed.

 

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This isn't to criticize how you personally did yours it is for future readers to understand they need to do a proper shimming check when ever a new bearing is installed.

Ordinarily I'd agree 100% but wow... 287k miles? The original preload couldn't have been too wrong... :grin:

 

Do you not think in a case like this (or other examples where the original bearing went to a long life) it might be OK to mic the old and new bearings and adjust out any difference with shim selection? I know this is not technically kosher but after measuring a few myself I've found it can be difficult to come up with a figure that you can be confident to within a few thousandths, or at least it was for me. If what I measured was different than what existed for 100k+ miles in actual operation with no problems, frankly I wouldn't know which to trust more. And again I am only referring to a unit that has had a known long service life and no other work is being done than crown bearing replacement... of course if you are servicing a unit that died early or doing a complete rebuild, all bets are off.

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Afternoon Seth

 

We don't know if that was all his original miles or the bike was bought used with a bearing or two replaced in it’s history.

 

To answer your question, sure you could mike the bearing but it obviously has enough wear now to cause wheel movement. That means you would have no idea where the center race was originally at "laterally" compared to the outer race when it was originally installed & shimmed.

 

Some do just toss a bearing in & hope it will all work out. That is more than likely how a lot of dealers do it. Probably also why there are a lot of multiple bearing failures in the same drive at about the same mileage.

 

At the very least lightly re-tighten the cover bolts by finger when re-assembling (without O ring). Get the cover to housing gap even. Then give it a rap with a rubber mallet. Then see if the cover gap to drive housing is too much-- if so it is shimmed to tight, if the cover gap to case is too small then it is shimmed too loose. Not real precise but should show if grossly out of shim spec. (don't forget to remove cover & re-install the O ring before final torquing).

 

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Understood. Of course I wasn't suggesting simply tossing in a new bearing and hoping, but rather doing it advisedly with a knowledge of the prior service life (if you can be sure you have that, point taken) and with measurements of the old and new bearings. If you don't have any of these then of course you couldn't proceed. Again, not trying to argue that any short cut is advisable because usually they aren't, but in cases where you have the known data above vs. a 'kind of close' measurement (the best I have really been able to achieve) then just considering which is actually the less of two evils.

 

That means you would have no idea where the center race was originally at "laterally" compared to the outer race when it was originally installed & shimmed.

Does that matter? It seems like the only critical factor (in terms of making the shim pack measurement) is the width of the outer race(?)

 

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---

Does that matter? It seems like the only critical factor is the width of the outer race(?)

 

Evening Seth

 

Yes it does. The outer race controls the bearing position in the cover, the inner race controls the bearing position on the spool (that also controls the cross side bearing position from the R/H tapered bearing), both outer race to cover & inner race to spool + shim thickness control preload .

 

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--- Typing faster than I was thinking. :)

 

Evening Seth

 

That warms my heart to hear as it means I'm not the only one to do that. Problem is I'm a slow typist.

 

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perfectionist vs pragmatist.

 

Ball bearings ARE very precise, and if you get the same brand and same clearance a pragmatist would say almost all the time preload would be the same.

 

The bearing is easy and fast to change. Harbor freight has a Allen socket set that has the odd 7mm? size as well as the one needed for the pivot bearings. Mine works excellent.

 

Then ride.

 

A perfectionist will insist on measuring the preload, and all kinds of other things. They will also buy all the tools from Snap On

 

You will be riding sooner with more gas and beer money.

 

My opinion.

 

I am a pragmatist.

 

Rod

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realshelby
Ball bearings ARE very precise, and if you get the same brand and same clearance a pragmatist would say almost all the time preload would be the same.

 

The bearing is easy and fast to change. Harbor freight has a Allen socket set that has the odd 7mm? size as well as the one needed for the pivot bearings. Mine works excellent.

 

A perfectionist will insist on measuring the preload, and all kinds of other things. They will also buy all the tools from Snap On

 

 

Rod

 

I VERY carefully measured the old bearing outer and inner race dimensions with a micrometer when I rebuild my final drive a while back. They were within about 2 tenths of each other ( .0002" ). Same maker, very exacting tolerances. Should back up your claim about just replacing the bearing.

 

Upon measuring preload I arrived at .008"!!! Even allowing for any measuring error on my part that means the bearings measure quite differently under preload. What you cannot measure with a micrometer is the way the bearing acts under side load. No, I don't think my preload was that far off with the original bearing, it would not have made it 52K that way. So while some may get by with just dropping a new bearing in, in my opinion that is a pure gamble and the odds are not in your favor.

 

I probably don't have 10 tools with "Snap On" stamped onto them.......

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Morning Terry

 

Yes, that pretty well fits with my past experience. Unless a person is superman he/she has no idea what the "C" factor is on the old bearing VS. the replacement bearing. Something as simple as the bearing "C" factor can change how much movement in the bearing under side loading or pre loading. Even bearing ID or OD can change the ball loading as assembled & that changes the preload as the inner race to outer race lateral bearing movement could be different.

 

Unless BMW predicted thousands of crown bearing failures in it's future at the time of 1100/1150 manufacture there is just no way they had ENOUGH replacement bearings made up in advance. So that means the replacement crown bearing they now sell comes from different manufacturing times, more than likely a different manufacturing process, heck maybe even a different century. We don't (at least I don't) know what the OEM bearing C factor was spec'd at, we could maybe get the C factor on the replacement if we re-searched enough.

 

The crown bearing has also been changed a few times in past history from 19 ball to 17 ball to some back at 19 ball to who knows what at this time. With all the BMW crown bearing failures in past history who knows what spec has been changed or tightened or loosened on the replacement bearings.

 

I check them all at installation & few work out as using the same shim as it had. Some could have squeezed by on the original shim but that would have left me wondering the big (IF) & the big (WHEN) on future failure.

 

So far any I have set up (correctly) haven't failed again-- just luck "maybe", or maybe precisely controlled "luck".

 

Just doesn't take that much longer to do it right.

 

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Yes, original owner, original FD, first FD related problem.

 

UPDATE:

After replacing the clutch cable I made it to the BMW shop for a quick wiggle test and set up a service appt.

Their thoughts: Not sure if the wiggle is from the FD or forward of that. Last spring they replaced the drive shaft (to much wear on the splines) and think maybe a connection (?) at the rear of that might need to be retorqued. On Mon they'll be checking that and replacing the seal.

 

So thinking positive about a quick and simple fix; Thur, I'll be on my way for a 2 1/2 wk ride??? No, even if that is the fix, the smart thing would be some long test rides first for some reassurance.

[too bad there isn't something out there, available, that could give me some peace of mind with this FD, some kind of FD Minder ;) hey Terry]

 

Thinking less positive and more of MY reality:

I did look at Paul G's step by step, seems too easy. I did look at the differing techniques in this thread. All valuable info, but too much for me to get into. Big THANKS for all of it though.

I understand this fix is a pretty delicate operation, requiring skilled hands . Do you folks have any suggestions on a support group, i.e. someone skilled, not necessarily representing BMW but experienced in this operation.

Do you know anybody that can fix this right?

Do I want this done right or just good enough?, That is the Q.

How many more miles do I want?

 

 

 

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  • 2 weeks later...

 

UPDATE 2:

Dealer retorqued the pivot bearings, gave it another 1/8 turn. That eliminated the wiggle.

Then he replaced the shaft seal.

 

Road test: 600 miles later, no leaks, no wiggle.

 

Phase 2 of my road test was a 200 mi ride. At about 150 mi the motor quits puffing, ?.

Still about 0.8 gal of fuel remaining, no sound from the fuel pump (which as preventive maintenance I had replaced this spring), blown fuse #6. Easy road side fix.

Fuse #6 was also an original part, can we just say it was an old and worn out part? :/

 

 

What’s the life expectancy of a Gremlin Bell?

 

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----

Fuse #6 was also an original part, can we just say it was an old and worn out part? :/

 

 

Evening Greg

 

Probably not a defective fuse. Very seldom does a fuse just up & fail without something overloading it. Look CLOSELY at the fuse to see if it has a cracked element or if the element is blown away.

 

Some had a 10 amp fuse & some had a 15 amp fuse. So make sure it was at least a 10 amp.

 

My guess (from years of automotive experience) is something blew that fuse. While it could be about anything on that #6 fuse circuit like the fuel pump or purge solenoid what I usually find is the 02 sensor wire contacting the hot exhaust & shorting out or cut by the R/H TB cam. (make sure the 02 sensor harness is routed to be clear of everything)

 

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----

:/

 

 

Hey DR,

Yes there's usually a cause for a blown fuse, thus the :/

The 15A fuse element showed just a small crack at the end where it connects to the blade. A small crack w/ a tiny dot of molten wire.

I believe the #6 fuse is dedicated to the fuel pump, fuel injector and pump relay.

 

I just replaced the clutch cable, may be possible that the O2 sensor wire shifted.

 

___________

 

Trivia Question?

What is the cheapest fix on a B'mer?

 

Could it be a fuse.

 

 

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Hi Greg

 

Whilst I greatly admire dirt riders experience, no slight intended, I have seen quite a few fuses over the years where fatigue seems to have been the original cause of non operating electrical equipment.

 

So in your case it now more a chicken & egg situation was the crack there first allowing the circuit to operate and burn some of the close / touching ends or a partially melted fuse element that cracked.

 

Either could be the case, but at lease the fault is sorted now.

 

But as DR says check the other points he raised for possible damage / future problems.

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UPDATE 2:

Dealer retorqued the pivot bearings, gave it another 1/8 turn. That eliminated the wiggle.

Then he replaced the shaft seal.

 

Road test: 600 miles later, no leaks, no wiggle.

I would pull the drain plug on the final drive and check the magnet to see what kind of particles, bits or paste is coming off your FD. If you are getting pieces, not just paste, your bearing is breaking apart - either the ball bearings or the channels of the races. It's only 230 CCs of gear oil. Peace of mind or an early warning.

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