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Discussion Starter #1
My current project involves designing and proto-typing a "Warning Light System" for impending Final Drive failure.

So far in this endeavor I have good news. Although, my design is moving and evolving I do feel this one is a "beta version". The system is in 3 parts: 1) Final Drive sensor 2) Electronic package to process the sensor detector 3) A rider viewable "Red Warning Light" with auto reset. This is the version that I have tested with small and large particles. It does a remarkable job triggering consistently on even small hair sized ferrous and non ferrous metal particles. Should one ignore the warning and the sensor gets wiped out the IC unit will continue to hold the Red Warning Light for 45 seconds.

The only way you can detect the early signs of a FD failure is by changing the GL and examining the magnet. If you find by doing a rear wheel axial and radial movement (center stand) your way past even moderate inner race/ball bearing failure. And, of course your now stopped and possibly precariously parked on some heavily sloped loose gravel shoulder.......................... 125 miles beyond the last town........................ And, it is true that the failure is not linear in time/ distance. Catastropic end failure comes very quickly. Most often you are stuck when and where you stop.

We know no OEM support has evolved. And, it would be nearly impossible to make any changes to our existing Final Drive casting and bearings. And, considering the very difficult manner to correctly and consistently shim the crown bearing we need to produce a device that passively "detects and warns" during all of our riding time. We need a Final Drive Warning Light System (FDWLS)!

What say you, BMWLT sages?! I would think this basic system would give confidence to those who worry about their FD failing seemingly without warning. And, of course, this system will function on just about any shaft drive FD that has a plug drainable wet sump.

I have this system presently installed on my KLT. It actually is an attention getter especially from other motorcyclist that fancy shaft drive.................. aaaaaah hello RT, GS and GT's, Goldwings etc.

What do you all think?
 

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:histerica This may be the best post in a LOOOOONNNNNGGGG time. :rotf:

It gets my vote! :check:

(hey Jeff, is there a bullshit flag in the emoticons?):feedtroll

BTW Carl, you should NEVER start a sentence with a conjunction unless you are REALLY clever .... AND .... you can take that to the bank! :p
 

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Hi carl

I have read and re-read your post and while I applaud you for your inginuity, I would not like this on my bike I would probably spend so much time looking at the light hoping it wasnt going to come on that I would forget where I was going taking the enjoyment out of the ride. :( If the final drive is going to fail (it hasnt yet) then it will fail, it probably wont change the end result of "where are you going to break down and can I get help" however should BMW catch wind of your invention you might makes a stack of dough $$$$$ to keep it off the market :D good luck with it I hope it works well for you I am sure you will have a lot of support.
 

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Tourdog said:
And, of course your now stopped and possibly precariously parked on some heavily sloped loose gravel shoulder.......................... 125 miles beyond the last town........................
I also applaud your attempt to reduce some of the worrying that some experience due to the FD failure issue. (I personally think of the issue sometimes, but try not to worry about it.)

Your on the same shoulder as described above, or pulling away from it, and the light comes on.

Closest town is 125mi, and has one gas pump representing the full extent of the towns services. My questions are:
Now what?
Do you try to make it to town, and if you make it there, try for home?
Call the tow truck?
Change the FD fluid and see what is going on? (Did you bring a qt of fluid?)

With a failure indication, do you assume failure is imminent and go for a rebuild? (Either at the next town with a dealer or when you get it home.)

I think I would keep going anyway. Especially since there aren't any nice alternatives. When I can move the wheel using the center stand test I know I'm out of options and the only question is how to get it to a dealer.

That said, I think you should continue your project. Keep us informed. It certainly is interesting.
 

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Hi Carl,

Your system sounds interesting. Which hole would you use for your sensor?

I have also been interested in trying to monitor the condition of the FD and I simply did it with a oil temperature gauge. I did this in conjunction with my new dash project in which I needed three new (simple enough) gauges.
http://picasaweb.google.com/pozoizquierdo/RESHAPINGTHEDASHAGAIN

I bought the VDO gauges and sensors, one for the engine oil with 18 mm sensor and one for the FD with 14 mm sensor. The engine oil sensor was no problem and it simply replaced the oil drain plug and I never need to unplug it as I drain the oil from the oil filter cap anyway.

But the VDO 14 mm sensor for the FD was a problem. It was too long and could not go all the way in through the drain hole. I wanted to install the sensor in place of the drain plug as I thought this would give a more reliable reading than the fill plug.
Now I had to choose another (non-VDO) sensor which was not so long and could fit in the drain hole but this sensor has different resistance and it gives about 10 degrees (Centigrade) too low reading. This is really no big problem as it is the temperature CHANGE that I am interested, not the actual real reading.

So far I have had the shorter sensor and gauge in operation for 8000 km. At first I used a genuine oil temperature gauge with a scale of 50 - 140 deg C (122 - 284 deg F). This worked OK with the engine oil gauge but the FD gauge never gave any readings. Then I bought another VDO gauges (made for hydraulic oil temperature) with a scale of 20 - 100 deg C (68-212 deg F).
Now with the new gauge I get a reading and I have noticed that usually the reading goes to about 40 - 45 deg C (105 - 113 F ) after close to an hour of driving. In Germany two up on autobahn it climbed to 60 - 65 C (140 -150 F). (These readings are corrected upwards with the 10 deg C error.)

I am not 100% happy with my installations since I was not able to use the original VDO sensor and my next trial is to use the fill plug hole for the sensor installation where the VDO probe will fit. Let's see what kind of readings that would give...

Regards
 

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ALL Y'ALL CRAZY!

My wife just carries one of these when we ride the LT. She shoots the rear end as we go down the road. If the thing shows over 500 degrees F we just pull over and phone for help.

"ONE HUNDRED FORTY EIGHT DEGREES AND ALL IS WELL!" Shouts Carol.

"DID YOU SAY YOUR KNEES ARE ABOUT TO FREEZE?" Shouts Warden Ross.

 

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If you are going to just measure temperature, get a household digital peak reading inside-outside gage for about $10 at many stores. Mount the outside thingy on the FD with some epoxy & stick the display inside the rear case (or wherever). But I don't think a failing bearing is going to show that much operating temperature shift until things are really trashed out.

Rather, I suggest a way to listen to the rear housing while underway on a smooth road. If the crown bearing is spalling chunks from the races(and that seems to be the predominate mode of failure), the acoustic rumble will be unmistakable, and will be the earliest indicator of a bearing failure.
 

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While this is the first time I have heard of using it on a motorcycle, it isn't new technology. I spent 8 years working on CH-47D helicopters in the Army. There are chip detectors all over the multiple transmissions that are involved with the drive line of the helicopter.

This technology is decades old and I am sure that it would be useful to know that your FD is about to fail but as stated in other posts once it starts to go bad its not like you can just change the oil and all will be OK. Your options are still to either rebuild or buy a new FD. Its not really a preventative system. It just lets you know that you have to drop hundreds of dollars to fix it.
 

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Discussion Starter #11 (Edited)
Many thanks to all who have responded. Ari, I think your temperature approach has much merit especially in conjunction with other "sense" indicators. Niel has offered the "acoustic" approach but that is a branch of engineering I do not know.
I think my approach using the existing magnetic plug in the sump (quiescent zone) has so far indicated promise. I've included a picture of my FD crown bearing from last years failure. The inner race has begun to cut the balls and even in this picture the grooving is heavily in evidence. No noise that a human can hear or obtuse movement of the rear wheel was evident (axial or radial). It is prior to this stage where I would like to set the "Red Light" to illuminate. Now one could get off the road and do a rear wheel check and perhaps then head slowly to civilization with a GL and magnetic plug check in order. I think the known stages of going beyond the point of simply running for ever.......... and that point of heading ever excelerating towards bearing destruction is the difficult one. At present I have set 1mm or .040" and when that gap fills or is struck even for a split second and then is swirled away the warning will hold for the riders notice. All this is quite easy to do with an integrated circuit and a few capacitors and resistors.
Ari, your approach and mine do not cost alot. Niel, I would hope you could amplify the acoustic process. Should a seal be blown and the GL is lost Ari's approach would pick that up whereas mine would be waiting for "debris" to load up.................... without the GL would the "noise" of the balls get transmitted? There are good arguments for a multi- pronged approach. I think the FDWLS can be built (DIY) for < 30 dollars.

The last picture shows "The Light You Never Want to See". Unless it is part of your pre-ride check with a push of the PTT (push to test).

Jeremy, no reference is made for the FDWLS to be a "preventative system" for FD failure. It does however give you an early warning and the difference in cost of overhauling a FD that has "failed the crown bearing" vs one that additionally requires R & R of the other 3 bearings plus gear damage is significant". Early detection is key to not only safety but cost. You damage beyond the Crown Bearing and the options narrow. Last time I checked a new FD was 1200 dollars plus labor. Catch it early and most any shop can change a crown bearing which would at least get you home. You do carry a spare crown bearing plus seal, right?!
 

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Looking at your picture got me to thinking and looking around the net for possible answers. I found a useful site that had some things to say.

http://machinerylubrication.com/article_detail.asp?articleid=664&relatedbookgroup=Lubrication

Even when operating correctly, rolling element bearings will eventually fail as a result of a surface fatigue phenomenon. Rolling element bearing surface fatigue is characterized by spalling. It starts after some variable time of service as embryonic particles that are liberated from the surface of a race or rolling element in the load zone. Surface fatigue leaves craters that act as stress concentration sites. Subsequent contacts at those sites cause progression of the spalling process.

The duration of satisfactory performance depends largely on the durability of bearing surfaces. Generally, there are three types of surface contact damage that can occur under proper operational conditions: surface distress, fatigue pitting, and fatigue spalling. Other surface damage can occur due to improper mounting or improper operating conditions. Spalling leaves deeper cavities at contact surfaces with a depth of 20 µm to 100 µm as shown in Figure 2. It must be noted here that no common definitions have been established to distinguish spalling from pitting in the literature. In most of the literature, spalling and pitting have been used indiscriminately, and in some other literature, spalling and pitting were used to designate different severities of surface contact fatigue. For instance, Tallian defined “spalling” as macroscale contact fatigue caused by fatigue crack propagation and reserved “pitting” as surface damage caused by sources other than crack propagation.

One of the reasons for the confusing definitions is probably due to the fact that the physical causes of pitting and spalling have not yet been established. To discuss spalling and pitting on a common ground, the following discussion rests on the definitions according to the phenomena as described in the foregoing; that is, pitting is the formation of shallow craters by surface-defect fatigue, and spalling is the formation of deeper cavities by subsurface-defect fatigue.

By thier descriptions it just may be that BMW used a bearing size too small for the task asked of it. If this is true then there really is no answer to preventing failure (short of a redesigned FD housing), it is GOING to happen, the only question is when and where.

This seems to be the best description of the FD bearing failures
Bearing Fatigue: Fatigue means the fatiguing of the metal in the components of the bearing. It is a result of stress reversals produced when rotating members create flexing of the metal. Fatigue develops due to the magnitude of the load and the number of times it is repeated. Actually, the rolling elements create a wave of metal in front of them as they roll. Thus, the metal in the components is alternately put in tension and then compression. This action eventually results in flaking of the metal.

So, in leiu of ultra sensitive, descriminating sound pickups, your "light" is probably the best way to warn of an impending failure.
And I don't buy into the "I'll spend all of my time looking for the light" argument. All modern aircraft have a multitude of warning lights and messages they COULD present to the pilot but does he worry about "what light/message is going to come up" and get distracted from flying the plane? Doubtful.
 

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We currently use what we call "chip detectors" on out helicopters to get a warning light if there is metal in the oil of an engine or gearbox. It is a much simpler thing that what you have developed in that it is just a magnetic drain plug that has current running to it. When a piece of metal large enough is attracted to the magnetic and completes the circuit...it turns a light on in the cockpit.


Here are the drawbacks:

1-Slug, such as normally found on the drain plug would give you a false positive. Yes it happens to us also.

2-Some metal particles are too large and can not get to the drain plug. Example, we had a tooth from a ring gear in a main transmission of a Hughes 500 that broke off. The knocking sound in that case was our only indication.

Actually the current helicopter that I am flying has not got chip detectors on either of the 2 tail rotor gear boxes.

A lot of helicopters have a Chip Zapper that will actually burn through any real fine metallic slivers . It is used to check for false positives before making a precautionary landing.

Just my 2 cents ,

Ron
 

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My FD failure was found at the very early stage. I found it when changing fd oil, which I was taught to do at each 6K oil change. This decision saved me a ton of money, as the warrenty expired about a week before the failure was discovered. I had just returned from a "Bunburner 1500" with a friend. Steve asked if I would teach him how to service our bikes. When we droped the fd oil, it came out as glitter with small pieces of metal. There was no other sign. I was able to replace just the bearing.
 

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Discussion Starter #15
Nogills2,
Good that you caught yours early. The early "catch" is what this is all about. We have a remotely enabled warning light to do this and very importantly, passively provide that "warning" all the time you are on the m/c. The early discovery is important for safety................ grief and dollars. I am running that system (FDWLS) presently on my K1200LT/sc.

Ron,
Great points. I intend to have a "chip zapper" but not an auto zapper. It will be an add-on and initiated by the rider with a "press to clear fault". Fault clearing in this manner is an easy and often times cure for these early break down slivers.

Morley,
Thanks much for the research................. and the good words. There is a positive synergy from every view and the technical study confirms what so many of us use as guidance. Great one!

One must realize that doing a GL (Gear Lube) change and magnetic plug clean-up probably provides 300 miles of peace of mind. IMO it is way < than 1000 miles. The point of no return of running forever (?) and that "run towards destruction" on this crown wheel bearing problem is probably cast in stone for some combinations of load, speed, bumps, 18 of the 19 balls are good, wrong side load (preload shim), outter race insufficiently clamped to preclude fretting, metallurgy incorrect for any and all components and differential expansion for the steel and aluminum used in the FD............. the variables are quite huge.

It would seem that we can work out (multi-pronged perhaps) a method to provide a remote and passive means to warn of an impending failure without spending too much to do so.
 

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Having gone through a FD failure I think this is a great idea. It would help save the cost of replacing all other bearings in the FD if you were alerted early enough that the large crown bearing has gone into failure mode. The bearing starts generating small bits of ball & race in quantity that I believe would be adequate to trigger a detection device like you are developing. I would definitely be a potential customer for one of these systems. This would be great to have the early warning system then you could really justify carrying the replacement bearing with you.
 

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pozo_izquierdo said:
Your system sounds interesting. Which hole would you use for your sensor?
Let's see, I'm tooling along some twisty road, miles from home, when I suddenly feel 'that feeling' of a final drive failure....

I'd place the sensor in the hole that puckers...... :)

(thankfully, no pics attached)
 

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Hey Carl, any update on this project?
 

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Airplane engines have sensors in the oil that detect metal particles might be a good place to start on FD.
 

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Discussion Starter #20
To all interested,

My FDWLS is on and continues to work very well. It will warn of sensor contamination (steel and/or aluminum) as expected. I have added audio warning (90 + decibels if desired).

It certainly raises the bar for "immediate feed back" since it is always collecting the data, so to speak, necessary to switching on the Red Warning Light and now the Aural Warning Siren audio.

And, know that it will function with any gear box that has a removable magnetic drain plug and or a quietzone sump plug.

It is designed simply and with the exception of the drain plug all the parts can be had locally and for not much money. (- 50 dollars)

Hopefully this will help in bringing you up-to-date.
 
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