Hi everyone, Berber here. Born in Nottingham 6/1964. Migrated to Australia with parents and brother in 1968.

I have just become a member and have read some of the posts and found some useful information already. I have a 1990 K100 RT Ex-Police bike which I've owned since 7/2002. I ride my bike to and from work five days a week. A round trip of about 65 Km on mostly main roads with 100 Kph speed limits. One night, a few years ago, I was on my way home and I went to take off from the traffic light. There was a horrible sound and the bike just sat there with no drive and the engine reving. My first thought was that the clutch had failed as there was a grinding sound which seemed to be comming from the bell housing area. Funny how sound can travel. It turned out to be a failed spline joint where the drive shaft meets the final drive unit, a common failure from what I have read. I had a mechanic look at it and was offered three choices. 1/ He would buy it off me for $500 to strip for parts. What!! No way mate!! 2/ I could pay around $1800 for new parts plus his labour to fit them. Again not an option, didn't have the funds. 3/ Fit used parts from a bike he had stripped earlier for $700 plus labour. Now we had a winner so gave the go ahead. I have to say that I've had my money's worth out of those used parts so I can't complain.

Ok, so I've given you some history, now I have a question about a problem that started earlier this week. After riding to work I got off the bike and happened to look down to see a wet patch on the rear wheel. On closer inspection I found oil had leaked out of the final drive through the vent and was also running onto the wheel and tyre. This just happened suddenly, it was fine after riding home the day before. For those of you thinking it, no I hadn't recently serviced the final drive and over filled it with oil. It has been a while since I have done anything to the final drive. So can anyone tell me what fault or failure this kind of leak could indicate please?

Thanks in advance and cheers, Berber.

Hi Berber,
I suggest you open up the fill plug and take a look at the oil level is it higher or lower than you set it to when you serviced it. We know you have lost oil out the vent so is that because water has entered and pushed the level up because oil floats on water. What does the oil look like when you drain it is it contaminated with water?
Regards,
K-BIKE

Hi K-BIKE,

When I opened the filler plug the oil level was up to the bottom of the thread as it should be. The bike hadn't been ridden for a few days and was on the centre stand and cold when I looked. The oil is due to be renewed but I can't tell if water is mixed in with it. Last time it was renewed it was done by a mechanic during a major service so I can't say if it was over filled or not. I haven't had a chance to realy look at the colour or condition of the oil yet. I am yet to drain the oil to see if water comes out with it. I don't realy think that water ingress is the cause as the last time I rode in the rain was a few weeks ago. I am a fair weather rider and tend to drive my car when it looks like raining and only ride in the rain when I get caught out. Riding in the rain has never been a problem in the past however when the bike was my only mode of transport. I have ridden in some very heavy downpours where water is a few inches deep over the road and have never experienced water ingress into the final drive. Don't get me wrong, I appreciate your suggestion, and can't definately rule it out as a possible cause. I guess if I were to drain the final drive and top it up with new oil to the bottom of the thread and it doesn't leak then problem solved. But what if it continues to leak out of the vent? Is it possible for oil to flow from somewhere else, through the drive shaft, into the final drive and thus overfill it and cause it to leak? I can't see that happening.

Thanks again for your response,
Berber

Berber wrote:Hi everyone, Berber here. Born in Nottingham 6/1964. Migrated to Australia with parents and brother in 1968.

Bit you by one year, I arrived in 1967 BTW is that the Movember look of a permanent fixture.

I have just become a member and have read some of the posts and found some useful information already... I had a mechanic look at it and was offered three choices. 1/ He would buy it off me for $500 to strip for parts. What!! No way mate!! 2/ I could pay around $1800 for new parts plus his labour to fit them. Again not an option, didn't have the funds. 3/ Fit used parts from a bike he had stripped earlier for $700 plus labour. Now we had a winner so gave the go ahead. I have to say that I've had my money's worth out of those used parts so I can't complain.

Welcome. One idea is to look for an auction and get a bike which is a write off for about $500. I let one slip in Sydney about a year ago... it went for $460 ... it had to be delivered in bits on a pallet. Do it your self is my moto,that is why I have two bikes...just in case one is not working ... that is my excuse anyway.
Good place to look is here: http://www.manheimfowles.com.au/?gclid=CLzWm9mhsKUCFQvbbgod7Q2p_g

... I have a question about a problem that started earlier this week. ...For those of you thinking it, no I hadn't recently serviced the final drive and over filled it with oil. It has been a while since I have done anything to the final drive. So can anyone tell me what fault or failure this kind of leak could indicate please?

Final drive?... I see no way for the oil to suddenly materialise from nowhere. KB suggests to check the oil level and that is sensible. I would just dump the oil (5 min) inspect for water etc, check the volume, remove the vent cover and check, remove the speedo sensor and renew the O ring.

BTW Have you removed the final drive before. It may be worth the look to see the thing from the spline end of things, and yes, it is a good chance to lube it. It should not take more than a few hours.

Are you sure of the location of the leak? I had a leak from the rubber boot that goes over the clutch lever/pushrod because it was torn. Can be tough to see the tear until it's removed.

Hi there.
Are yu shure that is final drive oil, gear oil has a peculiar odor and the chances of a leak by the breather are no very hig. Ill sugest that you check the speed sensor can cause and small spill wen the oring fails and the rear shock, this one creates a notable splil wen the seal fails.
Best regards
JAP

I've a brother just up the road from you in Logan Village. I'm on the southern end of the Gold Coast. I ride right through Beenleigh and then along Wuraga to Hein roads to get there. That's a good little motorbike road when the coppers aren't patrolling it.

I'd drain off the old oil, check it for water, then refill it to the proper level using hypoid API class GL5, which is 260cc (.46 Imperial pints). I never just fill to the bottom of the threads, as some suggest. Overfilling even slightly builds pressure and forces oil out the easiest way it can find. It could just be the large o-ring or seal that's begun to weep. They do that now and again. Check the crush washer at the drain plug too.

I have not heard of this before (but who am I??). I would have a good look at your rear shock, see if it leaks (as that would leak onto the top of the FD).

Yep, I'm with ReneZ on this one, I had the same thing happen a couple of years back. I discovered the oil on the rear rim and on closer inspection it was found to be from the (original) rear shock. I replaced the shock with a Hagon unit from Darrel Groat (google Moose Racing). It seems to work fine for me, and we do a lot of 2-up touring fully loaded.

Hope this helps,
Dennis

Hi everyone,

Thanks for your responses, much appreciated.

Just want to answer your questions and reply to your suggestions.

Ned, yes the facial hair is pretty much a permanent fixture. Every now and then I go crazy and shave till all I have is eyebrows and start all over again. The pic is a few years old and I've gone greyer and whiter since. Also I have let it grow till I'm almost ready to give Santa a run for his money. I have been thinking of buying a "parts bike" for some time, great minds think alike. Yep, DIY is my way too, as much as I can with the tools I have. Thanks for the link too. Its a pitty oil doesn't "suddenly materialise from nowhere" as we would all be rich. Checked the vent cover, it seems ok to me. After cleaning the bike down and another ride more oil has leaked out but this time I think it is comming from the speedo sensor, so my first plan of attack is to replace the o-ring. If that doesn't fix it I will try other suggestions next month when I am on holidays.

I haven't pulled the FD off before, I got the mechanic to do all that last time it had a major service. I have been a DIY mechanic for some time now and have a workshop manual and advice from this and other forums to refer to so I am confident that I can do it. I will probably pull the FD off when on holidays and lube the spline and renew the oil too as it is due for it anyways.

As for water being the culprit, no offence but I very much doubt it. I have been through some pretty heavy rain and on roads with a sheet of water over them with no problems before. In all the years I have owned the bike, since 2002, no significant amount of water has ever entered the FD, except maybe condensation. I have the later version of the vent cap fitted to my FD which makes it very unlikely that water will enter. Unless you ride in water deeper than the vent I guess, which I haven't.

The "large o-ring or seal" which may be weeping? I think you are talking about the o-ring between the housing and housing cover. I don't think that is happening, but I am not going to rule it out either. Thanks for the suggestion. After cleaning all the oil away and going for a ride more oil has leaked out. On inspection the most oily area was around the speedo sensor and oil had run down the FD and onto the wheel. From this latest observation I have changed my opinion to the most likely cause being a leaking speedo sensor o-ring. My thoughts are that when I first noticed the leak oil may have blown, or was flung, up to and around the vent area which made it look like this was where it was leaking from.

I repalced the rear shockie a couple of years ago so I have ruled out this as the source of the leak. I remember how the damper oil was dripping off the lower mount. The lower mount is dry and there is no degradation of the ride comfort that was obvious when the original shockie failed. The replacement shockie is in perfect working order, but thanks for the suggestion all the same.

There is no evidence of an oil leak at the clutch lever area. The only fresh oily areas are the FD and rear wheel. There is no trail of oil leading from the clutch area back to the FD. Thanks for the suggestion though.

Thanks again and cheers,
Berber

Hey Berber, I could give you a hand with your FD spline lube if you want, but I'm limited to Saturday and Sundays only (family stuff permitting).

I have known of people water blasting their final drive and getting water in the unit, in fact I recall several instances of that happening over the years the mix looks like a milk shake. Common sense would make one think keep the blaster away from the vent, but that's the problem with common sense it is not that common sadly. Good to know you have localised it.
Regards,
K-BIKE

Hi again one and all,

First of all thanks heaps to blakey for his very kind offer to help me with the FD spline lube. Oh and blakey, my name is Neil too, you are a champion. How can I contact you when the time comes?

K-BIKE, you can't teach someone common sense, they have to learn it through their own experiences, or not. The difference between a smart person and a fool is not whether they make mistakes or not. It is whether or not they learn from them.

When I get a new o-ring and get a chance to fit it and test ride the bike I will let you all know how it went. Lets hope that is all it takes.

Cheers, Berber

Neil, click on my name (on the right of the screen) and you will be taken to my profile.

Look for the heading CONTACT USER BLAKEY and just under that you will see that you can send me an email.

Champion is a bit much...hero sounds better

Hi again y'all,

I have good news and bad news.

The good news is that I seem to have stopped the oil leak. I am being conservative by saying "seem" as I wont be convinced till I have ridden the bike to work and back a few times without it leaking. But after a reasonable test ride on Sunday night I saw no evidence of a leak, and there was much rejoicing!!

The bad news is that when I contacted The BM Shop to see if they had a new speedo sensor o-ring they couldn't help me. I was told that there was no listing for the o-ring. The only listing was for the speedo sensor complete with o-ring. It would seem that BMW want us to spend around $150, based on what it cost me to replace a faulty sensor a few years ago, on a complete unit just to replace a failed o-ring. Pretty expensive o-ring don't you think?

Ok so how did I get around buying a new speedo sensor to replace the o-ring? Simple, either use a bead of silicon sealant, or do like I did and seal it with the old o-ring still in place with Loctite No.3 Aviation Gasket Sealant. I did this on Saturday and left it to set over night and into Sunday evening before I went for a test ride. Like I said, it worked for that test ride but I'm waiting for a few rides to and from work to see if it fails or not. I guess I could have sourced an o-ring from somewhere but it would have been a pain given the hours I work. It was the mechanic's suggestion to use silicon as there "isn't much pressure in that area". I didn't have any silicon so I used the gasket sealant instead.

So thanks to all of you for your help and regards,
Berber

Item 13 - order number in the list.

If you can take the sensor off, wire and all, and go to your local bearing shop and ask them to find one that fits. They have a huge stock of sizes, but you will need to have your part in hand so that they can take measurements.

2nd option is to go to your friendly car accessory shop and ask them to sell you an o ring from their kit box. Again take your part with you.

I get all my o rings from the bearing shop and I've managed to match even an odd size BMW uses.
At times i had to buy a minimum quantity (usually 10) and pay $5 or so, but that is not too bad for odd sizes.

61 31 1 459 030 is the OEM BMW part number for the final drive speed sensor 'gasket'. It should cost somewhere around $1.50 in the US and Canada and $29.00 in Australia and New Zealand...

Go to this link to see the catalogue image from Real OEM: http://www.realoem.com/bmw/showparts.do?model=0503&mospid=51751&btnr=61_2723&hg=61&fg=33

Hi all,

Rene, a man of few words, but you are correct of course. I've seen it listed on the microfiche since.

Ned, thanks for the ideas. The gasket goo seems to be holding up for the moment but I will be looking for a replacement o-ring to do a proper fix soon.

Two Wheels Better, I've found another web site that has the same type of microfiche images and have started downloading them, there are quite a lot all up. I used to have all of them as jpeg files on my PC but lost them after a hard drive failed. Didn't get around to backing them up.

Rode the bike to work and back Monday with no oil leaks!! I'm not expecting this to last as long as a proper o-ring, but as long as it lasts till I'm on holidays I will be happy.

Cheers, Berber

Hi all,

Hope everyone had a great Christmas. Don't know if anyone is still looking at this thread but I have an update for ya.

Ok, so I've been on holidays for the last two weeks and it has only just stopped raining yesterday. So having said that I haven't been on the bike for just as long and was itching for a ride today. Do you remember I said I used Loctite No.3 to stop the oil leaking from the speedo sensor? Well anyways, it gave up during the ride and I got home to see oil had leaked again. After a long ride at highway speeds it just got too hot and sort of melted. So I can honestly say now, from past experience, that using Loctite No.3 is, at best, a temporary fix to get you out of a slippery situation till you can get a replacement o-ring. Guess what I'm going shopping for today? Sorry, a little tipsy so amusing myself by adding lots of emoticons. Oooh look, a pink !

Cheers all, and Happy New Year. :joker:
Berber

Wishing you all the best mate, getting close to your time now (new year that is!)

Take the inside diameter of the housing and the inside diameter of the groove on the pickup sensor + the width of the groove and go to see anybody selling O'rings. Tell them that this is a static O'ring and they should be able to give you something for about 50 cents.
This should be very easy to fix. I was an hydraulic technician for 4 years, and we always replaced O'rings with generic ones.

G'day everyone,

For those of you who are still watching this thread, Happy New Year!!!

Now for what may be the last of my posts for this thread as the oil leak is fixed. Yes folks, I went all out, spared no expense, and bought a shiny new o-ring the other day. After fitting it I went for a test ride and, what do ya know, no oil leak. Just goes to show, if you wanna fix it right first time you just gotta use the right parts and do it right...the first time.

Cheers,
Berber

I think that we can tag this as "SOLVED"

Hi y'all,

Thanks to everyone who read my original post and offered their advice and help. All the best for the New Year to one and all.

We can indeed tag this as "SOLVED", and there was much rejoicing!

Cheers,
Berber