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I recently had my FD overhauled due to slivers and flakes found on drain plug magnet. The FD was making a tire rubbing noise most noticeable while decelerating. There was no oil leakage or play of any kind at the rear wheel.The gentleman who did the overhaul replaced all bearings and seals and was quite surprised to find the FD had 150000 km. on it. I am a helicopter mechanic. All helicopters use similar magnetic drian plugs except they wire them to a warning light on the panel. When that light comes on it always means land as soon as possible.This would be a fairly easy modification to do on a LT or any other BMW for that matter.I would like feed back from anyone intersted. Dan Beck
 

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Dan, someone else brought up something along these lines earlier, and it was not enthusiastically received. I believe the main reason for the lack of approval had to do with just what you do if the light does come on!

That being said, since I am also a Helo Maintenance / Aircrewman type (USCG 24 years of Sikorsky experience) and am still involved in the oversight of Helos, I believe it is worth trying! I would suggest at least considering the "Fuzzburner" type of Chip Detector however, since we do often have fuzz on the mag plug when we pull it.

Let me know if you want some feedback or assistance on this project.

John
 

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beck0007 said:
I recently had my FD overhauled due to slivers and flakes found on drain plug magnet. The FD was making a tire rubbing noise most noticeable while decelerating. There was no oil leakage or play of any kind at the rear wheel.The gentleman who did the overhaul replaced all bearings and seals and was quite surprised to find the FD had 150000 km. on it. I am a helicopter mechanic. All helicopters use similar magnetic drian plugs except they wire them to a warning light on the panel. When that light comes on it always means land as soon as possible.This would be a fairly easy modification to do on a LT or any other BMW for that matter.I would like feed back from anyone intersted. Dan Beck
Hi, Dan - welcome aboard. Hope you enjoy our 'spread out' community, helpful folks all.

Have a question for ya. There are several members here who are helicopter pilots, so this may spark some interest from their viewpoints, as well. Question - what triggers the warning light to come on to indicate an urgency to land and take care of a problem. Is it the amount of sludge that is built up on the magnetic plug, for example? Or content of the sludge? I dunno; just asking. In the ~35 or so final drive fluid changes that ole Toad has gone thru, there seems to 'always' be sludge on the drain plug. Some more than others, butt always some. I never got an indication of the two final drive bearing failures by 'reading' the sludge - admittedly, cuz it always looks the same. Even tho I looked for the supposedly large enough shards of shiney metal to tip me off.

Thanks for the post. Just got me to thinking and wondering what the process is for the read off the magnetic plug that triggers the dash light to glow.
 

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beck0007 said:
I recently had my FD overhauled due to slivers and flakes found on drain plug magnet. The FD was making a tire rubbing noise most noticeable while decelerating. There was no oil leakage or play of any kind at the rear wheel.The gentleman who did the overhaul replaced all bearings and seals and was quite surprised to find the FD had 150000 km. on it. I am a helicopter mechanic. All helicopters use similar magnetic drian plugs except they wire them to a warning light on the panel. When that light comes on it always means land as soon as possible.This would be a fairly easy modification to do on a LT or any other BMW for that matter.I would like feed back from anyone intersted. Dan Beck
I am very interested in this item. Like Dick,I wonder how much trash it takes to trigger the sensor. If the cost is less than $200,I can see doing it.

Dan Martin
 

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Dick said:
Hi, Dan - welcome aboard. Hope you enjoy our 'spread out' community, helpful folks all.

Have a question for ya. There are several members here who are helicopter pilots, so this may spark some interest from their viewpoints, as well. Question - what triggers the warning light to come on to indicate an urgency to land and take care of a problem. Is it the amount of sludge that is built up on the magnetic plug, for example? Or content of the sludge? I dunno; just asking. In the ~35 or so final drive fluid changes that ole Toad has gone thru, there seems to 'always' be sludge on the drain plug. Some more than others, butt always some. I never got an indication of the two final drive bearing failures by 'reading' the sludge - admittedly, cuz it always looks the same. Even tho I looked for the supposedly large enough shards of shiney metal to tip me off.

Thanks for the post. Just got me to thinking and wondering what the process is for the read off the magnetic plug that triggers the dash light to glow.
I'll be glad to answer your question here Dick! The light is triggered by a relay, typically with a holding circuit, which in turn is energized (or grounded) when the inner post on the Chip Detector is able to reach the outer portion via metal flakes, or enough "Fuzz", which is fine metal filings that conduct the current real well!

Now the stuff we see on our Mag Plugs is definitely magnetic, but is it a good enough conductor to create the necessary path for the current flow which would actuate the Relay and illuminate the Light? Need to do some tests next time we change the FD oil I guess!

HTH,

John
 

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I find the concept of a helicopter type warning system interesting, but I have a bunch of questions:

How well do these systems actually work in helicopters? Do the copter gearboxs generate the same amount of metal "mud" that the KLT final drive does? I imagine that copter gearboxes have a rebuild interval just like other required "To Be Overhauled" engine components?

I have seen two types of metal in final drives: the normal "mud" seen during lube changes, and the large metal shards of a failed bearing retainer. I suspect that once the metal shards of the bearing retainer start showing up the rider is going to know of bearing failure in just a couple miles. If this is the case, the difference between having a warning light come on and feeling the the roughness in the ride is going to be a very short distance.

So, I don't see a warning system that would detect the bigger pieces of a bearing retainer saving anyone from a roadside breakdown. The final drives seem to go from no problem to big problem in a hurry.

HOWEVER, I see the advantage of such a detection system as a safety feature. So far, no one has gotten hurt (that I know of) from a final dive failure. But I also think we have been lucky. Imagine a sudden final drive failure during aggressive riding in the twisties where gear oil ends up on the rear brake rotor and tire. A warning system that detects the bigger pieces of a failed bearing retainer might save a rider by indicating "Land Now!" :)
 

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The chip detector may trip from fuzz, but at least it is a better-than-nothing indicator that the drain plug should be removed & checked for larger stuff.

I wish there was a way to listen to the FD housing at low speed on a smooth road, but the only thing I can think of would be a mounted accelerometer driving an audio input of something. Grumbling would be a sure sign of bearing race or ball spalling.
 

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I too have a fair amount of time in the helicopter arena. Debris on chip detectors usually fall into several categories. Paste or mud, flakes, slivers and last but not least stuff so big you'd think you could read part numbers off of it. The problem with the subject failures is how much time is there between when it starts to "make metal" and what does the debris look like; and ultimately when it fails? Not sure if anyone has been able to quantify it. It's really sad that we're even having to discuss this but I understand why. Probably the best option would be a self sealing bayonet mag plug installed in place of the drain plug. A female housing would be installed in place of the FD drain plug. There is a spring loaded poppet valve that will close when you pushed and turned the mag plug to remove and inspect. No wires or chip lights while riding. What it would allow is a quick 10 second pre-ride check of your FD for signs of metal without loosing any lube. Unfortunately I've never seen a self sealing assembly small enough to fit in a hole that small. Not saying it doesn't exist just don't know of one. I bet if someone made one it would sell! Heck I'd buy one if it was under $100.
 

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beck0007 said:
I recently had my FD overhauled due to slivers and flakes found on drain plug magnet. The FD was making a tire rubbing noise most noticeable while decelerating. There was no oil leakage or play of any kind at the rear wheel.The gentleman who did the overhaul replaced all bearings and seals and was quite surprised to find the FD had 150000 km. on it. I am a helicopter mechanic. All helicopters use similar magnetic drian plugs except they wire them to a warning light on the panel. When that light comes on it always means land as soon as possible.This would be a fairly easy modification to do on a LT or any other BMW for that matter.I would like feed back from anyone intersted. Dan Beck
As a former helo pilot I know what you are talking about, I also had to do some fast landings due to chip warning.

Yes I would deinately like a warning system like that.

Even if there is sludge forming we could atleast get an indication that it is time to change the FD oil.
 

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I made a comment about this the last time someone had an idea like this. I too have been around helicopters, as a mechanic in the U.S. Army working on CH47D Chinooks. :rant: This idea still doesn't warrant any value other than knowing your screwed. Most of the posts of final drive failures have all said that when theirs failed they heard a grinding noise or tire rubbing noise. This all happens very quickly from my understanding of the situation.

Most of the time it has to due with metal fatigue and if that happens, those bearings will probably chew themselves up by the time you even get stopped. So when it comes down to it, you basically have a light that comes on seconds before you would have heard it anyway.

About changing the oil because of sludge, unless you have a chip detector that is able to burn off false positives I think the idea of having one to let you know when to change your final drive oil is a little ridiculous. You will be changing your oil a lot. Might as well carry gear oil in one of the compartments just in case if that's how your going to use the indicator light. :rant: JM2CW Have a nice day!
 

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All of you have good questions about the viability of a "Final Drive Warning Light System" (FDWLS). The comparisons to a "chip detector" is close but not totally correct. Chip detectors can use various methods to "see" debris. How much debris and its composition is always a design consideration too. I chose not to use a "proximity sensor" ie "chip detector" because of durability (most are pvc faced) and max temperature of <160 degrees F. We have a very good magnetic plug which collects the ferrous fines and later the curved shards of the inner race, and the meniscus shaped platelets of the balls themselves. The shaped casting around the magnetic plug creates an area where the aluminum can rest also (somewhat). These are all some of the reasons the design was made so that "both" steel and aluminum would trip the system. I also have now included a short timed electrical current method to clear nuisance faults. So the first step after getting the dreaded "Red Light" is to stop and do a "fault check". If you look at the pictures that were included on my 2nd post that amount of ball bearing damage is more than what I was/am shooting for to trip the warning light. It works using the same particles. The system is being run every day on my K1200LT/ Hannigan KLT sidecar. We need to have some idea how our Final Drive is doing (in real time) and not simply think "all is well" because of a FD GL change! IMO doing frequent GL changes gets you a look at your drain plug and argubly 100 to 500 miles of some degree of less worry. Look at the pictures and you'll see this is not rocket science but it works.

http://www.bmwlt.com/forums/showthread.php?t=37092&highlight=warning+light+rear+drive
 

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Try this "Tourdog" thread............ look at the pictures attached to my 2 nd reply.

http://www.bmwlt.com/forums/showthread.php?t=37092

The "FDWLS" is fairly simple. It does include a digital I.C. that enables logic not available to the 1950's analog technology of basic "chip detectors". We have < than 14 mm to work with and doing a complete "bore out" on the OEM drain plug would enable only an 8 mm diameter "proximity sensor". Capacitive or inductive sensors can be had (all stainless) with mm sense ranges close to what we need but using the old "chip detector" gap method and retaining the all important magnetic attribute and then adding in newer digital "sense" logic brings about a better out come (IMO).
 

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I too chimed in on a previous discussion on this topic.

What bugs me is I know my light would come on approx 200 mi from the nearest town, and in that town the only shop would be Goobers filling station. So do I call a tow truck, assuming I can get to a phone or find a signal? Is Goober going to be able to change the extra bearing I've been carrying?

If there is even the slightest possibility of a false warning, and I had my trip ruined or altered severely due to that false warning, I think I'd be more upset than an actual FD failure in the middle of nowhere.

That said, I think if it would bring others piece of mind to have such a device then someone should go forward with it. I just don't think it is for me.
 

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I contend an audio microphone on the FD housing would give an earlier and more qualitative indicator.
 

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This discussion is fascinating to me because being relatively new to the BMW community (but working in bike shops most of my life) I am amazed at the lengths you guys will go to in order to to to detect and/or prevent a problem. The "techie" side of BMW ownership.

We're actually discussing "listening systems" for rear drive failures....and early warning lights for the same. I swear, if we saw this on a Harley site we would be ragging them to death. :histerica

Sure hope they don't see this thread! Just Ride It! :D
 

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Wish I Had One! 1994 K1100lt. Was In 40mph Lay Down & Flipover On Freeway Off Ramp In San Diego In 1999.bmw Shop There Did All Repairs & Had Bike Crated & Trucked To Eastern Washington. Don't Know If Damage To Fd Was Accident Related Or Caused By Idiot Tow Truck Driver (they Called An Old Hook Style, Not The Tilt Bed Type To Haul It To The Bwm Shop) The Owner Of The Shop Told Me When It Arrived, It Was Swinging On The Hook Like A Drunken Sailor On Leave.this Happened In July. Next Spring, Went With Wife For First Ride Of The Year, After I Took The Bike To Work On A Saturday. I Noticed When I Applied The Rear Brake It Was Very Mushy On The First Application. If I Released The Pedal & Then Pushed It Again The Brakes Worked Fine. After About 75 Miles Into The 150 Mile Ride I Kept Hearing A Growling/howling Noise. I Could Not Locate The Source & Thought It Was Road Noise As The Highway We Were On Was In Need Of Paving. Took The Off Ramp From I-82 To I-182 & In The Curve, The Back End Twiched Violently. Stopped The Bike & As Wife Got Off I Smelled The Unmistakible Oder Of Burning Oil. Guages Read Good & Idiot Light Was Not Lit. When I Got Off, I Noticed An Enlarging Pool Of Oil Under Rear Wheel. Rear Seal Had Let Go & All Fluid Was Going, Going, Gone. Took Several Months To Locate A Replacement Rear End, But Bike Is Still On The Road. The Brake Problem Was Caused By Oil Seeping Onto The Pads, & The Twich Was From Oil On The Edge Of The Tire That Only Came In Contact With The Pavement On A Turn. If We Had Gone Another 2 Miles Down The Hill On A Straight Portion Of The Interstate, Then Taken Our Usual Exit, A 270 Degree Off Ramp, We Would Have Been Off The Road & Into The Trees @ 45mph.
 

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cccpastorjack said:
We're actually discussing "listening systems" for rear drive failures....and early warning lights for the same. I swear, if we saw this on a Harley site we would be ragging them to death. :histerica

Sure hope they don't see this thread! Just Ride It! :D
If we saw this on a harley site it would be useless due to all the other noises and rattles that a harley makes, it would just be constant warning lights...Your bike is about to explode. Brilliant engine design, really thought they were going somewhere with those new confangled liquid cooled motors a few years back. Wow that stuff was cutting edge in the motorcycle industry. Seriously though, I would ride one but will never spend the money on one.
 
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