final drive query/question

[GWC]

Greetings, a strange occurance and hopefully someone may be able to shed some light. I changed all of my oils prior to my vacation. From Ontario Canada to Idaho via US2, return through Canada.

On the return leg, east of Sault Ste Marie Ontario, I pulled over as I felt something strange with the bike. On the centre stand the rear wheel wobbled left to right and the final drive housing was hot.

Once the mechanics opened it up, they informed me there was no oil in the housing. During the trip I checked twice daily visually, no leaks, seepage etc. Has anyone heard of such an occurrance?

[jingdog]

Well think about it. Who changed the FD oil last and how long ago? You maybe? Did you fill it or check it since it was filled? Pretty strange to have no oil with no sign of a leak! Pretty strange to not fill the FD after a change! (and put the plugs back in)
Heres whats happening. There WAS oil in there. Mechanics know BMWs have trouble with FDs. So as not to alienate ANOTHER customer, they made up a big mysterious BS story about there being NO oil! WOOOO! WOOOO! WOOOO! Mysterious! WOOOO! WOOOO WOOOO! No Oil! WE CANT FIGGER IT OUT!

[rbertalotto]

Or someone very simply forgot to put fluid in the FD the last time it was changed.

I'm not sure how far you could get with no oil at all..........But if it wasn't leaking, it can't simply disappear.

[GWC]

Thanks for the replies. I knew after I posted this query that one strong viewpoint would be that the final drive did not have any oil put in. I can assure everyone that it was, I am very anal about changing my oils and ensuring the levels are correct.

To balance that viewpoint I would ask if the final drive could go 6933 km without any oil before failing. The shop that I am dealing with is not a BMW dealership and that is for another discussion. Perhaps the oil is in the dry shaft or at the bottom of the boot. I need to go and discuss this with them today.

I realize that the oil cannot just disappear, so yes one can assume that I didn't put any in or it has leaked somewhere...all are reasonable viewpoints.

[flars]

If there is no external sign of a leak, there are only two possibilities:
1. The oil leaked into the swingarm and boot through the pinion seal (this would be a first, I think).
2. No oil in the FD to start with.

[jingdog]

You still have to consider the possibility the shop is making that up. The owner didnt actually see the FD empty. Something is pretty weird here.

[bikerfish1100]

If there is no external sign of a leak, there are only two possibilities:
1. The oil leaked into the swingarm and boot through the pinion seal (this would be a first, I think).
2. No oil in the FD to start with.

1. it is totally normal for oil to leak past the pinion seal and up into the boot (typically, not until 60K+ miles or so). it can't fight gravity tho, and will not (substantially) migrate up into the shaft. Get a few tablespoons of oil in the boot, and it WILL leak out. so, given that there's no sign of leakage, your seal is good.
2. sure sounds like no oil to begin with. if it had been there, it had to go somewhere, and there is absolutely no way that it can evaporate, nor can it exit thru any other fashion without some evidence of its journey.

[GWC]

An update. What the mechanic should have stated was no oil came out. Upon visiting the shop it was noted the large amount of sludge at the bottom of the housing. No doubt that sludge is the oil mixed with the metal that came apart. I believe it is the ball bearing housing and bevel and whatever else that assembly is or more correctly was.

So, no oil really disappeared, it wasn't dry. Poor communication and explanation all around. Bottom line, new fd.

Thanks for the insight, suggestions etc.

G

[jingdog]

Shoot I thought I was on to something big there! Another one for the books.